Читать книгу The SAGE Encyclopedia of Stem Cell Research - Группа авторов - Страница 366

The most readily identified potential for harm with SCT is that of tumorigenesis (secondary cancerous growths), since the cell’s inherent “stemness” is directly related to oncogenes such as cMyc, Rb, and ARF. In fact, a cell’s potential for tumorigenesis in the lab correlates directly to the cell’s stem viability ranking. While some consider it definitively impossible to separate the stem and tumorigenic character of iASC, there has been success in creating less tumor-prone mesenchymal stem cells as well as inducing adult stems cells after removal of the volatile oncogenes. Nonetheless, the possibility of secondary neoplasts remains significant. Theory suggests that iPSC/iASC might have a lesser tendency for tumor formation than embryonic stems cells; however, studies to date show both to be at roughly equal risk.

The most common tumors formed are teratomas, a generally benign encapsulated tumor resembling a normal derivative germ layer. Because teratomas are benign, risk can be mitigated based on transplant location, that is, tumor growth in cartilage is significantly less concerning than tumor growth in the central nervous system (CNS). However, recognized deaths resulting from SCT tumorigenesis have been documented, though it is unclear whether there is a generally increased mortality risk in SCT compared to other studies. Two famous cases involving the death of three Filipino legislators (treated out-of-country) and an infant treated at a private German clinic have drawn publicity to this concern; however, definitive evidence linking the congressmen’s deaths to SCT has not yet been found and the baby’s death was due to internal hemorrhaging from the procedure. The widespread proliferation of unapproved, medically unsupervised SCT may be skewing this data.