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Therapeutic efficacy of intra-articular injection of human adipose-derived mesenchymal stem cells in a sheep model of knee osteoarthritis

Stem Cell Research & Therapy volume 16, Article number: 24 (2025) Cite this article

Abstract

Background

Mesenchymal stem cells have great potential for repairing articular cartilage and treating knee osteoarthritis (KOA). Nonetheless, little is known about the efficacy of human adipose-derived mesenchymal stem cells (haMSCs) for KOA in large animal models.

Methods

This study evaluated the therapeutic efficacy of haMSCs in knee articular cartilage repair in a sheep model of KOA. haMSCs were isolated, cultured, and characterized. KOA was surgically induced by anterior cruciate ligament transection and medial meniscectomy, followed by intra-articular injection of saline (negative control group) or haMSCs (haMSC group) into the right knee joint at 6 and 9 weeks after surgery. Sheep were sacrificed 21 weeks after surgery, and samples (whole knee joints, femoral condyles, and tibias) were collected, processed, and analyzed. Changes in knee articular cartilage were assessed by magnetic resonance imaging, micro-computed tomography, macroscopic analysis, histology, and immunohistochemistry.

Results

KOA caused the degeneration of the medial femoral condyle in the sheep model of KOA. Conversely, haMSCs repaired chondral defects and increased the thickness of knee articular cartilage.

Conclusions

These data suggest that the intra-articular injection of haMSCs can effectively repair articular cartilage defects in the knee.

Introduction

Knee osteoarthritis (KOA) is a degenerative disease characterized by progressive knee articular cartilage degeneration and chronic synovial inflammation. KOA is caused by repetitive impact loading. Osteoarthritis (OA) is a leading cause of chronic pain and functional disability worldwide, imposing a significant economic and health burden by decreasing work productivity and the ability to perform activities of daily living. The prevalence of OA increases with age [1,2,3,4,5].

Articular cartilage is a hyaline connective tissue composed predominantly of chondrocytes, which secrete large amounts of type II collagen and proteoglycan and smaller amounts of type VI, IX, XI, and XIV collagen [4]. Articular cartilage has a limited capacity for spontaneous repair because this tissue has low metabolic activity and lacks blood supply, lymphatic drainage, and innervation [4]. Therefore, there is an urgent need to develop minimally invasive, effective, and safe therapeutic strategies for OA.

Mechanical and humoral factors are involved in the pathogenesis of KOA. Nonetheless, the pathogenic mechanisms of KOA are unclear, limiting the development of disease-modifying therapeutics. Moreover, current treatments for KOA have limited efficacy and focus on symptom management rather than articular cartilage repair, and total knee arthroplasty is indicated only to patients with advanced disease [6, 7]. Stem cell therapy is a promising approach for joint tissue regeneration [4]. Mesenchymal stem cells (MSCs) have great potential for treating KOA and chondral defects [8, 9]. Large amounts of MSCs can be harvested from adipose tissue using simple, reproducible, and minimally invasive methods. Furthermore, the quantity and quality of MSCs are significantly higher in adipose tissue than in other tissues. These advantages render adult human adipose tissue an accessible, abundant, and reliable source of MSCs for tissue engineering and regenerative medicine applications [10].

Several animal models have been used to study the onset and progression of OA and determine the efficacy of novel therapies. The selection of appropriate animal models depends on several factors, including animal size, cost, and method of inducing OA [11]. Small animal models are commonly used to analyze the pathophysiology of cartilage degeneration. The advantages of these models include low cost, ease of handling, and high availability. Nonetheless, small animals have a small amount of synovial fluid, which is difficult to collect. Mouse and rabbit models are unsuitable for assessing cartilage repair because repair occurs spontaneously in these models [12, 13]. Moreover, there are marked differences in biomechanical loading and cartilage anatomy between mice and humans.

The advantages of large animal models of OA include anatomic similarity to humans (cartilage thickness and joint size), better suitability for long-term follow-up, high prevalence of naturally occurring primary idiopathic and secondary OA, and capability to perform diagnostic imaging, arthroscopic interventions, synovial fluid collection, and postoperative management. Therefore, these models can generate more clinically relevant data and are usually required for regulatory approval. The disadvantages of these models include high cost, difficulty of handling, longer time to maturity, slower disease progression, and ethical considerations [4, 11, 12, 14]. Another disadvantage of using goats and sheep is that they are not prone to spontaneous OA and thus only serve as models of OA induced surgically by acute joint injury [11, 14].

Little is known about the efficacy of human adipose-derived MSCs (haMSCs) in large animal models of KOA. This study assessed the therapeutic efficacy of haMSCs in a sheep model of KOA surgically induced by anterior cruciate ligament transection (ACLT) and medial meniscectomy (MM).

Materials and methods

Isolation and culture of haMSCs

haMSCs were isolated and cultured as described previously [15]. Briefly, haMSCs were isolated from lipoaspirates of healthy young adult donors who gave written informed consent. haMSCs were cultured in T75 cell culture flasks with α-minimum essential medium (α-MEM, C12571500BT, Gibco, USA) supplemented with 5% EliteGro (EPAGMP-500, EliteCell, USA) in a humidified incubator at 37 °C with 5% CO2 for 24 h. Detached cells were removed. The remaining cells were maintained in α-MEM and defined as passage 0 (P0). The medium was changed every 2 days. Cells were cultured to 80% confluence. Then, adherent cells were trypsinized and sub-cultured. haMSCs at passage 7 (P7) were harvested for further analysis.

Flow cytometric analysis

haMSCs (1.0 × 106 cells) at P7 were resuspended in 100 µL of PBS and incubated with 1 µg of phycoerythrin-conjugated, allophycocyanin-conjugated, fluorescein isothiocyanate-conjugated, or peridinin-chlorophyll-protein-Cy5.5-conjugated anti-human monoclonal antibodies for 30 min at 4 °C in the dark [16]. The following antibodies (all from Biolegend, USA) were used: CD73 (#344016), CD90 (#328118), CD105 (#800508), CD14 (#982502), CD45 (#304008), and HLA-DR (#307603). haMSCs were washed with cold 1×PBS and analyzed using a flow cytometer (EPICS XL, Beckman Coulter, Palo Alto, CA, USA).

Trilineage differentiation of haMSCs in vitro

Trilineage differentiation of haMSCs was performed as described previously [15]. For adipogenic and osteogenic differentiation, haMSCs at P7 were seeded onto 12-well plates at 1.0 × 104 cells and 5.0 × 103 cells per cm2, respectively, and cultured in a humidified incubator at 37 °C with 5% CO2 until 90% confluence. The StemPro® adipogenic or osteogenic differentiation medium (A1007201, A1007001, Gibco, USA) was added to the culture plates, followed by incubation at 37 °C for 2 to 4 weeks. For chondrogenic differentiation, 1.6 × 107 cells were resuspended in 1 mL of chondrogenic differentiation medium (A1007101, Gibco, USA), centrifuged at 300g for 5 min, and cultured in conical tubes for 4 weeks at 37 °C. Samples were fixed in 4% paraformaldehyde for 30 min. The induction of adipogenesis and osteogenesis was confirmed by Oil Red O staining (SC-0843, Sciencell, USA) and Alizarin Red staining (SC-0223, Sciencell, USA), respectively. Chondrogenic pellets were cut using a cryostat. Cryosections were stained with Alcian blue (SC-8348, Sciencell, USA).

Animals and treatments

Eleven male small-tailed Han sheep aged 15–18 months, with a mean weight of 75 ± 10 kg, were used in this study. After an adaptation period of at least 14 days, the animals were randomly divided into three groups, with three to five animals per group. The normal group (NG) did not undergo treatment. The negative control (NC) group underwent ACLT and MM in the right knee to induce KOA surgically, followed by the intra-articular injection of 5 mL of sterile saline into the knee joint at 6 weeks (one dose) and 9 weeks (one dose) after surgery. The haMSC-treated group (haMSC) underwent surgery as described above, followed by intra-articular injection of haMSCs (1.0 × 108 cells suspended in 5 mL of sterile saline) into the knee joint at 6 weeks (one dose) and 9 weeks (one dose) after surgery [17]. Before surgery, sheep were intramuscularly injected with antibiotics (ceftriaxone sodium, 50 mg/kg) and atropine (0.05 mg/kg). Anesthesia was maintained by the intramuscular injection of Zoletil (2 mg/kg) and Sumianxin II (0.02 mL/kg). Surgery was performed under general anesthesia and sterile conditions, as described previously [18]. After surgery, sheep were intramuscularly injected with buprenorphine (0.01 mg/kg) and ceftriaxone sodium (50 mg/kg) for 3 consecutive days. The NC and haMSC groups were allowed to walk freely. The animals were euthanized at 21 weeks after surgery by the intramuscular injection of Zoletil (2 mg/kg) and the intravenous injection of potassium chloride solution (2 mmol/kg). Samples (whole knee joints, femoral condyles, and tibias) were collected, processed, and examined. The animal studies adhered to the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines 2.0.

MRI

Three sheep were randomly selected from each group for MRI. Imaging was performed on a 3.0 T MRI scanner (MAGNETOM Skyra, Siemens Healthcare, Erlangen, Germany) at 21 weeks after surgery. Cartilage repair was evaluated by an investigator blinded to treatment allocation using the magnetic resonance observation of cartilage repair tissue (MOCART) scoring system, as previously described [19].

Macroscopic analysis and micro-computed tomography (CT) scanning

Macroscopic analysis and micro-CT scans of knee joints were performed to assess the degree of degeneration of the articular cartilage of the femoral condyle and cartilage thickness of the tibial plateau, respectively, as detailed previously [17]. Right femoral condyles were collected and imaged. Cartilage repair was assessed by an observer blinded to treatment allocation using the International Cartilage Research Society (ICRS) criteria [20].

Micro-CT scans of the proximal tibial plateau were performed using the following parameters: voxel size, 45 mm; tube voltage, 70 kVp; tube current, 114 µA; integration time, 200 ms; acquisition time, 15–30 min. Image segmentation was performed using histogram thresholding (threshold value of 30-1000) and the following Gauss filter parameters: sigma, 1.2; support, 2. Average cartilage thickness in segmented images was measured using distance transformation algorithms [21]. CT images were analyzed by an investigator blinded to treatment allocation.

Histological and immunohistochemical analyses

Femoral condyles were fixed in 4% paraformaldehyde for 24 h. The specimens were washed with distilled water, decalcified in EDTA, dehydrated in a graded ethanol series, dewaxed with dimethylbenzene, and embedded in paraffin. The specimens were serially sectioned at a thickness of 5 μm and used for hematoxylin and eosin (H&E), Safranin O/Fast Green, and immunohistochemical staining. The degree of articular degeneration was graded histologically using Mankin scores [22]. Cartilage thickness was measured by an investigator blinded to treatment allocation as detailed previously [23].

For immunohistochemical staining, tissue sections were incubated with polyclonal rabbit anti-sheep collagen II (Abcam, 1:100) or collagen X (Abcam, 1:100) antibodies at 4 °C overnight, followed by incubation with biotin-conjugated anti-rabbit IgG (Abcam, 1:500) at room temperature for 1 h. Sections were imaged using a light microscope (AxioScope A1, Carl Zeiss MicroImaging GmbH, Germany). The area stained positive for collagen II and the number of chondrocytes expressing collagen X per field were analyzed using ImageJ software (NIH, USA).

Statistical analysis

Statistical analysis was performed using GraphPad Prism version 10.0 (GraphPad Software Inc., La Jolla, CA). Normally distributed continuous variables were expressed as mean ± standard error of the mean. The significance of differences between means was assessed by one-way analysis of variance followed by Newman-Keuls post-hoc test. P-values of less than 0.05 were considered statistically significant.

Results

Characterization of haMSCs in vitro

haMSCs were characterized by flow cytometry and histology (trilineage differentiation). Cytometric analysis showed that these cells were positive for CD73, CD90, and CD105 (≥ 95%) and negative for CD14, CD45, and HLA-DR (≤ 2%) (Fig. 1A). Histology showed that haMSCs differentiated into adipocytes, osteocytes, or chondrocytes in the presence of differentiation medium (Fig. 1B). These results demonstrate that isolated cells had phenotypic characteristics of MSCs.

Fig. 1
figure 1

Characterization of human adipose-derived mesenchymal stem cells (haMSCs). (A) Flow cytometric analysis of cell surface markers CD73, CD90, CD105, CD14, CD45, and HLA-DR on haMSCs. (B) Trilineage differentiation of haMSCs into adipocytes, osteocytes, and chondrocytes based on Oil Red O, Alizarin Red, and Alcian Blue staining. Scale bar: 50 μm

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MRI of changes in knee articular cartilage

The therapeutic efficacy of haMSCs on articular cartilage repair was investigated by MRI. At 6 weeks post-surgery, MRI showed joint effusion (red arrows), osteophyte formation (yellow arrowhead), bone marrow edema (red arrowhead), articular cartilage with ill-defined margins, and the absence of the anterior cruciate ligament (ACL) and medial meniscus, indicating the successful creation of the sheep model of KOA (Fig. 2A). haMSCs reduced these effects at 21 weeks post-surgery, evidenced by the finding that the knee cartilage in the haMSC-treated group was continuous, smooth, and intact, similar to cartilage in the NG (Fig. 2A). KOA significantly decreased MOCART scores, while haMSCs reversed this effect (p < 0.05) (Fig. 2B). These data indicate that cellular treatment repaired knee cartilage defects.

Fig. 2
figure 2

Magnetic resonance imaging (MRI) of knee articular cartilage in normal sheep and in a sheep model of knee osteoarthritis surgically induced by anterior cruciate ligament transection and medial meniscectomy, followed by intra-articular injection of sterile saline (NC) or haMSCs into the right knee joint at 6 weeks (one dose) and 9 weeks (one dose) after surgery. (A) MRI analysis of changes in articular cartilage in different groups. The red arrows, yellow arrowhead, and red arrowhead indicate joint effusion, osteophyte formation, and bone marrow edema. Scale bar: 2 cm. (B) MOCART scores based on MRI results in different groups (three animals per group). *p < 0.05. Abbreviations: NC, negative control; haMSCs, human adipose-derived mesenchymal stem cells

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haMSCs improve the morphology of femoral condyles

The therapeutic efficacy of haMSCs on knee cartilage repair was evaluated by the macroscopic analysis of the articular cartilage of the femoral condyle and tibial plateau. The results showed that KOA caused the degeneration of the medial femoral condyle, while haMSCs reduced the degeneration (Fig. 3A). KOA significantly decreased ICRS scores (p < 0.01), while haMSCs reduced this effect (p < 0.05) (Fig. 3B). Nonetheless, macroscopic analysis showed that haMSCs did not improve tibial plateau morphology to a significant extent (Fig. 4A).

Fig. 3
figure 3

Macroscopic analysis of sheep femoral condyles. (A) Macroscopic observation of femoral condyles in normal sheep and in a sheep model of knee osteoarthritis surgically induced by anterior cruciate ligament transection and medial meniscectomy followed by intra-articular injections of sterile saline (NC) or haMSCs into the right knee joint at 6 weeks (one dose) and 9 weeks (one dose) after surgery. The dotted circles show the medial condyle. (B) Cartilage repair was assessed using ICRS criteria (three to five animals per group). *p < 0.05, **p < 0.01. Abbreviations: NC, negative control; haMSCs, human adipose-derived mesenchymal stem cells; ICRS, International Cartilage Repair Society

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Fig. 4
figure 4

Macroscopic analysis and micro-computed tomography (micro-CT) scans of sheep tibial plateau. (A) Macroscopic analysis of tibial plateaus in normal sheep and sheep who underwent knee osteoarthritis surgically induced by anterior cruciate ligament transection and medial meniscectomy, followed by intra-articular injections of sterile saline (NC) or haMSCs into the right knee joint at 6 weeks (one dose) and 9 weeks (one dose) after surgery. (B) Micro-CT scans of the tibial plateau in experimental and control groups. (C) Measurement of cartilage thickness in the tibial plateau of the experimental and control groups (three animals per group). Abbreviations: NC, negative control; haMSCs, human adipose-derived mesenchymal stem cells; NS, not significant

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Micro-CT scans showed no notable changes in the microstructure of tibial plateau cartilage in the three groups (Fig. 4B). Further, there were no significant between-group differences in tibial plateau cartilage thickness (Fig. 4C). These findings indicate that two intra-articular injections of haMSCs can effectively repair knee articular cartilage defects in the sheep model of KOA.

haMSCs promote knee cartilage regeneration

The effects of haMSCs on cartilage repair were assessed by histological analysis of femoral condyle cartilage at 21 weeks post-surgery. H&E and Safranin O/Fast Green staining revealed that the articular cartilage surface was rough and heterogeneous in the NC group. haMSCs attenuated these pathological changes, and the cartilage surface was smooth and continuous, with a high concentration of proteoglycans (Fig. 5A). KOA significantly increased Mankin scores (p < 0.001) and decreased femoral cartilage thickness (p < 0.01); haMSC treatment attenuated these effects (p < 0.01) (Fig. 5B, C). These results demonstrate that haMSCs promote articular cartilage regeneration in the sheep model of KOA.

Fig. 5
figure 5

Histological analysis of knee articular cartilage in sheep. (A) H&E staining and Safranin O/Fast Green staining of cartilage sections of normal sheep and sheep who underwent knee osteoarthritis surgically induced by anterior cruciate ligament transection and medial meniscectomy, followed by intra-articular injections of sterile saline (NC) or haMSCs into the right knee joint at 6 weeks (one dose) and 9 weeks (one dose) after surgery. (B) Analysis of the degree of cartilage degeneration using the Mankin scoring system in the experimental and control groups (three animals per group). **p < 0.01, ***p < 0.001. (C) Measurement of femoral condyle cartilage thickness (three animals per group). **p < 0.01. Abbreviations: H&E, hematoxylin and eosin; NC, negative control; haMSCs, human adipose-derived mesenchymal stem cells

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haMSCs reverse the changes in the cartilage matrix induced by KOA

The effects of haMSCs on the articular cartilage matrix were evaluated by determining the immunohistochemical expression of collagen II and collagen X at 21 weeks post-surgery. KOA markedly decreased the area stained positive for type II collagen (p < 0.05) and increased the number of hypertrophic chondrocytes expressing type X collagen in the deep zone (p < 0.01); haMSCs reversed these effects (Fig. 6A-C). These findings suggest that cellular treatment can promote femoral cartilage repair in the sheep model of KOA.

Fig. 6
figure 6

Immunohistochemical expression of type II and X collagen in femoral condyle cartilage. (A) Immunohistochemical expression of type II and X collagen in the femoral articular cartilage of normal sheep and in a sheep model of knee osteoarthritis surgically induced by anterior cruciate ligament transection and medial meniscectomy, followed by the intra-articular injection of sterile saline (NC) or haMSCs into the right knee joint at 6 weeks (one dose) and 9 weeks (one dose) after surgery. Scale bars: 1000, 500, and 50 μm. (B) Area stained positive for type II collagen (three animals per group). *p < 0.05. (C) Number of hypertrophic chondrocytes expressing type X collagen per field. The red squares are magnified images (three animals per group). **p < 0.01. Abbreviations: NC, negative control; haMSCs, human adipose-derived mesenchymal stem cells

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Discussion

Given that repeated injections of umbilical cord-derived MSCs were better than a single injection for WOMAC and pain scores in patients with KOA [24], we performed two intra-articular injections of haMSCs in our animal model of KOA at weeks 6 and 9 after surgery. We found that cartilage defects were more evident in the medial femoral condyle than in the lateral condyle. ACL deficiency causes maximum erosion in the medial compartment without notable changes in the lateral compartment because the former supports more mechanical load than the latter [25, 26]. Our results also suggest that the medial condyle is more prone to wear than the lateral condyle. Additionally, there were no changes in the thickness of the tibial plateau cartilage in the study groups. Articular cartilage wear is higher on the femoral side than on the tibial side because a larger area of the cartilage is used on the femoral side during knee motion [26].

Chondrocyte hypertrophy is a hallmark of OA [27]. Hypertrophic chondrocytes can cause cartilage matrix degradation by secreting inflammatory and metabolic markers, including collagen X and MMP13 [28]. Therefore, chondrocyte hypertrophy inhibition is a promising therapeutic target for OA. Consistent with these results, we found that at 21 weeks post-surgery, KOA caused cartilage defects in the medial femoral condyle, decreased the expression of type II collagen in the cartilage matrix, and increased the number of hypertrophic chondrocytes expressing type X collagen in the deep zone. haMSCs attenuated these effects, indicating that cellular treatment reduced KOA progression by inhibiting chondrocyte hypertrophy. Furthermore, we previously showed that multiple intra-articular injections of haMSCs promoted articular cartilage regeneration in a rabbit model of OA [15]. In line with these findings, we showed that two intra-articular injections of haMSCs reduced KOA progression by promoting knee articular cartilage repair and increasing cartilage thickness in a sheep model of KOA.

Aging affects the ability of chondrocytes to maintain and restore articular cartilage. Aging is associated with fewer chondrocytes, chondrocyte senescence, and chondrocyte apoptosis, increasing the risk of articular cartilage degeneration [4]. Therefore, aging decreases the therapeutic efficacy of MSCs in OA [29]. Participation in sports involving high axial and torsional loading increases the risk of joint injuries and degeneration [2]. The sheep model of KOA does not entirely mimic aging-related KOA but mimics post-traumatic KOA. Many preclinical studies used animal models of surgically induced KOA. Nonetheless, animal models cannot accurately mimic the pathology of human aging-related KOA. KOA in animal models of naturally occurring disease progresses slowly. Hence, the duration of disease and treatment is long in these models [30]. Our study used an animal model of post-traumatic KOA with or without haMSC treatment. This model can mimic some aspects of human pathology because post-traumatic KOA occurs in humans. However, further studies are needed to assess whether haMSCs can treat aging-related KOA.

The effects of haMSCs on cartilage repair were assessed using a sheep model of KOA induced by ACLT and MM. The findings showed that haMSCs promoted knee articular cartilage repair in this model. Consistent with this finding, our pilot studies and clinical trials showed that intra-articular injections of haMSCs reduced pain scores and improved cartilage regeneration and physical function in patients with KOA [10, 31, 32]. Other studies suggest that exogenous MSCs do not differentiate into chondrocytes but participate in cartilage repair by regulating local inflammation and paracrine signaling [33, 34]. Further, MSCs secrete enzymes, chemokines, cytokines, growth factors, and microRNAs [34, 35].

Growth factors promote cartilage repair by stimulating the proliferation of endogenous joint-resident MSCs, which differentiate into chondrocytes and induce the formation of cartilage-associated extracellular matrix [36,37,38,39,40,41,42]. Consistent with these results, we identified and quantified various growth factors in the conditioned medium of haMSCs, including vascular endothelial growth factor, platelet-derived growth factor, hepatocyte growth factor, and fibroblast growth factor 2 (FGF-2) (Supplementary Table 1). FGF-2 promotes the repair of full-thickness defects of articular cartilage by activating the proliferation and migration of MSCs [43].

MSC-derived exosomes contain growth factors and microRNAs that reduce inflammation and induce tissue repair [34, 44,45,46], demonstrating that haMSC-derived exosomes can potentially repair KOA-induced cartilage defects. We previously showed that hsa-miR-92a-3p in haMSC-derived exosomes enhanced chondrogenesis and suppressed cartilage degradation by targeting Wnt5a [44, 47]. Our results suggest that two intra-articular injections of haMSCs can repair chondral defects in the medial femoral condyle in a sheep model of KOA.

Many pilot studies and clinical trials have assessed the efficacy of human stem cell-based therapies for KOA. Nonetheless, few clinical studies have evaluated the effects of these therapies on cartilage structure, and few preclinical studies have evaluated the effects of these therapies in large animal models of KOA. Our results showed that haMSCs improved knee cartilage structure in sheep, supporting the clinical application of haMSCs. Additionally, haMSCs are routinely cultured for GMP production and have a good safety profile. We intend to use a 3D culture system to increase production scale and efficiency and decrease production costs. Although MSCs are currently used for treating KOA, several treatment parameters need to be determined in large animal models of KOA, including the optimal dose and frequency, the interval between injections, and the efficacy of different MSC passages.

This study has limitations. First, functional outcomes were not assessed in our model. Second, repeated intra-articular injections of haMSCs in our model may cause immune reactions. Although we previously demonstrated the safety of haMSC-based therapies for KOA [10, 31, 32], potential side effects and risks should be evaluated. Further, combination therapy with MSCs and bioactive compounds may have better therapeutic effects on KOA than MSCs alone [48,49,50,51]. For instance, we showed that intra-articular injection of sheep autologous or allogeneic adipose MSCs combined with hyaluronic acid ameliorated osteoarthritis in sheep [17, 52], demonstrating the potential applicability of combination therapies for cartilage repair in patients with KOA [53]. However, further studies are needed to assess whether combination therapies can improve cartilage regeneration in large animal models of KOA.

Conclusion

Intra-articular injection of haMSCs can repair articular cartilage defects in the femoral condyle in a sheep model of KOA, demonstrating the potential of MSCs for treating OA.

Data availability

All other data are included in the article and its Supplementary Information files or available from the corresponding authors upon reasonable request.

Abbreviations

KOA:

Knee osteoarthritis

haMSCs:

human adipose-derived mesenchymal stem cells

OA:

Osteoarthritis

ACLT:

Anterior cruciate ligament transection

MM:

Medial meniscectomy

NG:

Normal group

NC:

Negative control

MRI:

Magnetic resonance imaging

MOCART:

Magnetic resonance observation of cartilage repair tissue

micro-CT:

micro-computed tomography

ICRS:

International Cartilage Research Society

H&E:

Hematoxylin and eosin

VEGF:

Vascular endothelial growth factor

PDGF:

Platelet-derived growth factor

HGF:

Hepatocyte growth factor

FGF:

Fibroblast growth factor

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Acknowledgements

We are grateful to the members of the haMSC production team and the quality assurance/quality control team from Cellular Biopharma (Shanghai) Co., Ltd. We thank Hongjiang Yuan and his team from PharmaLegacy (Shanghai) Co., Ltd. for technical assistance in performing animal experiments. We also thank TopEdit (www.topeditsci.com) for English language editing.

Funding

This research was funded by Cellular Biopharma (Shanghai) Co., Ltd.

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Authors and Affiliations

  1. Cellular Biopharma (Shanghai) Co., Ltd, Building 3, No.85, Faladi Road, Pudong New Area, Shanghai, 200233, China

    Jigang Lei, Xingyi Chen, Haohao Xie, Yuhao Dai, Zhongjin Chen & Liang Xu

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  1. Jigang Lei
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  2. Xingyi Chen
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  3. Haohao Xie
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Contributions

Liang Xu and Jigang Lei interpreted the results. Xingyi Chen, Haohao Xie, Yuhao Dai, and Zhongjin Chen provided suggestions on data presentation. Jigang Lei analyzed the data and wrote the manuscript. Liang Xu and Jigang Lei critically revised the manuscript for important intellectual content. All authors approved the final manuscript.

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Correspondence to Liang Xu.

Ethics declarations

Ethics approval and consent to participate

Project 1: (1) Title of approved project: Isolation of lipoaspirates from healthy young adult donors; (2) Name of the institutional approval committee or unit: the Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine; (3) Approval number: SH9H-T62-3; (4) Date of approval: November 22, 2014. Project 2: (1) Title of approved project: Therapeutic effects of haMSCs on ACLT and MM-induced sheep model of knee osteoarthritis; (2) Name of the institutional approval committee or unit: Institutional Animal Care and Use Committee of PharmaLegacy (Shanghai) Co., Ltd.; (3) Approval number: PL16-0043-01; (4) Date of approval: June 27, 2016.

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Not applicable.

Competing interests

Jigang Lei, Xingyi Chen, Haohao Xie, Yuhao Dai, Zhongjin Chen, and Liang Xu are current employees of Cellular Biopharma (Shanghai) Co., Ltd. The authors declare that they have no competing financial interests.

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Lei, J., Chen, X., Xie, H. et al. Therapeutic efficacy of intra-articular injection of human adipose-derived mesenchymal stem cells in a sheep model of knee osteoarthritis. Stem Cell Res Ther 16, 24 (2025). https://doiorg.publicaciones.saludcastillayleon.es/10.1186/s13287-025-04143-6

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Keywords

Stem Cell Research & Therapy

ISSN: 1757-6512