The effects of human lower limb immobilization on regenerative skeletal muscle stem cell characteristics in vitro
Lead Research Organisation:
University of Nottingham
Department Name: School of Medicine
Abstract
Skeletal muscle represents the largest organ and protein reservoir in the human body. Maintenance of skeletal muscle is key for human movement and health. The proteins and DNA containing nuclei within skeletal muscle are constantly being synthesised and degraded. This constant turnover provides an efficient mechanism for the removal of damaged proteins and replacement with new proteins to maintain health.
Many situations can negatively impact this balance of protein turnover of skeletal muscle throughout life. These include, the natural ageing process itself, development of chronic diseases more prevalent in later life, malnutrition, trauma, but also "immobilisation", which can be a consequence of enforced bed rest due to hospitalisation, general lack of physical activity, or casting of a leg or arm due to bone fracture. Ultimately this causes loss of muscle size and strength which causes a host of problems, such as weakness and increased risk of falls and development of chronic health conditions.
Muscle has within itself a cell than enables regeneration. This cell is called a satellite or stem cell. The aim of this project is to determine the impact of limb (leg) immobilisation - which causes muscle wasting and loss of strength - upon muscle satellite cell function. We hypothesise that extracting these cells from immobilised muscle and examining their behaviour in a laboratory setting will show that immobilisation leads to defects in their function affecting their regenerative capability.
This research will have significance to understanding how brief bouts of immobilisation - which commonly occur throughout life - might impact muscle regenerative capacity.
We would hope then to seek answers as to how this works and potentially seek therapies to encourage regenerative capacity of these muscle cells that are important to health to improve recovery from bouts of immobilisation.
Many situations can negatively impact this balance of protein turnover of skeletal muscle throughout life. These include, the natural ageing process itself, development of chronic diseases more prevalent in later life, malnutrition, trauma, but also "immobilisation", which can be a consequence of enforced bed rest due to hospitalisation, general lack of physical activity, or casting of a leg or arm due to bone fracture. Ultimately this causes loss of muscle size and strength which causes a host of problems, such as weakness and increased risk of falls and development of chronic health conditions.
Muscle has within itself a cell than enables regeneration. This cell is called a satellite or stem cell. The aim of this project is to determine the impact of limb (leg) immobilisation - which causes muscle wasting and loss of strength - upon muscle satellite cell function. We hypothesise that extracting these cells from immobilised muscle and examining their behaviour in a laboratory setting will show that immobilisation leads to defects in their function affecting their regenerative capability.
This research will have significance to understanding how brief bouts of immobilisation - which commonly occur throughout life - might impact muscle regenerative capacity.
We would hope then to seek answers as to how this works and potentially seek therapies to encourage regenerative capacity of these muscle cells that are important to health to improve recovery from bouts of immobilisation.
Technical Summary
We hypothesise that in vivo immobilisation will lead to impaired muscle satellite cell function in vitro that could negatively impact in vivo recovery characteristics. This project will harvest satellite cells from both immobilised and non-immobilised legs (using a unilateral immobilisation model so being internally controlled). These cells will be cultured in vitro and compared for aspects of proliferation behaviours (e.g., cell population doubling, DNA synthesis, cell cycle staging) and for differentiation characteristics (e.g., myotube formation, fusion and expression of differentiation markers such as contractile proteins and protein turnover). Methods used will include flow cytometry, BrDU incorporation, protein turnover using stable isotope tracers and mass spectrometry, in addition to key mRNA (RT-PCR) targets and follow-up Western Blotting for key myogenic targets.
