Lack of muscle stem cell proliferation and myocellular hypertrophy in sIBM patients following blood-flow restricted resistance training
Kasper Yde Jensen, Jakob Lindberg Nielsen, Henrik Daa Schrøder, Mikkel Jacobsen, Eleanor Boyle, Anders Nørkær Jørgensen, Rune Dueholm Bech, Ulrik Frandsen, Per Aagaard, Louise Pyndt Diederichsen, Kasper Yde Jensen, Jakob Lindberg Nielsen, Henrik Daa Schrøder, Mikkel Jacobsen, Eleanor Boyle, Anders Nørkær Jørgensen, Rune Dueholm Bech, Ulrik Frandsen, Per Aagaard, Louise Pyndt Diederichsen
Abstract
Sporadic inclusion body myositis (sIBM) is characterised by skeletal muscle inflammation, progressive muscle loss and weakness, which is largely refractory to immunosuppressive treatment. Low-load blood-flow restricted (BFR) training has been shown to evoke gains in myofibre cross sectional area (mCSA) in healthy adults. This could partially be due to the activation and integration of muscle satellite cells (SC) resulting in myonuclei addition. Consequently, this study investigated the effect of 12-weeks lower limb low-load BFR resistance training in sIBM patients on SC and myonuclei content, myofibre size and capillarization. Muscle biopsies from sIBM patients randomised to 12-weeks of low-load BFR resistance training (n = 11) or non-exercising controls (CON) (n = 9) were analysed for SC and myonuclei content, myofibre size and capillarization using three-colour immunofluorescence microscopy and computerised quantification procedures. No between-group differences (time-by-group interactions) or within-groups changes were observed for resident SCs (Pax7+/Six1+), proliferating SCs (Pax7+/ Ki67+), myonuclei (Six1+), type 1 mCSA or capillary number (CD31+). However, a time-by-group interaction for type 2 mCSA was observed (p = 0.04). Satellite cell content, myonuclei number, mCSA and capillary density remained unaffected following 12-weeks low-load BFR resistance training, indicating limited myogenic capacity and satellite cell plasticity in long-term sIBM patients.
Trial registration: ClinicalTrials.gov NCT02317094.
Keywords: Capillaries; Exercise; Myogenic plasticity; Myonuclei; Myositis; Satellite cells.
Conflict of interest statement
Declaration of Competing Interest ANJ was employed by Orphazyme A/S, who is developing pharmaceuticals for patients affected by sporadic inclusion body myositis. Orphazyme A/S does not have any financial nor scientific interest in the data presented in this article.
Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.
Source: PubMed