iPSC-derived mesenchymal stromal cells stimulate neovascularization less than their primary counterparts.

Aims: Mesenchymal stromal cells (MSCs) are being tested and accepted as a source for cell therapy worldwide. However, the advanced age of the patients, together with the difficulties in achieving the required cell amounts, impede autologous treatments. Reprogramming of MSCs into induced pluripotent stem cells (iPSCs), followed by re-differentiation to MSCs has emerged as a promising and safe method to facilitate the cell expansion and the removal of aging-associated characteristics. However, the effect of reprogramming on the MSC's pro-angiogenicity is poorly understood.

Materials And Methods: In this study, we use a microfluidic organ-on-a-chip platform designed for vascularization assays to study and compare the effects of bone marrow MSCs (BM-MSCs) and iPSC-derived MSCs (iMSCs) in stimulating the formation of vessels by endothelial cells. Cells were loaded in fibrin hydrogels, injected into the microfluidic channel, and grown for ten days.

Key Findings: Fluorescence microscopy revealed that BM-MSCs promote the formation of long and interconnected endothelial vessels, while iMSCs barely stimulate neoangiogenesis. This was further confirmed and explained by bulk RNA sequencing, showing a decrease of pro-angiogenic agents in both of the iMSCs co-cultures. Furthermore, transmission electron microscopy revealed that BM-MSCs closely associate with the new vessels as perivascular cells, while iMSCs just remain in proximity.

Significance: These results highlight iMSCs as a promising substitute for BM-MSCs in the treatment of diseases with pernicious vascularization, such as osteoarthritis, ocular degeneration, and cancer.