Fetal Tissue Engineering: Regenerative Capacity of Fetal Stem Cells

Abstract

Considerable debate has focused on the contrasting merits of embryonic and adult stem cells. Fetal stem cells represent an intermediate cell type in this controversy. Adult stem cells have limited capacity to differentiate into fully functioning mature cell types of their tissue of origin (multipotent), whereas embryonic stem cells (ESCs) have the advantageous capacity to develop into all tissue types (pluripotent), including trophoblasts (totipotent). However, ESC research has been hampered by both safety concerns and ethical reservations due to requisite destruction of the blastocyst during harvesting. Transplantation of ESCs is almost invariably followed by the development of embryonal teratomas, precluding cell transplantation. On the other hand, adult stem cells have the advantage of greater accessibility, but the disadvantage of more limited proliferative capacity and restricted plasticity. Nevertheless, adult mesenchymal stem cells (MSCs) can differentiate into a range of mesoderm-derived tissues such as bone, fat and cartilage, while adult haemopoietic stem cells (HSCs) can reconstitute the haemopoietic system. The plasticity of ESC might seem to give them a therapeutic advantage over adult stem cells, whereas, in effect, this limits potential therapeutic application as a result of oncogenicity. So it is adult stem cells that hold promise for cell transplantation, while the eventual clinical use for ESCs is likely to be in tissue engineering applications.