College of Science and Health Theses and Dissertations

Date of Award

Summer 8-22-2014

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Dorothy Kozlowski, Ph.D.

Second Advisor

Aleksandra Glavaski-Joksimovic, Ph.D.

Third Advisor

Carolyn Martineau, Ph.D.

Abstract

Traumatic brain injury (TBI) affects thousands of individuals annually who have limited options for treatment. The use of mesenchymal stem cells derived from bone marrow (BMSC) has therapeutic potential, free from ethical ramifications. Previous transplant studies have grafted naive BMSCs into injured brain tissue or infused them intraventricularly (i.v.) with varying results (Bonilla 2012, Osani 2012, Bakhitany 2010, Li 2009).. In this study, we transplanted Notch-induced rat BMSCs (BMSC-NICD) with properties of neuroprogenitor-like cells, into the rat controlled cortical impact (CCI) model of TBI. Adult rat BMSC were harvested from femur and tibia of adult Fischer 344 rats. These cells were further transfected with the intracellular domain of the Notch1 (NICD) gene and the neomycin resistance gene to generate BMSC-NICD cells. Cells effective transfected with the NICD were selected for resistance to G418. Following selection, BMSC-NICD were infected with lentivirus harboring green fluorescent protein (GFP) and grown under non-adherent conditions to promote formation of Nestin-expressing neurospheres. Adult male Fisher 344 rats (n=8) were injected with BMSC-NICD-derived neurospheres on day 7 following unilateral CCI of the forelimb sensorimotor cortex. Two injections were made posterior to the injured cortex or within the dorsolateral striatum (25,000 cells/μl at 2 μl/injection totaling 100,000 cells/rat). Transplanted BMSC-NICD neurospheres were examined for: 1) survival, 2) effect on contusion size, and 3) effect on behavioral functions. Limb use and foot fault behavioral tests were performed to examine deficits in and possible recovery of forelimb function following CCI in transplanted rats compared to CCI only rats (n=4). A baseline measurement was taken at day 0 before CCI.

Following, CCI, behavioral tests were performed at day 5 (pre- transplant), and day 12 (5 days post-transplant). Rats were euthanized on day 14 and brains were sectioned and examined for surviving GFP+ cells and for cortical volume. All rats showed marked impairment of the forelimb contralateral to the injury on day 5.

Both cortical and striatal transplants enhanced behavioral recovery of forelimb function compared to CCI only rats by day 12. Survival of transplanted cells was seen in both areas; however, rats with cortical transplants showed decreased numbers of GFP+ cells compared to rats with striatal transplants. Transplantation of cells did not affect lesion size as inferred from total cortical volume. This pilot study suggests that transplantation of neurospheres derived from BMSC-NICD neurospheres at the site of injury and/or in subcortical targets decreases behavioral impairments. Also, subcortical targets such as the striatum, rather than the site of cortical contusion, appear to be a better site for transplant survival.

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