Functional Germ Cells From Non-Testicular Adult Stem Cells: A Dream or Reality?

Abstract

Some research studies provided evidence for the differentiation capacity of adult stem cells (ASCs) into germ cells (GCs). Since the generation of GCs from stem cells (SCs) has been proposed as a potential way for treatment of infertility, many research groups have begun their creative studies on generation of new GCs both in vitro and in vivo, and utilized different ASC types such as bone marrow mesenchymal stem cells (BM-MSCs), skin stem cells, pancreatic stem cells, and adipose tissue MSCs. Despite many interesting reports with promising results, an obvious problem in the research projects was the functionality of the produced GCs. In this paper, we have reviewed the results of almost all previously published reports on derivation of male and female GCs from ASCs to provide a better insight into this field of research. The most evaluated papers have shown that ASCs from various tissues can differentiate into GCs but rarely were the produced GCs functional and could form fertile gametes neither in vitro, nor in vivo (after transplantation into the gonads). There are still so many unknown issues about gametogenesis. Perhaps making alterations in treatment methods and utilizing creative techniques like tissue engineering and gene targeting help to achieve a standard method of in vitro GC production from ASCs.