| Stem cells (SCs) have the ability to develop into | | | | drugs. |
| many other types of cells. Totipotent cells known | | | | Treatment of a child with leukemia would no |
| as blastomeres have the additional ability to | | | | longer require a time-consuming and possibly |
| develop into an individual organism. Pluripotent cells | | | | fruitless search for a bone marrow donor. Those |
| can develop into any kind of cell. Multipotent cells | | | | requiring a new kidney or new lung could provide |
| can develop into a variety of cells in a given | | | | skin cells which would be directed to grow the |
| lineage such as connective tissue cells or epithelial | | | | needed organ. Replacement parts would no longer |
| cells. | | | | be sought from parents, siblings, or first cousins. |
| Pluripotent cells include embryonic stem cells, | | | | Graft-versus-host disease, which has the potential |
| certain cells isolated from umbilical cord blood, and | | | | to kill the recipient, would be eliminated by using |
| adult stem cells which are found in bone marrow, | | | | the patient's own tissue to create the transplant. |
| the brain, and other locations. Overall, SCs may be | | | | SC research will also lead to new developments in |
| able to provide replacement tissue for treatment | | | | gene therapy for conditions such as muscular |
| of many life-threatening diseases. Specialized cells | | | | dystrophy and Huntington's disease. At present, a |
| and tissues derived from SCs may be used to | | | | significant roadblock to successful gene therapy is |
| treat Alzheimer's disease, Parkinson's disease, | | | | the mechanism of delivery of the replacement |
| stroke, Huntington's disease, amyotrophic lateral | | | | genes. Early approaches packaged the |
| sclerosis (Lou Gehrig's disease), cancer, diabetes, | | | | replacement genes into viruses, using the viral |
| multiple sclerosis, muscular dystrophies, and | | | | particles as the as the delivery vector. The field |
| rheumatoid arthritis. | | | | of gene therapy effectively came to a sudden |
| Also, research on SCs may lead to the ability to | | | | halt in 1999 when a teenager died as a result of |
| grow organs such as the heart, kidney, liver, and | | | | being treated with such a viral vector. Insertion of |
| pancreas. These brand-new organs would be used | | | | replacement genes in stem cells derived from the |
| for transplantation, solving the ongoing severe | | | | patient will eliminate the possibility of such harms. |
| shortages of suitable available replacements. | | | | Successful treatment of chronic disease. |
| Ultimately it may be possible to grow organs | | | | Successful treatment of genetic disease. Slowing |
| from stem cells derived from a person's own | | | | of the aging process. Organ transplantation. |
| somatic cells (such as a skin cell). A skin cell would | | | | Improved methods of treating severe injuries. |
| be reprogrammed to become an induced | | | | Stem cell research and the possibility of |
| pluripotent stem cell (iPS cell), and the iPS cell | | | | regenerative medicine are pointing the way |
| would be directed to become a kidney, liver, or | | | | toward improved health and well-being for |
| whatever organ was needed. The astounding | | | | hundreds of millions of people around the world. |
| benefit of being able to use iPS cells is that the | | | | Many practical roadblocks remain and there are |
| donor and the recipient are the same person. The | | | | many grand challenges in this brand-new field. The |
| organ created is an automatic immunologic match, | | | | key is to make possible ongoing research. |
| thus avoiding the need for immunosuppressive | | | | |