title: Proliferation of Multiple Cell Types in the Skeletal Muscle Tissue Elicited by Acute p21 Suppression.
abstract: Although in the last decades the molecular underpinnings of the cell cycle have been unraveled, the acquired knowledge has been rarely translated into practical applications. Here, we investigate the feasibility and safety of triggering proliferation in vivo by temporary suppression of the cyclin-dependent kinase inhibitor, p21. Adeno-associated virus (AAV)-mediated, acute knockdown of p21 in intact skeletal muscles elicited proliferation of multiple, otherwise quiescent cell types, notably including satellite cells. Compared with controls, p21-suppressed muscles exhibited a striking two- to threefold expansion in cellularity and increased fiber numbers by 10 days post-transduction, with no detectable inflammation. These changes partially persisted for at least 60 days, indicating that the muscles had undergone lasting modifications. Furthermore, morphological hyperplasia was accompanied by 20% increases in maximum strength and resistance to fatigue. To assess the safety of transiently suppressing p21, cells subjected to p21 knockdown in vitro were analyzed for γ-H2AX accumulation, DNA fragmentation, cytogenetic abnormalities, ploidy, and mutations. Moreover, the differentiation competence of p21-suppressed myoblasts was investigated. These assays confirmed that transient suppression of p21 causes no genetic damage and does not impair differentiation. Our results establish the basis for further exploring the manipulation of the cell cycle as a strategy in regenerative medicine.
authors: Department of Cell Biology and Neurosciences, National Institute of Health, Rome, Italy.
authors: Maria Grazia
authors: MG
authors: Biferi
authors: Institute Pasteur Cenci-Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, IIM, Sapienza University of Rome, Rome, Italy.
authors: Carmine
authors: C
authors: Nicoletti
authors: Department of Cell Biology and Neurosciences, National Institute of Health, Rome, Italy; Institute of Cell Biology and Neurobiology, National Research Council, Monterotondo, Italy.
authors: Germana
authors: G
authors: Falcone
authors: Department of Cell Biology and Neurosciences, National Institute of Health, Rome, Italy.
authors: Eleonora M R
authors: EMR
authors: Puggioni
authors: Department of Cell Biology and Neurosciences, National Institute of Health, Rome, Italy.
authors: Nunzia
authors: N
authors: Passaro
authors: Department of Cell Biology and Neurosciences, National Institute of Health, Rome, Italy.
authors: Alessia
authors: A
authors: Mazzola
authors: Department of Cell Biology and Neurosciences, National Institute of Health, Rome, Italy.
authors: Deborah
authors: D
authors: Pajalunga
authors: Molecular Cardiology Laboratory, IRCCS-Policlinico San Donato, Milan, Italy.
authors: Germana
authors: G
authors: Zaccagnini
authors: Department of Mechanical and Aerospace Engineering, IIM, Sapienza University of Rome, Rome, Italy.
authors: Emanuele
authors: E
authors: Rizzuto
authors: Division of Medical Genetics, Department of Translational Medicine, "Federico II" University, Naples, Italy; Telethon Institute of Genetics and Medicine, Pozzuoli, Italy.
authors: Alberto
authors: A
authors: Auricchio
authors: Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy.
authors: Lorena
authors: L
authors: Zentilin
authors: Department of Ematology, Oncology and Molecular Medicine, National Institute of Health, Rome, Italy.
authors: Gabriele
authors: G
authors: De Luca
authors: Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy.
authors: Mauro
authors: M
authors: Giacca
authors: Molecular Cardiology Laboratory, IRCCS-Policlinico San Donato, Milan, Italy.
authors: Fabio
authors: F
authors: Martelli
authors: Institute of Biomedical and Genetic Research, National Research Council, Pisa, Italy; Tumour Institute of Tuscany, Florence, Italy.
authors: Antonio
authors: A
authors: Musio
authors: Institute Pasteur Cenci-Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, IIM, Sapienza University of Rome, Rome, Italy; Center for Life Nano Science@Sapienza, Italian Institute of Technology, Genova, Italy.
authors: Antonio
authors: A
authors: Musarò
authors: Department of Cell Biology and Neurosciences, National Institute of Health, Rome, Italy. Electronic address: marco.crescenzi@iss.it.
authors: Marco
authors: M
authors: Crescenzi
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D049109:Cell Proliferation; D002869:Chromosome Aberrations; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics* / Q000378:metabolism; D000229:Dependovirus / Q000145:classification / Q000235:genetics; D005347:Fibroblasts; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D009119:Muscle Contraction / Q000235:genetics; D018482:Muscle, Skeletal / Q000166:cytology* / Q000378:metabolism*; D009154:Mutation; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology / Q000378:metabolism; D065288:Serogroup; D014161:Transduction, Genetic
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D034741:RNA, Small Interfering