Satellite cell numbers in young and older men 24 hours after eccentric exercise

Abstract

We tested the hypothesis that the expansion of satellite cell numbers, 24 h after maximal eccentric knee extensor exercise, is blunted in older men. Muscle biopsies were obtained from the vastus lateralis of 10 young (23-35 years) and 9 older (60-75 years) men. Satellite cells were identified immunohistochemically using an antibody to neural cell adhesion molecule. After 92 maximal eccentric contractions, the mean number of satellite cells per muscle fiber increased to a greater extent among the young men (141%; P < 0.001) than older men (51%; P = 0.002) from preexercise levels. Similar results were obtained when satellite cells were expressed as a proportion of all sublaminar nuclei. We conclude that a single bout of maximal eccentric exercise increases satellite cell numbers in both age groups, with a significantly greater response among the young men. These data suggest that age-related changes in satellite cell recruitment may contribute to muscle regeneration deficits among the elderly.

Expression of growth-related genes in young and older human skeletal muscle following an acute stimulation of protein synthesis

“…Specifically, mib2 cleaves the intracellular domain of the Notch ligand complex, thereby contributing to a cascade of events that eventually leads to expression of Notch regulated genes associated with satellite cell proliferation. The current data indicate that the lack of mib2 induction may be correlative (albeit weakly) with the blunted satellite cell response reported in older subjects following a bout of resistance exercise (20). Further investigation is warranted to evaluate mib2 in proliferating satellite cells post REϩEAA in human skeletal muscle.…”

Prostaglandin E2 is essential for efficacious skeletal muscle stem-cell function, augmenting regeneration and strength

“…MuSCs are crucial to development and regeneration (1-3, 24, 36-38), and their numbers dramatically increase in response to insults that damage the muscles in mice and humans (5,20,(39)(40)(41)(42). Injections of MuSCs into injured muscles lead to their exponential increase, whereas injection of their myoblast derivatives results in a decline in numbers, revealing a remarkable distinction in regenerative capacity of these two cell types (24).…”

Sera from young and older humans equally sustain proliferation and differentiation of human myoblasts

“…Furthermore, in an analysis of young and old male and female subjects who underwent sixteen weeks of strength training exercise (Petrella et al 2006) and who were subsequently clustered into cohorts of responders and nonresponders (Petrella et al 2009), the ability of responders to increase myofibre crosssectional area was correlated with increased satellite cell and myonuclear number, independently of age. In the short term however, there is some evidence that the exercise mediated increase in satellite cell number may be blunted in older subjects either following a bout of acute resistance exercise (Dreyer et al 2006) or a short period (4 weeks) of rehabilitation immediately following a 2 week period of cast immobilization (Carlson et al 2009). It is important to note that satellite cell activation measured following resistance exercise is a different model to that used in most animal studies (muscle damage, cross transplantation) and may involve quite different signals to those that we are able to study in vitro.…”