[ investigation of the simultaneous effects of bone morphogenic protein [BMP]-4 and static magnetic field on viability and proliferation rates of rat bone marrow stem cells]

This study investigated the possible synergistic effect of simultaneous treatment of bone morphogenic protein [BMP]-4 as a chemical stimulator and static magnetic field [SMF] as a physical stimulator on viability percent and proliferation rate in rat bone marrow stem cells. Passage 5 cells were trypsinized, and a cell suspension prepared after which the cells were counted and cultured in 25 cm[2] flasks. Cells were incubated for one day and washed with phosphate-buffered saline. We added BMP-4 at the optimum concentration of 25 ng/ml at different times [24, 48 and 96 h] into the medium. The cells were exposed at an optimum intensity of 4 mT of the SMF at different exposure times [24, 48, and 96 h]. Subsequently cells were washed with phosphate-buffered saline, trypsinized, and separate cell suspensions were prepared from each flask. We investigated the viability and proliferation rates of treated cells by staining them with Trypan blue and performed cell counts with an optical microscope. The mean numbers of whole cells and living cells were considered to be the proliferation and survival rates, respectively. Increased SMF exposure and BMP-4 increased the viability percent and change in proliferation rate in the treated groups compared with their corresponding controls. The maximum increased viability was observed in the group that was treated with BMP-4 for 96 h. Our results have supported the hypothesis that SMF alters the viability and proliferation rate of treated BMSCs, which was enhanced when the cells were treated simultaneously with SMF and BMP-4

Evaluating survivin gene expressiion changes in adult mice following sciatic nerve injury

Because of the necessity of more effective treatments for the nervous system injuries and considering the role of survivin in cellular proliferation and apoptotic cell death, we have monitored survivin gene expression changes during the course of regeneration in injured sciatic nerves and also L4-L6 segments of spinal cord. We used adult male NMRI mice as a model. After anesthetizing the animals, the right sciatic nerve was transected and at the indicated times [3, 6, 12, 24, 48, 96 and 144 hours] the animals were sacrificed and both distal and proximal segments of the transected sciatic nerve, intact left sciatic nerve and L4-L6 segments of spinal cord were dissected. The total RNA was extracted from each sampled and semi-quantitative RT-PCR with specific primers for survivin and also beta2-microglobulin genes, as an internal control, was performed. To determine cellular distribution of survivin protein, 6 days [144 hours] after the axotomy, survivin protein expression was evaluated using immunohistochemistry technique. Our results demonstrated the expression of both survivin140 and survivin40 in distal and proximal segments of sciatic nerve with different intensity, where the expression of survivin140 was higher than survivin40. In spinal cord segments, only survivin140 expression was detected. In immunohistochemistry analysis of spinal cord segments, both the nuclear and cytoplasmic distribution of survivin protein was observed. In contrast, survivin protein has not been detected in either distal or proximal segments of sciatic nerve. Our data suggest that survivin is differentially expressed and spliced during the course of regeneration in damaged nerve and spinal cord. It seems that manipulation of expression and/or splicing of survivin could potentially affect the process of regeneration in nerve and/or spinal cord injuries