There are two broad types of stem cells: 

Embryonic stem cells: Derived from up to 5th-day fertilized eggs (blastocyst stage). Due to their origin, they are highly controversial and the subject of many bioethical debates in the media. 

Adult stem cells: Adult stem cells are isolated from newborns, children and adults

There are many populations of adult stem cells, such as hematopoietic, mesenchymal, endothelial etc. Mesenchymal stem cells can be isolated from many tissues, such as bone marrow, umbilical cord, adipose tissue etc. More specifically, the section known as “Wharton’s Jelly”, is a rich and readily available source of non-hematopoietic mesenchymal stem cells. These cells are different from hematopoietic stem cells of umbilical cord blood and cannot, therefore, be used for hematological disorders.

The umbilical cord tissue is rich in mesenchymal stem cells. It may, also, contain further resident stem cell populations with enhanced potency, which we do not know at present, due to its appearance during the early developmental period of ontogenesis. The immunogenicity of mesenchymal stem cells in combination with their broad differentiation to a variety of specialized cell types have important implications for the functional improvement/regeneration of diseased tissues. The beneficial effects of these cells can be, also, exerted in cotransplantation with hematopoietic stem cells, whereby the mesenchymal stem cells promote the faster engraftment and expansion of the hematopoietic stem cells.

The lack of stringent histocompatibility requirements, also, increases the potential use of these stem cells by all members of the donor’s family.

The results of clinical trials using umbilical cord mesenchymal stem cells for tissue or organ regeneration (Regenerative Medicine) are highly promising for the treatment of currently refractory and degenerative diseases. Equally successful are the results of Tissue Engineering studies based on these stem cells, which have been used to generate artificial heart valves and blood capillaries.