1
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Collins BC, Shapiro JB, Scheib MM, Musci RV, Verma M, Kardon G. Three-dimensional imaging studies in mice identify cellular dynamics of skeletal muscle regeneration. Dev Cell 2024; 59:1457-1474.e5. [PMID: 38569550 PMCID: PMC11153043 DOI: 10.1016/j.devcel.2024.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 12/06/2023] [Accepted: 03/08/2024] [Indexed: 04/05/2024]
Abstract
The function of many organs, including skeletal muscle, depends on their three-dimensional structure. Muscle regeneration therefore requires not only reestablishment of myofibers but also restoration of tissue architecture. Resident muscle stem cells (SCs) are essential for regeneration, but how SCs regenerate muscle architecture is largely unknown. We address this problem using genetic labeling of mouse SCs and whole-mount imaging to reconstruct, in three dimensions, muscle regeneration. Unexpectedly, we found that myofibers form via two distinct phases of fusion and the residual basement membrane of necrotic myofibers is critical for promoting fusion and orienting regenerated myofibers. Furthermore, the centralized myonuclei characteristic of regenerated myofibers are associated with myofibrillogenesis and endure months post injury. Finally, we elucidate two cellular mechanisms for the formation of branched myofibers, a pathology characteristic of diseased muscle. We provide a synthesis of the cellular events of regeneration and show that these differ from those used during development.
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Affiliation(s)
- Brittany C Collins
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Jacob B Shapiro
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Mya M Scheib
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Robert V Musci
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Mayank Verma
- Department of Pediatrics, Division of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Gabrielle Kardon
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA.
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2
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Endo T. Postnatal skeletal muscle myogenesis governed by signal transduction networks: MAPKs and PI3K-Akt control multiple steps. Biochem Biophys Res Commun 2023; 682:223-243. [PMID: 37826946 DOI: 10.1016/j.bbrc.2023.09.048] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/06/2023] [Accepted: 09/18/2023] [Indexed: 10/14/2023]
Abstract
Skeletal muscle myogenesis represents one of the most intensively and extensively examined systems of cell differentiation, tissue formation, and regeneration. Muscle regeneration provides an in vivo model system of postnatal myogenesis. It comprises multiple steps including muscle stem cell (or satellite cell) quiescence, activation, migration, myogenic determination, myoblast proliferation, myocyte differentiation, myofiber maturation, and hypertrophy. A variety of extracellular signaling and subsequent intracellular signal transduction pathways or networks govern the individual steps of postnatal myogenesis. Among them, MAPK pathways (the ERK, JNK, p38 MAPK, and ERK5 pathways) and PI3K-Akt signaling regulate multiple steps of myogenesis. Ca2+, cytokine, and Wnt signaling also participate in several myogenesis steps. These signaling pathways often control cell cycle regulatory proteins or the muscle-specific MyoD family and the MEF2 family of transcription factors. This article comprehensively reviews molecular mechanisms of the individual steps of postnatal skeletal muscle myogenesis by focusing on signal transduction pathways or networks. Nevertheless, no or only a partial signaling molecules or pathways have been identified in some responses during myogenesis. The elucidation of these unidentified signaling molecules and pathways leads to an extensive understanding of the molecular mechanisms of myogenesis.
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Affiliation(s)
- Takeshi Endo
- Department of Biology, Graduate School of Science, Chiba University, Yayoicho, Inageku, Chiba, Chiba 263-8522, Japan.
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3
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Ma N, Chen D, Lee JH, Kuri P, Hernandez EB, Kocan J, Mahmood H, Tichy ED, Rompolas P, Mourkioti F. Piezo1 regulates the regenerative capacity of skeletal muscles via orchestration of stem cell morphological states. SCIENCE ADVANCES 2022; 8:eabn0485. [PMID: 35302846 PMCID: PMC8932657 DOI: 10.1126/sciadv.abn0485] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 01/26/2022] [Indexed: 05/08/2023]
Abstract
Muscle stem cells (MuSCs) are essential for tissue homeostasis and regeneration, but the potential contribution of MuSC morphology to in vivo function remains unknown. Here, we demonstrate that quiescent MuSCs are morphologically heterogeneous and exhibit different patterns of cellular protrusions. We classified quiescent MuSCs into three functionally distinct stem cell states: responsive, intermediate, and sensory. We demonstrate that the shift between different stem cell states promotes regeneration and is regulated by the sensing protein Piezo1. Pharmacological activation of Piezo1 is sufficient to prime MuSCs toward more responsive cells. Piezo1 deletion in MuSCs shifts the distribution toward less responsive cells, mimicking the disease phenotype we find in dystrophic muscles. We further demonstrate that Piezo1 reactivation ameliorates the MuSC morphological and regenerative defects of dystrophic muscles. These findings advance our fundamental understanding of how stem cells respond to injury and identify Piezo1 as a key regulator for adjusting stem cell states essential for regeneration.
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Affiliation(s)
- Nuoying Ma
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Bioengineering Graduate Program, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Delia Chen
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ji-Hyung Lee
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paola Kuri
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Edward Blake Hernandez
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jacob Kocan
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hamd Mahmood
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Elisia D. Tichy
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Panteleimon Rompolas
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Foteini Mourkioti
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Penn Institute for Regenerative Medicine, Musculoskeletal Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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4
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Sharma P, Ruel TD, Kocha KM, Liao S, Huang P. Single cell dynamics of embryonic muscle progenitor cells in zebrafish. Development 2019; 146:dev.178400. [PMID: 31253635 DOI: 10.1242/dev.178400] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/12/2019] [Indexed: 01/13/2023]
Abstract
Muscle stem cells hold a great therapeutic potential in regenerating damaged muscles. However, the in vivo behavior of muscle stem cells during muscle growth and regeneration is still poorly understood. Using zebrafish as a model, we describe the in vivo dynamics and function of embryonic muscle progenitor cells (MPCs) in the dermomyotome. These cells are located in a superficial layer external to muscle fibers and express many extracellular matrix (ECM) genes, including collagen type 1 α2 (col1a2). Utilizing a new col1a2 transgenic line, we show that col1a2+ MPCs display a ramified morphology with dynamic cellular processes. Cell lineage tracing demonstrates that col1a2+ MPCs contribute to new myofibers in normal muscle growth and also during muscle regeneration. A combination of live imaging and single cell clonal analysis reveals a highly choreographed process of muscle regeneration. Activated col1a2+ MPCs change from the quiescent ramified morphology to a polarized and elongated morphology, generating daughter cells that fuse with existing myofibers. Partial depletion of col1a2+ MPCs severely compromises muscle regeneration. Our work provides a dynamic view of embryonic muscle progenitor cells during zebrafish muscle growth and regeneration.
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Affiliation(s)
- Priyanka Sharma
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, 3330 Hospital Drive, Calgary, AB T2N 4N1, Canada
| | - Tyler D Ruel
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, 3330 Hospital Drive, Calgary, AB T2N 4N1, Canada
| | - Katrinka M Kocha
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, 3330 Hospital Drive, Calgary, AB T2N 4N1, Canada
| | - Shan Liao
- Inflammation Research Network, The Snyder Institute for Chronic Diseases, Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive, Calgary, AB T2N 4N1, Canada
| | - Peng Huang
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, 3330 Hospital Drive, Calgary, AB T2N 4N1, Canada
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5
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Dumont NA, Bentzinger CF, Sincennes MC, Rudnicki MA. Satellite Cells and Skeletal Muscle Regeneration. Compr Physiol 2016; 5:1027-59. [PMID: 26140708 DOI: 10.1002/cphy.c140068] [Citation(s) in RCA: 492] [Impact Index Per Article: 54.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Skeletal muscles are essential for vital functions such as movement, postural support, breathing, and thermogenesis. Muscle tissue is largely composed of long, postmitotic multinucleated fibers. The life-long maintenance of muscle tissue is mediated by satellite cells, lying in close proximity to the muscle fibers. Muscle satellite cells are a heterogeneous population with a small subset of muscle stem cells, termed satellite stem cells. Under homeostatic conditions all satellite cells are poised for activation by stimuli such as physical trauma or growth signals. After activation, satellite stem cells undergo symmetric divisions to expand their number or asymmetric divisions to give rise to cohorts of committed satellite cells and thus progenitors. Myogenic progenitors proliferate, and eventually differentiate through fusion with each other or to damaged fibers to reconstitute fiber integrity and function. In the recent years, research has begun to unravel the intrinsic and extrinsic mechanisms controlling satellite cell behavior. Nonetheless, an understanding of the complex cellular and molecular interactions of satellite cells with their dynamic microenvironment remains a major challenge, especially in pathological conditions. The goal of this review is to comprehensively summarize the current knowledge on satellite cell characteristics, functions, and behavior in muscle regeneration and in pathological conditions.
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Affiliation(s)
- Nicolas A Dumont
- Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - C Florian Bentzinger
- Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Nestlé Institute of Health Sciences, EPFL Campus, Lausanne, Switzerland
| | - Marie-Claude Sincennes
- Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Michael A Rudnicki
- Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
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6
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Webster MT, Manor U, Lippincott-Schwartz J, Fan CM. Intravital Imaging Reveals Ghost Fibers as Architectural Units Guiding Myogenic Progenitors during Regeneration. Cell Stem Cell 2015; 18:243-52. [PMID: 26686466 DOI: 10.1016/j.stem.2015.11.005] [Citation(s) in RCA: 151] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 10/24/2015] [Accepted: 11/06/2015] [Indexed: 12/16/2022]
Abstract
How resident stem cells and their immediate progenitors rebuild tissues of pre-injury organization and size for proportional regeneration is not well understood. Using 3D, time-lapse intravital imaging for direct visualization of the muscle regeneration process in live mice, we report that extracellular matrix remnants from injured skeletal muscle fibers, "ghost fibers," govern muscle stem/progenitor cell behaviors during proportional regeneration. Stem cells were immobile and quiescent without injury whereas their activated progenitors migrated and divided after injury. Unexpectedly, divisions and migration were primarily bi-directionally oriented along the ghost fiber longitudinal axis, allowing for spreading of progenitors throughout ghost fibers. Re-orienting ghost fibers impacted myogenic progenitors' migratory paths and division planes, causing disorganization of regenerated muscle fibers. We conclude that ghost fibers are autonomous, architectural units necessary for proportional regeneration after tissue injury. This finding reinforces the need to fabricate bioengineered matrices that mimic living tissue matrices for tissue regeneration therapy.
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Affiliation(s)
- Micah T Webster
- Department of Embryology, Carnegie Institution of Washington, 3520 San Martin Drive, Baltimore, MD 21218, USA
| | - Uri Manor
- Cell Biology and Metabolism Branch, Eunice Kennedy Shriver National Institutes of Child Health and Human Development, National Institute of Health, Building 35A, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Jennifer Lippincott-Schwartz
- Cell Biology and Metabolism Branch, Eunice Kennedy Shriver National Institutes of Child Health and Human Development, National Institute of Health, Building 35A, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Chen-Ming Fan
- Department of Embryology, Carnegie Institution of Washington, 3520 San Martin Drive, Baltimore, MD 21218, USA.
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7
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Yamaguchi M, Watanabe Y, Ohtani T, Uezumi A, Mikami N, Nakamura M, Sato T, Ikawa M, Hoshino M, Tsuchida K, Miyagoe-Suzuki Y, Tsujikawa K, Takeda S, Yamamoto H, Fukada SI. Calcitonin Receptor Signaling Inhibits Muscle Stem Cells from Escaping the Quiescent State and the Niche. Cell Rep 2015; 13:302-14. [PMID: 26440893 DOI: 10.1016/j.celrep.2015.08.083] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 06/09/2015] [Accepted: 08/31/2015] [Indexed: 01/26/2023] Open
Abstract
Calcitonin receptor (Calcr) is expressed in adult muscle stem cells (muscle satellite cells [MuSCs]). To elucidate the role of Calcr, we conditionally depleted Calcr from adult MuSCs and found that impaired regeneration after muscle injury correlated with the decreased number of MuSCs in Calcr-conditional knockout (cKO) mice. Calcr signaling maintained MuSC dormancy via the cAMP-PKA pathway but had no impact on myogenic differentiation of MuSCs in an undifferentiated state. The abnormal quiescent state in Calcr-cKO mice resulted in a reduction of the MuSC pool by apoptosis. Furthermore, MuSCs were found outside their niche in Calcr-cKO mice, demonstrating cell relocation. This emergence from the sublaminar niche was prevented by the Calcr-cAMP-PKA and Calcr-cAMP-Epac pathways downstream of Calcr. Altogether, the findings demonstrated that Calcr exerts its effect specifically by keeping MuSCs in a quiescent state and in their location, maintaining the MuSC pool.
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Affiliation(s)
- Masahiko Yamaguchi
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yoko Watanabe
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takuji Ohtani
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Akiyoshi Uezumi
- Division for Therapies Against Intractable Diseases, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake, Toyoake, Aichi 470-1192, Japan
| | - Norihisa Mikami
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Miki Nakamura
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takahiko Sato
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Masahito Ikawa
- Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Mikio Hoshino
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Kunihiro Tsuchida
- Division for Therapies Against Intractable Diseases, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake, Toyoake, Aichi 470-1192, Japan
| | - Yuko Miyagoe-Suzuki
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Kazutake Tsujikawa
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shin'ichi Takeda
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Hiroshi Yamamoto
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - So-ichiro Fukada
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan.
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8
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Ogawa R, Ma Y, Yamaguchi M, Ito T, Watanabe Y, Ohtani T, Murakami S, Uchida S, De Gaspari P, Uezumi A, Nakamura M, Miyagoe-Suzuki Y, Tsujikawa K, Hashimoto N, Braun T, Tanaka T, Takeda S, Yamamoto H, Fukada SI. Doublecortin marks a new population of transiently amplifying muscle progenitor cells and is required for myofiber maturation during skeletal muscle regeneration. Development 2015; 142:51-61. [DOI: 10.1242/dev.112557] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Muscle satellite cells are indispensable for muscle regeneration, but the functional diversity of their daughter cells is unknown. Here, we show that many Pax7+MyoD− cells locate both beneath and outside the basal lamina during myofiber maturation. A large majority of these Pax7+MyoD− cells are not self-renewed satellite cells, but have different potentials for both proliferation and differentiation from Pax7+MyoD+ myoblasts (classical daughter cells), and are specifically marked by expression of the doublecortin (Dcx) gene. Transplantation and lineage-tracing experiments demonstrated that Dcx-expressing cells originate from quiescent satellite cells and that the microenvironment induces Dcx in myoblasts. Expression of Dcx seems to be necessary for myofiber maturation because Dcx-deficient mice exhibited impaired myofiber maturation resulting from a decrease in the number of myonuclei. Furthermore, in vitro and in vivo studies suggest that one function of Dcx in myogenic cells is acceleration of cell motility. These results indicate that Dcx is a new marker for the Pax7+MyoD− subpopulation, which contributes to myofiber maturation during muscle regeneration.
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Affiliation(s)
- Ryo Ogawa
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yuran Ma
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Masahiko Yamaguchi
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Takahito Ito
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yoko Watanabe
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Takuji Ohtani
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Satoshi Murakami
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Shizuka Uchida
- Institute of Cardiovascular Regeneration, Centre for Molecular Medicine, Goethe University Frankfurt, Theodor-Stern-Kai 7, Frankfurt am Main 60590, Germany
| | - Piera De Gaspari
- Max Planck Institute for Heart and Lung Research, Ludwigstrasse 43, Bad Nauheim 61231, Germany
| | - Akiyoshi Uezumi
- Division for Therapies Against Intractable Diseases, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake, Toyoake, Aichi 470-1192, Japan
| | - Miki Nakamura
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yuko Miyagoe-Suzuki
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-higashi, Kodaira, Tokyo 187-8502, Japan
| | - Kazutake Tsujikawa
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Naohiro Hashimoto
- Department of Regenerative Medicine, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, 35 Gengo, Morioka, Oobu, Aichi 474-8522, Japan
| | - Thomas Braun
- Max Planck Institute for Heart and Lung Research, Ludwigstrasse 43, Bad Nauheim 61231, Germany
| | - Teruyuki Tanaka
- Department of Developmental Medical Sciences, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shin'ichi Takeda
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-higashi, Kodaira, Tokyo 187-8502, Japan
| | - Hiroshi Yamamoto
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - So-ichiro Fukada
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
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9
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Abstract
Adult skeletal muscle in mammals is a stable tissue under normal circumstances but has remarkable ability to repair after injury. Skeletal muscle regeneration is a highly orchestrated process involving the activation of various cellular and molecular responses. As skeletal muscle stem cells, satellite cells play an indispensible role in this process. The self-renewing proliferation of satellite cells not only maintains the stem cell population but also provides numerous myogenic cells, which proliferate, differentiate, fuse, and lead to new myofiber formation and reconstitution of a functional contractile apparatus. The complex behavior of satellite cells during skeletal muscle regeneration is tightly regulated through the dynamic interplay between intrinsic factors within satellite cells and extrinsic factors constituting the muscle stem cell niche/microenvironment. For the last half century, the advance of molecular biology, cell biology, and genetics has greatly improved our understanding of skeletal muscle biology. Here, we review some recent advances, with focuses on functions of satellite cells and their niche during the process of skeletal muscle regeneration.
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Affiliation(s)
- Hang Yin
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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10
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Abstract
The fusion of myoblasts into multinucleate syncytia plays a fundamental role in muscle function, as it supports the formation of extended sarcomeric arrays, or myofibrils, within a large volume of cytoplasm. Principles learned from the study of myoblast fusion not only enhance our understanding of myogenesis, but also contribute to our perspectives on membrane fusion and cell-cell fusion in a wide array of model organisms and experimental systems. Recent studies have advanced our views of the cell biological processes and crucial proteins that drive myoblast fusion. Here, we provide an overview of myoblast fusion in three model systems that have contributed much to our understanding of these events: the Drosophila embryo; developing and regenerating mouse muscle; and cultured rodent muscle cells.
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Affiliation(s)
- Susan M Abmayr
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
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11
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Ishido M, Kasuga N. In situ real-time imaging of the satellite cells in rat intact and injured soleus muscles using quantum dots. Histochem Cell Biol 2010; 135:21-6. [PMID: 21132508 DOI: 10.1007/s00418-010-0767-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2010] [Indexed: 12/26/2022]
Abstract
The recruitment of satellite cells, which are located between the basement membrane and the plasma membrane in myofibers, is required for myofiber repair after muscle injury or disease. In particular, satellite cell migration has been focused on as a satellite cell response to muscle injury because satellite cell motility has been revealed in cell culture. On the other hand, in situ, it is poorly understood how satellite cell migration is involved in muscle regeneration after injury because in situ it has been technically very difficult to visualize living satellite cells localized within skeletal muscle. In the present study, using quantum dots conjugated to anti-M-cadherin antibody, we attempted the visualization of satellite cells in both intact and injured skeletal muscle of rat in situ. As a result, the present study is the first to demonstrate in situ real-time imaging of satellite cells localized within the skeletal muscle. Moreover, it was indicated that satellite cell migration toward an injured site was induced in injured muscle while spatiotemporal change in satellite cells did not occur in intact muscle. Thus, it was suggested that the satellite cell migration may play important roles in the regulation of muscle regeneration after injury. Moreover, the new method used in the present study will be a useful tool to develop satellite cell-based therapies for muscle injury or disease.
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Affiliation(s)
- Minenori Ishido
- Faculty of Education, Creative Arts and Sciences, Aichi University of Education, Igaya-cho, Kariya, Aichi, Japan.
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12
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Nicholas A, Kraytsberg Y, Guo X, Khrapko K. On the timing and the extent of clonal expansion of mtDNA deletions: evidence from single-molecule PCR. Exp Neurol 2009; 218:316-9. [PMID: 19426731 PMCID: PMC2724894 DOI: 10.1016/j.expneurol.2009.04.029] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 04/27/2009] [Accepted: 04/28/2009] [Indexed: 01/07/2023]
Abstract
mtDNA deletions are pathogenic mutations that remove substantial portions of the mitochondrial genome. mtDNA deletions accumulate with age and have been implicated in various degenerative diseases. There are multiple mtDNA per cell and mtDNA mutations become toxic only if they accumulate to substantial intracellular levels, i.e. exceed so-called "phenotypic threshold". This is usually achieved via clonal expansion of a single initial mutated molecule. Intracellular mitochondrial genomes are analogous to a population of individuals in that mitochondria are born by division and die by degradation. Clonal expansion within cells is thus analogous to genetic drift within populations and is driven by a combination of random processes and selection. mtDNA mutations occurring early in development are expected to end up spread across tissues, while mutations of late origin are expected to be localized, i.e. limited a single post-mitotic cell or progeny of a single stem cell. We have explored the extent and timing of clonality of mtDNA deletion in human muscle using single-molecule PCR. We analyzed deletions from two nearby locations within the same tissue sample. Altogether we analyzed over 130 mutant molecules, but almost every deletion type detected was represented by several identical mutant molecules, so that altogether there were only 21 different kinds of deletions, implying that essentially all deletions were clonal. At the same time the sets of deletions in the two locations were completely different. This observation implies that all of the clonal expansions spanned very small areas and therefore that the corresponding mutations were likely events of older age. More studies are necessary to further validate these findings in muscle and to explore the other tissues.
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Affiliation(s)
- Alexander Nicholas
- Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
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13
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Praud C, Vauchez K, Lombes A, Fiszman MY, Vilquin JT. Myoblast Xenotransplantation as a Tool to Evaluate the Appropriateness of Nanoparticular versus Cellular Trackers. Cell Transplant 2008; 17:1035-43. [DOI: 10.3727/096368908786991588] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Myoblast transplantation is being considered as a potential strategy to improve muscle function in myopathies; hence, it is important to identify the transplanted cells and to have available efficient reagents to track these cells. We first validated a human to mouse xenotransplantation model warranting the complete and rapid rejection of the cells. We then used this model to assess the appropriateness of a nanoparticle reagent to track the transplanted cells. Human myoblasts were loaded with ferrite nanoparticles and injected into the tibialis muscle of immunocompetent mice. Upon collection and histological analysis of muscle sections at different time points, we observed the total disappearance of the human cells within 6 days while ferrite particles remained detectable and colocalized with mouse infiltrating and neighboring cells at the injection site. These results suggest that the use of exogenous markers such as ferrite nanoparticles may lead to false-positive results and misinterpretation of cell fate.
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Affiliation(s)
- C. Praud
- Inserm U582, Institut de Myologie, UPMC Univ Paris 06, Paris, France
| | - K. Vauchez
- Inserm U582, Institut de Myologie, UPMC Univ Paris 06, Paris, France
- Genzyme S.A., Saint Germain en Laye, France
| | - A. Lombes
- Inserm U582, Institut de Myologie, UPMC Univ Paris 06, Paris, France
| | - M. Y. Fiszman
- Inserm U582, Institut de Myologie, UPMC Univ Paris 06, Paris, France
| | - J.-T. Vilquin
- Inserm U582, Institut de Myologie, UPMC Univ Paris 06, Paris, France
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14
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Kroehne V, Heschel I, Schügner F, Lasrich D, Bartsch JW, Jockusch H. Use of a novel collagen matrix with oriented pore structure for muscle cell differentiation in cell culture and in grafts. J Cell Mol Med 2008; 12:1640-8. [PMID: 18194451 PMCID: PMC2680279 DOI: 10.1111/j.1582-4934.2008.00238.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Tissue engineering of skeletal muscle from cultured cells has been attempted using a variety of synthetic and natural macromolecular scaffolds. Our study describes the application of artificial scaffolds (collagen sponges, CS) consisting of collagen-I with parallel pores (width 20–50 μm) using the permanent myogenic cell line C2C12. CS were infiltrated with a high-density cell suspension, incubated in medium for proliferation of myoblasts prior to further culture in fusion medium to induce differentiation and formation of multinucleated myotubes. This resulted in a parallel arrangement of myotubes within the pore structures. CS with either proliferating cells or with myotubes were grafted into the beds of excised anterior tibial muscles of immunodeficient host mice. The recipient mice were transgenic for enhanced green fluorescent protein (eGFP) to determine a host contribution to the regenerated muscle tissue. Histological analysis 14–50 days after surgery showed that donor muscle fibres had formed in situ with host contributions in the outer portions of the regenerates. The function of the regenerates was assessed by direct electrical stimulation which resulted in the generation of mechanical force. Our study demonstrated that biodegradable CS with parallel pores support the formation of oriented muscle fibres and are compatible with force generation in regenerated muscle.
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Affiliation(s)
- V Kroehne
- Developmental Biology & Molecular Pathology, Bielefeld University, Bielefeld, Germany.
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15
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Gayraud-Morel B, Chrétien F, Flamant P, Gomès D, Zammit PS, Tajbakhsh S. A role for the myogenic determination gene Myf5 in adult regenerative myogenesis. Dev Biol 2007; 312:13-28. [PMID: 17961534 DOI: 10.1016/j.ydbio.2007.08.059] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 08/13/2007] [Accepted: 08/13/2007] [Indexed: 11/27/2022]
Abstract
The myogenic determination genes Myf5, Myod and Mrf4 direct skeletal muscle cell fate prenatally. In adult myogenesis, Myod has been shown to regulate myoblast differentiation, however, our understanding of satellite cell regulation is incomplete since the roles of Myf5 and Mrf4 had not been clearly defined. Here we examine the function of Myf5 and Mrf4 in the adult using recently generated alleles. Mrf4 is not expressed in normal or Myf5 null satellite cells and myoblasts, therefore excluding a role for this determination gene in adult muscle progenitors. Skeletal muscles of adult Myf5 null mice exhibit a subtle progressive myopathy. Crucially, adult Myf5 null mice exhibit perturbed muscle regeneration with a significant increase in muscle fibre hypertrophy, delayed differentiation, adipocyte accumulation, and fibrosis after freeze-injury. Satellite cell numbers are not significantly altered in Myf5 null animals and they show a modest impaired proliferation under some conditions in vitro. Mice double mutant for Myf5 and Dystrophin were more severely affected than single mutants, with enhanced necrosis and regeneration. Therefore, we show that Myf5 is a regulator of regenerative myogenesis and homeostasis, with functions distinct from those of Myod and Mrf4.
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Affiliation(s)
- Barbara Gayraud-Morel
- Stem Cells and Development, Dept. of Developmental Biology, Pasteur Institute, CNRS URA 2578, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France
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16
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Matsuo S, Kurisaki A, Sugino H, Hashimoto I, Nakanishi H. Analysis of skin graft survival using green fluorescent protein transgenic mice. THE JOURNAL OF MEDICAL INVESTIGATION 2007; 54:267-75. [PMID: 17878676 DOI: 10.2152/jmi.54.267] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Skin grafting has become a basic and established operation technique; however, it is not clear how skin grafts adapt to recipient beds and replace their functions. In this study, we analyzed the origin of cells in adapted transplants by using green fluorescent protein (GFP) transgenic mice, which emits green fluorescence in the whole body. The dorsal skins of GFP transgenic mice were transplanted to the back of wild-type mice. Similarly, wild-type skins were transplanted to the back of GFP transgenic mice. Since transplantation with full thickness back skin was not successful due to severe immunorejection, tail skins, which contain fewer epidermal Langerhans cells, were used for the experiments. Six months after transplantation, immunohistochemical analysis of the grafts revealed that tissues derived from ectodermal origin such as the epidermis, hair follicles, and sebaceous glands survived in transplanted grafts, but that other tissues such as the dermis, nerves and blood vessels are partly replaced by tissues from recipient beds. Our results further demonstrated that transplantation analyses with GFP transgenic mice could be a useful approach to study the origin of cells in transplants.
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Affiliation(s)
- Shinji Matsuo
- Department of Plastic and Reconstructive Surgery, Institute of Health Biosciences The University of Tokushima Graduate School, Tokushima, Japan
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17
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Jockusch H, Eberhard D. Green fluorescent protein as a tracer in chimeric tissues: the power of vapor fixation. Methods Mol Biol 2007; 411:145-154. [PMID: 18287644 DOI: 10.1007/978-1-59745-549-7_11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Green fluorescent protein (GFP) and its variants, small, highly soluble proteins, are routinely used as reporters for patterns of gene expression and the origin of cells in transplantation experiments. When not linked as fusion proteins to other polypeptides, they distribute rapidly in the cytoplasm of a given cell, thus allowing real-time observations on living material. For histological analysis, previous bath fixation of whole organs or tissues seemed obligatory, because, during drop fixation of sections, GFP rapidly leaks from cells whose membrane has been damaged by freezing and/or sectioning. The fluorescence of GFP and its derivatives is retained upon fixation, but most enzyme and antigenic activities of interest will be lost in the whole sample as a consequence of formaldehyde (FA) fixation. We have therefore developed an alternative method to fix GFP in frozen tissue sections by FA vapor. This method prevents leakage and redistribution of GFP and allows any cytochemical method to be applied to unfixed adjacent serial sections.
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Affiliation(s)
- Harald Jockusch
- Developmental Biology and Molecular Pathology, Bielefeld University, Germany
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18
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Zieseniss A, Schroeder U, Buchmeier S, Schoenenberger CA, van den Heuvel J, Jockusch BM, Illenberger S. Raver1 is an integral component of muscle contractile elements. Cell Tissue Res 2006; 327:583-94. [PMID: 17096167 DOI: 10.1007/s00441-006-0322-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Accepted: 08/04/2006] [Indexed: 01/25/2023]
Abstract
Raver1, a ubiquitously expressed protein, was originally identified as a ligand for metavinculin, the muscle-specific isoform of the microfilament-associated protein vinculin. The protein resides primarily in the nucleus, where it colocalises and may interact with polypyrimidine-tract-binding protein, which is involved in alternative splicing processes. During skeletal muscle differentiation, raver1 translocates to the cytoplasm and eventually targets the Z-line of sarcomeres. Here, it colocalises with metavinculin, vinculin and alpha-actinin, all of which have biochemically been identified as raver1 ligands. To obtain more information about the potential role of raver1 in muscle structure and function, we have investigated its distribution and fine localisation in mouse striated and smooth muscle, by using three monoclonal antibodies that recognise epitopes in different regions of the raver1 protein. Our immunofluorescence and immunoelectron-microscopic results indicate that the cytoplasmic accumulation of raver1 is not confined to skeletal muscle but also occurs in heart and smooth muscle. Unlike vinculin and metavinculin, cytoplasmic raver1 is not restricted to costameres but additionally represents an integral part of the sarcomere. In isolated myofibrils and in ultrathin sections of skeletal muscle, raver1 has been found concentrated at the I-Z-I band. A minor fraction of raver1 is present in the nuclei of all three types of muscle. These data indicate that, during muscle differentiation, raver1 might link gene expression with structural functions of the contractile machinery of muscle.
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Affiliation(s)
- Anke Zieseniss
- Cell Biology, Zoological Institute, Technical University of Braunschweig, Biocentre, Spielmannstrasse 7, 38092 Braunschweig, Germany
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Wagers AJ, Conboy IM. Cellular and molecular signatures of muscle regeneration: current concepts and controversies in adult myogenesis. Cell 2005; 122:659-67. [PMID: 16143100 DOI: 10.1016/j.cell.2005.08.021] [Citation(s) in RCA: 302] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adult skeletal muscle generates force in a controlled and directed manner through the contraction of highly specialized, postmitotic, multinucleated myofibers. Life-long muscle function relies on maintenance and regeneration of myofibers through a highly regulated process beginning with activation of normally quiescent muscle precursor cells and proceeding with formation of proliferating progenitors that fuse to generate differentiated myofibers. In this review, we describe the historical basis and current evidence for the identification of satellite cells as adult muscle stem cells, critically evaluate contributions of other cells to adult myogenesis, and summarize existing data regarding the origins, genetic markers, and molecular regulation of satellite cells in normal, diseased, and aged muscle.
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Affiliation(s)
- Amy J Wagers
- Joslin Diabetes Center and Department of Pathology Harvard Medical School, Boston, Massachusetts 02215, USA.
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20
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Washabaugh CH, Ontell MP, Ontell M. Nonmuscle stem cells fail to significantly contribute to regeneration of normal muscle. Gene Ther 2005; 11:1724-8. [PMID: 15385949 DOI: 10.1038/sj.gt.3302353] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Whole, normal extensor digitorum longus muscles (EDL) were orthtopically transplanted into transgenic mice, expressing nuclear localing beta-galactosidase (nlsbeta-gal) under control of a muscle-specific promoter, in order to determine the extent to which nonmuscle derived, multipotent stem cells (which under experimental conditions exhibit myogenic potential) are spontaneously recruited from distal, nonmuscle organs to participate in the graft's regeneration. The host's contribution to the graft's regeneration was determined by evaluating the number and distribution of beta-gal positive myonuclei in regenerated grafts. Fibers with beta-gal positive nuclei accounted for approximately 1% of the long-term (28- and 56-day) graft's myofibers. All were confined to the graft's periphery, adjacent to host's muscles. Failure to find myofibers with beta-gal positive nuclei across the revascularized graft's girth demonstrated that there was no meaningful recruitment of nonmuscle stem cells from distal host organs, which must arrive at the graft via the circulation. Rather, stem cells residing in the graft at the time of transplantation accounted for approximately 99.9% of the regenerated graft's myonuclei, with a minor contribution from the surrounding host muscles' myosatellite cells (that occurred when the epimysia of graft or host muscles were damaged during transplantation). The significance of these findings to gene therapy for Duchenne muscular dystrophy is discussed.
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Affiliation(s)
- C H Washabaugh
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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21
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Eberhard D, Jockusch H. Patterns of myocardial histogenesis as revealed by mouse chimeras. Dev Biol 2005; 278:336-46. [PMID: 15680354 DOI: 10.1016/j.ydbio.2004.11.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2004] [Revised: 10/13/2004] [Accepted: 11/09/2004] [Indexed: 11/17/2022]
Abstract
In order to study the pattern of clonal myocyte distribution during mammalian heart development, we have exploited embryo aggregation chimeras using, as cellular markers, an enhanced jellyfish green fluorescent protein (eGFP) transgene and a desmin-promoter-driven, nuclear-localized beta-galactosidase (nlacZ) knock-in. In neonatal, weanling, and adult chimeric atria and ventricles, irregularly formed patches of various sizes rather than highly dispersed cardiomyocytes were observed. Most of the smaller patches and single cardiomyocytes were found in spatial neighborhood of large patches. This indicated largely coherent clonal growth during myocardial histogenesis combined with tangential displacement or active migration of myocytes. The patterns of ventricular walls were simpler than those of the septum and the atria. In the adult heart, large myocardial volumes devoid of eGFP-positive cardiomyocytes indicated a lack of secondary immigration of blood-borne stem cells into the myocardium. The patterns of oligoclonal expansions revealed in this work might be helpful in detecting and analyzing cell-lineage-based pathological processes in the heart.
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Affiliation(s)
- Daniel Eberhard
- Developmental Biology and Molecular Pathology, Bielefeld University, W7 D-33501 Bielefeld, Germany
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22
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Abstract
It is generally assumed that somatic mtDNA mutations are originally created in the cells where these mutations are currently found. Accumulating data indicate, however, that cells with a particular mtDNA mutation tend to "cluster," that is, occur repeatedly within a given sample, but not in the others. Clusters likely are clonal, which implies that mtDNA mutations do not originate in the cells that currently carry them, but rather in those cells' progenitors, such as stem or satellite cells, or even earlier in the development. Importantly, a majority of mtDNA mutations appear to belong to such clusters, and thus mutational events in progenitor cells may be one of the major sources of mtDNA mutations in healthy aging tissue. More research including the analysis of multiple samples per individual is needed to confirm the existence of clustering and to distinguish between the possible clustering mechanisms.
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Affiliation(s)
- Konstantin Khrapko
- Gerontology Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Burlington Ave. 21-27, Room 554E, Boston, MA 02215, USA.
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23
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Eberhard D, Jockusch H. Intermingling versus clonal coherence during skeletal muscle development: Mosaicism in eGFP/nLacZ-labeled mouse chimeras. Dev Dyn 2004; 230:69-78. [PMID: 15108310 DOI: 10.1002/dvdy.20039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
To study the relative contributions of clonal coherence vs. myoblast intermingling to the formation of mammalian skeletal muscles, enhanced green fluorescent protein (eGFP) and nLacZ labels were used to analyze neonatal and adult mouse embryo aggregation chimeras. The eGFP marker allowed us to estimate absolute levels of the eGFP transgenic parental contributions as well as variances of levels within a chimeric individual; nLacZ served as a counter-label in neonatal chimeras. In mature chimeric muscle, free intracellular diffusion of eGFP led to an averaging of the eGFP level in individual myofibers. Chimerism, i.e., differing eGFP levels, was evident between corresponding right and left muscles, between adjacent back, body wall, limb (shank, foot), and extraocular muscles and among myofibers within these muscles. Inhomogeneities in muscles far from their somitic origin indicated unbalanced sampling from small founder pools. The results obtained with adult eGFP<-->0 chimeras were corroborated by neonatal chimeras with complementary eGFP<-->nLacZ labels.
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Affiliation(s)
- Daniel Eberhard
- Developmental Biology and Molecular Pathology, Bielefeld University, Bielefeld, Germany
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