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Stem Cell Therapy and Neurodegenerative Diseases
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ew diseases are as terrifying as neurodegenerative diseases. Classified as disorders that target the central or peripheral nervous system, neurodegenerative diseases are amongst the most difficult disorders for patients, doctors, and researchers.1 Without long term symptomatic relief from existing treatments, these diseases place the healthcare system under considerable strain.2 Of all the conditions encompassed by the broad umbrella of neurodegenerative disease, Huntington’s disease (HD) and Parkinson’s disease (PD) are two common disorders that affect seven million people worldwide.2 Each disease has unique molecular mechanisms that present challenges to existing modes of treatment. Huntington’s disease is an inherited disease linked to a dominant genetic mutation that triggers the production of toxic proteins that kill medium spiny neurons, a type of neuron that performs the crucial function of receiving dopamine signals.3 Unlike Huntington’s disease, which induces damage to receptor cells, Parkinson’s disease is characterized by a loss of dopamine-supplying (DA) neurons due to an accumulation of misfolded proteins. This may alter the cellular environment enough to damage DNA and compromise neuron survival.3 Huntington’s disease patients generally suffer neuropsychiatric symptoms, while PD patients are affected by both motor and psychiatric symptoms. Both diseases are considered “incurable,” in that current treatments are only stop-gap measures, toothless against the inevitable breakdown of the brain. Even symptomatic-relief care for PD sometimes fails, as the strategy of supplying
Written By Beatrice Han Designed By Avi Singh
pharmaceutical agents that convert to dopamine in the brain suffers from declining efficacy over time. Worse, it triggers adverse side effects, including worsening motor control and impulse control disorders.4 Fortunately, stem cell therapies offer an alternative option. Stem cells differentiate into many other cell lines and have the capacity to restore lost neurons and repair damaged cellular environments. For HD especially, marked by the loss of a specific cell line, stem cell therapy is an especially attractive option. With no natural consistent source of neurogenesis in the central nervous system, where most neurodegenerative diseases are localized, the need for stem cell therapies is especially urgent.5 Mesenchymal stem cells (MSCs) provide a promising solution for neurodegenerative disease treatment with their ability to differentiate into non-mesoderm derived cells like neurons. Unlike embryonic stem cells–the prototypical stem cell with almost unlimited differentiation capacity– MSCs are adult stem cells taken from mesodermal tissue, including bone, cartilage, and muscle.5 MSCs sidestep the thorny ethical controversies that plague ESCs, which face pushback because they are sourced from fetal tissue.2 Because MSCs display the unique capacity to “home” in on injured tissues, they are considered promising targets for future treatments.7 This selectivity is especially important because MSCs may be able to cross the blood brain barrier–which Spring 2022 | PENNSCIENCE JOURNAL 29
