Non-Viral Co-Delivery of the Four Yamanaka Factors for Generation of Human Induced Pluripotent Stem Cells via Calcium Phosphate Nanocomposite Particles

Generating of induced pluripotent stem cells (iPSCs) can be achieved by ectopic expression of defined transcription factor sets. However, most instances of iPSC induction have been achieved using viral vectors, which carry the risk of unpredictable genetic dysfunction. Here, for the first time, a non-viral vector based on calcium phosphate nanoparticles for the generation of virus-free iPSCs from human umbilical cord mesenchymal stem cells (HUMSCs) via co-delivery of the four plasmids (Oct4, Sox2, Klf4, and c-Myc) is reported. As a result, a total of 98 colonies from 200 000 cells have been obtained, with a reprogramming efficiency of 0.049%. The iPSCs shows positive expression of pluripotency markers, including OCT4, SSEA-3, SSEA-4, NANOG, and TRA-1-81. Moreover, the iPSCs are able to differentiate into all three germ layers in vitro. Subcutaneous injection of the iPSCs into immunocompromised mice results in the formation of teratomas containing a variety of tissues from all three germ layers. These findings indicate that co-delivery of the four Yamanaka factors via plasmid-encapsulated calcium phosphate nanoparticles can provide a simple, safe, and efficient method for the generation of virus-free iPSCs, which is crucial for their future clinical applications in the field of regenerative medicine.