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Hypoxia alters the biological functions of skeletal muscle cells to proliferate and differentiate into myotubes. However, the cellular responses of myoblasts to hypoxia differ according to the levels of oxygen and the types of cells studied. This study examined the effect of hypoxia (1% oxygen) on bovine satellite cells. Hypoxia significantly increased the proliferation of satellite cells cultured in a growth medium. In addition, the levels of PCNA, cyclin D1, cyclin-dependent kinase-1 (CDK1) and CDK2 expression were increased. Hypoxia facilitated the formation of myotubes as well as the stimulation of MyoD, myogenin, and myosin heavy chain (MHC) expression in differentiating medium (DM) cultures. In particular, satellite cells cultured under hypoxic/DM conditions showed increased p21 expression but not p27. The transfection of satellite cells with antisense MyoD oligonucleotides resulted in a decrease in the MHC, myogenin, MRF4 RNA and protein levels with the concomitant decrease in fused cells to levels similar to those observed under normoxia/DM conditions. This indicates that MyoD up-regulation is closely associated with hypoxia-stimulated myogenic differentiation. In conclusion, hypoxia stimulates the proliferation of satellite cells and promotes their myogenic differentiation with MyoD playing an important role.

Mechanical stress leads to satellite cell activation, which is an important event in the development, growth, and remodeling of postnatal skeletal muscle. Although there is a considerable knowledge on the events involved in skeletal muscle regeneration and development, the precise role of mechanical stress on activation of satellite cells remains unclear. Previously, satellite cells were isolated from adult bovine muscle and it was shown that the cells are multipotent, i.e., capable of proliferating and to differentiating into both myoblasts and adipocytes. This study investigated the cellular mechanisms by which cyclic mechanical stretching modulates the proliferation and differentiation of adult bovine satellite cells. The application of cyclic stretch induced the proliferation of satellite cells and inhibited their differentiation into myotubes. This response is believed to be closely related to the stretch-mediated changes in the expression of myogenic and cell cycle regulatory factors. Cyclic stretching increased the level of extracellular signal-regulated kinase (ERK) phosphorylation, whereas a specific ERK inhibitor (PD98058) blocked the stretch-mediated inhibition of myogenesis in a dose-dependent manner. Overall, this study demonstrates for the first time that cyclic mechanical stretch induces the proliferation of bovine satellite cells and suppresses their myogenic differentiation through the activation of ERK.

This study examined the role of Higher Educational Institutions (HEIs) in promoting, creating, and sustaining social innovation. Recently, HEIs have extended their contribution beyond the traditional function of teaching and research to perform in socio-economic problem-solving. Considering the increasing trends of higher education involvement in social innovation practices, this study tries to examine the tools such as learning processes and systemic thinking approach that could be helpful to align the function and responsibilities of HEIs towards social innovation. The objective is to develop a theoretical understanding of the “co-creation for social innovation” concept and to understand the functions and activities of HEIs that can contribute to this process. To promote co-creation for social innovation, HEIs should actively encourage collaborative learning tools that focus on open platforms for collective action and systemic change that help them to engage with society and strengthen their collaboration with social actors. Different activities such as mutual learning and knowledge diffusion using a transdisciplinary approach, technology-based learning and collaboration, and relational transformation are key enablers that can promote social innovation.