Children with cerebral palsy (CP) have muscle growth impairments (muscle contractures), altered walking patterns and show markers of inflammation. During muscle repair macrophages coordinate with muscle stem cells-satellite cells (MuSC), which have previously been shown to be altered in abundance and function in children with CP. We investigated: 1) if macrophage populations in contractured muscles of children with CP are similar to typically developing (TD) children with a chronic ACL-tear, and 2) if macrophages, capillaries, MuSC, myonuclei, centrally nucleated fibers were associated with each other, indicative of repair. Thirty-six subjects participated in this study (CP: 11.2 ±0.7 years, 18M/12F, TD: 13.5 ±0.8 years, 3M/3F). Muscle biopsies were obtained during surgical correction for muscle contractures-adductors/ gastrocnemius (CPCon), or vastus lateralis (TD-ACL and CP NonCon). Muscle cross-sections were immunohistochemically labeled for total, anti-inflammatory (M2) macrophages, capillaries, myofiber boundaries, while MuSC abundance, activation and proliferation information were used from a prior study. Macrophage subpopulations in CP Con were similar to TD-ACL muscles. Within CPCon there were positive associations between total, M1 macrophages, and MuSC content (r= 0.54, r=0.70, p<0.05, respectively), but not in the CP NonCon muscles. Centrally-nucleated fibers, myonuclear abundance and MuSC content were also positively associated with each other only in the CPCon muscles (r=0.65, r=0.46, r=0.66, p<0.05, respectively). In TD-ACL injured muscles similar associations were seen between macrophages and MuSC, central nucleation and myonuclear abundance. Collectively, our data suggest that contractured muscles in children with CP may be in a state of repair, similar to ACL-injured TD children.
Meza et al. (Wed,) studied this question.