The Secretome of iPSC-Derived Mesenchymal Stem Cells Alters Glial and Vascular Responses in SCI-Relevant Paradigms

Cell-free therapies based on the mesenchymal stem cells (MSCs) secretome are being widely explored for spinal cord injury (SCI). Induced pluripotent stem cells (iPSCs) provide a scalable source for generating mesenchymal stem cells (iMSCs), but limited studies have evaluated the modulatory capacity of iMSCs for CNS applications. Due to the importance of the glial and vascular responses to SCI progression, this study evaluated the activity of the iMSCs secretome on glial and endothelial cells in SCI-relevant paradigms. In primary mixed spinal cord cultures, the secretome was tested under supplement withdrawal and hyperosmotic injury conditions, while endothelial network formation was assessed in a morphogenesis assay. In vitro, the iMSCs secretome promoted a modest protective effect on cell survival, modulated astrocyte morphology and preserved myelin basic protein expression within the oligodendroglial lineage, without clear alterations in microglial morphometric readouts. Secretome treatment also increased Arg1 expression in mixed spinal cord cultures. In endothelial cultures, the secretome promoted a denser and more interconnected endothelial network. In a mouse thoracic SCI model, the secretome was administered intravenously, and tissue was analyzed one week after injury. In vivo, the secretome reduced perilesional GFAP coverage and increased selected vascular morphometric parameters without altering lesion size or microglia morphological readouts. Overall, these findings indicate that the iMSCs secretome produced context-dependent changes in glial and vascular cells, mainly regarding morphological parameters, supporting further studies of iPSC-derived MSCs as a scalable source for secretome-based strategies.