Editing Germ cell (section)

==Induced differentiation==
Inducing differentiation of certain cells to germ cells has many applications. One implication of induced differentiation is that it may allow for the eradication of male and female factor infertility. Furthermore, it would allow same-sex couples to have biological children if sperm could be produced from female cells or if eggs could be produced from male cells. Efforts to create sperm and eggs from skin and embryonic stem cells were pioneered by Hayashi and Saitou's research group at Kyoto University.<ref>{{cite journal | vauthors = Hayashi K, Ogushi S, Kurimoto K, Shimamoto S, Ohta H, Saitou M | title = Offspring from oocytes derived from in vitro primordial germ cell-like cells in mice | journal = Science | volume = 338 | issue = 6109 | pages = 971–975 | date = November 2012 | pmid = 23042295 | doi = 10.1126/science.1226889 | s2cid = 6196269 | bibcode = 2012Sci...338..971H | doi-access = free }}</ref> These researchers produced primordial germ cell-like cells (PGLCs) from embryonic stem cells (ESCs) and skin cells in vitro.

Hayashi and Saitou's group was able to promote the differentiation of embryonic stem cells into PGCs with the use of precise timing and bone morphogenetic protein 4 (Bmp4). Upon succeeding with embryonic stem cells, the group was able to successfully promote the differentiation of induced pluripotent stem cells (iPSCs) into PGLCs. These primordial germ cell-like cells were then used to create spermatozoa and oocytes.<ref>{{cite journal | vauthors = Cyranoski D | title = Stem cells: Egg engineers | journal = Nature | volume = 500 | issue = 7463 | pages = 392–394 | date = August 2013 | pmid = 23969442 | doi = 10.1038/500392a | doi-access =  | bibcode = 2013Natur.500..392C | s2cid = 34253 }}</ref>

Efforts for human cells are less advanced due to the fact that the PGCs formed by these experiments are not always viable. In fact Hayashi and Saitou's method is only one third as effective as current in vitro fertilization methods, and the produced PGCs are not always functional. Furthermore, not only are the induced PGCs not as effective as naturally occurring PGCs, but they are also less effective at erasing their epigenetic markers when they differentiate from iPSCs or ESCs to PGCs.

There are also other applications of induced differentiation of germ cells. Another study showed that culture of [[human embryonic stem cell]]s in mitotically inactivated [[porcine ovarian fibroblast]]s (POF) causes differentiation into germ cells, as evidenced by [[gene expression]] analysis.<ref>{{cite journal | vauthors = Richards M, Fong CY, Bongso A | title = Comparative evaluation of different in vitro systems that stimulate germ cell differentiation in human embryonic stem cells | journal = Fertility and Sterility | volume = 93 | issue = 3 | pages = 986–994 | date = February 2010 | pmid = 19064262 | doi = 10.1016/j.fertnstert.2008.10.030 | doi-access = free }}</ref>