Transplanted brain stem cells might survive without anti-rejection drugs


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A recent experiment, testing brain stem cells transplant, has shown a positive result and might eliminate the need for life long anti-rejection drugs.

The John Hopkins Medicine researchers have developed a way to successfully transplant protective brain cells in mice, without the need of anti-rejection drugs. The report was published in September in the science journal, Brain, elaborating on the findings and presenting a new approach towards the advancement.

Approximately 1 out of every 100,000 children in US suffer some type of brain deformity, including Pelizaeus Merzbacher disease – characterized by infants missing certain developmental milestones. The patients might suffer from muscular spasms and partial paralysis of the limbs.

The research could increase the number of potential solutions/ therapies that could help children with rare genetic diseases – in which myelin, a protective coating of the neurons, in not produced, leading to a delay in transfer of messages.

According to Piotr Walczak, M.D., Ph.D., associate professor of radiology and radiological science at Johns Hopkins, “Because these conditions are initiated by a mutation causing dysfunction in one type of cell, they present a good target for cell therapies, which involve transplanting healthy cells or cells engineered to not have a condition to take over for the diseased, damaged or missing cells”.

He further explained, “A major obstacle to our ability to replace these defective cells is the mammalian immune system. The immune system works by rapidly identifying ‘self’ or ‘nonself’ tissues, and mounting attacks to destroy nonself or “foreign” invaders. While beneficial when targeting bacteria or viruses, it is a major hurdle for transplanted organs, tissue or cells, which are also flagged for destruction”.

Previously, the unspecific anti-rejection drugs, along with protecting the transplanted organ, weaken the immune system – leaving the patient vulnerable to infections and other side effects. Leaving them with the need to remain on the medicines indefinitely.

Walczak and his team injected the mouse brains with protective glial cells – that produce myelin sheath for neuron protection. The cells were previously inserted with the glowing gene to help the researchers detect them.

via Penn State

The cells were transplanted into three types of mice:

  1. Mice genetically engineered to not form the glial cells that create the myelin sheath
  2. Normal mice
  3. Lab bred mice that were unable to mount an immune response

Antibodies were used, for 6 days, to block an immune response against the transplanted cells. Afte the treatment, specialized cameras were used to detect the glowing cells – capturing the picture of the rodent’s brains. The results showed an increased death rate in the mice that did not receive the antibody treatment, and their glow was completely vanished by day 21.

The mice that received the antibody treatment managed to maintain a significant level of transplanted cells for over 200 days – showing they were not killed by the mouse’s T cells, even when there was no treatment.

The cells were also populating the correct parts of the brain and producing myelin sheath, proving the experiment was successful. According to the lead author of the study, Shen Li, M.D., “The fact that any glow remained showed us that cells had survived transplantation, even long after stopping the treatment. We interpret this result as a success in selectively blocking the immune system’s T cells from killing the transplanted cells.”


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