Low-dose risedronate sodium protects bone cells after abrupt oestrogen withdrawal

Synergic Action of Systemic Risedronate and Local Rutherpy in Peri-implantar Repair of Ovariectomized Rats: Biomechanical and Molecular Analysis

Postmenopausal osteoporosis and poor dietary habits can lead to overweightness and obesity. Bisphosphonates are the first-line treatment for osteoporosis. However, some studies show that they may increase the risk of osteonecrosis of the jaw. Considering the antimicrobial, angiogenic and vasodilatory potential of nitric oxide, this study aims to evaluate the local activity of this substance during the placement of surface-treated implants. Seventy-two Wistar rats were divided into three groups: SHAM (SHAM surgery), OVX + HD (ovariectomy + cafeteria diet), and OVX + HD + RIS (ovariectomy + cafeteria diet + sodium risedronate treatment), which were further subdivided according to the surface treatment of the future implant: CONV (conventional), TE10, or TE100 (TERPY at 10 or 100 μM concentration); n = 8 per subgroup. The animals underwent surgery for implant installation in the proximal tibia metaphysis and were euthanized after 28 days. Data obtained from removal torque and RT-PCR (OPG, RANKL, ALP, IBSP and VEGF expression) were subjected to statistical analysis at 5% significance level. For biomechanical analysis, TE10 produced better results in the OVX + HD group (7.4 N/cm, SD = 0.6819). Molecular analysis showed: (1) significant increase in OPG gene expression in OVX groups with TE10; (2) decreased RANKL expression in OVX + HD + RIS compared to OVX + HD; (3) significantly increased expressions of IBSP and VEGF for OVX + HD + RIS TE10. At its lowest concentration, TERPY has the potential to improve peri-implant conditions.

Clinical implications of bone marrow adiposity

Marrow adipocytes, collectively termed marrow adipose tissue (MAT), reside in the bone marrow in close contact to bone cells and haematopoietic cells. Marrow adipocytes arise from the mesenchymal stem cell and share their origin with the osteoblast. Shifts in the lineage allocation of the mesenchymal stromal cell could potentially explain the association between increased MAT and increased fracture risk in diseases such as postmenopausal osteoporosis, anorexia nervosa and diabetes. Functionally, marrow adipocytes secrete adipokines, such as adiponectin, and cytokines, such as RANK ligand and stem cell factor. These mediators can influence both bone remodelling and haematopoiesis by promoting bone resorption and haematopoietic recovery following chemotherapy. In addition, marrow adipocytes can secrete free fatty acids, acting as a energy supply for bone and haematopoietic cells. However, this induced lipolysis is also used by neoplastic cells to promote survival and proliferation. Therefore, MAT could represent a new therapeutic target for multiple diseases from osteoporosis to leukaemia, although the exact characteristics and role of the marrow adipocyte in health and diseases remain to be determined.

Effects of bisphosphonates on mandibular condyle of ovariectomized osteoporotic rats using micro-ct and histomorphometric analysis

OBJECTIVE

To evaluate microarchitectural changes in condylar cartilage and associated subchondral bone after bisphosphonates treatment using an ovariectomized (OVX) osteoporosis rat model.

METHODS

Thirty six-month-old female Sprague-Dawley rats were randomly divided into sham, OVX, and risedronate (RIS)-treated groups. Both OVX and RIS groups received bilateral ovariectomy. OVX group was treated subcutaneously with saline, whereas RIS group received risedronate treatment (2.4 μg/kg) subcutaneously for 3 months. At the end of 3 months, animals were sacrificed and the entire condyles were harvested for micro-CT and histological analyses. Immunohistochemistry (IHC) was performed to assess the expression of type I/II collagen protein by semiquantitative imaging analysis.

RESULTS

Micro-CT analysis showed OVX group had significant condylar subchondral bone loss compared to sham as shown by significant decrease in bone volume fraction (P = 0.028), trabecular thickness (P = 0.041), and significant increase in trabecular spacing (P = 0.003). In RIS group, partial inhibition of OVX-induced bone loss was detected. HE staining showed proliferative layer of condylar cartilage reduced, while hypertrophic chondrocyte layer increased significantly in RIS group compared to sham and OVX groups. IHC showed reduced expression of Col I in both the OVX and RIS groups, whereas expression of Col II was reduced in the OVX group but increased in the RIS group.

CONCLUSION

Our findings suggest that systemic bisphosphonate treatment influences the structure and ossification of condylar cartilage and it has a dual action on condyle in a postmenopausal osteoporosis rat model which raises the concerns for the potential side effects of BPs on condyle to elder patients.

Effects of risedronate on the morphology and viability of gingiva-derived mesenchymal stem cells

Risedronate has been used for the prevention and treatment of postmenopausal and corticosteroid-induced osteoporosis. The present study was performed to evaluate the effects of risedronate on the morphology and viability of human stem cells derived from the gingiva. Stem cells derived from the gingiva were grown in the presence of risedronate at concentrations that ranged from 1 to 10 µM. The morphology of the cells was viewed under an inverted microscope, and cell proliferation was analyzed with a cell counting kit-8 (CCK-8) on days 2, 4 and 7. The untreated control group showed a spindle-shaped, fibroblast-like morphology. The shapes of the cells treated with 1 and 5 µM risedronate were similar to that of the control group on day 2. However, morphology of the 10 µM group markedly differed from that of the control group. The shapes of the cells in the 1, 5 and 10 µM groups were rounder, and pronounced alterations when compared with the untreated control group were noted in all groups on day 7. The cultures growing in the presence of risedronate showed decreased CCK-8 values on day 7. In conclusion, risedronate produced notable alterations in the morphology of the cells and reduced the viability of gingival mesenchymal stem cells.