This continuation proposal will examine the cellular events regulating survival of fetal neural transplants, particularly as they relate to the cerebrovasculature and the blood-brain barrier (BBB). Findings will be related to those seen in normal brain development and brain injuries. Neurotransplants provide a circumstance in which angiogenic and BBB disturbances occur. The PI has a long interest in studying the metabolic and anatomic circumstances associated with this disruption. Since neurotransplants must survive for many days without normal vascularization, tissue must be subjected to metabolic stress including hypoxia and acidosis. The PI has been a leader in studying the integrity and disruption of the BBB by biochemical and anatomic means. In this renewal, the PI will examine the early critical periods when CNS grafts, initially without a physiologically regulated blood flow, are subject to altered cerebrovascular events and subsequent abnormal metabolism or oxidative stress. Insight into basic aspects of transplant viability and function could improve transplantation strategies. Neocortical and nigral grafts will be studied. Based on the PI's previous experiments, he hypothesizes that fetal tissue transplants may have BBB and vascular phenotypic modulations which could permit the entry of bioactive compounds into graft, host and CSF. Such changes in angiogenic events will be examined before and after physiological BBB manipulation using immunocytochemistry, autoradiography, and laser confocal microscopy. Because of the protracted delay in vascularization during a critical developmental period, fetal grafted neurons are uncoupled from BBB-regulated energy substrates and may have alternate metabolic profiles. These potential changes in aspects of glucose or other substrate usage will be studied. Because of the fact that fetal CNS grafts are without blood flow and intrinsic vessels are eventually re-perfused it is possible that the tissue is subject to ischemic/anoxic injury. Studies will examine certain ischemia-sensitive cellular parameters such as cytoskeletal proteins by immunocytochemistry, vascular growth factors by in vitro autoradiography, and protein synthesis by in vivo autoradiography using amino acid uptake and confocal microscopy.
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