title: Biglycan potentially regulates angiogenesis during fracture repair by altering expression and function of endostatin.
abstract: The small proteoglycan biglycan (Bgn) is highly expressed in the organic matrix of bone and plays a role in bone formation. Previous work implicated Bgn in vessel growth during bone healing [1]. By infusing barium sulfate (BaSO4) into WT and Bgn-deficient mice we discovered the positive effect of Bgn in modulating angiogenesis during fracture healing. Using micro-computed tomography angiography we found significant differences in the vessel size and volume among other parameters. To further understand the mechanistic basis for this, we explored the relationship between Bgn and the anti-angiogenic protein endostatin. Immunohistochemistry (IHC) showed co-localization of Bgn and endostatin in regions of bone formation, with increased endostatin staining in Bgn-KO compared to WT at 14days post-fracture. To further elucidate the relationship between Bgn and endostatin, an endothelial cell tube formation assay was used. This study showed that endothelial cells treated with endostatin had significantly decreased vessel length and vessel branches compared to untreated cells, while cells treated with endostatin and Bgn at a 1:1M ratio had vessel length and vessel branches comparable to untreated cells. This indicated that Bgn was able to mitigate the inhibitory effect of endostatin on endothelial cell growth. In summary, these results suggest that Bgn is needed for proper blood vessel formation during fracture healing, and one mechanism by which Bgn impacts angiogenesis is through inhibition of endostatin.
authors.affiliation: Craniofacial and Skeletal Diseases Branch, NIDCR, NIH, Bethesda, MD 20892, United States.
authors.forename: Maja
authors.initials: M
authors.lastname: Myren
authors.affiliation: Craniofacial and Skeletal Diseases Branch, NIDCR, NIH, Bethesda, MD 20892, United States.
authors.forename: David J
authors.initials: DJ
authors.lastname: Kirby
authors.affiliation: Craniofacial and Skeletal Diseases Branch, NIDCR, NIH, Bethesda, MD 20892, United States.
authors.forename: Megan L
authors.initials: ML
authors.lastname: Noonan
authors.affiliation: Craniofacial and Skeletal Diseases Branch, NIDCR, NIH, Bethesda, MD 20892, United States.
authors.forename: Azusa
authors.initials: A
authors.lastname: Maeda
authors.affiliation: Life Cell Corporation, Branchburg, NJ 08876, United States.
authors.forename: Rick T
authors.initials: RT
authors.lastname: Owens
authors.affiliation: University of Lyon, UMR 5246 CNRS - University Lyon 1, ICBMS, 69622 Villeurbanne, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Ricard-Blum
authors.affiliation: Craniofacial and Skeletal Diseases Branch, NIDCR, NIH, Bethesda, MD 20892, United States.
authors.forename: Vardit
authors.initials: V
authors.lastname: Kram
authors.affiliation: Craniofacial and Skeletal Diseases Branch, NIDCR, NIH, Bethesda, MD 20892, United States.
authors.forename: Tina M
authors.initials: TM
authors.lastname: Kilts
authors.affiliation: Craniofacial and Skeletal Diseases Branch, NIDCR, NIH, Bethesda, MD 20892, United States. Electronic address: Myoung@dir.nidcr.nih.gov.
authors.forename: Marian F
authors.initials: MF
authors.lastname: Young
mesh_terms: D000818:Animals; D058578:Biglycan / Q000235:genetics / Q000378:metabolism*; D000072226:Computed Tomography Angiography; D015536:Down-Regulation; D043169:Endostatins / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D017102:Fracture Healing; D055786:Gene Knockout Techniques; D051379:Mice; D018919:Neovascularization, Physiologic; D055114:X-Ray Microtomography
chemical_list: C546885:Bgn protein, mouse; D058578:Biglycan; D043169:Endostatins
keywords: Angiogenesis; Biglycan; Endostatin; Fracture healing