**5. Induced pluripotent stem cells seeded for bone tissue engineering**

Yamanaka's group is one of the pioneers of studies related to induced pluripotent stem cells. Yamanaka et al. studies like [30] where they reported the possibility of reprogramming of somatic cells into a primordial embryonic stem cell-like state, capable of differentiating into all three germ layers. There are several studies demonstrating the application of iPSCs in tissue engineering like [31], where they reported the ability of polyethersulfone scaffolds seeded with iPSCs to regenerate cranial bone. The authors concluded that iPSCs seeded with polyethersulfone scaffolds promoted and stimulated cranial bone formation compared to scaffold alone. In similar scaffold study design, Liu used an Arg-Gly-Asp-grafted calcium phosphate cement scaffold seeded with iPSC-MSCs overexpressing NELL1 that were efficient to improve osteogenic differentiation process [32]. However, this report was challenged by [33] reporting that osteogenic abilities of iPSCs can only be realized by scaffolds fabricated with calcium phosphate alone in an ex vivo model. The use of iPSCs in tissue engineering has been reported using animal model by Lian and colleagues, in their mouse model of limb ischemia study. They reported that iPSC-MSCs were more efficient compared to adult BM-MSCs [34] based on their more efficient survival and engraftment abilities after transplantation to induce tissue regeneration.
