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. We prepared 3D co-cultures of endothelial cells and supporting cells in fibrin gels. The supporting cells were either bone marrow mesenchymal stromal cells (BMSC) or iPSC-derived mesenchymal stromal cells (iMSCs). The endothelial cells were human umbilical vein endothelial cells (HUVECs). The cells were in the gel in a 1:2 ratio (5x10^6 Supporting Cells and 10x10^6 HUVECs). The gels were cultured for 10 days with EGM MV2 media (PromoCell). The gels were minced and the RNA was isolated for a comparative RNA study.