Regenerative Medicine and the Promise of Stem Cell Research

Stem cells (SCs) have the ability to develop into many other types of cells. Totipotent cells known as blastomeres have the additional ability to develop into an individual organism. Pluripotent cells can develop into any kind of cell. Multipotent cells can develop into a variety of cells in a given lineage such as connective tissue cells or epithelial cells.

Pluripotent cells include embryonic stem cells, certain cells isolated from umbilical cord blood, and adult stem cells which are found in bone marrow, the brain, and other locations. Overall, SCs may be able to provide replacement tissue for the treatment of many life-threatening diseases. Specialized cells and tissues derived from SCs may be used to treat Alzheimer's disease, Parkinson's disease, stroke, Huntington's disease, amyotrophic lateral sclerosis (Lou Gehrig's disease), cancer, diabetes, multiple sclerosis, muscular dystrophies, and rheumatoid arthritis.

Also, research on SCs may lead to the ability to grow organs such as the heart, kidney, liver, and pancreas. These brand-new organs would be used for transplantation, solving the ongoing severe shortages of suitable available replacements. Ultimately it may be possible to grow organs from stem cells derived from a person's own somatic cells (such as a skin cell). A skin cell would be reprogrammed to become an induced pluripotent stem cell (iPS cell), and the iPS cell would be directed to become a kidney, liver, or whatever organ was needed. The astounding benefit of being able to use iPS cells is that the donor and the recipient are the same person. The organ created is an automatic immunologic match, thus avoiding the need for immunosuppressive drugs.

Treatment of a child with leukemia would no longer require a time-consuming and possibly fruitless search for a bone marrow donor. Those requiring a new kidney or new lung could provide skin cells that would be directed to grow the needed organ. Replacement parts would no longer be sought from parents, siblings, or first cousins. Graft-versus-host disease, which has the potential to kill the recipient, would be eliminated by using the patient's own tissue to create the transplant.

SC research will also lead to new developments in gene therapy for conditions such as muscular dystrophy and Huntington's disease. At present, a significant roadblock to successful gene therapy is the mechanism of delivery of the replacement genes. Early approaches packaged the replacement genes into viruses, using the viral particles as the delivery vector. The field of gene therapy effectively came to a sudden halt in 1999 when a teenager died as a result of being treated with such a viral vector. Insertion of replacement genes in stem cells derived from the patient will eliminate the possibility of such harm.

Stem cells have been used in the successful treatment of chronic disease, slowing of the aging process, organ transplantation, and improved methods of treating severe injuries. Stem cell research and the possibility of regenerative medicine are pointing the way toward improved health and well-being for hundreds of millions of people around the world. Many practical roadblocks remain and there are many grand challenges in this brand-new field. The key is to make possible ongoing research.