Adult Stem Cells (ASCs), by definition, are unspecialized or undifferentiated cells that not only retain their ability to divide mitotically while still maintaining their undifferentiated state but also, given the right conditions, have the ability to differentiate into different types of cells including cells of different germ-origin an ability referred to as transdifferentiation or plasticity.1,2 In vitro, the conditions under which transdifferentiation occurs can be brought about by modifying the culture medium in which the cells are cultured. In vivo, the same changes are seen when the ASCs are transplanted into a tissue environment different to their own tissue-of origin. Though the exact mechanism of this transdifferentiation of ASCs is still under debate, this ability of ASCs along with their ability to self-renew is of great interest in the field of Regenerative Medicine as a therapeutic tool in being able to regenerate and replace dying, damaged or diseased tissue.

Clinically, however, there are a few criteria that ASCs need to fulfill before they can be viewed as a viable option in Regenerative Medicine. These are as follows:3

Adds Millions of Stem Cells Back into Circulation.

Adipose Tissue Yields an Abundance of ASCs

Compared to any other source, the high concentrations of regenerative cells found in adipose tissue (depots of fat for storing energy) especially in the abdominal region, by sheer volume of availability, ensure an abundance in number of ASCs ranging in the millions per unit volume. The sheer number available also has the added advantage of not needing to be cultured in a laboratory over days in order to get the desired number of ASCs to achieve what is called therapeutic threshold i.e. therapeutic benefit. In addition, harvesting ASCs from adipose tissue through simple, minimally invasive liposuction under local anesthesia is relatively easier and painless and poses minimal risk to the patient compared to all other possible methods.

Adipose tissue ASCs (AT-ASCs) are extremely similar to stem cells isolated from bone marrow (BMSCs). The similarities in profile between the two types of ASCs range from morphology to growth to transcriptional and cell surface phenotypes.4,5 Their similarity extends also to their developmental behavior both in vitro and in vivo. This has led to suggestions that adipose-derived stem cells are in fact a mesenchymal stem cell fraction present within adipose tissue.6

Clinically, however, stromal vascular fraction-derived AT-ASCs have the advantage over their bone marrow-derived counterparts, because of their abundance in numbers eliminating the need for culturing over days to obtain a therapeutically viable number and the ease of the harvest procedure itself being less painful than the harvest of bone marrow. This, in theory, means that an autologous transplant of adipose-derived ASCs will not only work in much the same way as the successes shown using marrow-derived mesenchymal stem cell transplant, but also be of minimal risk to the patient.

AT-ASCs, like BM-ASCs, are called Mesenchymal ASCs because they are both of mesodermal germ-origin. This means that AT-ASCs are able to differentiate into specialized cells of mesodermal origin such as adipocytes, fibroblasts, myocytes, osteocytes and chondrocytes.7,8,9 AT-ASCs are also able (given the right conditions of growth factors) to transdifferentiate into cells of germ-origin other than their own. Animal model and human studies have shown AT-ASCs to undergo cardiomyogenic 10, endothelial (vascular)11, pancreatic (endocrine) 12, neurogenic 13, and hepatic trans-differentiation14 , while also supporting haematopoesis15.

Low Risk to the Patient

Excerpt from:
AdiStem -- Adult Stem Cells Derived from Adipose Tissue ...