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Impaired Expression of Noncollagenous Bone Matrix Protein mRNAs During Fracture Healing in Ascorbic Acid–Deficient Rats
Author(s) -
Sugimoto Mizuo,
Hirota Seiichi,
Sato Motohiko,
Kawahata Hirohisa,
Tsukamoto Ikuyo,
Yasui Natsuo,
Kitamura Yukihiko,
Ochi Takahiro,
Nomura Shintaro
Publication year - 1998
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1998.13.2.271
Subject(s) - osteopontin , endochondral ossification , osteonectin , chondrogenesis , ascorbic acid , osteocalcin , cartilage , endocrinology , chemistry , medicine , calcification , ossification , bone healing , matrix gla protein , microbiology and biotechnology , alkaline phosphatase , biology , biochemistry , ectopic calcification , anatomy , food science , enzyme
In scorbutic patients, fractures are slow to heal because of impaired collagen synthesis. To investigate the influence of impaired collagen synthesis on the differentiation and proliferation of osteogenic and chondrogenic cells, we examined the expression of genes encoding bone matrix proteins, including osteonectin (ON), osteopontin (OPN), osteocalcin (OC), and matrix Gla protein (MGP), as differentiation markers for osteogenic and chondrogenic cells during fracture healing in Osteogenic Disorder Shionogi (ODS) rats, which have a hereditary defect in the ability to synthesize ascorbic acid (Asc). In ODS rats without Asc supplementation, intramembranous ossification was completely inhibited. Although a few fibroblast‐like cells expressing ON mRNA were observed, no OPN mRNA‐expressing cells were detected. During endochondral ossification, a small amount of metachromatic staining cartilage appeared at the fracture site, but there was no provisional calcification zone in the cartilage. Chondrocytes expressed ON and MGP mRNAs, but not OPN mRNA. When Asc was given to these rats, callus formation was soon detected around the fracture site, while OPN mRNA was expressed by differentiated osteoblasts and hypertrophic chondrocytes. Our data indicate that impaired collagen synthesis due to Asc deficiency inhibited the increase of ON and MGP mRNA‐expressing cells as well as the appearance of OPN mRNA‐expressing cells. Since OPN is considered to play an important role in normal and pathological mineralization, lack of OPN mRNA expression accompanying impaired collagen synthesis may have a role in defective mineralization and delayed fracture healing in scurvy.