Hiromasa Kawana

Publications (2)2.48 Total impact

• Article: PDGFBB promotes PDGFRα-positive cell migration into artificial bone in vivo.

  Shigeyuki Yoshida, Ryotaro Iwasaki, Hiromasa Kawana, Yoshiteru Miyauchi, Hiroko Hoshi, Hiroya Miyamoto, Tomoaki Mori, Hiroya Kanagawa, Eri Katsuyama, Atsuhiro Fujie, Wu Hao, Tami Kobayashi, Yuiko Sato, Kana Miyamoto, Hideo Morioka, Morio Matsumoto, Kazuhiro Chiba, Yoshiaki Toyama, Taneaki Nakagawa, Takeshi Miyamoto
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  ABSTRACT: Bone defects caused by traumatic bone loss or tumor dissection are now treated with auto- or allo-bone graft, and also occasionally by artificial bone transplantation, particularly in the case of large bone defects. However, artificial bones often exhibit poor affinity to host bones followed by bony union failure. Thus therapies combining artificial bones with growth factors have been sought. Here we report that platelet derived growth factor bb (PDGFBB) promotes a significant increase in migration of PDGF receptor α (PDGFRα)-positive mesenchymal stem cells/pre-osteoblastic cells into artificial bone in vivo. Growth factors such as transforming growth factor beta (TGFβ) and hepatocyte growth factor (HGF) reportedly inhibit osteoblast differentiation; however, PDGFBB did not exhibit such inhibitory effects and in fact stimulated osteoblast differentiation in vitro, suggesting that combining artificial bones with PDGFBB treatment could promote host cell migration into artificial bones without inhibiting osteoblastogenesis.
  Biochemical and Biophysical Research Communications 04/2012; 421(4):785-9. · 2.48 Impact Factor
• Article: Cell fusion in osteoclasts plays a critical role in controlling bone mass and osteoblastic activity

  Ryotaro Iwasaki, Ken Ninomiya, Kana Miyamoto, Toru Suzuki, Yuiko Sato, Hiromasa Kawana, Taneaki Nakagawa, Toshio Suda, Takeshi Miyamoto
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  ABSTRACT: The balance between osteoclast and osteoblast activity is central for maintaining the integrity of bone homeostasis. Here we show that mice lacking dendritic cell specific transmembrane protein (DC-STAMP), an essential molecule for osteoclast cell–cell fusion, exhibited impaired bone resorption and upregulation of bone formation by osteoblasts, which do not express DC-STAMP, which led to increased bone mass. On the contrary, DC-STAMP over-expressing transgenic (DC-STAMP-Tg) mice under the control of an actin promoter showed significantly accelerated cell–cell fusion of osteoclasts and bone resorption, with decreased osteoblastic activity and bone mass. Bone resorption and formation are known to be regulated in a coupled manner, whereas DC-STAMP regulates bone homeostasis in an un-coupled manner. Thus our results indicate that inhibition of a single molecule provides both decreased osteoclast activity and increased bone formation by osteoblasts, thereby increasing bone mass in an un-coupled and a tissue specific manner.
  Biochemical and Biophysical Research Communications.