Alterations in muscle fiber types in children with end-stage liver disease undergoing liver transplantation
Introduction: Low muscle mass is common in children waiting for liver transplantation and can make recovery after transplant more difficult. Muscles are made up of different fibers which have different functions. Some muscle fibers are better for endurance activity (slow muscle fibers [type I]), where some are better for power and strength (fast muscle fibers [type IIA and IID]). Little is known how these muscle fibers are affected by the loss of muscle that happens with liver disease. This study aims to describe the differences in muscle (fiber types, and size) in children who have experienced loss of muscle and those who have not.
Methods: Children were recruited from the Stollery Children’s Hospital Pediatric Transplant Clinics. Muscle mass was determined from MRI or CT scans done at time of transplant assessment and was corrected for height to determine muscle index (cm2/m2). Low muscle mass was determined by comparing muscle index of healthy controls to children with liver disease. Biopsy samples of the abdominal muscles were taken at time of transplant. Muscle fiber histology was performed to determine the amount and proportions of different types of muscle fibers present within the biopsy sample.
Results: 18 children (0.3 – 15.0 years) have been recruited. 14 children have been transplanted, 2 subjects are currently awaiting transplant, and 2 have died waiting for transplant. The most common type of liver disease was biliary atresia (39%), followed by Alagille’s syndrome (17%) and other (44%). A total of 33.3% of children had low muscle mass. The percentage of fiber types were: type I (56.8 ± 11.1%), type IIA (47.3% ± 16.6%) and type IID (8.2 ± 3.2%). However, no differences were seen the proportions of muscle fibers in children with and without low muscle mass.
Conclusions: This data suggests that children with liver disease who have normal muscle mass and low muscle mass both have similar proportions of muscle fiber types.