title: GFP chimeric models exhibited a biphasic pattern of mesenchymal cell invasion in tendon healing.
abstract: The healing of an injured musculoskeletal system requires an influx of mesenchymal cells that can differentiate into osteoblasts, fibroblasts, chondroblasts, and skeletal myoblasts. However, whether these mesenchymal cells arise from the circulation (bone marrow) or the injured tissues themselves has been controversial. To reveal the spatiotemporal characteristics of the reparative mesenchymal cells, we investigated the healing process after patellar tendon injury using two types of green fluorescent protein (GFP) chimeric rats; one expressing GFP in the circulating cells, and the other expressing it in the patellar tendon. We analyzed the behavior of GFP-positive cells after experimental tendon injury in both chimeric rats to clarify the origin of reparative cells. At 24 h after the injury, the wound contained circulation-derived cells but not tendon-derived cells. Tendon-derived cells first appeared in the wounded area at 3 days after the injury, and had significantly increased in number with time and had maintained a high level of proliferative activity until 7 days after the injury, whereas the circulation-derived cells had decreased in number and had been replaced by the tendon-derived cells. These findings suggest that circulation-derived and tendon-derived cells contribute to the healing of tendons in different periods as part of a biphasic process.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Kajikawa
authors.forename: Toru
authors.initials: T
authors.lastname: Morihara
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Watanabe
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Matsuda
authors.forename: Masashi
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Oshima
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Yoshida
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kawata
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation; D002678:Chimera / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D008954:Models, Biological; D051381:Rats; D013708:Tendon Injuries / Q000378:metabolism / Q000503:physiopathology*; D013710:Tendons / Q000098:blood supply / Q000166:cytology* / Q000378:metabolism; D014945:Wound Healing / Q000235:genetics / Q000502:physiology*
chemical_list: D049452:Green Fluorescent Proteins