The effect of temperature on apoptosis and adipogenesis on skeletal muscle satellite cells derived from different muscle types

Abstract

Satellite cells are multipotential stem cells that mediate postnatal muscle growth and respond differently to temperature based upon aerobic versus anaerobic fiber-type origin. The objective of this study was to determine how temperatures below and above the control, 38°C, affect the fate of satellite cells isolated from the anaerobic pectoralis major (p. major) or mixed fiber biceps femoris (b. femoris). At all sampling times, p. major and b. femoris cells accumulated less lipid when incubated at low temperatures and more lipid at elevated temperatures compared to the control. Satellite cells isolated from the p. major were more sensitive to temperature as they accumulated more lipid at elevated temperatures compared to b. femoris cells. Expression of adipogenic genes, CCAAT/enhancer-binding protein β (C/EBPβ) and proliferator-activated receptor gamma (PPARγ) were different within satellite cells isolated from the p. major or b. femoris. At 72 h of proliferation, C/EBPβ expression increased with increasing temperature in both cell types, while PPARγ expression decreased with increasing temperature in p. major satellite cells. At 48 h of differentiation, both C/EBPβ and PPARγ expression increased in the p. major and decreased in the b. femoris, with increasing temperature. Flow cytometry measured apoptotic markers for early apoptosis (Annexin-V-PE) or late apoptosis (7-AAD), showing less than 1% of apoptotic satellite cells throughout all experimental conditions, therefore, apoptosis was considered biologically not significant. The results support that anaerobic p. major satellite cells are more predisposed to adipogenic conversion than aerobic b. femoris cells when thermally challenged.

Regeneration of Skeletal Muscle After Eccentric Injury

“…Decreasing the temperature of cultured satellite cells cells by 5°C under normal 37°C culture conditions reduces their proliferation rate, but also decreases apoptosis, or programmed cell death 54 . In rats subjected to an ischemia/reperfusion muscle injury, cryotherapy applied three hours after the injury reduces neutrophil accumulation and reactive oxygen species formation, and enhances the metabolic function of mitochondria 55 .…”

“…In a rat muscle crush-injury model, however, reducing the temperature of muscle by 12°C for 20 minutes after inducing the injury results in reduced inflammation in the acute phase, but delayed muscle regeneration in the long term 56 . When muscle stem cells are warmed by 5°C over their normal 37°C temperature in vitro, their proliferation rate is increased, but so is the amount of apoptosis 54 . In muscle cells cultured from chicks, the application of therapeutic ultrasound in vitro results in elevated progenitor cell proliferation and an increase in the size of differentiated myotubes 57 .…”

Timing Is Everything—The High Sensitivity of Avian Satellite Cells to Thermal Conditions During Embryonic and Posthatch Periods

“…Accumulation of lipid droplets was noticed shortly upon heat stress of cultured SCs (Harding et al, 2015;Clark et al, 2017), in SCs derived from heat-treated chicks (Piestun et al, 2017), and later, as the cells underwent differentiation, in myotubes and myofibers. The lipid accumulation was due to the induction of adipogenic gene and protein expression in the SCs (Harding et al, 2015;Clark et al, 2017;Piestun et al, 2017;Patael et al, 2019), suggesting transdifferentiation of these cells to the adipogenic lineage. Interestingly, these SCs did not seem to lose their myogenic characteristics completely, and along with the fat deposition, they underwent terminal differentiation to myotubes and fusion to myofibers.…”

“…Detailed studies on cultured SCs from broilers (Harding et al, 2015(Harding et al, , 2016 and turkeys (Clark et al, 2016(Clark et al, , 2017 revealed that the pectoralis muscle, in particular, is highly sensitive to temperature changes. Yet, a decline in SCs did not result from increased apoptosis in either cultured cells (Harding et al, 2015) or the treated chicks (Patael et al, 2019). A surprising finding was that the heat stress caused dramatic changes in SC fate toward adipogenesis and in muscle structure toward myopathy.…”

“…Thermal stress, especially during the early growth period, probably further aggravates this situation, leading to myodegeneration, expansion of the muscle's interstitial fibro-adipogenic progenitors (Contreras et al, 2016), and/or recruitment of myofibroblasts and adipogenic cells from nearby tissues, resulting in increased fibrotic tissue and fat deposition between the myofibers (Bailey et al, 2015). This is in parallel to the reduction in the number of SCs and their changes in fate, which may lead to ineffective myofiber function (Harding et al, 2015;Piestun et al, 2017;Patael et al, 2019). In contrast, featherless broilers subjected to cold stress during the first week posthatch developed a better vascular system and had a higher number of muscle cell progenitors and better muscle hypertrophy than feathered broilers (Hadad et al, 2014a,b).…”