title: Parabiosis model does not show presence of circulating osteoprogenitor cells.
abstract: The goal of this study was to determine the presence of osteoprogenitor cells in the peripheral blood. Experiments were conducted with a parabiosis model in which osteoblast specific transgenic mice (Col2.3GFP or hOC-GFP) were surgically joined with a transgenic mouse where herpes virus thymidine kinase gene is under the control of the collagen alpha1 promoter (Col2.3DeltaTK). This method permits conditional ablation of osteoblasts by ganciclovir (GCV) treatment. In parabionts treated with GCV for 15 days or 1.5-2 months, GFP (hOC-GFP or Col2.3GFP) expression was not detected in histological preparations or in marrow stromal cell cultures from the Col2.3DeltaTK parabiont. Finally, Col2.3GFP/Col2.3DeltaTK pairs were treated with GCV for 15 days and allowed to recover from GCV for 3 months. Again there was a failure to detect Col2.3GFP expressing cells in the Col2.3DeltaTK parabiont. These observations, at least within the limits of this model system, allow the conclusion that osteoprogenitor cells do not readily circulate.
authors.affiliation: Department of Genetics and Developmental Biology, University of Connecticut Stem Cell Institute, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
authors.forename: Ivana
authors.initials: I
authors.lastname: Boban
authors.forename: Tatjana
authors.initials: T
authors.lastname: Barisic-Dujmovic
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Clark
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics; D005260:Female; D005434:Flow Cytometry; D015774:Ganciclovir / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010227:Parabiosis; D011401:Promoter Regions, Genetic / Q000235:genetics; D018139:Simplexvirus / Q000201:enzymology; D017154:Stromal Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D000998:Antiviral Agents; D024042:Collagen Type I; D049452:Green Fluorescent Proteins; D013937:Thymidine Kinase; D015774:Ganciclovir