Introduction

Spastic cerebral palsy (CP) is caused by a non-progressive brain lesion, often hypoxemia/ischemia, that results in motor dysfunction. While caused by a neurologic injury, the resulting muscular pathology drives functional limitation. CP-associated muscle pathology is characterized by a pathological extracellular matrix diminished fiber size and reduced satellite cells. There are currently no validated small animal models that demonstrate this muscular pathology. To address this knowledge gap, we aimed to validated a CP mouse model for its associated muscular pathology by comparing myofiber area and satellite cell abundance between CP and wild-type (WT) mice.   

Methods 

Hypoxic-ischemic brain injury was surgically induced in the following manner: WT C57BL/6 5-day old mouse pups were anesthetized with isoflurane 1.5% and the carotid arteries were temporarily ligated (5 minutes on each side) and then placed in a hypoxia chamber (8% O2) for 20 minutes. Controls received anesthesia and sham incision. At 60-days, all mice were sacrificed. Immunofluorescence analysis was performed with antibodies for Pax7 to quantify satellite cells. Satellite cell abundance (N=8 and myofiber cross-sectional area (N=7) were quantified using ImageJ software. T-tests were used to compare these metrics in controls and WT mice.  

Results 

A mean of 4.3% (SD 0.9%) were determined to be satellite cells in WT mice, but only 2.0% (SD 0.08%; p=0.016) in CP muscle samples. Compared to WT mice, mean myofiber was also decreased in CP mice (1395.1 vs. 1254.9 um2, p=0.035).  

Conclusions 

Our results are the first step in validating CP muscular pathology in our murine CP model, demonstrating analogous findings to human CP muscle. Future studies will include analysis of ECM composition, abundance, and crosslinking, which have been implicated in CP muscle pathology. With further validation, this model may be used to study the origins of muscular pathology and develop targeted treatments to improve patient function.