Jonathan Palmer
Effects of Hypoxia on Skeletal Muscle Cell Proliferation and Differentiation
Mentor: Micah Drummond, PHD
Department: Physical Therapy
Background/Purpose
Moderate-severity hypoxia has been shown to be associated with skeletal muscle hypertrophy. To further investigate this effect, we studied the effects of hypoxia on skeletal muscle cell proliferation and differentiation.
Methods
C2C12 skeletal muscle cells were grown in vitro. To assess proliferation, the cells were divided into 4 groups (control, hypoxia, control-ACF, and hypoxia-ACF). The cells were incubated overnight and proliferation was assessed via BrdU incorporation and expressed as the ratio of BrdU to total cells (DAPI). To assess differentiation, the cells were allowed to differentiate and then divided into the same 4 groups. Myotube area, diameter, and viability were assessed by staining with MF20 and DAPI.
Results
Cellular proliferation and viability were not affected by 24 hours in a 1% O2 environment. Cells treated with ACF demonstrated decreased viability in both the control and hypoxia conditions, indicating that HIF-1α is necessary for skeletal muscle survival in both conditions. Additionally, there was no significant difference in myotube area, diameter, and viability between the control and hypoxia conditions in the differentiation experiment. Myotubes treated with ACF had significantly lower myotube areas in both the normoxic and hypoxic conditions.
Conclusions
Severe hypoxia (1% O2) does not enhance or negatively affect skeletal muscle proliferation or differentiation. Regardless, the transcriptional function of HIF-1α is necessary for skeletal muscle survival in both normoxic and hypoxic conditions. These findings suggest that the previously reported benefits of whole-body hypoxia on skeletal muscle recovery from disuse are not driven by muscle cells alone.
