Current uses of Stem Cell Treatments
Stroke and traumatic brain injury lead to cell death, characterized by a loss of neurons and oligodendrocytes within the brain. Healthy adult brains contain neural stem cells, these divide and act to maintain general stem cell numbers or become progenitor cells.
In healthy adult animals, progenitor cells migrate within the brain and function primarily to maintain neuron populations for olfaction (the sense of smell). Interestingly, in pregnancy and after injury, this system appears to be regulated by growth factors and can increase the rate at which new brain matter is formed.
In the case of brain injury, although the reparative process appears to initiate, substantial recovery is rarely observed in adults, suggesting a lack of robustness.
Recently, results from research conducted in rats subjected to stroke, suggested that administration of drugs to increase the stem cell division rate and direct the survival and differentiation of newly formed cells could be successful. In the study referenced below, biological drugs were administered after stroke to activate two key steps in the reparative process.
Findings from this study seem to support a new strategy for the treatment of stroke using a simple elegant approach, aimed at directing recovery from stroke by potentially protecting and/or regenerating new tissue. The authors found that, within weeks, recovery of brain structure is accompanied by recovery of lost limb function suggesting the potential for development of a new class of stroke therapy or brain injury therapy in humans.
Research injecting neural (adult) stem cells into the brains of dogs has shown to be 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 induced intracranial tumours in rodents.
Then, they injected human neural stem cells. Within days the cells had migrated into the cancerous area and produced cytosine deaminase, an enzyme that converts a non-toxic pro-drug into a chemotheraputic agent. As a result, the injected substance was able to reduce tumor mass by 81 percent. The stem cells neither differentiated nor turned tumorigenic.
Some researchers believe that the key to finding a cure for cancer is to inhibit cancer stem cells, where the cancer tumor originates. Currently, cancer treatments are designed to kill all cancer cells, but through this method, researchers would be able to develop drugs to specifically target these stem cells.
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 that she can now walk on her own, without difficulty.
The patient had not been able stand up for roughly 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. 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.
The researchers have followed up with a case study write-up on their work. It is located in the journal Cytotherapy. According to the October 7, 2005 issue of The Week, University of California researchers injected human embryonic stem cells 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 which insulates neural impulses and speeds them up, facilitating communication with the brain (damage to which is often the cause of neurological injury in humans).
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.
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