Proliferative activity of skeletal myoblast sheet by paracrine effects of mesenchymal stem cells

Abstract

ObjectivesThe purpose of this study was to examine the proliferative activity enhancement of skeletal myoblasts in the presence and absence of mesenchymal stem cells (MSC). MethodsWe artificially fabricated two types of cell sheets by co-culturing rabbit skeletal myoblast sheets with rabbit MSCs using type IA collagen gel (MC+), and cell sheets without rabbit MSCs (MC−). ResultsThe results of hematoxylin and eosin staining revealed that MC+ was thicker than MC− on day 7. Immunohistochemical staining revealed a low level of desmin expression in both sheets on day 2. Desmin expression increased at days 7 and 12, and desmin localization was consistent with the stratified area. Reverse transcription PCR revealed the presence of MyoD and PAX7 in both sheets on days 2, 7, and 12. The presence of myogenin was confirmed in both sheets on days 7 and 12. Hepatocyte growth factor expression was evident in MC+ on day 2, and in both sheets on day 7. Measurement of cell proliferative activity based on DNA cell cycle analysis indicated that MC+ had significantly higher cell proliferative activity than MC− on day 7. There were no significant differences in cell proliferative activity between MC+ and MC− on day 12. ConclusionsThis study demonstrated that the presence of MSCs could transiently enhance the proliferative activity of myoblasts, but that this enhancement is ultimately diminished due to contact inhibition.