Henry E. Young, Mark O. Speight.
Numerous studies demonstrated the ability of stem cells in general, and endogenous adult stem cells in particular, to be a positive influence in the field of regenerative medicine. Endogenous naturally-occurring stem cells comprise approximately 50% of all cells in an adult organism. Within this group are two categories of cells based on the absence or presence of the enzyme telomerase. Telomerase-negative stem cells comprise approximately 40% of all cells in a post-natal adult, while the telomerase-positive stem cells comprise approximately 10%. Telomerasenegative stem cells are comprised of multipotent adult progenitor cells, mesenchymal stem cells, medicinal signaling cells, multilineage differentiating stress enduring cells, etc. Telomerase-negative progenitor stem cells have a restricted ability for cell doubling, based on Hayflick’s Limit for humans of 50-70 population doublings before programmed senescence and cell death. While there has been a virtual explosion of papers detailing the attributes of various forms of telomerase-negative stem cells in the field of regenerative medicine, relatively few papers have been published with respect to telomerase-positive stem cells. The following is a review of work detailing the basic science characterization of telomerase-positive stem cells as well as their use in regenerative medicine.View pdf