Osteocyte morphology and orientation in relation to strain in the jaw bone / 国际口腔科学杂志·英文版

Bone mass is important for dental implant success and is regulated by mechanoresponsive osteocytes. We aimed to investigate the relationship between the levels and orientation of tensile strain and morphology and orientation of osteocytes at different dental implant positions in the maxillary bone. Bone biopsies were retrieved from eight patients who underwent maxillary sinus-floor elevation with β-tricalcium phosphate prior to implant placement. Gap versus free-ending locations were compared using 1) a three-dimensional finite-element model of the maxilla to predict the tensile strain magnitude and direction and 2) histology and histomorphometric analyses. The finite-element model predicted larger, differently directed tensile strains in the gap versus free-ending locations. The mean percentage of mineralised residual native-tissue volume, osteocyte number (mean ± standard deviations: 97 ± 40/region-of-interest), and osteocyte shape (~90% elongated, ~10% round) were similar for both locations. However, the osteocyte surface area was 1.5-times larger in the gap than in the free-ending locations, and the elongated osteocytes in these locations were more cranially caudally oriented. In conclusion, significant differences in the osteocyte surface area and orientation seem to exist locally in the maxillary bone, which may be related to the tensile strain magnitude and orientation. This might reflect local differences in the osteocyte mechanosensitivity and bone quality, suggesting differences in dental implant success based on the location in the maxilla.

novel approach on drug delivery: investigation of a new nano-formulation of liposomal doxorubicin and biological evaluation of entrapped doxorubicin on various osteosarcoma cell lines

Objective: In this study we prepared a novel formulation of liposomal doxorubicin [L-DOX]. The drug dose was optimized by analyses of cellular uptake and cell viability of osteosarcoma [OS] cell lines upon exposure to nanoliposomes that contained varying DOX concentrations. We intended to reduce the cytotoxicity of DOX and improve characteristics of the nanosystems

Materials and Methods: In this experimental study, we prepared liposomes by the pH gradient hydration method. Various characterization tests that included dynamic light scattering [DLS], cryogenic transmission electron microscopy [Cryo-TEM] imaging, and UV-Vis spectrophotometry were employed to evaluate the quality of the nanocarriers. In addition, the CyQUANT[registered] assay and fluorescence microscope imaging were used on various OS cell lines [MG-63, U2-OS, SaOS-2, SaOS-LM7] and Human primary osteoblasts cells, as novel methods to determine cell viability and in vitro transfection efficacy

Results: We observed an entrapment efficiency of 84% for DOX within the optimized liposomal formulation [L-DOX] that had a liposomal diameter of 96 nm. Less than 37% of DOX released after 48 hours and L-DOX could be stored stably for 14 days. L-DOX increased DOX toxicity by 1.8-4.6 times for the OS cell lines and only 1.3 times for Human primary osteoblasts cells compared to free DOX, which confirmed a higher sensitivity of the OS cell lines versus Human primary osteoblasts cells for L-DOX. We deduced that L-DOX passed more freely through the cell membrane compared to free DOX

Conclusion: We successfully synthesized a stealth L-DOX that contained natural phospholipid by the pH gradient method, which could encapsulate DOX with 84% efficiency. The resulting nanoparticles were round, with a suitable particle size, and stable for 14 days. These nanoparticles allowed for adequately controlled DOX release, increased cell permeability compared to free DOX, and increased tumor cell death. L-DOX provided a novel, more effective therapy for OS treatment