Editing Stem cell (section)

===Identification===
In practice, stem cells are identified by whether they can regenerate tissue. For example, the defining test for bone marrow or [[hematopoietic stem cell]]s (HSCs) is the ability to transplant the cells and save an individual without HSCs. This demonstrates that the cells can produce new blood cells over a long term. It should also be possible to isolate stem cells from the transplanted individual, which can themselves be transplanted into another individual without HSCs, demonstrating that the stem cell was able to self-renew.

Properties of stem cells can be illustrated ''[[in vitro]]'', using methods such as [[clonogenic assay]]s, in which single cells are assessed for their ability to differentiate and self-renew.<ref>{{cite journal | vauthors = Friedenstein AJ, Deriglasova UF, Kulagina NN, Panasuk AF, Rudakowa SF, Luriá EA, Ruadkow IA | title = Precursors for fibroblasts in different populations of hematopoietic cells as detected by the in vitro colony assay method | journal = Experimental Hematology | volume = 2 | issue = 2 | pages = 83–92 | year = 1974 |id={{INIST|PASCAL7536501060}} {{NAID|10025700209}} | pmid = 4455512 }}</ref><ref>{{cite journal | vauthors = Friedenstein AJ, Gorskaja JF, Kulagina NN | title = Fibroblast precursors in normal and irradiated mouse hematopoietic organs | journal = Experimental Hematology | volume = 4 | issue = 5 | pages = 267–274 | date = September 1976 | pmid = 976387 }}</ref> Stem cells can also be isolated by their possession of a distinctive set of cell surface markers. However, ''in vitro'' culture conditions can alter the behavior of cells, making it unclear whether the cells shall behave in a similar manner ''[[in vivo]]''. There is considerable debate as to whether some proposed adult cell populations are truly stem cells.<ref>{{Cite journal | vauthors = Sekhar L, Bisht N |date=2006-09-01 |title=Stem Cell Therapy |journal=Apollo Medicine |volume=3 |issue=3 |pages=271–276 |doi= 10.1016/S0976-0016(11)60209-3 }}</ref>