Stem-cell therapy

Medical researchers believe that stem cell treatments have the potential to change the face of human disease and alleviate suffering. A number of current stem cell treatments already exist, although they are not commonly used because they tend to be experimental and not very cost-effective. In the future, medical researchers anticipate being able to use technologies derived from stem cell research to treat cancer, spinal cord injuries, and muscle damage, amongst a number of other diseases and impairments.

However, there still exists a great deal of social and scientific uncertainty surrounding stem cell research, which will only be overcome through years of intensive research and by gaining the acceptance of the public.

Furthermore, many technical difficulties remain which hinder the ultimate goals in stem cell therapeutics. Expanding stem cell populations extracted from patients remains a large problem. Also, even once these populations are expanded, implanted stem cells may not expand or grow efficiently enough to add enough corrective factor to be beneficial for treatment. These and other technical problems remain to be solved.

Current treatments

For over 30 years, bone marrow (adult) stem cells have been used to treat cancer patients with conditions such as leukemia and lymphoma. During chemotherapy, most growing cells are killed by the cytotoxic agents. These agents not only kill the leukemia or neoplastic cells, but also those which release the stem cells from the bone marrow. These are therefore removed before chemotherapy, and are re-injected afterwards.

Potential treatments

Cancer

Research injecting neural (adult) stem cells into the brains of dogs can be very successful in treating cancerous tumors. With traditional techniques brain cancer is almost impossible to treat because it spreads so rapidly. Researchers at the Harvard Medical School injected adult stem cells genetically engineered to convert a separately injected non-toxic substance into a cancer-killing agent. Within days the adult stem cells had migrated into the cancerous area and the injected substance was able to reduce tumor mass by 80 percent.

Spinal cord injury

A team of Korean researchers reported on November 25, 2004, that they had transplanted multipotent adult stem cells from umbilical cord blood to a patient suffering from a spinal cord injury and she can now walk on her own, without difficulty. The patient had not even been able stand up for the last 19 years. The team was co-headed by researchers at Chosun University, Seoul National University and the Seoul Cord Blood Bank (SCB). For the unprecedented clinical test, the scientists isolated adult stem cells from umbilical cord blood and then injected them into the damaged part of the spinal cord. While exciting, many more studies are required to establish that such treatments are effective.

Using stem cells, the tests were able to avoid triggering a negative bodily reaction, which are common in other transplantations, according to Hoon Han, one of the researchers. "We don’t need a strict match between cord blood stem cell type and the immune system of a patient because the latter accepts the former pretty well thanks to its immaturity," Han said. [1] [2] [3] [4] The Korean researchers have followed up on their original work. The original treatment was conducted in November 2004. On April 18, 2005, the researchers announced that they will be conducting a second treatment on the woman. [5] The researchers have followed up with a case study write-up on their work. It is located in the journal Cytotherapy. [6]

According to the October 7, 2005 issue of The Week, University of California researchers injected stem cells from aborted human fetuses into paralyzed mice, which resulted in the mice regaining the ability to move and walk four months later. The researchers discovered upon dissecting the mice that the stem cells regenerated not only the neurons, but also the cells of the myelin sheath, a layer of cells with which nerve fibers communicate with the brain (damage to which is often the cause of neurological injury in humans). [7]

In January 2005, researchers at the University of Wisconsin-Madison differentiated human blastocyst stem cells into neural stem cells, then into the beginnings of motor neurons, and finally into spinal motor neuron cells, the cell type that, in the human body, transmits messages from the brain to the spinal cord. The newly generated motor neurons exhibited electrical activity, the signature action of neurons. Lead researcher Su-Chun Zhang described the process as "you need to teach the blastocyst stem cells to change step by step, where each step has different conditions and a strict window of time."

Transforming blastocyst stem cells into motor neurons had eluded researchers for decades. The next step will be to test if the newly generated neurons can communicate with other cells when transplanted into a living animal; the first test will be in chicken embryos. Su-Chun said their trial-and-error study helped them learn how motor neuron cells, which are key to the nervous system, develop in the first place.

The new cells could be used to treat diseases like Lou Gehrig's disease, muscular dystrophy, and spinal cord injuries.

Muscle damage

Adult stem cells are also apparently able to repair muscle damaged after heart attacks. Heart attacks are due to the coronary artery being blocked, starving tissue of oxygen and nutrients. Days after the attack is over, the cells try to remodel themselves in order to become able to pump harder. However, because of the decreased blood flow this attempt is futile and results in even more muscle cells weakening and dying. Researchers at Columbia-Presbyterian found that injecting bone-marrow stem cells, a form of adult stem cells, into mice which had had heart attacks induced resulted in an improvement of 33 percent in the functioning of the heart. The damaged tissue had regrown by 68 percent.

Heart damage

Several types of heart disease have been treated in clinical trials and therapy is commercially available. Patients such as Jeannine Lewis[8] and legendary Hawaiian crooner Don Ho[9]have traveled to Thailand to receive stem cell therapy for their heart disease.

Using the patient's own bone marrow derived stem cells or more recently, peripheral blood-derived stem cells, Dr. Amit Patel at the University of Pittsburgh, McGowan Institute of Regenerative Medicine has shown a dramatic increase in ejection fraction for patients with congestive heart failure. He works with many other countries such as Argentina, Uruguay, Ecuador, Greece, Japan, and Thailand where he has taught minimally invasive techniques for the treatment of non-ischemic (idiopathic) and ischemic heart failure.

Low blood supply

In December 2004, a team of researchers led by Dr. Luc Douay at the University of Paris developed a method to produce large numbers of red blood cells. The Nature Biotechnology paper, entitled Ex vivo generation of fully mature human red blood cells, describes the process: precursor red blood cells, called hematopoietic stem cells, are grown together with stromal cells, creating an environment that mimics the conditions of bone marrow, the natural site of red blood cell growth. Erythropoietin, a growth factor, is added, coaxing the stem cells to complete terminal differentiation into red blood cells.

Further research into this technique will have potential benefits to gene therapy, blood transfusion, and topical medicine.

Baldness

Hair follicles also contain stem cells, and some researchers predict research on these follicle stem cells may lead to successes in treating baldness through "hair multiplication," also known as "hair cloning," as early as 2007. This treatment is expected to work through taking stem cells from existing follicles, multiplying them in cultures, and implanting the new follicles into the scalp. Later treatments may be able to simply signal follicle stem cells to give off chemical signals to nearby follicle cells which have shrunk during the aging process, which in turn respond to these signales by regenerating and once again making healthy hair. Hair Cloning Nears Reality as Baldness Cure (WebMD Nov. 2004)

Missing teeth

In 2004, scientists at King's College discovered a way to cultivate a complete tooth in mice [10] and were able to grow them stand-alone in the laboratory. Researchers are confident that this technology can be used to grow live teeth in human patients.

In theory, stem cells taken from the patient could be coaxed in the lab into turning into a tooth bud which, when implanted in the gums, will give rise to a new tooth, which would be expected to take two months to grow. [11] It will fuse with the jawbone and release chemicals that encourage nerves and blood vessels to connect with it. The process is similar to what happens when humans grow their original adult teeth.

Its estimated that it may take until 2009 before the technology is widely available to the general public, but the genetic research scientist behind the technique, Professor Paul Sharpe of King's College, estimates the method could be ready to test on patients by 2007 [12]. His startup company, Odontis, fully expects to offer tooth replacement therapy by the end of the decade.

Blindness

Since 2003, researchers have successfully transplanted retinal stem cells into damaged eyes to restore vision. Using embryonic stem cells, scientists are able to grow a thin sheet of totipotent stem cells in the laboratory. When these sheets are transplanted over the damaged retina, the stem cells stimulate renewed repair, eventually restoring vision [13].

The latest development was in June of 2005, when researchers at the Queen Victoria Hospital of Sussex, England were able to restore the sight of forty patients using the same technique. The group, led by Dr. Sheraz Daya, was able to successfully use adult stem cells obtained from the patient, a relative, or even a cadaver. Further rounds of trials are ongoing [14].

As more research yields increasingly precise techniques, stem cell transplantation to restore vision may become viable on a large scale. However, the success rate of the procedure is still low, from 20 to 70 percent [15], and further clinical research is intensely required before any credible claim can be made.