Skeletal Muscle Regeneration in Survivors of Critical Illness: How to Prevent Satellite Cell Failure?

Modern intensive care enables patients to survive insults that in the past would have been supralethal. Nonetheless, increased number of survivors suffer from failed functional outcomes associated with prolonged muscle weakness and fatiguability. Whilst alterations of skeletal muscle biology that occur during critical illness slowly disappear over the period of months, muscle weakness remains. Recent pilot studies have shown that muscle weakness is associated with loss and alteration of satellite skeletal muscle cells, which are supposed to proliferate and repair damaged muscle tissue. The pathogenesis of this phenomenon has not been fully understood. In this grant project, we will study function and structure of satellite cells and their organelles (particularly mitochondria) using both classical bioenergetics and advanced microscopic techniques. Satellite cells will be isolated from biopsies taken from critically ill patients with developed muscle weakness in the acute and protracted phase of a disease and after 6 months. In time points, an ultrasound examination of muscle mass will be performed, and metabolism will be assessed using insulin clamps. In an in vitro experiments, we will test also effect of nutritional and anabolic factors and drugs, commonly used in ICU, on satellite cells. In a control branch, cells will be isolated from skeletal muscle of volunteers undergoing elective hip replacement surgery. Results of this study could significantly contribute to understanding of mechanisms leading to ICU acquired muscle weakness and to identify therapeutic strategy in future.