title: Prospects for osteoprogenitor stem cells in fracture repair and osteoporosis.
abstract: OBJECTIVE
  Bone regeneration and fracture repair are the complex processes of mesenchymal stem cell invasion, chondrogenesis, osteogenesis and angiogenesis. The coordinated actions of these principal processes result in the reconstruction of a normal bone and restoration of a structural unit. However, these normal bone regenerative mechanisms breakdown during fracture repair failure and postmenopausal osteoporosis.
  
  
  RESULTS
  Recent discoveries of circulating multipotent stem cells with mixed characteristics of endothelial cell and osteogenic capacity have raised interest in new and potentially breakthrough therapies for fracture and pathologic bone loss. The cooperative actions of other mesenchymal stem cell lineage such as adipocytes and processes such as angiogenesis in bone repair could also serve as novel therapeutic targets. Recent data suggest that anabolic parathyroid hormone therapy, already approved for the treatment of osteoporosis, may recruit osteoprogenitor cells and also have a role in fracture repair.
  
  
  CONCLUSIONS
  The present review will highlight recent information on stem cells and bone repair and examine potential avenues for future research.
authors.affiliation: Division of Endocrinology and Metabolism, University of Virginia, Charlottesville, Virginia 22908-1420, USA. gc4z@virginia.edu
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Clines
mesh_terms: D050156:Adipogenesis; D000818:Animals; D001861:Bone Regeneration; D049109:Cell Proliferation; D020219:Chondrogenesis; D017102:Fracture Healing; D050723:Fractures, Bone / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D045164:Mesenchymal Stem Cell Transplantation; D039902:Multipotent Stem Cells / Q000637:transplantation*; D018919:Neovascularization, Physiologic; D010006:Osteoblasts / Q000637:transplantation*; D010012:Osteogenesis; D010024:Osteoporosis / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D023822:Tissue Engineering