Question

Stem cells have been long chosen for different types of tissue engineering. Therefore, the stem cells should be number one choice of any type of tissue engineering, do you agree? Why or why not?

Answer 1

Stem cells are capable of self renewal and can differentiate in different lineages of cells. These differentiate cells can the repair damaged tissue/organ and function as the original tissue/organ. The stem cells used in tissue engineering can be from same donor(autologous) or different donor (allogenic). It is beneficial as different tissues types can be obtained, if environmental conditions for differentiation are optimal. Human cardiomyocytes can be used to prevent heart diseases. As the stem cells can self-renew, large number of tissue cells can be obtained form the small number of stem cells.

However, stem cells have some disadvantages. Allogenic transplants may cause immune reactions. Although immunosuppressants may have to be administered, rejection of stem cells is a primary concern. Gene editing of induced pluripotent stem (iPS)cells have been used to correct the defects in the donor stem cells, which can then be used for tissue engineering. These edited stem cells will reduce donor rejections

They may become oncogenic as in iPS cells, there is use of oct4, SOX and other genes that can turn oncogenic. Stem cells have unlimited capacity to divide and hence can turn oncogenic an induce tumors/teratomas. There are also issue with compatibility, transplantation and long-term survival of stem cells in engineered tissues. There are also ethical and social issues liked to use of embryonic stem cells. Compatibility of the tissue engineering material also has hindered the use of these stem cells for tissue engineering. Costs are also high in developing this technology. Adult stem cells are difficult to isolate and have limited applications. Further, stem cell technology is still in its infancy and more research has to be done before it can be successfully applied to many fields. Stem are cultured on feeder layers, which increase the possibility of xenografic transfer of infections etc. Differentiation protocols of many cells from stem cells are still unknown.

Hence, even if stem cells are attractive cells for tissue engineering, the technology has still drawbacks that need to be addressed before being first line of choice in tissue engineering.