Muscle fiber satellite cells are located at a greater distance from capillaries in patients with COPD compared with healthy controls

Abstract

Chronic obstructive pulmonary disease (COPD) is a disease characterized by skeletal muscle dysfunction. A spatial relationship exists between satellite cells and muscle fiber capillaries, which has been suggested to be of major importance for satellite cell function. In the present study we compared the spatial relationship between satellite cells and capillaries in patients with COPD and age-matched healthy older adults.Muscle biopsies were obtained from thevastus lateralisof n=18 patients with COPD (8f/10 m, 66±5 y, mild to severe airflow obstruction) and n=18 age-, gender- and BMI-matched healthy control adults (8f/10 m, 68±5 y). Immunohistochemistry was used to assess type I/II muscle fiber size, distribution, myonuclear content, satellite cell number, and fiber capillarization. In addition, type I/II muscle fiber satellite cell distance to its nearest capillary was assessed.The percentage of type II muscle fibers was significantly greater in patients with COPD (62±10%) compared with control (50±12%, p<0.05). Muscle fiber capillarization was significantly lower in patients with COPD compared with controls (p<0.05). Whereas satellite cell content was not different between groups, type I and type II satellite cell distance to its nearest capillary was significantly greater in patients with COPD (type I: 21.3±4.8 and type II: 26.7±9.3 µm) compared with controls (type I: 16.1±3.5 and type II: 22.7±5.8 µm; p<0.05).Satellite cells are located at a greater distance from their nearest capillary in patients with COPD compared with age-matched controls. This increased distance could play a role in impaired satellite cell function in patients with COPD.