A current challenge of endothelial cell (EC) therapy for ischaemia is the need to co-transplant ECs with mesenchymal stromal cells (MSCs) to support engraftment. A study in Nature now describes a single-cell-type strategy for vascular cell therapies that involves the artificial transplantation of mitochondria to ECs, which promotes mitophagy and facilitates the formation of functional vessels in ischaemic tissue without the need for MSC support.

Given that the presence of mitochondrial transfer between cells of the vascular system had not yet been described, the investigators assessed whether mitochondrial transfer from MSCs could influence the survival of ECs during engraftment in a xenograft model, in which a mixture of human ECs and MSCs in a collagen-based hydrogel was implanted subcutaneously into immunodeficient nude mice. A continuous transfer of mitochondria between MSCs and ECs through tunnelling nanotubes was observed in the early days after cell transplantation. Blocking this transfer in MSCs resulted in impaired EC engraftment.