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Isolation of Mesenchymal Stem Cells from Human Alveolar Periosteum and Effects of Vitamin D on Osteogenic Activity of Periosteum-derived Cells
Published on: May 4, 2018
Type V OI primary osteoblasts display increased mineralization despite decreased COL1A1 expression
Adi Reich1, Alison S Bae, Aileen M Barnes
1Bone and Extracellular Matrix Branch (A.R., A.S.B., A.M.B., W.A.C., J.C.M.), Eunice Kennedy Shriver National Institute of Child Health and Human Development, and Department of Diagnostic Radiology (S.C.H.), National Institutes of Health Clinical Center, National Institutes of Health, Bethesda, Maryland 20892; Physiology and Experimental Medicine Program (A.H.), Heart Center, Hospital for Sick Children, University of Toronto, Ontario, Canada M5S 3OA4; Division of Diagnostic Imaging (J.S.), Department of Pediatrics, and Division of Clinical and Metabolic Genetics (D.C.), Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada M5G 1X8; and The Prenatal Diagnosis and Medical Genetics Program (D.C.), Department of Obstetrics and Gynecology, Mt Sinai Hospital, University of Toronto, Toronto, Ontario, Canada M5G 1Z5.
Type V osteogenesis imperfecta (OI) involves an IFITM5 mutation causing osteoblasts to over-mineralize bone. This leads to increased mineralization but decreased type I collagen, establishing it as a collagen defect.
Area of Science:
- Genetics and Molecular Biology
- Skeletal Biology
- Biochemistry
Background:
- Type V osteogenesis imperfecta (OI) is linked to a dominant IFITM5 mutation affecting bone-restricted interferon-induced transmembrane-like protein (BRIL) in osteoblasts.
- Skeletal features include hyperplastic callus, forearm interosseous membrane ossification, and dense metaphyseal bands.
Purpose of the Study:
- Investigate osteoblast role in type V OI mineralization.
- Determine the IFITM5 mutation's effect on type I collagen.
Main Methods:
- Identified eight patients with the IFITM5 c.-14C>T mutation.
- Utilized cultured osteoblasts from type V OI patients to assess differentiation and mineralization.
Main Results:
- Type V OI osteoblasts showed increased differentiation markers and enhanced mineralization.
- COL1A1 transcripts and type I collagen protein were significantly decreased in later differentiation stages.
- Observed decreased cross-linked collagen and altered matrix fibrils.
Conclusions:
- Type V OI mineralization exhibits a gain-of-function mechanism at the osteoblast level, driving excessive tissue mineralization.
- Reduced type I collagen expression and incorporation confirm type V OI as a collagen-related defect.
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