Transplantation of embryonic stem cell-derived motor neurons maintains the regenerative capacity of a chronically denervated peripheral nerve

Chronic denervation;transplantation;Neuroscience

Cashman, Christopher RDong, Xinghong ;

Johns Hopkins University

关键词: Chronic denervation;    transplantation;    Neuroscience;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/60673/%2aDissertationFINAL.docx?sequence=2&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Peripheral nerve injuries are common and often debilitating. While the peripheral nervous system can regenerate more efficiently than the central nervous system, it is severely limited by the slow rate of regeneration and long distance between the central nervous system and end organs in large animals like humans; distal areas of the nerve become chronically denervated and unable to support extending axons, even as the proximal aspect of the injury may be appropriately supportive of regeneration.To reduce chronic denervation in nerves, we propose the transplantation of motor neurons to effectively reduce the time and distance necessary for regeneration by creating a relay from the spinal cord to the muscle.Additionally, the transplanted neurons may widen the window to effective regeneration by supporting host cells that are responsible for guiding and facilitating regeneration until the nerve is fully recovered. In this dissertation, the preparation of mouse embryonic stem cell (mESC)-derived motor neurons was optimized, best transplant conditions identified, and regeneration assayed with examination of relay formation and endogenous support.In vitro co-culture systems were also developed to test primary rat motor neuron to mESC-derived motor neuron synaptogenesis, where calcium imaging during electrical depolarization suggested the two populations can form functional glutamatergic synapses.Pilot studies on immunodeficient animals prompted an investigation of the effect of immunodeficiency and degeneration.Ultimately, only mild differences in axonal degeneration and macrophage infiltration were observed between immunocompetent and immunodeficient animals, with no differences in myelin phagocytosis.Finally, mESC-derived motor neurons were transplanted into immunosuppressed rats where they supported host regeneration in a chronically denervated nerve effected by two- and three-month gaps between transplant and repair. Facilitation of regeneration resulted from both relay formation and endogenous support.The finding that transplanted neurons may facilitate regeneration in a chronically denervated nerve suggests that future therapies, such as neuron-embedded nerve guides connected serially to span a gap or secretion of the factors that support host cells, may minimize the morbidity of otherwise devastating peripheral nerve injuries.