Search

Synchrotron X-ray computed tomography (SXCT) allows 3D imaging of tissue with a very large field of view and an excellent micron resolution and enables the investigation of muscle fiber atrophy in 3D. The study aimed to explore the 3D micro-architecture of healthy skeletal muscle fibers and muscle fibers at different stages of atrophy (stroke sample = muscle atrophy; spinal cord injury (SCI) sample = severe muscle atrophy). Three muscle samples: a healthy control sample; a stroke sample (atrophic sample), and an SCI sample (severe atrophic sample) were imaged using SXCT, and muscle fiber populations were segmented and quantified for microarchitecture and morphology differences. The volume fraction of muscle fibers was 74.7%, 70.2%, and 35.3% in the healthy, stroke (atrophic), and SCI (severe atrophic) muscle fiber population samples respectively. In the SCI (severe atrophic sample), 3D image analysis revealed fiber splitting and fiber swelling. In the stroke sample (atrophic sample) muscle fiber buckling was observed but was only visible in the 3D analysis. 3D muscle fiber population analysis revealed new insights into the different stages of muscle fiber atrophy not to be observed nor quantified with a 2D histological analysis including fiber buckling, loss of fibers and fiber splitting. [ABSTRACT FROM AUTHOR]

Skeletal muscle in individuals with CP also contains lower amounts of mtDNA, potentially indicating fewer mitochondria in CP skeletal muscle compared with typically developing muscle. We compared skeletal muscle samples from children with cerebral palsy (CP) and typically developing children and observed evidence of reduced mtDNA and OXPHOS protein content in CP skeletal muscle, indicating reduced mitochondrial abundance. Cerebral palsy (CP) muscle contains fewer energy-generating organelles than typically developing muscle. [Extracted from the article]

Cerebral palsy (CP) is a non-progressive motor disorder that affects posture and gait due to contracture development. The purpose of this study is to analyze a possible relation between muscle stiffness and gene expression levels in muscle tissue of children with CP. Next-generation sequencing (NGS) of gene transcripts was carried out in muscle biopsies from gastrocnemius muscle (n = 13 children with CP and n = 13 typical developed (TD) children). Passive stiffness of the ankle plantarflexors was measured. Structural changes of the basement membranes and the sarcomere length were measured. Twelve pre-defined gene target sub-categories of muscle function, structure and metabolism showed significant differences between muscle tissue of CP and TD children. Passive stiffness was significantly correlated to gene expression levels of HSPG2 (p = 0.02; R2 = 0.67), PRELP (p = 0.002; R2 = 0.84), RYR3 (p = 0.04; R2 = 0.66), C COL5A3 (p = 0.0007; R2 = 0.88), ASPH (p = 0.002; R2 = 0.82) and COL4A6 (p = 0.03; R2 = 0.97). Morphological differences in the basement membrane were observed between children with CP and TD children. The sarcomere length was significantly increased in children with CP when compared with TD (p = 0.04). These findings show that gene targets in the categories: calcium handling, basement membrane and collagens, were significantly correlated to passive muscle stiffness. A Reactome pathway analysis showed that pathways involved in DNA repair, ECM proteoglycans and ion homeostasis were amongst the most upregulated pathways in CP, while pathways involved in collagen fibril crosslinking, collagen fibril assembly and collagen turnover were amongst the most downregulated pathways when compared with TD children. These results underline that contracture formation and motor impairment in CP is an interplay between multiple factors. [ABSTRACT FROM AUTHOR]

• Significant different gene expression levels were observed between adults with CP and typical developing (TD) adults in various genes. • Differences in muscle contraction (MYH1 & MYBPC2), mitochondrial function (ATP5J, CYCS & NDUFB6), and calcium handling (CAMK2B & ATP2A). • Variant frequencies of the mtDNA and the mitochondrial content did not differ when comparing muscle tissue from adult CP and TD individuals. • The ion levels of Ca2+, Na+, K+ and Cl− were significantly different in adults with CP when compared to TD adults. Cerebral palsy (CP) is the most common cause of movement disorders in children. Next generation sequencing (NGS) studies have previously shown that expression levels are fundamentally different in children with CP compared to typically developing (TD). However, given that children are in full development, we might expect gene expression levels to change once maturity is reached. Therefore, the main purpose of this study was to investigate gene expression levels of 93 target genes in adults with CP using NGS on muscle biopsies of the gastrocnemius, taken from 22 participants (n = 12 adults with CP; n = 10 TD adults). Subsequently, we carried out NGS of the mitochondrial genome to identify mtDNA variants, and additionally we studied the mitochondrial content using transmission electron microscopy images of the gastrocnemius muscle. Finally, we compared systemic ion levels between TD adults and adults with CP. Differential gene expression levels were found in genes involved in muscle contraction (MYH1 and MYBPC2), mitochondrial function kATP5J, CYCS and NDUFB6), calcium handling (CAMK2B and ATP2A), metabolism (LPL) , muscle signaling (MYC, CREB1, ACVR2B, LMNA and TRIM54), and ECM (TNC). There was no statistical significant difference between CP and TD for mtDNA variant frequencies and mitochondrial content. The ion levels of Ca2+, Na+ and K+ were statistically significantly reduced while the Cl− levels were significant increased in adults with CP compared to TD adults. These results highlight that most transcriptional differences are related to muscle function in adults with CP and that mitochondrial function might be altered but not mitochondrial content. [ABSTRACT FROM AUTHOR]