Intravenous Administration of Marrow Stromal Cells (MSCs) Increases the Expression of Growth Factors in Rat Brain after Traumatic Brain Injury

This study was designed to investigate the effects of intravenous administration of marrow stromal cells (MSCs) on the expression of growth factors in rat brain after traumatic brain injury (TBI). The fate of transplanted MSCs and expression of growth factors was examined by immunohistochemistry. In addition, the level of growth factors was measured quantitatively using enzyme linked immunosorbent assay (ELISA). Growth factors that were studied included nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and basic fibroblast growth factor (bFGF). For immunohistochemical studies, 12 male Wistar rats were subjected to TBI and then divided into three groups with the first group receiving no treatment, the second group receiving saline (placebo) and the third group receiving MSCs intravenously 1 day after TBI. The neurological function of rats was studied by using Rotarod motor test and modified neurological severity scores. The animals were sacrificed 15 days after TBI and brain sections stained by immunohistochemistry to study the distribution of MSCs as well as expression of growth factors NGF, BDNF, and bFGF. For quantitative analysis, a second set of male Wistar rats (n = 18) was subjected to TBI and then injected with either saline (n = 9) or MSCs (n = 9) 1 day after injury. These rats were sacrificed on days 2, 5, and 8 after TBI and brain extracts used to measure NGF, BDNF, and bFGF. We found that after transplantation, MSCs preferentially migrated into the injured hemisphere and there was a statistically significant improvement in the functional outcome of MSC-treated rats compared to control rats. NGF, BDNF, and bFGF were expressed in the injured brain of both treated as well as control rats; however, quantitative ELISA studies showed that expression of NGF and BDNF was significantly increased (p < 0.05) in the treated group. This study shows that intravenous administration of MSCs after TBI increases the expression of growth factors (NGF, BDNF), which possibly contributes to the improvement in functional outcome seen in these rats.