The role of extracellular matrix proteins in traumatic brain injury and cell transplantation
Tate, Ciara Caltagirone
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With over 50,000 deaths and 80,000 disorders annually in the United States resulting from traumatic brain injury (TBI), there is a demand for improved therapeutic strategies. Cell transplantation offers the potential to treat TBI by targeting multiple mechanisms in a sustained fashion. However, efforts are needed to improve survival and integration of transplanted cells, and ultimately enhance functional recovery. Using tissue engineering strategies, we aimed to mimic key aspects of fetal tissue grafts by combining neural stem cells with a fibronectin or laminin based scaffold that could be delivered to the injured brain in a minimally invasive fashion. We found that the incorporation of extracellular matrix proteins into a cell transplantation paradigm led to improved donor cell survival and restored cognitive ability for treated animals. To begin to examine how fibronectin and laminin mediate these improvements, we first examined the endogenous role of these two proteins in the injured brain. Using a clinically-relevant model of TBI, we found both proteins are increased in the injured brain at acute time points. The spatial localization of fibronectin and laminin with specific support cells in the brain suggests a role for these proteins in repair, warranting further investigation. Using conditional plasma fibronectin knockout animals, we found that fibronectin is neuroprotective to the traumatically injured brain. Specifically, injured fibronectin knockout animals had more severe motor and cognitive deficits, increased cell death, and decreased retention of phagocytic cells compared to injured wild type animals. Thus, we have identified novel therapeutic treatments for TBI which utilize tissue engineered transplants and/or exploit endogenous repair mechanisms for fibronectin.