Departments: Surgery, University of Toronto
We are interested in endogenous and exogenous neural stem/progenitor cell approaches for spinal cord injury. Neural stem/progenitor cells exist in certain regions of the adult brain and spinal cord. We are specifically interested in adult stem/progenitor cells derived from the periventricular region of the spinal cord which includes the ependymal cells lining the central canal. Lower vertebrates, such as newts and salamanders, can completely regenerate their spinal cord even after complete transection, which is due in part to the ependymal cells which rapidly proiferate, migrate, and differentiate to regenerate the spinal cord. In adult mammals, limited proliferative activity persists in the ependyma under normal conditions. However, we and others have shown that an endogenous ependymal cell response occurs after spinal cord injury, and this response can be augmented in the presence of growth factors. This endogenous ependymal cell response appears to have only limited capacity for repair, and therefore, we are also examining the transplantation of these cells to enhance the regenerative potential. We have cultured adult spinal cord stem/progenitor cells as neurospheres which are self-renewing and multipotent, able to form all three cells of the neural lineage. We have generated these stem cells from transgenic animals expressing green fluorescent protein, so that we can track the cells in vivo. Recently, we have transplanted these cells into the spinal cord and are examining their ability to improve functional recovery after spinal cord injury and to remyelinate focal demyelination lesions. We are also using stem cell and tissue engineering approaches to examine different strategies involving biodegradable synthetic guidance channels (chitosan) and drug delivery systems for spinal cord repair.