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Osteocyte-specific dentin matrix protein 1: the role of mineralization regulation in low-magnitude high-frequency vibration enhanced osteoporotic fracture healing
- Source :
- Bone & Joint Research, Vol 11, Iss 7, Pp 465-476 (2022)
- Publication Year :
- 2022
- Publisher :
- The British Editorial Society of Bone & Joint Surgery, 2022.
-
Abstract
- Aims: There is an increasing concern of osteoporotic fractures in the ageing population. Low-magnitude high-frequency vibration (LMHFV) was shown to significantly enhance osteoporotic fracture healing through alteration of osteocyte lacuno-canalicular network (LCN). Dentin matrix protein 1 (DMP1) in osteocytes is known to be responsible for maintaining the LCN and mineralization. This study aimed to investigate the role of osteocyte-specific DMP1 during osteoporotic fracture healing augmented by LMHFV. Methods: A metaphyseal fracture was created in the distal femur of ovariectomy-induced osteoporotic Sprague Dawley rats. Rats were randomized to five different groups: 1) DMP1 knockdown (KD), 2) DMP1 KD + vibration (VT), 3) Scramble + VT, 4) VT, and 5) control (CT), where KD was performed by injection of short hairpin RNA (shRNA) into marrow cavity; vibration treatment was conducted at 35 Hz, 0.3 g; 20 minutes/day, five days/week). Assessments included radiography, micro-CT, dynamic histomorphometry and immunohistochemistry on DMP1, sclerostin, E11, and fibroblast growth factor 23 (FGF23). In vitro, murine long bone osteocyte-Y4 (MLO-Y4) osteocyte-like cells were randomized as in vivo groupings. DMP1 KD was performed by transfecting cells with shRNA plasmid. Assessments included immunocytochemistry on osteocyte-specific markers as above, and mineralized nodule staining. Results: Healing capacities in DMP1 KD groups were impaired. Results showed that DMP1 KD significantly abolished vibration-enhanced fracture healing at week 6. DMP1 KD significantly altered the expression of osteocyte-specific markers. The lower mineralization rate in DMP1 KD groups indicated that DMP1 knockdown was associated with poor fracture healing process. Conclusion: The blockage of DMP1 would impair healing outcomes and negate LMHFV-induced enhancement on fracture healing. These findings reveal the importance of DMP1 in response to the mechanical signal during osteoporotic fracture healing. Cite this article: Bone Joint Res 2022;11(7):465–476.
Details
- Language :
- English
- ISSN :
- 20463758
- Volume :
- 11
- Issue :
- 7
- Database :
- Directory of Open Access Journals
- Journal :
- Bone & Joint Research
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.675e24ab136c463f871d208a4ee1436a
- Document Type :
- article
- Full Text :
- https://doi.org/10.1302/2046-3758.117.BJR-2021-0476.R2