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Epilepsy is a group of disorders in which an individual suffers from seizures. The seizures can be mild to severe, and a variety of factors can induce the seizure in the individual. Often times, the cause of the epilepsy is unknown, a condition called idiopathic epilepsy. The seizures are believed to be caused by over active nerve cells within various regions of the brain, although this has not been definitively proven. When the nerve cells become over active, they fire continuously, causing muscle spasms and other symptoms associated with seizures. The seizures can cause injury if the patient falls or is repeatedly hitting a hard surface during the seizure.

Treatments for epilepsy involve administration of anti-seizure medications. However, in some severe cases, the medication is not sufficient to prevent seizures, and more advanced treatments are not yet available. Epileptic seizures can cause significant problems with day to day life. Many patients with severe forms of epilepsy have to limit daily activities in order to prevent accidental injury should a seizure occur. Even everyday activities such as driving can be very dangerous for a patient with epilepsy. Most treatments for epilepsy are preventative and must be taken long-term. A method to stop seizures permanently would significantly enhance quality of life for patients.

Cell therapy is an active area of research for epilepsy treatment. Many research teams have tried implanting inhibitory neural cells into the brain in hopes of stopping the rapid, uncontrolled firing of nerves that causes seizures. However, none of these studies have had successful results until recently. Researchers from the University of California at San Francisco have recently found a way to permanently treat epilepsy in a mouse model of epilepsy. The researchers implanted a specific nerve cell, called medial ganglionic eminence cells, into brains of the mice. Medial ganglionic eminence cells help to inhibit over active nerve signals. The cells were implanted into the hippocampus of the mice, which is a region of the brain associated with seizures. Once implanted into the hippocampus, the medial ganglionic eminence cells were able to permanently stop seizures in the mice. When the medial ganglionic eminence cells were transplanted into other areas of the brain, such as the amygdala, did not stop seizures in the mice.

There are still many caveats and concerns with moving this cell therapy into human patients. Firstly, mouse models of disease are artificially induced by humans. While they can approximate symptoms, and possibly even the cause of disease, the models are still different than the natural disease that occurs in humans. This alone makes it difficult to move potential therapies from mouse to humans. The mouse model of epilepsy was based on a severe, drug-resistant type of human epilepsy called mesial temporal lobe epilepsy. This form of epilepsy usually develops in adolescence, and normally occurs many years after a fever-induced seizure. Normal inhibitory neural cells are often depleted during the course of epilepsy, which may permit over active stimulation of neurons and result in seizures. In mice, the condition is induced using chemicals, which is a very different mechanism than induction by fever. The mouse model does have some similarities to human temporal lobe epilepsy. The seizures are very serious, and the inhibitory nerve cells are deleted as a result of the condition. The time frame is also very different, as mice have a much shorter lifespan than humans. Even though the injection of medial ganglionic eminence cells permanently stopped seizures in the mice, it may not be effective permanently in humans due to the different lifespan of mice and humans.

One of the many difficulties with developing successful cell therapy strategies is finding a method to generate a sufficient quantity of cells to treat patients. Another team of researchers at the University of California San Francisco also found a way to develop cells with similar functions to medial ganglionic eminence cells. When these cells were similarly injected in mice, the seizures were also stopped. However, the cells that are being transplanted into the patient would be donated from another person, or made from stem cells. This increases the likelihood of transplant rejection, which could be particularly problematic with the transfer of cells into the brain. In addition, transplantation of cells that have been developed from stem cells could potentially cause tumors. Stem cell therapy is also in experimental stages, and researchers and clinicians are still trying to determine optimized protocols to prevent such serious side effects.


References:

http://www.sciencedaily.com/releases/201...230317.htm