Background:  A number of reports have shown that mesenchymal stem cells (MSCs) from various sources expressed a number of germ cell (GC)-specific genes innately,  but almost none of these studies were quantitative in nature. This study, however, tried to determine and compare the expression levels of some famous GC-specific genes in human male bone marrow (BM)- and peripheral blood (PB)-MSCs.
Methods: Human BM- and PB-MSCs were isolated using a density gradient factor and centrifuging. Then, Passage 3 of both cell types were characterized through flow cytometric analysis and the differentiation test. They were then evaluated by real time RT-PCR for the expression levels of GC-specific genes.  
Results: Both cell types obviously expressed c-kit, Dazl, Fragilis, Itgb1, Nanos3, Oct4 and Blimp1 at high levels. The only exception was Itgb1, which was expressed at a higher level in PB-MSCs than in BM-MSCs (p<0.05). The levels of expression for other markers were almost similar in both cell types. Different levels of Itgb1 expression could be due to their different niches. Furthermore, both cell types were negative for Fkbp6, Stra8, Scp3, Tex13 and Vasa, and they both expressed Stella weakly. Moreover, it should be stated that BM-MSCs had low expression levels of Piwil2, and that this marker was not expressed in PB-MSCs.
Conclusion: Overall, it could be concluded that BM- and PB-MSCs have a little bit different GC-specific gene expression patterns. Although these results are very revealing, many detailed and creative research studies need to be conducted to find appropriate ways of using MSCs in cell-based therapies of infertility.