Date of this Version
Most, M. 2019. Fetal programming of intrauterine growth restricted skeletal muscle stem cell function. Undergraduate Honors Thesis. University of Nebraska-Lincoln.
Intrauterine growth restriction (IUGR) reduces skeletal muscle mass in fetuses and offspring. The objective of this study was to determine if myoblasts (skeletal muscle stem cells) from maternal inflammation induced intrauterine growth-restricted (MI-IUGR) fetuses are less responsive to proliferation-stimulating factors in culture. Ovine MI-IUGR fetal myoblasts were isolated at 125 days of gestational age (dGA, term = 150 dGA), grown for 72 hours in complete growth media spiked with insulin, tumor necrosis factor α (TNFα), or unspiked (basal), and analyzed for ex vivo proliferative capacity via a 2 hour EdU pulse. A second set of myoblasts were differentiated in differentiation media (2% fetal bovine serum) for 96 hours. MI-IUGR reduced (p < 0.05) fetal weight by ~22% at 125dGA compared to controls. No interacting effects of experimental group x media condition were observed for proliferation or differentiation rates. MI-IUGR increased (p < 0.05) myoblast ex vivo proliferation rates relative to controls independent of media condition. Incubation with insulin increased (p < 0.05) ex vivo myoblast proliferation rates independent of experimental group. No differences in proliferation rates were observed in media spiked with TNFα compared to basal media. The response to insulin and the lack of response to TNFα for proliferation indicate that fetal myoblast proliferation is not responsive to the effects of cytokines during this stage of development. MI-IUGR myoblasts exhibited diminished (p < 0.05) biomarkers for ex vivo differentiation rates. The early differentiation marker, myogenin, was present in fewer (p < 0.06) MI-IUGR myoblasts following 4d differentiation relative to controls; the late differentiation marker, desmin, was also expressed by fewer (p < 0.05) MI-IUGR myoblasts relative to controls regardless of media condition. Fewer cells (p < 0.05) cultured in TNFα-spiked media stained positive for desmin relative to basal and insulin media treatments, regardless of experimental group, indicating that myoblast differentiation is responsive to cytokines at the fetal stage. Based on these findings, we conclude that MI-IUGR creates intrinsic fetal myoblast dysfunction that interferes with their ability to exit the cell cycle (proceed from proliferation to differentiation), which results in their reduced capacity to facilitate muscle growth.