Axial mechanical loading to ex vivo mouse long bone regulates endochondral ossification and endosteal mineralization through activation of the BMP-Smad pathway during postnatal growth
Mechanical loading contributes to bone development, growth, and metabolism. However, the mechanisms underlying long bone mineralization via changes in loading during the growth period are unclear. The aim of the present study was to investigate the regulatory mechanisms underlying endochondral ossif...
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| Format: | Article |
| Language: | English |
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Elsevier
2021-12-01
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| Series: | Bone Reports |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352187221003442 |
| _version_ | 1830414204442509312 |
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| author | Satoshi Miyamoto Hideki Yoshikawa Ken Nakata |
| author_facet | Satoshi Miyamoto Hideki Yoshikawa Ken Nakata |
| author_sort | Satoshi Miyamoto |
| collection | DOAJ |
| description | Mechanical loading contributes to bone development, growth, and metabolism. However, the mechanisms underlying long bone mineralization via changes in loading during the growth period are unclear. The aim of the present study was to investigate the regulatory mechanisms underlying endochondral ossification and endosteal mineralization by developing an ex vivo organ culture model with cyclic axial mechanical loads. The metacarpal bones of 3-week-old C57BL/6 mice were exposed to mechanical loading (0, 7.8, and 78 mN) for 1 h/day for 4 days. Histomorphometry revealed that axial mechanical loading regulated the thickness of the calcified zone in the growth plate and endosteal mineralization in the diaphysis in a load-dependent manner. Mechanical loading also resulted in load-dependent upregulation of endochondral ossification and bone mineralization-related genes, including bone morphogenetic protein 2 (Bmp2). Recombinant human BMP-2 administration caused similar changes in tissue structures. Conversely, inhibition of the BMP-Smad pathway diminished the stimulatory effects of mechanical loading and BMP-2 administration, suggesting that the effects of mechanical loading may be exerted through activation of the BMP-Smad pathway with the results of gene ontology and pathway analyses. Mechanical loading increased alkaline phosphatase activity and decreased carbonic anhydrase IX (Car9) mRNA expression, resulting in a significant pH increase in the culture supernatant. We hypothesize that, through activation of the BMP-Smad pathway, mechanical loading downregulates Car9, which may alkalize the local milieu, thereby inducing bone formation and long bone mineralization. Our results showed that cyclic axial mechanical loading increased endochondral ossification and endosteal mineralization in developing mouse long bones, which may have resulted from changes in the pH, ALP activity, and Pi/PPi of the extracellular environment. These findings advance our understanding of the regulation of mineralization mechanisms by mechanical loading mediated through activation of the BMP-Smad pathway. |
| first_indexed | 2024-12-20T20:37:43Z |
| format | Article |
| id | doaj.art-e87b11ea0a8f44ea9fd32dca5d89b09f |
| institution | Directory Open Access Journal |
| issn | 2352-1872 |
| language | English |
| last_indexed | 2024-12-20T20:37:43Z |
| publishDate | 2021-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Bone Reports |
| spelling | doaj.art-e87b11ea0a8f44ea9fd32dca5d89b09f2022-12-21T19:27:11ZengElsevierBone Reports2352-18722021-12-0115101088Axial mechanical loading to ex vivo mouse long bone regulates endochondral ossification and endosteal mineralization through activation of the BMP-Smad pathway during postnatal growthSatoshi Miyamoto0Hideki Yoshikawa1Ken Nakata2Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Yamadaoka 2-2, Suita, Osaka 565-0871, JapanDepartment of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Yamadaoka 2-2, Suita, Osaka 565-0871, JapanMedicine for Sports and Performing Arts, Department of Health and Sport Sciences, Osaka University Graduate School of Medicine, Yamadaoka 2-2, Suita, Osaka 565-0871, Japan; Corresponding author at: Medicine for Sports and Performing Arts, Department of Health and Sport Sciences, Osaka University Graduate School of Medicine, Yamadaoka 2-2, Suita, Osaka 565-0871, Japan.Mechanical loading contributes to bone development, growth, and metabolism. However, the mechanisms underlying long bone mineralization via changes in loading during the growth period are unclear. The aim of the present study was to investigate the regulatory mechanisms underlying endochondral ossification and endosteal mineralization by developing an ex vivo organ culture model with cyclic axial mechanical loads. The metacarpal bones of 3-week-old C57BL/6 mice were exposed to mechanical loading (0, 7.8, and 78 mN) for 1 h/day for 4 days. Histomorphometry revealed that axial mechanical loading regulated the thickness of the calcified zone in the growth plate and endosteal mineralization in the diaphysis in a load-dependent manner. Mechanical loading also resulted in load-dependent upregulation of endochondral ossification and bone mineralization-related genes, including bone morphogenetic protein 2 (Bmp2). Recombinant human BMP-2 administration caused similar changes in tissue structures. Conversely, inhibition of the BMP-Smad pathway diminished the stimulatory effects of mechanical loading and BMP-2 administration, suggesting that the effects of mechanical loading may be exerted through activation of the BMP-Smad pathway with the results of gene ontology and pathway analyses. Mechanical loading increased alkaline phosphatase activity and decreased carbonic anhydrase IX (Car9) mRNA expression, resulting in a significant pH increase in the culture supernatant. We hypothesize that, through activation of the BMP-Smad pathway, mechanical loading downregulates Car9, which may alkalize the local milieu, thereby inducing bone formation and long bone mineralization. Our results showed that cyclic axial mechanical loading increased endochondral ossification and endosteal mineralization in developing mouse long bones, which may have resulted from changes in the pH, ALP activity, and Pi/PPi of the extracellular environment. These findings advance our understanding of the regulation of mineralization mechanisms by mechanical loading mediated through activation of the BMP-Smad pathway.http://www.sciencedirect.com/science/article/pii/S2352187221003442Mechanical loadingBone mineralizationEndochondral ossificationBone morphogenetic protein 2 |
| spellingShingle | Satoshi Miyamoto Hideki Yoshikawa Ken Nakata Axial mechanical loading to ex vivo mouse long bone regulates endochondral ossification and endosteal mineralization through activation of the BMP-Smad pathway during postnatal growth Bone Reports Mechanical loading Bone mineralization Endochondral ossification Bone morphogenetic protein 2 |
| title | Axial mechanical loading to ex vivo mouse long bone regulates endochondral ossification and endosteal mineralization through activation of the BMP-Smad pathway during postnatal growth |
| title_full | Axial mechanical loading to ex vivo mouse long bone regulates endochondral ossification and endosteal mineralization through activation of the BMP-Smad pathway during postnatal growth |
| title_fullStr | Axial mechanical loading to ex vivo mouse long bone regulates endochondral ossification and endosteal mineralization through activation of the BMP-Smad pathway during postnatal growth |
| title_full_unstemmed | Axial mechanical loading to ex vivo mouse long bone regulates endochondral ossification and endosteal mineralization through activation of the BMP-Smad pathway during postnatal growth |
| title_short | Axial mechanical loading to ex vivo mouse long bone regulates endochondral ossification and endosteal mineralization through activation of the BMP-Smad pathway during postnatal growth |
| title_sort | axial mechanical loading to ex vivo mouse long bone regulates endochondral ossification and endosteal mineralization through activation of the bmp smad pathway during postnatal growth |
| topic | Mechanical loading Bone mineralization Endochondral ossification Bone morphogenetic protein 2 |
| url | http://www.sciencedirect.com/science/article/pii/S2352187221003442 |
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