title: Pericyte response to contraction mode-specific resistance exercise training in human skeletal muscle.
abstract: Skeletal muscle satellite cells (SCs) are important for muscle repair and hypertrophy in response mechanical stimuli. Neuron-glial antigen 2-positive (NG2(+)) and alkaline phosphatase-positive (ALP(+)) pericytes may provide an alternative source of myogenic progenitors and/or secrete paracrine factors to induce Pax7(+) SC proliferation and differentiation. The purpose of this study was to investigate NG2(+) and ALP(+) cell quantity, as well as SC content and activation, in human skeletal muscle following prolonged concentric (Conc) or eccentric (Ecc) resistance training. Male subjects engaged in unilateral resistance training utilizing isolated Ecc or Conc contractions. After 12 wk, muscle biopsies were analyzed for NG2(+) and ALP(+) pericytes, total Pax7(+) SCs, activated SCs (Pax7(+)MyoD(+)), and differentiating myogenic cells (Pax7(-) MyoD(+)). NG2(+) cells localized to CD31(+) vessels and the majority coexpressed ALP. NG2(+) pericyte quantity decreased following both Conc and Ecc training (P < 0.05). ALP(+) pericyte quantity declined following Conc (P < 0.05) but not Ecc training. Conversely, total Pax7(+) SC content was elevated following Conc only (P < 0.001), while Pax7(+)MyoD(+) SC content was increased following Conc and Ecc (P < 0.001). Follow up analyses demonstrated that CD90(+) and platelet-derived growth factor receptor-α (PDGFRα)(+) mononuclear cell proliferation was also increased in response to both Conc and Ecc training (P < 0.01). In summary, resistance training results in a decline in pericyte quantity and an increase in mesenchymal progenitor cell proliferation, and these events likely influence SC pool expansion and increased activation observed posttraining.
authors.affiliation: Section of Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark;
authors.forename: Jean
authors.initials: J
authors.lastname: Farup
authors.affiliation: Department of Kinesiology and Community Health and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Illinois; and.
authors.forename: Michael
authors.initials: M
authors.lastname: De Lisio
authors.affiliation: Section of Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark;
authors.forename: Stine Klejs
authors.initials: SK
authors.lastname: Rahbek
authors.affiliation: Section of Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark;
authors.forename: Jonas
authors.initials: J
authors.lastname: Bjerre
authors.affiliation: Department of Internal Medicine and Endocrinology and Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Mikkel Holm
authors.initials: MH
authors.lastname: Vendelbo
authors.affiliation: Department of Kinesiology and Community Health and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Illinois; and.
authors.forename: Marni D
authors.initials: MD
authors.lastname: Boppart
authors.affiliation: Section of Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark; vissing@ph.au.dk.
authors.forename: Kristian
authors.initials: K
authors.lastname: Vissing
mesh_terms: D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D020286:Pericytes / Q000378:metabolism*; D055070:Resistance Training / Q000379:methods*; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins
keywords: eccentric exercise; mesenchymal stem cells; pericytes; satellite cells