| Summary: | 博士 === 國立交通大學 === 生物科技學系 === 99 === Mesenchymal stem cells (MSC) can be isolated from almost any tissue of the body have been recognized to constitute a powerful tool in regenerative medicine due to their multi-lineage differentiation ability and their capacity for tissue repair.
Pulsed electromagnetic fields (PEMF) have been clinically employed for many years. Despite the clinical success, there are contradictory data concerning the effect of PEMF stimulation on in vitro proliferation of some osteogenic cell lines or primary osteoblasts, so it is a fact that the mechanism underlying how PEMF promotes the formation of bone on cellular level is still not fully understood. For the first time, the effect of PEMF exposure to stem cells was described in this study. We discovered that a shorter lag phase and a higher percentage of G0/G1 phase of bone marrow mesenchymal stem cells (BMMSC) after the first PEMF treatment. Although the surface phenotype, morphology, differentiation potential and growth rates of BMMSC during the exponential growth phase were not significantly affected, the cell densities achieved by PEMF stimulation were significantly higher than those achieved in non-treated conditions. This observation of accelerated growth of BMMSC due to PEMF provides a possible explanation for the clinical success. In addition, according to above-mentioned reports and our new data, our hypothesis was that PEMF not only modifies the osteogenesis of BMMSC but also induces different response of cell proliferation depending on the osteogenic stage of cells. This finding helps us to understand more about the in vitro and in vivo interaction of PEMFs with bone cells. Furthermore, since the morphology and the multi-lineage differentiation potential of the BMMSC were not significantly changed by the PEMF, the stirred bioreactor can combine with microcarriers and PEMF device to be a powerful tool for in vitro BMMSC expansion in the future.
Due to its provision of high specific surface area and three-dimensional culture condition, microcarrier culture (MC) has garnered great interest for its potential to expand anchorage-dependent stem cells. This study utilises semi-continuous MC as compared with control plate culture (PC) or serial bead-to-bead transfer MC (MC Bead-T) for in vitro expansion of human MSC including of BMMSC and adipose-drived stem cell (ADSC), and analyses its effects on growth kinetics, cell phenotypes, and the differentiation potential. The maximum cell density and overall fold increase in cell growth were similar between PCs and MCs with similar starting conditions, but the lag phase of BMMSC growth differed substantially between the two growth conditions; moreover, MC cells exhibited reduced granularity and higher CXCR4 expression. Differentiation of BMMSC into osteogenic and adipogenic lineages was enhanced after 3 days in MC. However, MC Bead-T resulted in changes in cell granularity and lower osteogenic and adipogenic differentiation potential. However, the results of MC cells exhibited reduced granularity and higher C-X-C chemokine receptor type 4 (CXCR-4) expressions were not exist in ADSC. Although ADSC could proliferate in MC with serum-free medium with higher growth rate than BMMSC or ADSC in MC, the osteogenic and adipogenic lineages were not enhanced after 3 days in MC. In conclusion, MC could support the expansion of MSC in a scalable three-dimensional culture system, but the different types of MSC or different culture systems would result differential quality of stem cell homing ability and osteogenic and adipogenic differentiation of MSC.
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