Researchers are expanding their understanding of identified adult stem cells, which include blood-forming, brain, skin and skeletal muscle stem cells, while working to isolate stem cells for the lung, liver, kidney, heart and other tissues. This work is providing the basis for ongoing preclinical and clinical trials of organ and tissue regeneration from healthy adult stem cells.With the capability of self-renewal, pluripotency and differentiation, stem cells have been believed to be useful for treatment of a wide variety of diseases in the future, including stroke, traumatic brain injury, Alzheimer’s disease, Parkinson’s disease, spinal cord injury, baldness, blindness, deafness, wound healing, amyotrophic lateral-sclerosis, myocardial infarction, muscular dystrophy, osteoarthritis rheumatoid arthritis, Crohn’s disease, and diabetes. Amongst the applications, a number of adult stem cell therapies have already been practiced clinically. As an example, hematopoietic stem cell transplantation has been successfully applied to treat leukemia.
In addition to cell replacement therapy using stem cells, organ transplantation has been successfully practiced in clinics for organ failure of the liver or kidney. However, the severe shortage of donor organs has become the main obstacle to expand the organ transplant program. Generation of biological or semi-biological organs could be an alternative approach to solve the problem of the donor organ shortage. Notably, researchers have been hunting for ways to establish a whole organ using stem cells.
Although organogenesis is a complex process, the organ generation systems using stem cells or a combination of stem cells and tissue engineering may be applied, or at least raise the hope, to treat organ failure in humans in the near future. Besides adult tissue stem cells and embryonic stem cells, recent burgeoning and promising development of technology of induced pluripotent stem cells opens a new avenue for potential cell replacement and organ generation. Relevant to generation of functional organs, it is worth-mentioning that functional hepatocyte-like cells can be generated from induced pluripotent stem cells and the liver can be partially reconstituted.
Stem cell therapy may one day not only repair tissue damage but also generate new tissues for tissue/organ transplantation. Even though it is still at an infancy stage, these studies may hold promise for generation of specific functional organs for organ transplantation, to help solve the clinical problem of donor shortage.