title: Pericytes for the treatment of orthopedic conditions.
abstract: Pericytes and other perivascular stem cells are of growing interest in orthopedics and tissue engineering. Long regarded as simple regulators of angiogenesis and blood pressure, pericytes are now recognized to have MSC (mesenchymal stem cell) characteristics, including multipotentiality, self-renewal, immunoregulatory functions, and diverse roles in tissue repair. Pericytes are typified by characteristic cell surface marker expression (including αSMA, CD146, PDGFRβ, NG2, RGS5, among others). Although alone no marker is absolutely specific for pericytes, collectively these markers appear to selectively identify an MSC-like pericyte. The purification of pericytes is most well described as a CD146+CD34-CD45-cell population. Pericytes and other perivascular stem cell populations have been applied in diverse orthopedic applications, including both ectopic and orthotopic models. Application of purified cells has sped calvarial repair, induced spine fusion, and prevented fibrous non-union in rodent models. Pericytes induce these effects via both direct and indirect mechanisms. In terms of their paracrine effects, pericytes are known to produce and secrete high levels of a number of growth and differentiation factors both in vitro and after transplantation. The following review will cover existing studies to date regarding pericyte application for bone and cartilage engineering. In addition, further questions in the field will be pondered, including the phenotypic and functional overlap between pericytes and culture-derived MSC, and the concept of pericytes as efficient producers of differentiation factors to speed tissue repair.
authors: School of Dentistry, University of California, Los Angeles, United States; Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, United States; Orthopedic Hospital Research Center, University of California, Los Angeles, United States; Department of Pathology, Johns Hopkins University, Baltimore, MD, United States. Electronic address: awjames@jhmi.edu.
authors: Aaron W
authors: AW
authors: James
authors: Department of Trauma and Orthopaedic Surgery, The University of Edinburgh, Edinburgh, United Kingdom.
authors: Paul
authors: P
authors: Hindle
authors: Department of Trauma and Orthopaedic Surgery, The University of Edinburgh, Edinburgh, United Kingdom; BHF Center for Vascular Regeneration & MRC Center for Regenerative Medicine, University of Edinburgh, Edinburgh, United Kingdom.
authors: Iain R
authors: IR
authors: Murray
authors: BHF Center for Vascular Regeneration & MRC Center for Regenerative Medicine, University of Edinburgh, Edinburgh, United Kingdom; Department of Plastic and Reconstructive Surgery, St. Johns Hospital, Livingston, United Kingdom.
authors: Christopher C
authors: CC
authors: West
authors: Department of Trauma and Orthopaedic Surgery, The University of Edinburgh, Edinburgh, United Kingdom; BHF Center for Vascular Regeneration & MRC Center for Regenerative Medicine, University of Edinburgh, Edinburgh, United Kingdom; Department of Orthopaedics, Ramathibodi Hospital, Madihol University, Thailand.
authors: Tulyapruek
authors: T
authors: Tawonsawatruk
authors: School of Dentistry, University of California, Los Angeles, United States.
authors: Jia
authors: J
authors: Shen
authors: School of Dentistry, University of California, Los Angeles, United States.
authors: Greg
authors: G
authors: Asatrian
authors: School of Dentistry, University of California, Los Angeles, United States.
authors: Xinli
authors: X
authors: Zhang
authors: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, United States.
authors: Vi
authors: V
authors: Nguyen
authors: Department of Trauma and Orthopaedic Surgery, The University of Edinburgh, Edinburgh, United Kingdom.
authors: A Hamish
authors: AH
authors: Simpson
authors: School of Dentistry, University of California, Los Angeles, United States.
authors: Kang
authors: K
authors: Ting
authors: Orthopedic Hospital Research Center, University of California, Los Angeles, United States; BHF Center for Vascular Regeneration & MRC Center for Regenerative Medicine, University of Edinburgh, Edinburgh, United Kingdom.
authors: Bruno
authors: B
authors: Péault
authors: Orthopedic Hospital Research Center, University of California, Los Angeles, United States; Department of Surgery, University of California, Los Angeles, Los Angeles, CA, United States.
authors: Chia
authors: C
authors: Soo
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000166:cytology; D002356:Cartilage / Q000166:cytology; D002454:Cell Differentiation; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology; D009140:Musculoskeletal Diseases / Q000473:pathology / Q000628:therapy*; D020286:Pericytes / Q000166:cytology*; D012377:Rodentia; D013234:Stem Cells / Q000166:cytology; D023822:Tissue Engineering / Q000379:methods*
keywords: Bone; Cartilage; MSC; Mesenchymal stem cell; PSC; Perivascular stem cell