Science fiction was once the genre that best fit stem cell therapy. But for patients suffering from conditions as varied as cancer, heart disease, broken bones, and paralysis, stem cell therapy may soon become science fact.
Stem cells are the building blocks of our bodies that have not yet been assigned special tasks. Think of them as blank microchips before they have been programmed. Stem cells can turn into a variety of different cells, from a heart cell to a nerve cell; given particular chemical signals they can be transformed into anything.
Adult stem cells exist in a wide range of tissues including bone marrow, muscle, the brain and liver. They are already halfway down the career path to becoming a certain type of cell.
Around 600 clinical trials are presently underway worldwide involving stem cells. The UK looks to be a center for more research and may perhaps even set the pace for everyone one else.
New uses for stem cells include treatment for diseases that are major killers and cause long-term disability. For instance, bone-marrow transplants, used for some time as a treatment for leukemia, may soon be replaced with stem cell therapies. Other potential uses of stem cells range from creating new faces and hair, to growing sperm, building replacement limbs, growing new heart cells, and growing new retina tissue for the visually impaired.
Splints and bandages or casts remain the status quo as treatment for broken bones. This has not changed for many centuries. There could be a shake-up in treatment methods soon as clinical trials are underway evaluating stem cells and their capacity to mend fractured bones. Researchers are looking at the notion of repairing fractures with stem cells and as a growth factor to accelerate bone healing. Osteoporosis, which causes brittle bones, is also a prospective candidate for therapeutic stem cell treatment. Eventually leading to osteoporosis, bone loss exceeds production as we age. Stem cell therapy could restore the balance.
Used in trials to tackle the damage caused by a heart attack, stem-cell therapy is already producing results as well as demonstrating the potential to grow new blood vessels to get around blockages. In the UK, almost three million people have heart disease. Limiting the quantity of damage, growing new heart muscle, and increasing the pumping ability of the heart is the idea behind administering stem cell injections after a heart attack. A second goal, a so-called grow-your-own bypass, involves injecting stem cells to grow new blood vessels and re-route blood and oxygen around damaged areas of the heart.
Stem cells have the potential to make radical changes in this area. Already used on a small number of patients, researchers hope that stem cells can be injected on to specially shaped scaffolds in order to help fill defects in the face. Stem cells taken from the hip bone to close the bone defect in cleft palate is also being investigated by dental researchers at the University of Brescia in Italy.
The most tantalizing image of stem-cell potential in dentistry is growing teeth, however changes are closer in other areas. Nippon Dental University researchers in Japan have shown that injecting stem cells into the area where a tooth has been extracted can strengthen the bone and support surrounding healthy teeth, while Orthodontists in Naples have found they can get stem cells from dental pulp in extracted molars.
There is currently no therapy to reverse the effects of brain injury, but studies on animals have shown that stem cells from bone marrow can improve outcomes. Around one in four children who suffer brain injury die as a result. A clinical trial involving children aged five to 14 with a serious head injury has begun at the University of Texas. The hope is that the stem cells will help with repairs. Within 36 hours of injury, the children will be given injections of stem cells to see how it affects their recovery.
Rheumatoid arthritis, where the immune system attacks healthy tissue, has been treated with stem-cell therapy. Around 700 patients have been treated with stem cells for this illness along with other autoimmune diseases. In this therapy, the old marrow is removed, chemotherapy is given to zap any remaining cells, and stem cells are used to build a new immune system. Research at Leiden University in Holland shows that in about one in three cases, remission has been achieved. Immunologists in America have reported the first case of a woman being treated with stem cells from her sister as opposed to most cases, where the patient’s own cells are used. The 52-year-old was in remission and not needing any drugs only a year after transplantation.
Cancer is the disease against which stem-cell therapy has been most widely used. Leukemia treatment is especially important, as success depends on getting rid of cancerous white blood cells and replacing them with healthy ones – usually achieved through a bone-marrow transplant. With more than 400 clinical trials under way, the use of stem cells to tackle cancer has been extended, almost every kind of malignancy is being looked at. In many of the trials, those cells that are killed by the use of chemotherapy are replaced with stem cells.
With type one diabetes, which usually develops in childhood, the body does not produce its own insulin and daily injections are needed. The aim of stem-cell therapy is to replace those insulin producing immune cells that have been destroyed by the body’s immune system. Patients are being given chemotherapy and then infused with stem cells from bone marrow in a trial being run by Northwest University in Chicago: “We hypothesized that reprogramming the immune system will stop immune aggression to the insulin-producing cells, allowing their regeneration,” say researchers.
Superman actor Christopher Reeve, paralyzed in a horse-riding accident, was one of the leading campaigners for stem-cell research. Scientists are reporting success with small numbers of paralyzed patients, although large clinical trials are still in the future. The idea behind the therapy is that the stem cells can grow into nerve cells to replace those that are permanently damaged, and bridge the gap between the severed pieces of the spinal cord. Researchers in Argentina are reporting the restoration of movement in two patients.
Thought to be caused by immune cells attacking tissue, Crohn’s disease is a bowel disorder. A trial is looking at the use of chemotherapy followed by an infusion of the patient’s own stem cells. “The purpose of the chemotherapy is to destroy the immune system completely. The purpose of the stem cell infusion is to restore the body’s blood production,” say Northwestern University researchers.
In MS, myelin, the protective coat that surrounds nerve cells, is damaged or destroyed by immune-system cells. The aim of stem-cell therapy is to use chemotherapy to destroy the malfunctioning immune system, and repopulate it with stem cells. A pilot study found that 18 of 19 MS patients stabilized or improved after treatment, according to the US National Institute of Allergy and Infectious Diseases and the Immune Tolerance Network, who are sponsoring one trial.
Parkinson’s and a number of other neurological diseases have hope in stem cell therapy. To replace cells lost to the disease, the idea is to coax stem cells into becoming dopamine-producing nerve cells. The treatment being explored is transplanting stem cells into the target sites of the brain that need dopamine. Dopamine is a chemical that allows messages to be sent to the parts of the brain that co-ordinate movement. Animal studies are under way.