Revealing Human Muscle Denervation Biomarkers Through Spatiogenomic Mapping

Le résumé fourni par la source

PURPOSE: Peripheral nerve injuries cause muscle denervation, leading to progressive weakness and functional decline secondary to sensorimotor deficits. While repair or transfer can re-establish axonal contact, recovery of meaningful strength remains unpredictable. Our prior work showed that preserved motor endplate morphology in denervated muscle biopsies may predict reinnervation success. To determine biomarkers for guiding patient selection and timing of nerve repair, we apply high-resolution spatial transcriptomics (Visium HD) to study denervation and reinnervation signatures in intra-operative human muscle biopsies from surgical procedures. METHODS: With IRB approval, intra-operative biopsies of healthy trapezius and denervated deltoid muscles (confirmed by electromyography) were collected during routine upper-extremity surgeries from consenting patients. Samples were flash-frozen in liquid nitrogen-cooled isopentane and profiled with Visium HD's 8-µm resolution using NIA R21AG078909-funded kits (M.H., R.G.). Unique molecular identifiers (UMIs) and gene expression counts were processed in Loupe Browser v8, where clustering was annotated using canonical markers for myofibers (fast, slow, developmental), fibro-adipogenic progenitors (FAPs), peripheral nerve, and other cell types. Percent-of-spot expression was quantified for neuromuscular junction genes (CHRNA1, MUSK). RESULTS: High-resolution spatial transcriptomics was successfully applied to intra-operative human muscle biopsies ( Figure 1 ). Visium HD detected 16,660 genes in 331,326 trapezius barcodes and 16,356 genes in 459,921 deltoid barcodes, with 90% valid barcodes and 98% on-target reads. At 8-µm resolution, healthy trapezius averaged 99.6 UMIs and 71.9 genes per barcode, while denervated deltoid averaged 173.2 UMIs and 125.8 genes, reflecting increased RNA density after denervation. Quality-control filtering removed 54,405 trapezius and 57,151 deltoid barcodes, 89% of which localized to fibrofatty regions, underscoring low RNA yield as a transcriptomic signature of fibrofatty degeneration. Among the clusters identified, trapezius revealed fast-fiber (33.4%) and slow-fiber (12.2%) clusters, a developmental-myosin cluster (9.7%), fibro-adipogenic progenitor (11.2%) clusters, and nerve-associated (1.3%) clusters. Denervated deltoid showed enrichment of slow-fiber clusters (37.2%), reduced fast-fiber clusters (16.6%), fewer developmental myosin fibers (5.7%), expanded fibro-adipogenic progenitors (24.5%), and no nerve-associated clusters. Notably, Visium HD resolved distinct core versus sarcolemmal rim clusters within myofibers ( Figure 2 ) and separated genetically unique subclusters within populations, demonstrating its resolution to map intracellular and extracellular architecture. Neuromuscular junction genes were markedly upregulated in the denervated deltoid when compared to the healthy trapezium, with CHRNA1 rising from 0.16% to 25.96% (162-fold) and MUSK from 0.02% to 6.09% (304-fold) ( Figure 3 ). CONCLUSION: Beyond feasibility, spatial transcriptomics of human muscle biopsies revealed molecular hallmarks of denervation, including preferential loss of fast-fiber profiles, expansion of fibro-adipogenic progenitors, and marked upregulation of neuromuscular junction genes (CHRNA1, MUSK). Characterizing spatiogenomic shifts after nerve injury enables biomarker identification to guide surgical decisions and personalize repair strategies.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.