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Differential Expression of Canonical Mitosis and DNA Damage Repair Pathways Characterize Muscle Satellite Cells Affected by Peripheral Arterial Disease

      Background

      Peripheral arterial disease (PAD) is associated with diminished muscle strength, even in claudicants with adequate resting perfusion. Muscle satellite cells (MuSC) regeneration may be deterred by PAD. We propose that MuSC in PAD have transcriptomic differences causing ischemia-induced myopathy.

      Methods

      Anterior tibialis segments were harvested during amputations for critical limb ischemia from viable (proximal) and ischemic (distal) muscle. Pressure indices documented perfusion. MuSC were isolated by antibody-mediated magnetic cell sorting. Control myocytes were purchased. Both were measured for myocyte fusion index (1 and 5 d). TruSeq stranded messenger RNA kits facilitated library creation for next-generation sequencing. Ingenuity pathway analysis was performed on differentially expressed genes with a false discovery rate P value of less than .05 for pathway enrichment.

      Results

      The myocyte fusion index in PAD (n = 8, proximal and distal) MuSC was one-half that of controls (P < .03; n = 4, analysis of variance). Pressure indices confirmed a perfusion gradient along the limb. The number of differentially expressed genes among PAD and controls are shown (Fig). MuSC in PAD vs controls had significant differences in canonical pathway expression including mitotic roles of polo-like kinase (z score = 7.5 distal, 13.5 proximal), and G2/M DNA damage checkpoint regulation (z score = 6.5 distal, 9.0 proximal). Genetic expression did not differ within PAD muscle as a function of perfusion.

      Conclusions

      Compared with controls, MuSC in PAD have significant differences in gene expression, even in better perfused muscle. Pathways affected included those essential to mitosis and DNA damage repair, both critical to cell survival and differentiation. These findings suggest perfusion-independent PAD effects on muscle that persist despite optimization. Adjunctive treatments beyond reperfusion may be required to mitigate muscle damage from arterial insufficiency.
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      FigDifferential gene expression among groups is shown. Red, Upregulate; green, downregulated; gray, no change.