Severe Combined Immunodeficiency (SCID), or “Bubble Boy Disease,” is caused by a genetic mutation that severely weakens the immune system. Stem cell approaches involve removing the blood-forming stem cells that eventually become immune cells, then modifying them so that they do not have the mutation. These blood-forming stem cells can then be transplanted back into the patient to make normal immune cells.
In leukemia, there is a population of cells, known as leukemia stem cells, that are resistant to treatment that works on other leukemia cells. Scientists are investigating the use of drugs that can specifically identify and then kill these leukemia stem cells. In essence, this type of therapy might not be classified as a stem cell therapy, but rather a therapy that treats a disease caused by stem cells.
Most tumors rely on a small population of cancer stem cells, which can be thought of as the "evil twins" of normal, "good" stem cells: rather than dividing to repair and heal tissue, they divide to form tumors. The cancerous cells can cloak themselves from the immune system and avoid attack, which is how they survive even after chemo and radiation. Clinical trials in California are testing a treatment to identify and "uncloak" the cancerous stem cells from the immune system, and to make sure they are completely wiped out by treatment, reducing the chance of a relapse.
Scientists are using stem cells from Parkinson’s disease (PD) patients to see if already-discovered drugs might be useful in treating symptoms of the disease. Another approach involves creating functional brain cells in the lab, with the hope that they might replace the cells that are damaged in PD. It’s possible that one day, cells could be transplanted into the brain of Parkinson’s patients to treat the disease.