Skip to main content

Mesenchymal stem cell exosome therapy: current research status in the treatment of neurodegenerative diseases and the possibility of reversing normal brain aging

Abstract

With the exacerbation of the aging population trend, a series of neurodegenerative diseases caused by brain aging have become increasingly common, significantly impacting the daily lives of the elderly and imposing heavier burdens on nations and societies. Brain aging is a complex process involving multiple mechanisms, including oxidative stress, apoptosis of damaged neuronal cells, chronic inflammation, and mitochondrial dysfunction, and research into new therapeutic strategies to delay brain aging has gradually become a research focus in recent years. Mesenchymal stem cells (MSCs) have been widely used in cell therapy due to their functions such as antioxidative stress, anti-inflammation, and tissue regeneration. However, accompanying safety issues such as immune rejection, tumor development, and pulmonary embolism cannot be avoided. Studies have shown that using exosome derived from mesenchymal stem cells (MSC-Exo) for the treatment of neurodegenerative diseases is a safe and effective method. It not only has the therapeutic effects of stem cells but also avoids the risks associated with cell therapy. Therefore, exploring new therapeutic strategies to delay normal brain aging from the mechanism of MSC-Exo in the treatment of neurodegenerative diseases is feasible. This review summarizes the characteristics of MSC-Exo and their clinical progress in the treatment of neurodegenerative diseases, aiming to explore the possibility and potential mechanisms of MSC-Exo in reversing brain aging.

Brain aging is a complex process that occurs at molecular and cellular levels and progresses to changes in organ function. In healthy adults, as they age, brain aging is manifested as a reduction in overall brain volume (brain atrophy), loss of gray and white matter, an increase in the width and depth of sulci, thinning of the cortex, loss of gyri and enlargement of ventricles. In pathological brain aging, it is characterized by neuronal cell atrophy, dendritic degeneration, demyelination, small vessel disease, slowed metabolism, microglial activation, and the formation of white matter lesions, leading to cognitive deficits and decreased motor performance [1]. These manifestations involve various factors, from cellular and molecular to genetic levels. In 2013, López-Otín’s team proposed nine original hallmarks of aging: genomic instability, telomere attrition, epigenetic alterations, mitochondrial dysfunction, loss of proteostasis, deregulated nutrient sensing, cellular senescence, stem cell exhaustion, and altered intercellular communication [2]. However, due to the complexity of aging mechanisms, a single hallmark template cannot explain the multifactorial nature of aging [3]. Consequently, researchers have explored new hallmarks of aging [4]: impaired autophagy [5], dysregulated microbiome, altered mechanical properties, splicing dysregulation, and chronic inflammation [6], integrating them with the original hallmarks for a more comprehensive understanding of aging mechanisms. Currently, many studies are investigating the links between aging phenotypes and characteristic molecules, seeking new strategies to treat brain aging and related neurodegenerative diseases [7]. Some research suggests that aging is a major risk factor for neurodegenerative diseases [8, 9], which, in turn, accelerate aging mechanisms and cause more pronounced changes in brain structure [1]. This raises the hypothesis: could the mechanistic pathways of neurodegenerative diseases be linked to those of natural brain aging, thereby applying strategies for treating neurodegenerative diseases to reverse brain aging?

In the past, cell therapy involving the direct transplantation of mesenchymal stem cells (MSCs) has made significant progress in combating aging-related conditions, including osteoarthritis (OA) associated with physiological aging [10,11,12], cardiovascular diseases [13, 14], frailty in aging [15, 16], and neurodegenerative diseases [17, 18]. MSC therapies have already carried out clinical trials in various disease fields. However, most MSC therapies have not passed the clinical trials, and only more than 300 clinical trials have been successfully completed. Among them, MSC therapies for only more than ten diseases such as acute myocardial infarction, spinal cord injury, and complex perianal fistulas have been globally approved [19, 20]. Some studies have found significant risks associated with direct transplantation of MSCs, such as significant adverse reactions, clonal chromosomal and genomic instability, and induced thrombus formation [21,22,23]. Besides the issues of safety risks, the possibility of poor treatment quality and efficiency also needs to be considered. Recent studies suggest that in MSC therapy for neurodegenerative diseases, MSCs primarily promote neurovascular regeneration, alleviate neuroinflammation, and modulate immunity through paracrine effects, thus restoring neural networks and improving cognitive function, mediated by exosome (Exo) [24, 25]. In vitro experiments usually use the conditioned medium or supernatant of MSCs (which contains cytokines such as neurotrophic factors, angiogenic factors, anti-inflammatory factors, and immunomodulatory factors secreted by MSCs) to observe the therapeutic effects of MSCs. The expression levels of relevant immune and inflammatory factors or the situations of cell proliferation, movement, and metabolism can be measured to evaluate their curative effects [26].Therefore, exosomes derived from different mesenchymal stem cells (MSC-Exo), which play a primary role, have gradually become a hot topic as an alternative to MSC therapy. Currently, MSC-Exo have shown enormous therapeutic potential as a safer and more efficient cell-free therapy in various aspects of clinical treatment, including cardiovascular diseases [27, 28], liver diseases [29, 30], kidney diseases [31, 32], lung diseases [33, 34]s, and neurological diseases [35, 36]. This review focuses on the research on the treatment of neurodegenerative diseases by exogenous MSC-Exo and their derivative products. However, at present, most studies tend to explore the mechanisms or treatment strategies of MSC-Exo for the symptoms related to brain aging caused by neurodegenerative diseases, while there are relatively few studies on the role of MSC-Exo in delaying physiological brain aging. Based on the fact that there is a correlation between the occurrence and development mechanisms of neurodegenerative diseases and aging, and MSC-Exo has shown great potential in the treatment of neurodegenerative diseases. Therefore, this paper aims to seek the possible correlative mechanisms for reversing physiological brain aging from the mechanisms of MSC-Exo in treating neurodegenerative diseases and explore the possibility of their realization.

Mesenchymal stem cells and their extracellular vesicles

Mesenchymal stem cells are multipotent stem cells originating from the mesoderm, present in various tissues including bone marrow, umbilical cord blood, adipose tissue, and placenta [37]. Since their first isolation from bone marrow in 1968, MSCs have been extensively studied [38]. Due to their strong multipotency and tissue regenerative properties, MSCs hold significant therapeutic potential in regenerative medicine [39]. Current research suggests that many of the therapeutic functions of MSCs are primarily attributed to the paracrine effects mediated by their derived secretory factors, such as tissue regeneration, antioxidative stress, anti-inflammatory, and antitumor effects [40,41,42]. These secretory factors are mainly released in the form of extracellular vesicles (Ev), and evidence has shown that MSC-Evs are crucial mediators of MSC efficacy. Using MSC-Evs can replicate the therapeutic potential of the parent cells and persist for a longer time, even if MSCs are rapidly cleared from the body, thereby demonstrating that MSCs’ therapeutic effects are mediated through EVs [43, 44]. Additionally, since MSC-Evs cannot self-replicate, they can avoid a series of adverse reactions associated with direct MSC cell therapy, including immune rejection, secondary infections, vascular embolism, and tumor proliferation [45].

Evs are primarily divided into three subtypes based on particle size: exosomes (30–200 nm), microvesicles (100–1000 nm), and apoptotic bodies (500–2000 nm). This review mainly focuses on exosomes. MSC-Exo have distinct characteristics and functions [46, 47], but their biogenesis pathways are largely similar. These pathways include early endosome (EE), intraluminal vesicle (ILV), late endosome (LE) and multivesicular body (MVB) formation and release (Fig. 1). The paracrine effects of MSCs are mediated through the release of Evs, which are transported via body fluids to distant sites or remain in the microenvironment. These Evs are then absorbed by target cells through ligand-receptor interactions, phagocytosis, or direct fusion with the plasma membrane, thereby participating in the regulation of target cell functions and signal transduction [48, 49]. Exosomes contain various bioactive molecules, such as proteins, RNA, DNA, and lipids [20]. Numerous neuroprotective factors have been identified within exosomes. For example, the endogenous catalase in MSC-Exos provides neuroprotection by reducing oxidative stress [50].

Fig. 1
figure 1

The biogenesis of exosomes begins with the entry of molecular cargo into the cell, followed by initial sorting in early endosomes. Early endosomes, originating from plasma membrane budding, primarily function in classifying endocytosed cargo: recyclable cargo is returned to the Golgi apparatus or plasma membrane, while non-recyclable cargo progresses to late endosomes. During this process, membrane structures invaginate into the lumen, forming intraluminal vesicles (ILVs) that encapsulate cargo, giving late endosomes a multivesicular body (MVB) morphology. Ultimately, MVBs can either fuse with the plasma membrane to release ILVs as exosomes or fuse with lysosomes, leading to cargo degradation.

Isolation and characterization of MSC-Exo

Given that Exos contain numerous and complex components, efficient, high-purity, and high-quality separation and enrichment methods are particularly important. It is usually obtained by multi-stage centrifugation of the supernatant of MSC conditioned medium (CM) or by directly using a kit for separation. At present, a variety of conditioned media have emerged on the market and are used for MSC-Exo culture separation and clinical transformation of derivative products. Currently, the recognized methods for exosome isolation include differential ultracentrifugation, density gradient ultracentrifugation, ultrafiltration, size exclusion chromatography, antibody affinity capture, precipitation, and microfluidic separation. The most commonly used methods for exosome purification are ultracentrifugation (both differential and density gradient ultracentrifugation). Each of these separation techniques has its advantages and disadvantages, and the appropriate method can be selected based on specific needs and practical conditions [46, 51]. In recent years, many commercial kits for exosome isolation have been introduced. Compared to traditional separation techniques, these kits are less time-consuming, offer higher compatibility and yield, and can be used for various exosome isolation purposes [52].

Based on the physicochemical properties of Exo, characterization is mainly performed using techniques such as mass spectrometry (MS), dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), tunable resistive pulse sensing (TRPS), flow cytometry (FCM), atomic force microscopy (AFM), confocal microscopy, Western blotting, and enzyme-linked immunosorbent assay (ELISA) to assess the size, morphology, and protein enrichment of the isolated Exo [53,54,55]. Exo can be secreted by various cell types, with markers such as CD63, CD9, and CD81. However, MSC-Exo exhibit heterogeneity, with characteristic markers including CD29, CD73, CD90, CD44, and CD105 [56, 57]. Different sources of MSC-Exos show slight variations in component and surface marker expression, but almost all human MSC-Exo contain CD44 and CD105, while CD90 is highly expressed in various mesenchymal stem cells (Fig. 2). Hematopoietic markers CD34 and CD45 have not been detected [46, 51].

Fig. 2
figure 2

Components and characterization of MSC-Exo. Exosomes have intrinsic markers such as CD63, CD9, and CD81. MSC-Exo possess characteristic markers including CD29, CD73, CD90, CD44, and CD105, with CD44 and CD105 being present in nearly all human MSC-Exo. Exosomes are a subset of the parent cell encapsulated by a lipid bilayer, containing specific bioactive molecules derived from the parent cell, such as proteins, RNA (mRNA, miRNA, long non-coding RNA, circular RNA), DNA, lipids, and other molecular components

The biological characteristics of MSC-Exo

Exosomes are extracellular vesicles with an average diameter of approximately 100 nm and a density of 1.13–1.19 g/mL, characterized by a lipid bilayer membrane structure. The lipid bilayer membrane encapsulates the contents of Exo, protecting them from degradation, and its small size allows it to traverse biological barriers [58, 59]. Under the microscope, Exo exhibits a classic cup-shaped structure, while under transmission electron microscopy, it appears spherical in solution [60]. Exosomes are considered a subset of parent cells, carrying specific biologically active molecules derived from the parent cells, whose content and composition depend on the parent cells. However, due to sorting mechanisms, there are significant differences in the content of RNA between Exo and parent cells [60, 61]. These complex biologically active molecules loaded in Exo include proteins, mRNA, miRNA, long non-coding RNA, circular RNA, DNA, lipids, and other molecules (Fig. 2). Exo serves as functional carriers, transferring and releasing these biologically active molecules to participate in intercellular communication and genetic information exchange [62, 63]. Different specific cargoes (functional proteins or mRNA) exert different functions in various diseases and have certain therapeutic effects [64] (Table 1). For example, MSC-Exo alleviate bronchopulmonary dysplasia by releasing the immunomodulatory protein TSG-6 [65]; MSC-Exo, with high C-C motif chemokine receptor-2 (CCR2) expression, acts as a “decoy” by binding C-C motif chemokine ligand 2 (CCL2) to reduce its bioavailability, thereby inhibiting the recruitment and activation of peripheral monocytes/macrophages and alleviating renal ischemia-reperfusion injury in mice.[66]; Adipose-derived stem cells (ASCs) promote angiogenesis by secreting exosomes carrying miR-31 to endothelial cells [67]. Exo originating from Bone Marrow Mesenchymal Stem Cells (BMMSCs) are enriched with Integrin α5 (Itgα5), Neuropilin-1 (NRP1), and associated microRNAs, potentially modulating the synaptic vesicle cycle signaling pathways in AD and thus holding therapeutic promise [68]. Exosomes derived from human umbilical cord mesenchymal stem cells (hUC-MSCs) may modulate the synaptic vesicle cycle signaling pathway associated with AD by targeting protein complex 2 subunit alpha 1 (AP2A1) and adaptor-related protein complex 2 subunit beta 1 (AP2B1), showcasing their therapeutic potential [69]. Exosomes derived from MSCs of different sources have slightly different characteristics and play different essential functions. Therefore, their applications in clinical treatment of neurodegenerative diseases also vary [46, 64].

Table 1 Different cargos found in MSC-Exo and the diseases to be treated

Abundant research has demonstrated that MSC-Exo possess characteristics derived from both MSCs and Exo themselves, including low toxicity, low immunogenicity, low tumorigenicity, long-term circulation, biodegradability, sustained release, tumor homing, tissue-specific homing, high permeability, biocompatibility, biological stability, encapsulation of endogenous biologically active molecules, and the ability to cross the blood-brain barrier (BBB) [51, 83, 84]. These properties lay the foundation for the clinical treatment of various systemic diseases with MSC-Exo and further expand their therapeutic potential. Compared to MSC cell therapy, nanoscale-sized Exo can avoid entrapment in the pulmonary capillary bed, reducing loss and risk, and after reaching the target organ, they are lodged in the small capillaries with high efficiency [85, 86]. Meanwhile, in comparison with MSC, MSC-Exo are unable to differentiate and express potentially immunogenic differentiation antigens. They possess lower biocompatibility and immunogenicity, and it is also safer to carry out modifications on them [20]. Furthermore, reducing their immunogenicity and biocompatibility has become a modification strategy, typically achieved through changes in culture conditions, engineering, selective packaging, pre-processing, etc [85]. Given the safety, circulatory stability, and targeting capability of MSC-Exo, they can serve as natural carriers for delivering drugs to treat neurological diseases. However, to meet the requirements of precision medicine, it is necessary to functionalize MSC-Exo, for example, by modifying the surface proteins of Exo or directly modifying parent cells to enhance their targeting and homing abilities, increase the half-life in circulation, and maximize the targeting of drugs to lesions [87, 88]. Through the engineering of exosomes to increase their cargo capacity for specific molecules, the delivery efficiency for therapeutics is thereby enhanced [89, 90]. Additionally, Exo engineering technology is also a direction for expanding their clinical applications, achieved by optimizing separation and acquisition methods or directly engineering artificial Exo to achieve large-scale production while ensuring safety and efficacy [84, 91]. Throughout this process, the pursuit of developing more efficient and accessible characterization techniques to refine the large-scale manufacturing workflow has emerged as a prevalent research approach [92].

Among these properties, the unique property of MSC-Exo to cross the blood-brain barrier and migrate to the brain lesion area provides the possibility for direct treatment of neurological diseases or drug delivery. Regarding the specific mechanism of crossing, existing studies suggest that it may be the brain microvascular endothelial cells (ECs) that internalize and transport Exo across the BBB through endocytosis, only a small portion of exosomes (Exo) cross the blood-brain barrier (BBB) through the paracellular pathway [93](Fig. 3). Although Exo can be uniformly taken up by the brain, the uptake mechanisms of Exo from different sources are diverse and often nonlinear, possibly related to brain-to-blood efflux [94]. Additionally, the complex components in MSC-Exo, such as various proteins, cytokines, and genetic materials, synergistically function through different targeting pathways, which are more efficient compared to single mechanisms [85].

As a treatment tool for clinical precision medicine, the tissue distribution and targeting mechanisms of MSC-Exo are also one of the research focuses. Currently, brain drug delivery methods include intravenous injection, oral administration, stereotactic injection, nasal administration, etc. Different delivery methods have their own advantages and disadvantages in the treatment of brain diseases and also present specific tissue distribution patterns. Most studies use intravenous injection and find that MSC-Exo accumulate most in the heart, liver and spleen [93, 95]. The non-invasive method of intranasal administration allows Exo to bypass the BBB more specifically and effectively deliver to the brain and accumulate in the damaged brain area [96, 97]. However, there are currently no studies directly comparing their biological distribution and efficiency through different administration methods in the same model.

The function and clinical significance of MSC-Exo

Based on the above characteristics, significant progress has been made in research on the treatment of neurodegenerative diseases using MSC-Exo, including studies on mechanistic pathways, analysis of molecular factors, exploration of optimal treatment regimens, gene modification or knockout to alter protein expression, improvement of MSC-Exo packaging, pharmacokinetics, and tissue-specific distribution. MSC-Exo can serve as nanocarriers to deliver drugs or small molecules to improve cognitive deficits in Alzheimer’s disease (AD) [98, 99]. MSC-Exo obtained from connective tissues such as bone marrow and adipose tissue can degrade Aβ peptides inside and outside brain cells or directly interact with Aβ to reduce the accumulation of the main pathogenic factor of AD in brain cells, while also exerting neuroprotective effects [100]. Transferring proteins or genetic materials (such as miRNA) carried by MSC-Exo into neurons to promote neural function recovery can be a potential therapeutic tool for Parkinson’s disease (PD) [101].

Most research results have demonstrated the favorable therapeutic benefits of MSC-Exo and significant post-modification effects [102]. Mechanistic studies on treating AD suggest that MSCs block the damage to neurons caused by soluble amyloid-β oligomers (AβOs) by releasing Exo that upregulate levels of IL-6, IL-10, and VEGF, while releasing catalase to alleviate oxidative stress and protect neurons [103]. A fundamental pathological feature of AD is mitochondrial dysfunction, and dysfunctional mitochondrial autophagy further exacerbates AD by accumulating AβOs. Engineered MSC-Exo with high expression of tyrosine phosphatase-2 (SHP2), can promote mitochondrial autophagy, thereby blocking this critical mechanism of AD [104]. It has been proposed that in the process of AD, the integrity of the BBB is disrupted, which may be a prerequisite for MSCs to enter the brain and exert therapeutic effects [105]. However, under normal intact BBB conditions, MSCs do not directly contact neurons but can still be efficacious, possibly due to MSC paracrine effects and the internalization mechanism of brain microvascular endothelial cells (BMECs), whereby MSCs secrete Exo that can be internalized by BMECs [103] (Fig. 3). This internalization process occurs in both healthy and inflammatory BBB models but only results in specific targeting and long-term accumulation of MSC-Exo, particularly in diseased non-healthy BBB states, such as in brain inflammation pathological areas [93, 106]. Therefore, MSC-Exo can traverse the BBB of normal aging brains, laying the groundwork for studying the reversal of normal brain aging using MSC-Exo.

Fig. 3
figure 3

MSC-Exo cross the blood-brain barrier (BBB) through endocytosis and internalization by brain microvascular endothelial cells (ECs) or via the paracellular pathway. The complex components within MSC-Exo mediate and regulate neuroprotective factors such as pro-inflammatory factors, anti-inflammatory factors, Aβ-degrading enzymes, as well as damaging factors, which target different nerve cells to exert their functions. Consequently, they can reduce Aβ deposition and oxidative stress, regulate neuroinflammatory responses, promote mitochondrial autophagy, and ultimately achieve the effect of treating neurodegenerative diseases

Studies have tracked the distribution of MSC-Exo in various models of neurodegenerative diseases and found that MSC-Exo migrate to inflammatory pathological brain areas and are specifically taken up by neurons, demonstrating the specific targeting homing ability of MSC-Exo, which provides the possibility of loading and delivering targeted drugs to brain lesion areas [106]. Meanwhile, there are studies on modifying MSC-Exo to improve their targeting homing ability. For example, exosomes derived from MSCs pre-treated with iron oxide nanoparticles (IONP) form magnetic nanovesicles (MNV). These can be magnetically guided to ischemic brain regions under an external magnetic field, and they carry a large amount of therapeutic growth factors produced by IONP stimulation. Compared to natural MSC-Exo, they exhibit higher targeting specificity and more significant efficacy [107]. Coupling the cyclic peptide (Arg-Gly-Asp-D-Tyr-Lys) [c(RGDyK)] to the exosome surface allows high-affinity binding to reactive brain vascular endothelial cells containing c(RGDyK) and integrin αvβ3, thereby targeting migration to the ischemic brain region [77]. One characteristic of MSC-Exo is their ability to encapsulate and deliver endogenous bioactive molecules. They contain various miRNAs and cytokines. Inducing the overexpression of one or more miRNAs and targeting their delivery to supplement key miRNAs lacking in diseases has become a current research hotspot. In the treatment of neurodegenerative diseases, overexpressing miR-188-3p in exosomes derived from adipose-derived stem cells (ADSC) targets NALP3 and CDK5 to inhibit autophagy and inflammation in PD model mice [108]. Intravenously infusing Interferon-γ (IFNγ) stimulated MSC-Exo (IFNγ-Exo) into experimental autoimmune encephalomyelitis (EAE) mouse models can reduce neuroinflammation and demyelination by decreasing pro-inflammatory factors, thereby improving the neurological dysfunction of EAE [85].

In terms of the treatment course, considering the relatively short half-life of MSC-Exo, most studies have adopted multiple intravenous injections at the affected sites [109]. The Exo complex after specific packaging has enhanced retention and targeting properties, is less likely to be cleared prematurely, and can reduce the number of injections [110, 111]. In the research on the treatment of Exo from miR-17-92 transfected MSCs in the mouse model of stroke, the researchers adopted the single tail vein injection method. The results indicated that Exo treatment could significantly promote the recovery of neurological function after stroke, and the efficacy of Exo transfected with miR-17-92 was even more remarkable [76]. In a few studies that have entered clinical trials, an ongoing research on the treatment of Alzheimer’s disease with different doses of MSC-Exo adopts the method of multiple intranasal administrations for 12 consecutive weeks [51]. Therefore, there is currently no unified conclusion regarding the dosage, administration method, and treatment course of MSC-Exo. It may still be necessary to conduct further exploration based on different disease models, target organs, administration methods, experimental methods, and differences in Exo products. Some researchers have conducted investigations on this and suggested making judgments based on treatment effects rather than direct quantitative comparisons [112].

In conclusion, the research on cell-free therapy using MSC-Exo in neurodegenerative diseases has become a current hotspot, demonstrating remarkable potential. Therefore, MSC-Exo also have great potential in alleviating debilitation and delaying the aging process by reducing oxidative stress, mitochondrial damage, cell apoptosis, and inflammatory responses, while releasing active substances such as neuroprotective factors [113, 114].

The potential mechanisms of MSC-Exo in neurodegenerative diseases and their association with brain aging

Currently, most research focuses on the therapeutic strategies of MSC-Exo in neurodegenerative diseases and the engineering strategies of MSC-Exo, while there is limited research on reversing normal brain aging with MSC-Exo to extend lifespan and improve quality of life. The studies have shown that EVs isolated from BMMSCs of young mice can reduce the expression of aging markers in naturally aged mice and Ercc1-deficient premature aging mice when administered via intraperitoneal injection, thereby prolonging the healthy lifespan of both naturally aged and premature aging mice. Similarly, EVs derived from human embryonic stem cell-derived mesenchymal stem cells (hESC-MSCs) also exhibit the same function. Meanwhile, the study found that aging can lead to MSC dysfunction, and Ev derived from young MSCs can reverse cellular aging and improve MSC functions, which provides a new idea for the selection of MSC sources [115]. This validates the potential of MSC-Exo in reversing aging, but it focuses on overall survival rates and aging markers rather than changes in brain aging and specific markers. Therefore, it is worth exploring the correlation and potential mechanisms of reversing natural brain aging with MSC-Exo based on the extensive research on MSC-Exo therapy for neurodegenerative diseases. Furthermore, another research strategy is to explore the mechanisms or methods of neuroprotection by MSC-Exo in neurodegenerative disease models. In the treatment of neurodegenerative diseases associated with astrocyte changes, MSC-Exo improves reactive astrogliosis, alleviates neuroinflammatory responses, regulates abnormal calcium signal transduction and mitochondrial dysfunction, and further restores learning and memory impairments caused by neuronal damage. It is suggested that the Nrf2 and NF-κB signaling pathway may be a potential mechanism of action [116]. Nrf2 is one of the key pathways in aging and neurodegenerative diseases, and it is also one of the targeted targets for the treatment of neurodegenerative diseases and the delay of aging based on antioxidant stress and neuroinflammation [117]. MSC-Exo is endowed with miRNA, inflammatory factors, and antioxidant factors. By activating the Nrf2 and NF-κB signaling pathway, it augments the anti-inflammatory and antioxidant capacities(Fig. 4), thereby playing crucial roles in protecting neurons, retarding aging, and treating neurodegenerative diseases [118, 119]. Additionally, microglia polarization induced by MSC-Exo from an inflammatory M1 phenotype to an immunosuppressive M2 phenotype leads to increased expression of related Aβ-degrading enzymes [such as neprilysin (NEP) and insulin-degrading enzyme (IDE)] and anti-inflammatory cytokines (such as IL-10 and TGF-β), and decreased expression of inflammatory cytokines (such as TNF-α, IL-18, IL-6, IL-12, IL-1β), thereby reducing inflammation and Aβ deposition [120]. In neurodegenerative diseases with vascular changes, MSC-Exo can promote angiogenesis [121, 122]. In summary, the mechanisms of neuroprotection by MSC-Exo can be summarized as inhibiting pathological processes and promoting regeneration. The former includes reducing damaged neurons, anti-apoptosis, immunomodulation, and reducing oxidative stress, while the latter includes promoting neurovascular regeneration and restoring the integrity of BBB, thereby improving motor, learning, and memory impairments caused by neurodegeneration [45, 123]. Combined with the research on aging mechanisms mentioned earlier, it can be observed that there is a high degree of overlap and correlation between the mechanisms of aging and the neuroprotective mechanisms of MSC-Exo in neurodegenerative disease models, indicating the enormous potential of applying MSC-Exo to reverse brain aging, but further research is still needed for validation.

Fig. 4
figure 4

MSC-Exo carry microRNAs (miRNAs), inflammatory factors and antioxidant factors. By activating the Nrf2 (up-regulation and nuclear translocation of Nrf2) and NF-κB (activation and translocation of NF-κB) signaling pathways, they enhance the anti-inflammatory and antioxidant capacities, thus playing a role in protecting neurons, delaying aging and treating neurodegenerative diseases

Summary and Outlook

MSC-Exo, as a cell-free therapy alternative to MSCs, has shown great potential in neurodegenerative diseases, not only possessing the functions of parent cells but also avoiding the risks associated with MSC cell therapy. The multiple neuroprotective mechanisms of MSC-Exo hold promising prospects for reversing brain aging, offering hope for prolonging lifespan, delaying aging, improving inconvenience caused by neurodegeneration, and enhancing the quality of life for the elderly, further providing significant benefits to society in alleviating population aging.

Although the therapeutic effects of MSC-Exo in neurodegenerative diseases and even normal aging models have been validated, most studies are still at the stage of animal experiments, with many limitations and uncertainties in clinical trials. The treatment duration and follow-up period in most studies are not long. Depending on the size of the experimental animals and the type of diseases, the follow-up period of most preclinical trials usually ranges from one week to one month. There are also studies with a follow-up period of less than one week or as long as one year [53]. Only a few studies have entered clinical trials and proved its safety. However, the limitation of this study lies in the relatively small sample size [124]. Meanwhile, before the large-scale production or clinical translation of MSC-Exo, there are also no small challenges.

Firstly, there is a lack of standardized protocols and quality control regarding the characterization, quantity, size, purity, content, and drug delivery of MSC-Exo treatment. Variability may exist during large-scale production, leading to batch differences and non-reproducibility. Some researchers have successively proposed methods for the large-scale production of MSC and MSC-Exo that comply with GMP. The standardized protocols and corresponding supervision mechanisms will also be increasingly improved [125]. Before Exo - therapy is approved, a series of rapid, strict, and cost - effective methods can also be used for its quality control. Especially during large - scale production, these methods can serve as an alternative to animal testing and include fingerprint identification detection, potency determination, mechanism testing, and safety testing [126, 127]. Secondly, there is still a deficiency in the large - scale isolation and target - tracking of MSC-Exo. However, more and more markers are emerging, and many researchers and institutions are working on the development of high - yield and high - performance Exo isolation methods or reagent kits [125]. Finally, the issue of safety is an inescapable key point in clinical trials. During the treatment process, repeated administrations are required to determine the optimal clinical dose and treatment course, and it must be ensured that there are no biotoxicity and other risks in this process. However, relevant studies on MSC-Exo therapy have indicated that its short-term safety is good, and no safety risks such as tumorigenicity, immunogenicity, and gene mutations related to the parental cells (MSC) have been found yet [12, 128].

In addition, many studies have currently proven the short-term safety of MSC-Exo therapy, but there are relatively few studies and discussions on long-term safety and ethical issues [127]. Of course, it is a necessary process for researchers to conduct risk assessments, including short-term risks and long-term risks, namely the immune responses caused by allogeneic infusion and multiple injections, as well as the potential risks of epigenetic modifications to the host cells due to long-term use [126]. Therefore, if MSC-Exo is to truly become a safer and more efficient clinical diagnosis and treatment tool, it still requires in-depth research by expert researchers in this field over a long period of time to identify and solve many potential problems.

Data availability

Not applicable.

Abbreviations

MSC:

Mesenchymal stem cell

Exo:

Exosome

OA:

Osteoarthritis

EV:

Extracellular vesicle

EE:

Early endosome

ILV:

Intraluminal vesicle

LE:

Late endosome

MVB:

Multivesicular body

MS:

Mass spectrometry

DLS:

Dynamic light scattering

NTA:

Nanoparticle tracking analysis

TEM:

Transmission electron microscopy

TRPS:

Tunable resistive pulse sensing

FCM:

Flow cytometry

AFM:

Atomic force microscopy

ELISA:

Enzyme-linked immunosorbent assay

CM:

Conditioned medium

CCR2:

C-C motif chemokine receptor-2

CCL2:

C-C motif chemokine ligand 2

ASCs:

Adipose-derived stem cells

BMMSCs:

Bone Marrow Mesenchymal Stem Cells

Itgα5:

Integrin α5

NRP1:

Neuropilin-1

AP2A1:

Protein complex 2 subunit alpha 1

AP2B1:

Adaptor-related protein complex 2 subunit beta 1

BBB:

Blood–brain barrier

ECs:

Endothelial cells

AD:

Alzheimer’s disease

PD:

Parkinson’s disease

AβOs:

Amyloid-β oligomers

SHP2:

Tyrosine phosphatase-2

BMECs:

Brain microvascular endothelial cells

IONP:

Iron oxide nanoparticles

MNV:

Magnetic nanovesicles

c(RGDyK):

Arg-Gly-Asp-D-Tyr-Lys

ADSC:

Adipose-derived stem cells

IFNγ:

Interferon-γ

EAE:

Experimental autoimmune encephalomyelitis

hESC-MSCs:

Human embryonic stem cell-derived mesenchymal stem cells

NEP:

Neprilysin

IDE:

Insulin-degrading enzyme

References

  1. Blinkouskaya Y, Caçoilo A, Gollamudi T, Jalalian S, Weickenmeier J. Brain aging mechanisms with mechanical manifestations. Mech Ageing Dev. 2021;200:111575.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  2. López-Otín C, Blasco MA, Partridge L, Serrano M, Kroemer G. The hallmarks of aging. Cell. 2013;153(6):1194–217.

    Article  PubMed  PubMed Central  Google Scholar 

  3. Gems D, de Magalhães JP. The hoverfly and the wasp: a critique of the hallmarks of aging as a paradigm. Ageing Res Rev. 2021;70:101407.

    Article  PubMed  PubMed Central  Google Scholar 

  4. Schmauck-Medina T, Molière A, Lautrup S, Zhang J, Chlopicki S, Madsen HB, et al. New hallmarks of ageing: a 2022 Copenhagen ageing meeting summary. Aging. 2022;14(16):6829–39.

    Article  PubMed  PubMed Central  Google Scholar 

  5. Wong SQ, Kumar AV, Mills J, Lapierre LR. Autophagy in aging and longevity. Hum Genet. 2020;139(3):277–90.

    Article  PubMed  Google Scholar 

  6. Ferrucci L, Fabbri E. Inflammageing: chronic inflammation in ageing, cardiovascular disease, and frailty. Nat Rev Cardiol. 2018;15(9):505–22.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  7. Lupo G, Gaetani S, Cacci E, Biagioni S, Negri R. Molecular signatures of the aging brain: finding the links between genes and phenotypes. Neurotherapeutics. 2019;16(3):543–53.

    Article  PubMed  PubMed Central  Google Scholar 

  8. Rim C, You MJ, Nahm M, Kwon MS. Emerging role of senescent microglia in brain aging-related neurodegenerative diseases. Transl Neurodegener. 2024;13(1):10.

    Article  PubMed  PubMed Central  Google Scholar 

  9. Zhang W, Chen T, Zhao H, Ren S. Glycosylation in aging and neurodegenerative diseases. Acta Biochim Biophys Sin (Shanghai). 2024;56(8):1208–20.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  10. Matas J, Orrego M, Amenabar D, Infante C, Tapia-Limonchi R, Cadiz MI, et al. Umbilical cord-derived mesenchymal stromal cells (MSCs) for knee osteoarthritis: repeated MSC Dosing is Superior to a single MSC dose and to Hyaluronic Acid in a controlled Randomized Phase I/II Trial. Stem Cells Transl Med. 2019;8(3):215–24.

    Article  CAS  PubMed  Google Scholar 

  11. Chahal J, Gómez-Aristizábal A, Shestopaloff K, Bhatt S, Chaboureau A, Fazio A, et al. Bone marrow mesenchymal stromal cell treatment in patients with Osteoarthritis results in overall improvement in Pain and symptoms and reduces synovial inflammation. Stem Cells Transl Med. 2019;8(8):746–57.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  12. Matas J, García C, Poblete D, Vernal R, Ortloff A, Luque-Campos N, et al. A phase I dose-escalation clinical trial to assess the safety and efficacy of umbilical cord-derived mesenchymal stromal cells in knee osteoarthritis. Stem Cells Transl Med. 2024;13(3):193–203.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  13. Bolli R, Mitrani RD, Hare JM, Pepine CJ, Perin EC, Willerson JT, et al. A phase II study of autologous mesenchymal stromal cells and c-kit positive cardiac cells, alone or in combination, in patients with ischaemic heart failure: the CCTRN CONCERT-HF trial. Eur J Heart Fail. 2021;23(4):661–74.

    Article  CAS  PubMed  Google Scholar 

  14. Tompkins BA, Balkan W, Winkler J, Gyöngyösi M, Goliasch G, Fernández-Avilés F, et al. Preclinical studies of Stem Cell Therapy for Heart Disease. Circ Res. 2018;122(7):1006–20.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  15. Golpanian S, DiFede DL, Khan A, Schulman IH, Landin AM, Tompkins BA, et al. Allogeneic human mesenchymal stem cell infusions for aging Frailty. J Gerontol Biol Sci Med Sci. 2017;72(11):1505–12.

    Article  CAS  Google Scholar 

  16. Tompkins BA, DiFede DL, Khan A, Landin AM, Schulman IH, Pujol MV, et al. Allogeneic mesenchymal stem cells ameliorate aging Frailty: a phase II randomized, Double-Blind, placebo-controlled clinical trial. J Gerontol Biol Sci Med Sci. 2017;72(11):1513–22.

    Article  CAS  Google Scholar 

  17. Lo Furno D, Mannino G, Giuffrida R. Functional role of mesenchymal stem cells in the treatment of chronic neurodegenerative diseases. J Cell Physiol. 2018;233(5):3982–99.

    Article  CAS  PubMed  Google Scholar 

  18. Zhang X, Kuang Q, Xu J, Lin Q, Chi H, Yu D. MSC-Based cell therapy in neurological diseases: a concise review of the literature in pre-clinical and clinical research. Biomolecules. 2024;14(5).

  19. Levy O, Kuai R, Siren EMJ, Bhere D, Milton Y, Nissar N, et al. Shattering barriers toward clinically meaningful MSC therapies. Sci Adv. 2020;6(30):eaba6884.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  20. Tan TT, Toh WS, Lai RC, Lim SK. Practical considerations in transforming MSC therapy for neurological diseases from cell to EV. Exp Neurol. 2022;349:113953.

    Article  CAS  PubMed  Google Scholar 

  21. Li C, Zhao H, Cheng L, Wang B. Allogeneic vs. autologous mesenchymal stem/stromal cells in their medication practice. Cell Biosci. 2021;11(1):187.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  22. Nikitina V, Astrelina T, Nugis V, Ostashkin A, Karaseva T, Dobrovolskaya E, et al. Clonal chromosomal and genomic instability during human multipotent mesenchymal stromal cells long-term culture. PLoS ONE. 2018;13(2):e0192445.

    Article  PubMed  PubMed Central  Google Scholar 

  23. Coppin L, Sokal E, Stéphenne X. Thrombogenic Risk Induced by Intravascular mesenchymal stem cell therapy: current status and future perspectives. Cells. 2019;8(10).

  24. Duncan T, Valenzuela M. Alzheimer’s disease, dementia, and stem cell therapy. Stem Cell Res Ther. 2017;8(1):111.

    Article  PubMed  PubMed Central  Google Scholar 

  25. Tashima T. Mesenchymal stem cell (MSC)-Based drug delivery into the brain across the blood-brain barrier. Pharmaceutics. 2024;16(2).

  26. Delfi I, Wood CR, Johnson LDV, Snow MD, Innes JF, Myint P et al. An in Vitro comparison of the neurotrophic and angiogenic activity of human and canine adipose-derived mesenchymal stem cells (MSCs): translating MSC-Based therapies for spinal cord Injury. Biomolecules. 2020;10(9).

  27. Feng Y, Bao X, Zhao J, Kang L, Sun X, Xu B. MSC-Derived Exosomes Mitigate Myocardial Ischemia/Reperfusion Injury by reducing Neutrophil Infiltration and the formation of Neutrophil Extracellular traps. Int J Nanomed. 2024;19:2071–90.

    Article  Google Scholar 

  28. Gong ZT, Xiong YY, Ning Y, Tang RJ, Xu JY, Jiang WY, et al. Nicorandil-pretreated mesenchymal stem cell-derived exosomes facilitate Cardiac Repair after myocardial infarction via promoting macrophage M2 polarization by targeting miR-125a-5p/TRAF6/IRF5 signaling pathway. Int J Nanomed. 2024;19:2005–24.

    Article  Google Scholar 

  29. Chen W, Lin F, Feng X, Yao Q, Yu Y, Gao F, et al. MSC-derived exosomes attenuate hepatic fibrosis in primary sclerosing cholangitis through inhibition of Th17 differentiation. Asian J Pharm Sci. 2024;19(1):100889.

    PubMed  PubMed Central  Google Scholar 

  30. Pei L, Li R, Wang X, Xu D, Gong F, Chen W, et al. MSCs-derived extracellular vesicles alleviate sepsis-associated liver dysfunction by inhibiting macrophage glycolysis-mediated inflammatory response. Int Immunopharmacol. 2024;128:111575.

    Article  CAS  PubMed  Google Scholar 

  31. Liu Y, Cui J, Wang H, Hezam K, Zhao X, Huang H, et al. Enhanced therapeutic effects of MSC-derived extracellular vesicles with an injectable collagen matrix for experimental acute kidney injury treatment. Stem Cell Res Ther. 2020;11(1):161.

    Article  PubMed  PubMed Central  Google Scholar 

  32. Chen L, Wang Y, Li S, Zuo B, Zhang X, Wang F, et al. Exosomes derived from GDNF-modified human adipose mesenchymal stem cells ameliorate peritubular capillary loss in tubulointerstitial fibrosis by activating the SIRT1/eNOS signaling pathway. Theranostics. 2020;10(20):9425–42.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  33. Ridzuan N, Zakaria N, Widera D, Sheard J, Morimoto M, Kiyokawa H, et al. Human umbilical cord mesenchymal stem cell-derived extracellular vesicles ameliorate airway inflammation in a rat model of chronic obstructive pulmonary disease (COPD). Stem Cell Res Ther. 2021;12(1):54.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  34. Feng Y, Guo K, Jiang J, Lin S. Mesenchymal stem cell-derived exosomes as delivery vehicles for non-coding RNAs in lung diseases. Biomed Pharmacother. 2024;170:116008.

    Article  CAS  PubMed  Google Scholar 

  35. Bodart-Santos V, de Carvalho LRP, de Godoy MA, Batista AF, Saraiva LM, Lima LG, et al. Extracellular vesicles derived from human Wharton’s jelly mesenchymal stem cells protect hippocampal neurons from oxidative stress and synapse damage induced by amyloid-β oligomers. Stem Cell Res Ther. 2019;10(1):332.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  36. Park SY, Kim DS, Kim HM, Lee JK, Hwang DY, Kim TH et al. Human mesenchymal stem cell-derived extracellular vesicles promote neural differentiation of neural progenitor cells. Int J Mol Sci. 2022;23(13).

  37. Andrzejewska A, Lukomska B, Janowski M. Concise Review: mesenchymal stem cells: from roots to Boost. Stem Cells. 2019;37(7):855–64.

    Article  PubMed  Google Scholar 

  38. Friedenstein AJ, Petrakova KV, Kurolesova AI, Frolova GP. Heterotopic of bone marrow. Analysis of precursor cells for osteogenic and hematopoietic tissues. Transplantation. 1968;6(2):230–47.

    Article  CAS  PubMed  Google Scholar 

  39. Ullah M, Liu DD, Thakor AS. Mesenchymal stromal cell homing: mechanisms and strategies for improvement. iScience. 2019;15:421–38.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  40. Fraile M, Eiro N, Costa LA, Martín A, Vizoso FJ. Aging and mesenchymal stem cells: Basic concepts, challenges and strategies. Biology (Basel). 2022;11(11).

  41. Lin L, Huang L, Huang S, Chen W, Huang H, Chi L, et al. MSC-Derived Extracellular vesicles alleviate NLRP3/GSDMD-Mediated neuroinflammation in mouse model of sporadic Alzheimer’s Disease. Mol Neurobiol. 2024;61(8):5494–509.

    Article  CAS  PubMed  Google Scholar 

  42. Huang D, Shen H, Xie F, Hu D, Jin Q, Hu Y, et al. Role of mesenchymal stem cell-derived exosomes in the regeneration of different tissues. J Biol Eng. 2024;18(1):36.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  43. Yin K, Wang S, Zhao RC. Exosomes from mesenchymal stem/stromal cells: a new therapeutic paradigm. Biomark Res. 2019;7:8.

    Article  PubMed  PubMed Central  Google Scholar 

  44. He X, Zhang C, Amirsaadat S, Jalil AT, Kadhim MM, Abasi M, et al. Curcumin-loaded mesenchymal stem cell-derived exosomes efficiently attenuate proliferation and inflammatory response in Rheumatoid Arthritis Fibroblast-Like synoviocytes. Appl Biochem Biotechnol. 2023;195(1):51–67.

    Article  CAS  PubMed  Google Scholar 

  45. Guy R, Offen D. Promising opportunities for treating neurodegenerative diseases with mesenchymal stem cell-derived exosomes. Biomolecules. 2020;10(9).

  46. Tang Y, Zhou Y, Li HJ. Advances in mesenchymal stem cell exosomes: a review. Stem Cell Res Ther. 2021;12(1):71.

    Article  PubMed  PubMed Central  Google Scholar 

  47. Ha DH, Kim HK, Lee J, Kwon HH, Park GH, Yang SH et al. Mesenchymal Stem/Stromal cell-derived exosomes for Immunomodulatory Therapeutics and skin regeneration. Cells. 2020;9(5).

  48. Palmulli R, van Niel G. To be or not to be… secreted as exosomes, a balance finely tuned by the mechanisms of biogenesis. Essays Biochem. 2018;62(2):177–91.

    Article  PubMed  Google Scholar 

  49. Oveili E, Vafaei S, Bazavar H, Eslami Y, Mamaghanizadeh E, Yasamineh S, et al. The potential use of mesenchymal stem cells-derived exosomes as microRNAs delivery systems in different diseases. Cell Commun Signal. 2023;21(1):20.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  50. Haney MJ, Klyachko NL, Zhao Y, Gupta R, Plotnikova EG, He Z, et al. Exosomes as drug delivery vehicles for Parkinson’s disease therapy. J Control Release. 2015;207:18–30.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  51. Yin T, Liu Y, Ji W, Zhuang J, Chen X, Gong B, et al. Engineered mesenchymal stem cell-derived extracellular vesicles: a state-of-the-art multifunctional weapon against Alzheimer’s disease. Theranostics. 2023;13(4):1264–85.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  52. Helwa I, Cai J, Drewry MD, Zimmerman A, Dinkins MB, Khaled ML, et al. A comparative study of serum exosome isolation using Differential Ultracentrifugation and three commercial reagents. PLoS ONE. 2017;12(1):e0170628.

    Article  PubMed  PubMed Central  Google Scholar 

  53. Shekari F, Nazari A, Assar Kashani S, Hajizadeh-Saffar E, Lim R, Baharvand H. Pre-clinical investigation of mesenchymal stromal cell-derived extracellular vesicles: a systematic review. Cytotherapy. 2021;23(4):277–84.

    Article  CAS  PubMed  Google Scholar 

  54. Théry C, Witwer KW, Aikawa E, Alcaraz MJ, Anderson JD, Andriantsitohaina R, et al. Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines. J Extracell Vesicles. 2018;7(1):1535750.

    Article  PubMed  PubMed Central  Google Scholar 

  55. Popovic M, Mazzega E, Toffoletto B, de Marco A. Isolation of anti-extra-cellular vesicle single-domain antibodies by direct panning on vesicle-enriched fractions. Microb Cell Fact. 2018;17(1):6.

    Article  PubMed  PubMed Central  Google Scholar 

  56. Tolomeo AM, Zuccolotto G, Malvicini R, De Lazzari G, Penna A, Franco C et al. Biodistribution of Intratracheal, Intranasal, and intravenous injections of human mesenchymal stromal cell-derived extracellular vesicles in a mouse model for Drug Delivery studies. Pharmaceutics. 2023;15(2).

  57. Sánchez-Abarca TLR, Muntión LI, Preciado S, Puig S, López-Ruano N. MSC surface markers (CD44, CD73, and CD90) can identify human MSC-derived extracellular vesicles by conventional flow cytometry. Cell Commun Signal. 2016;14:2.

    Article  PubMed  PubMed Central  Google Scholar 

  58. Casado-Díaz A, Quesada-Gómez JM, Dorado G. Extracellular vesicles derived from mesenchymal stem cells (MSC) in Regenerative Medicine: applications in skin Wound Healing. Front Bioeng Biotechnol. 2020;8:146.

    Article  PubMed  PubMed Central  Google Scholar 

  59. Jeppesen DK, Fenix AM, Franklin JL, Higginbotham JN, Zhang Q, Zimmerman LJ, et al. Reassessment Exosome Composition Cell. 2019;177(2):428–e4518.

  60. Zhang Y, Liu Y, Liu H, Tang WH. Exosomes: biogenesis, biologic function and clinical potential. Cell Biosci. 2019;9:19.

    Article  PubMed  PubMed Central  Google Scholar 

  61. Hu W, Liu C, Bi ZY, Zhou Q, Zhang H, Li LL, et al. Comprehensive landscape of extracellular vesicle-derived RNAs in cancer initiation, progression, metastasis and cancer immunology. Mol Cancer. 2020;19(1):102.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  62. Zhang H, Freitas D, Kim HS, Fabijanic K, Li Z, Chen H, et al. Identification of distinct nanoparticles and subsets of extracellular vesicles by asymmetric flow field-flow fractionation. Nat Cell Biol. 2018;20(3):332–43.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  63. Xie F, Zhou X, Fang M, Li H, Su P, Tu Y, et al. Extracellular vesicles in Cancer Immune Microenvironment and Cancer Immunotherapy. Adv Sci (Weinh). 2019;6(24):1901779.

    Article  CAS  PubMed  Google Scholar 

  64. Racchetti G, Meldolesi J. Extracellular vesicles of mesenchymal stem cells: therapeutic properties discovered with extraordinary success. Biomedicines. 2021;9(6).

  65. Chaubey S, Thueson S, Ponnalagu D, Alam MA, Gheorghe CP, Aghai Z, et al. Early gestational mesenchymal stem cell secretome attenuates experimental bronchopulmonary dysplasia in part via exosome-associated factor TSG-6. Stem Cell Res Ther. 2018;9(1):173.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  66. Shen B, Liu J, Zhang F, Wang Y, Qin Y, Zhou Z, et al. CCR2 positive exosome released by mesenchymal stem cells suppresses macrophage functions and alleviates Ischemia/Reperfusion-Induced Renal Injury. Stem Cells Int. 2016;2016:1240301.

    Article  PubMed  PubMed Central  Google Scholar 

  67. Kang T, Jones TM, Naddell C, Bacanamwo M, Calvert JW, Thompson WE, et al. Adipose-derived stem cells induce Angiogenesis via Microvesicle Transport of miRNA-31. Stem Cells Transl Med. 2016;5(4):440–50.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  68. Łabędź-Masłowska A, Vergori L, Kędracka-Krok S, Karnas E, Bobis-Wozowicz S, Sekuła-Stryjewska M, et al. Mesenchymal stem cell-derived extracellular vesicles exert pro-angiogenic and pro-lymphangiogenic effects in ischemic tissues by transferring various microRNAs and proteins including ITGa5 and NRP1. J Nanobiotechnol. 2024;22(1):60.

    Article  Google Scholar 

  69. Li S, Zhang J, Liu X, Wang N, Sun L, Liu J, et al. Proteomic characterization of hUC-MSC extracellular vesicles and evaluation of its therapeutic potential to treat Alzheimer’s disease. Sci Rep. 2024;14(1):5959.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  70. Zhu LP, Tian T, Wang JY, He JN, Chen T, Pan M, et al. Hypoxia-elicited mesenchymal stem cell-derived exosomes facilitates cardiac repair through miR-125b-mediated prevention of cell death in myocardial infarction. Theranostics. 2018;8(22):6163–77.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  71. Zhao J, Li X, Hu J, Chen F, Qiao S, Sun X, et al. Mesenchymal stromal cell-derived exosomes attenuate myocardial ischaemia-reperfusion injury through mir-182-regulated macrophage polarization. Cardiovasc Res. 2019;115(7):1205–16.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  72. Song BW, Lee CY, Kim R, Kim WJ, Lee HW, Lee MY, et al. Multiplexed targeting of miRNA-210 in stem cell-derived extracellular vesicles promotes selective regeneration in ischemic hearts. Exp Mol Med. 2021;53(4):695–708.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  73. Nakano M, Kubota K, Kobayashi E, Chikenji TS, Saito Y, Konari N, et al. Bone marrow-derived mesenchymal stem cells improve cognitive impairment in an Alzheimer’s disease model by increasing the expression of microRNA-146a in hippocampus. Sci Rep. 2020;10(1):10772.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  74. Sha S, Shen X, Cao Y, Qu L. Mesenchymal stem cells-derived extracellular vesicles ameliorate Alzheimer’s disease in rat models via the microRNA-29c-3p/BACE1 axis and the Wnt/β-catenin pathway. Aging. 2021;13(11):15285–306.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  75. Jahangard Y, Monfared H, Moradi A, Zare M, Mirnajafi-Zadeh J, Mowla SJ. Therapeutic effects of transplanted exosomes containing miR-29b to a rat model of Alzheimer’s Disease. Front Neurosci. 2020;14:564.

    Article  PubMed  PubMed Central  Google Scholar 

  76. Xin H, Katakowski M, Wang F, Qian JY, Liu XS, Ali MM, et al. MicroRNA cluster mir-17-92 cluster in Exosomes Enhance Neuroplasticity and functional recovery after stroke in rats. Stroke. 2017;48(3):747–53.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  77. Zhang H, Wu J, Wu J, Fan Q, Zhou J, Wu J, et al. Exosome-mediated targeted delivery of miR-210 for angiogenic therapy after cerebral ischemia in mice. J Nanobiotechnol. 2019;17(1):29.

    Article  Google Scholar 

  78. Liu Y, Fu N, Su J, Wang X, Li X. Rapid Enkephalin Delivery using exosomes to promote neurons recovery in ischemic stroke by inhibiting neuronal p53/Caspase-3. Biomed Res Int. 2019;2019:4273290.

    PubMed  PubMed Central  Google Scholar 

  79. Karimian F. An Invited Commentary on the article Feasibility and safety of bisegmentectomy 7–8 while preserving hepatic venous outflow of the right liver - A retrospective cohort study (. Int J Surg. 2020;80:101–2. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/j.ijsu.2020.05.075. available online 6 June 2020.

  80. Rezakhani L, Kelishadrokhi AF, Soleimanizadeh A, Rahmati S. Mesenchymal stem cell (MSC)-derived exosomes as a cell-free therapy for patients infected with COVID-19: real opportunities and range of promises. Chem Phys Lipids. 2021;234:105009.

    Article  CAS  PubMed  Google Scholar 

  81. Chen L, Lu FB, Chen DZ, Wu JL, Hu ED, Xu LM, et al. BMSCs-derived mir-223-containing exosomes contribute to liver protection in experimental autoimmune hepatitis. Mol Immunol. 2018;93:38–46.

    Article  CAS  PubMed  Google Scholar 

  82. Jing L, Hua X, Yuanna D, Rukun Z, Junjun M. Exosomal miR-499a-5p inhibits endometrial Cancer Growth and Metastasis via Targeting VAV3. Cancer Manag Res. 2020;12:13541–52.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  83. Sil S, Dagur RS, Liao K, Peeples ES, Hu G, Periyasamy P, et al. Strategies for the use of Extracellular vesicles for the delivery of therapeutics. J Neuroimmune Pharmacol. 2020;15(3):422–42.

    Article  PubMed  Google Scholar 

  84. Villata S, Canta M, Cauda V. EVs and bioengineering: from Cellular products to Engineered Nanomachines. Int J Mol Sci. 2020;21(17).

  85. Riazifar M, Mohammadi MR, Pone EJ, Yeri A, Lässer C, Segaliny AI, et al. Stem cell-derived exosomes as Nanotherapeutics for Autoimmune and Neurodegenerative disorders. ACS Nano. 2019;13(6):6670–88.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  86. Blanco E, Shen H, Ferrari M. Principles of nanoparticle design for overcoming biological barriers to drug delivery. Nat Biotechnol. 2015;33(9):941–51.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  87. Kooijmans SA, Aleza CG, Roffler SR, van Solinge WW, Vader P, Schiffelers RM. Display of GPI-anchored anti-EGFR nanobodies on extracellular vesicles promotes tumour cell targeting. J Extracell Vesicles. 2016;5:31053.

    Article  PubMed  Google Scholar 

  88. Kooijmans SAA, Fliervoet LAL, van der Meel R, Fens M, Heijnen HFG, van Henegouwen B et al. PMP,. PEGylated and targeted extracellular vesicles display enhanced cell specificity and circulation time. J Control Release. 2016;224:77–85.

  89. Long Y, Yang B, Lei Q, Gao F, Chen L, Chen W, et al. Targeting senescent alveolar epithelial cells using Engineered mesenchymal stem cell-derived extracellular vesicles to treat pulmonary fibrosis. ACS Nano. 2024;18(9):7046–63.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  90. Sun F, Sun Y, Wang X, Zhu J, Chen S, Yu Y, et al. Engineered mesenchymal stem cell-derived small extracellular vesicles for diabetic retinopathy therapy through HIF-1α/EZH2/PGC-1α pathway. Bioact Mater. 2024;33:444–59.

    CAS  PubMed  Google Scholar 

  91. Li YJ, Wu JY, Liu J, Xu W, Qiu X, Huang S, et al. Artificial exosomes for translational nanomedicine. J Nanobiotechnol. 2021;19(1):242.

    Article  Google Scholar 

  92. Nguyen VVT, Welsh JA, Tertel T, Choo A, van de Wakker SI, Defourny KAY, et al. Inter-laboratory multiplex bead-based surface protein profiling of MSC-derived EV preparations identifies MSC-EV surface marker signatures. J Extracell Vesicles. 2024;13(6):e12463.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  93. Xu M, Feng T, Liu B, Qiu F, Xu Y, Zhao Y, et al. Engineered exosomes: desirable target-tracking characteristics for cerebrovascular and neurodegenerative disease therapies. Theranostics. 2021;11(18):8926–44.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  94. Banks WA, Sharma P, Bullock KM, Hansen KM, Ludwig N, Whiteside TL. Transport of Extracellular vesicles across the blood-brain barrier: Brain Pharmacokinetics and effects of inflammation. Int J Mol Sci. 2020;21(12).

  95. Cohen O, Betzer O, Elmaliach-Pnini N, Motiei M, Sadan T, Cohen-Berkman M, et al. Golden’ exosomes as delivery vehicles to target tumors and overcome intratumoral barriers: in vivo tracking in a model for head and neck cancer. Biomater Sci. 2021;9(6):2103–14.

    Article  CAS  PubMed  Google Scholar 

  96. Kou L, Bhutia YD, Yao Q, He Z, Sun J, Ganapathy V. Transporter-guided delivery of nanoparticles to Improve Drug Permeation across Cellular barriers and drug exposure to selective cell types. Front Pharmacol. 2018;9:27.

    Article  PubMed  PubMed Central  Google Scholar 

  97. Betzer O, Perets N, Angel A, Motiei M, Sadan T, Yadid G, et al. In vivo neuroimaging of Exosomes using gold nanoparticles. ACS Nano. 2017;11(11):10883–93.

    Article  CAS  PubMed  Google Scholar 

  98. Iranifar E, Seresht BM, Momeni F, Fadaei E, Mehr MH, Ebrahimi Z, et al. Exosomes and microRNAs: new potential therapeutic candidates in Alzheimer disease therapy. J Cell Physiol. 2019;234(3):2296–305.

    Article  CAS  PubMed  Google Scholar 

  99. Wang H, Sui H, Zheng Y, Jiang Y, Shi Y, Liang J, et al. Curcumin-primed exosomes potently ameliorate cognitive function in AD mice by inhibiting hyperphosphorylation of the tau protein through the AKT/GSK-3β pathway. Nanoscale. 2019;11(15):7481–96.

    Article  CAS  PubMed  Google Scholar 

  100. Wang H, Liu Y, Li J, Wang T, Hei Y, Li H, et al. Tail-vein injection of MSC-derived small extracellular vesicles facilitates the restoration of hippocampal neuronal morphology and function in APP / PS1 mice. Cell Death Discov. 2021;7(1):230.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  101. Vilaça-Faria H, Salgado AJ, Teixeira FG. Mesenchymal Stem Cells-derived Exosomes: A New Possible Therapeutic Strategy for Parkinson’s Disease? Cells. 2019;8(2).

  102. Tieu A, Lalu MM, Slobodian M, Gnyra C, Fergusson DA, Montroy J, et al. An analysis of mesenchymal stem cell-derived extracellular vesicles for preclinical use. ACS Nano. 2020;14(8):9728–43.

    Article  CAS  PubMed  Google Scholar 

  103. de Godoy MA, Saraiva LM, de Carvalho LRP, Vasconcelos-Dos-Santos A, Beiral HJV, Ramos AB, et al. Mesenchymal stem cells and cell-derived extracellular vesicles protect hippocampal neurons from oxidative stress and synapse damage induced by amyloid-β oligomers. J Biol Chem. 2018;293(6):1957–75.

    Article  PubMed  Google Scholar 

  104. Xu F, Wu Y, Yang Q, Cheng Y, Xu J, Zhang Y, et al. Engineered Extracellular vesicles with SHP2 high expression promote Mitophagy for Alzheimer’s Disease Treatment. Adv Mater. 2022;34(49):e2207107.

    Article  PubMed  Google Scholar 

  105. Brkic M, Balusu S, Van Wonterghem E, Gorlé N, Benilova I, Kremer A, et al. Amyloid β oligomers disrupt Blood-CSF Barrier Integrity by activating Matrix metalloproteinases. J Neurosci. 2015;35(37):12766–78.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  106. Perets N, Betzer O, Shapira R, Brenstein S, Angel A, Sadan T, et al. Golden exosomes selectively target brain pathologies in neurodegenerative and neurodevelopmental disorders. Nano Lett. 2019;19(6):3422–31.

    Article  CAS  PubMed  Google Scholar 

  107. Kim HY, Kim TJ, Kang L, Kim YJ, Kang MK, Kim J, et al. Mesenchymal stem cell-derived magnetic extracellular nanovesicles for targeting and treatment of ischemic stroke. Biomaterials. 2020;243:119942.

    Article  CAS  PubMed  Google Scholar 

  108. Li Q, Wang Z, Xing H, Wang Y, Guo Y. Exosomes derived from mir-188-3p-modified adipose-derived mesenchymal stem cells protect Parkinson’s disease. Mol Ther Nucleic Acids. 2021;23:1334–44.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  109. Liu X, Yang Y, Li Y, Niu X, Zhao B, Wang Y, et al. Integration of stem cell-derived exosomes with in situ hydrogel glue as a promising tissue patch for articular cartilage regeneration. Nanoscale. 2017;9(13):4430–8.

    Article  CAS  PubMed  Google Scholar 

  110. Gangadaran P, Rajendran RL, Lee HW, Kalimuthu S, Hong CM, Jeong SY, et al. Extracellular vesicles from mesenchymal stem cells activates VEGF receptors and accelerates recovery of hindlimb ischemia. J Control Release. 2017;264:112–26.

    Article  CAS  PubMed  Google Scholar 

  111. Blázquez R, Sánchez-Margallo FM, Álvarez V, Usón A, Marinaro F, Casado JG. Fibrin glue mesh fixation combined with mesenchymal stem cells or exosomes modulates the inflammatory reaction in a murine model of incisional hernia. Acta Biomater. 2018;71:318–29.

    Article  PubMed  Google Scholar 

  112. Gupta D, Zickler AM, El Andaloussi S. Dosing extracellular vesicles. Adv Drug Deliv Rev. 2021;178:113961.

    Article  CAS  PubMed  Google Scholar 

  113. Zhao M, Liu S, Wang C, Wang Y, Wan M, Liu F, et al. Correction to mesenchymal stem cell-derived extracellular vesicles attenuate mitochondrial damage and inflammation by stabilizing mitochondrial DNA. ACS Nano. 2021;15(12):20692.

    Article  CAS  PubMed  Google Scholar 

  114. Zhang X, Liu T, Hou X, Zhou Z, Zhang F, Ma H, et al. Exosomes secreted by mesenchymal stem cells delay brain aging by upregulating SIRT1 expression. Sci Rep. 2023;13(1):13213.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  115. Dorronsoro A, Santiago FE, Grassi D, Zhang T, Lai RC, McGowan SJ, et al. Mesenchymal stem cell-derived extracellular vesicles reduce senescence and extend health span in mouse models of aging. Aging Cell. 2021;20(4):e13337.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  116. Xian P, Hei Y, Wang R, Wang T, Yang J, Li J, et al. Mesenchymal stem cell-derived exosomes as a nanotherapeutic agent for amelioration of inflammation-induced astrocyte alterations in mice. Theranostics. 2019;9(20):5956–75.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  117. George M, Tharakan M, Culberson J, Reddy AP, Reddy PH. Role of Nrf2 in aging, Alzheimer’s and other neurodegenerative diseases. Ageing Res Rev. 2022;82:101756.

    Article  CAS  PubMed  Google Scholar 

  118. Liu K, Cai GL, Zhuang Z, Pei SY, Xu SN, Wang YN, et al. Interleukin-1β-Treated mesenchymal stem cells inhibit inflammation in hippocampal astrocytes through exosome-activated Nrf-2 signaling. Int J Nanomed. 2021;16:1423–34.

    Article  Google Scholar 

  119. Xiong Y, Xiong Y, Zhang H, Zhao Y, Han K, Zhang J, et al. hPMSCs-Derived exosomal miRNA-21 protects against aging-related oxidative damage of CD4(+) T cells by targeting the PTEN/PI3K-Nrf2 Axis. Front Immunol. 2021;12:780897.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  120. Harrell CR, Jovicic N, Djonov V, Arsenijevic N, Volarevic V. Mesenchymal stem cell-derived exosomes and other Extracellular vesicles as new remedies in the Therapy of Inflammatory diseases. Cells. 2019;8(12).

  121. Han Y, Seyfried D, Meng Y, Yang D, Schultz L, Chopp M, et al. Multipotent mesenchymal stromal cell-derived exosomes improve functional recovery after experimental intracerebral hemorrhage in the rat. J Neurosurg. 2018;131(1):290–300.

    Article  PubMed  Google Scholar 

  122. Moon GJ, Sung JH, Kim DH, Kim EH, Cho YH, Son JP, et al. Application of mesenchymal stem cell-derived extracellular vesicles for stroke: Biodistribution and MicroRNA Study. Transl Stroke Res. 2019;10(5):509–21.

    Article  CAS  PubMed  Google Scholar 

  123. Harrell CR, Volarevic A, Djonov V, Volarevic V. Mesenchymal stem cell-derived exosomes as New Remedy for the treatment of Neurocognitive disorders. Int J Mol Sci. 2021;22(3).

  124. Zarrabi M, Shahrbaf MA, Nouri M, Shekari F, Hosseini SE, Hashemian SR, et al. Allogenic mesenchymal stromal cells and their extracellular vesicles in COVID-19 induced ARDS: a randomized controlled trial. Stem Cell Res Ther. 2023;14(1):169.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  125. Mahindran E, Wan Kamarul Zaman WS, Ahmad Amin Noordin KB, Tan YF, Nordin F. Mesenchymal stem cell-derived extracellular vesicles: hype or hope for skeletal muscle Anti-frailty. Int J Mol Sci. 2023;24(9).

  126. Reiner AT, Witwer KW, van Balkom BWM, de Beer J, Brodie C, Corteling RL, et al. Concise Review: developing best-practice models for the therapeutic use of Extracellular vesicles. Stem Cells Transl Med. 2017;6(8):1730–9.

    Article  PubMed  PubMed Central  Google Scholar 

  127. Shi MM, Yang QY, Monsel A, Yan JY, Dai CX, Zhao JY, et al. Preclinical efficacy and clinical safety of clinical-grade nebulized allogenic adipose mesenchymal stromal cells-derived extracellular vesicles. J Extracell Vesicles. 2021;10(10):e12134.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  128. Zhu YG, Shi MM, Monsel A, Dai CX, Dong X, Shen H, et al. Nebulized exosomes derived from allogenic adipose tissue mesenchymal stromal cells in patients with severe COVID-19: a pilot study. Stem Cell Res Ther. 2022;13(1):220.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

Download references

Acknowledgements

Thanks to the support of grants from Yunnan Province “High-level health technicians Talents Training Support Plan” (L-2017002) and famous doctors special project (RLMY20200010) for your support, and thanks to all authors for their contributions to this study. The authors declare that they have not use AI-generated work in this manuscript.

Funding

This work was supported by grants from Yunnan Province “High-level health technicians Talents Training Support Plan” (L-2017002) and famous doctors special project (RLMY20200010).

Author information

Authors and Affiliations

Authors

Contributions

ZGH conceived and Conceptualization, supervision, writing—review and editing. LQ designed the search strategy and conducted the literature search. QJL investigated, drafted the manuscript, prepared the tables and figures — original draft. All authors reviewed the manuscript.

Corresponding author

Correspondence to Gaohong Zhu.

Ethics declarations

Conflict of interest

There is no conflict of interest in this article.

Additional information

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Quan, J., Liu, Q., Li, P. et al. Mesenchymal stem cell exosome therapy: current research status in the treatment of neurodegenerative diseases and the possibility of reversing normal brain aging. Stem Cell Res Ther 16, 76 (2025). https://doiorg.publicaciones.saludcastillayleon.es/10.1186/s13287-025-04160-5

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doiorg.publicaciones.saludcastillayleon.es/10.1186/s13287-025-04160-5

Keywords