Scheme 1

Using engineered mesenchymal stem cells (MSCs) to detect cancer. Engineered MSCs (gray) secreting humanized Gaussia luciferase (hGluc) (green) are systemically administered into patients with cancer (breast cancer lung metastasis in this case). Engineered MSCs home to tumor (cyan) niche and persist, secreting hGluc into blood. Then patient blood can be collected and hGluc activity measured