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Extensive skeletal muscle cell mitochondriopathy distinguishes critical limb ischemia patients from claudicants
Terence E. Ryan, … , Espen E. Spangenburg, Joseph M. McClung
Terence E. Ryan, … , Espen E. Spangenburg, Joseph M. McClung
Published November 2, 2018
Citation Information: JCI Insight. 2018;3(21):e123235. https://doi.org/10.1172/jci.insight.123235.
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Research Article Metabolism

Extensive skeletal muscle cell mitochondriopathy distinguishes critical limb ischemia patients from claudicants

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Abstract

The most severe manifestation of peripheral arterial disease (PAD) is critical limb ischemia (CLI). CLI patients suffer high rates of amputation and mortality; accordingly, there remains a clear need both to better understand CLI and to develop more effective treatments. Gastrocnemius muscle was obtained from 32 older (51–84 years) non-PAD controls, 27 claudicating PAD patients (ankle-brachial index [ABI] 0.65 ± 0.21 SD), and 19 CLI patients (ABI 0.35 ± 0.30 SD) for whole transcriptome sequencing and comprehensive mitochondrial phenotyping. Comparable permeabilized myofiber mitochondrial function was paralleled by both similar mitochondrial content and related mRNA expression profiles in non-PAD control and claudicating patient tissues. Tissues from CLI patients, despite being histologically intact and harboring equivalent mitochondrial content, presented a unique bioenergetic signature. This signature was defined by deficits in permeabilized myofiber mitochondrial function and a unique pattern of both nuclear and mitochondrial encoded gene suppression. Moreover, isolated muscle progenitor cells retained both mitochondrial functional deficits and gene suppression observed in the tissue. These findings indicate that muscle tissues from claudicating patients and non-PAD controls were similar in both their bioenergetics profile and mitochondrial phenotypes. In contrast, CLI patient limb skeletal muscles harbor a unique skeletal muscle mitochondriopathy that represents a potentially novel therapeutic site for intervention.

Authors

Terence E. Ryan, Dean J. Yamaguchi, Cameron A. Schmidt, Tonya N. Zeczycki, Saame Raza Shaikh, Patricia Brophy, Thomas D. Green, Michael D. Tarpey, Reema Karnekar, Emma J. Goldberg, Genevieve C. Sparagna, Maria J. Torres, Brian H. Annex, P. Darrell Neufer, Espen E. Spangenburg, Joseph M. McClung

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Figure 8

Skeletal muscle stem cells from CLI patients display a unique bioenergetics gene expression signature.

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Skeletal muscle stem cells from CLI patients display a unique bioenerget...
Primary muscle progenitor cells (satellite cells) were isolated from muscle biopsies. Isolated myoblasts were differentiated into myotubes by serum withdrawal (A). (B) Cellular respiration was assessed using a Seahorse XF analyzer. Oligo, oligomycin; AmA, antimycin A; Asc, ascorbate; OCR, oxygen consumption rate. (C) Quantification of cellular respiration under different substrate/inhibitor combinations indicates impaired basal, maximal, and complex IV–linked respiration in cells from CLI patients (N = 8 for HA, N = 7 for IC, and N = 8 for CLI). (D) Citrate synthase activity was not different in cells (N = 4 for HA, N = 6 for IC, and N = 4 for CLI). (E) Quantification of mitochondrial volume from Z-stack confocal imaging of fluorescently labeled mitochondria in MPCs (N = 4 for HA, N = 4 for IC, and N = 4 for CLI). (F) Representative images of labeled mitochondria (TOMM20, green). Counterstaining was performed with DAPI (blue, nuclei) and phalloidin (red, actin). (G) Gene expression analysis by qRT-PCR indicated a unique gene signature related to mitochondrial metabolism. All sample sizes indicate independent MPC isolations from different patients. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 using ANOVA with Tukey’s multiple comparison test. NS, not significant. Data are presented as the mean ± SEM.

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