OBJECTIVE: To review the research progress of strontium (Sr) modified β-tricalcium phosphate composite biomaterials (SrTCP) promoting osteogenesis through immune regulation, and provides reference and theoretical support for the further development and research of SrTCP bone repair materials in bone tissue engineering in the future. METHODS: The literature about SrTCP promoting osteogenesis through immune regulation at home and abroad in recent years was extensively reviewed, and the preparation methods, immune mechanism and application of promoting osteogenesis were summarized and analyzed. RESULTS: The preparation methods of SrTCP include solid-state reaction sintering method, solution combustion quenching method, direct doping method, ion substitution method, etc. SrTCP has immune regulatory effects, which can play an immune regulatory role in inducing macrophage polarization, inducing angiogenesis and anti oxidative stress to promote osteogenesis. CONCLUSION At present, studies have shown that SrTCP can promote bone defect repair through immune regulation. Subsequent studies can start from the control of the optimal repair concentration and release rate of Sr, and further clarify the specific mechanism of SrTCP in promoting angiogenesis and anti oxidative stress, which is helpful to develop new materials for bone defect repair.
Calcium Phosphates/pharmacology* ; Strontium/pharmacology* ; Biocompatible Materials/pharmacology* ; Humans ; Osteogenesis/drug effects* ; Tissue Engineering/methods* ; Bone Substitutes/pharmacology* ; Bone Regeneration/drug effects* ; Animals ; Tissue Scaffolds/chemistry* ; Neovascularization, Physiologic/drug effects* ; Macrophages/immunology*

The ambiguity of etiology makes temporomandibular joint osteoarthritis (TMJOA) "difficult-to-treat". Emerging evidence underscores the therapeutic promise of exosomes in osteoarthritis management. Nonetheless, challenges such as low yields and insignificant efficacy of current exosome therapies necessitate significant advances. Addressing lower strontium (Sr) levels in arthritic synovial microenvironment, we studied the effect of Sr element on exosomes and miRNA selectively loading in synovial mesenchymal stem cells (SMSCs). Here, we developed an optimized system that boosts the yield of SMSC-derived exosomes (SMSC-EXOs) and improves their miRNA profiles with an elevated proportion of beneficial miRNAs, while reducing harmful ones by pretreating SMSCs with Sr. Compared to untreated SMSC-EXOs, Sr-pretreated SMSC-derived exosomes (Sr-SMSC-EXOs) demonstrated superior therapeutic efficacy by mitigating chondrocyte ferroptosis and reducing osteoclast-mediated joint pain in TMJOA. Our results illustrate Alix's crucial role in Sr-triggered miRNA loading, identifying miR-143-3p as a key anti-TMJOA exosomal component. Interestingly, this system is specifically oriented towards synovium-derived stem cells. The insight into trace element-driven, site-specific miRNA selectively loading in SMSC-EXOs proposes a promising therapeutic enhancement strategy for TMJOA.
MicroRNAs/metabolism* ; Mesenchymal Stem Cells/drug effects* ; Osteoarthritis/drug therapy* ; Exosomes/drug effects* ; Strontium/pharmacology* ; Synovial Membrane/cytology* ; Humans ; Animals ; Temporomandibular Joint Disorders/therapy* ; Temporomandibular Joint

OBJECTIVE: To investigate the preparation of decellularized small intestinal submucosa (dSIS) sponge scaffolds with chelated strontium (Sr) ions at different pH values, and to select the appropriate pH values for synthesizing Sr/dSIS scaffolds using the physicochemical properties and biocompatibility of the scaffolds as evaluation indexes. METHODS: (1) Sr/dSIS scaffolds preparation and grouping: After mixing dSIS solution and strontium chloride solution in equal volumes, adjusting pH of the solution to 3, 5, 7, and 9 respectively, porous scaffolds were prepared by freeze-drying method after full reaction at 37℃, which were named Sr/dSIS-3, -5, -7, and -9 respectively, and the dSIS scaffolds were used as the control group. (2) Physicochemical property evaluation: The bulk morphology of the scaffolds was observed in each group, the microscopic morphology analyzed by scanning electron microscopy, and the porosity and pore size determined, the surface elements analyzed by energy spectroscopy, the structure of functional groups analyzed by infrared spectroscopy, the chelation rate determined by atomic spectrophotometry, the water absorption rate detected by using specific gravity method, and the compression strength evaluated by universal mechanical testing machine.(3) Biocompatibility evaluation: The cytotoxicity and proliferative effect to bone mesenchymal stem cells (BMSCs) of each group were evaluated by Calcein-AM/PI double staining method. RESULTS: Scanning electron microscopy showed that the scaffolds of each group had an interconnected three-dimensional porous structure with no statistical difference in pore size and porosity. Energy spectrum analysis showed that strontium could be detected in Sr/dSIS-5, -7 and -9 groups, and strontium was uniformly distributed in the scaffolds. Functional group analysis further supported the formation of chelates in the Sr/dSIS-5, -7 and -9 groups. Chelation rate analysis showed that the Sr/dSIS-7 group had the highest strontium chelation rate, which was statistically different from the other groups (P < 0.05). The scaffolds in all the groups had good water absorption. The scaffolds in Sr/dSIS-5, -7 and -9 groups showed significantly improved mechanical properties compared with the control group (P < 0.05). The scaffolds in all the groups had good biocompatibility, and the Sr/dSIS-7 group showed the best proliferation of BMSCs. CONCLUSION When pH was 7, the Sr/dSIS scaffolds showed the highest strontium chelation rate and the best proliferation effect of BMSCs, which was the ideal pH value for the preparation of the Sr/dSIS scaffolds.
Tissue Scaffolds/chemistry* ; Biocompatible Materials ; Strontium/pharmacology* ; Ions ; Hydrogen-Ion Concentration ; Tissue Engineering/methods* ; Porosity

OBJECTIVETo investigate the growth activity of osteoblast on a novel strontium incorporated calcium sulfate and make comparison with normal calcium sulfate material.

METHODSOsteoblast was inoculated on samples and cell proliferation was measured on the 1st, 3rd, 5th days, and the activities of ALP and osteocalcin were observed on the 5th day. And microcosmic morphology of osteoblast was observed by scanning electron microscopy(SEM).

RESULTSOsteoblast grows robustly on tested material. Cell quantity on the surface of novel material was obviously higher than normal calcium sulfate material (P < 0.05). The activity of ALP and osteocalcin on novel material was 57.8% and 40.2% higher than on normal calcium sulfate material respectively (P < 0.05). On strontium incorporated surface, osteoblast spread well. Cells were polygonal with abundant cytoplasm and the morphology was active.

CONCLUSIONStrontium incorporated calcium sulfate can sustain robust growth activity of osteoblast, which is promising to be used for bone substitute materials.

3T3 Cells ; Alkaline Phosphatase ; metabolism ; Animals ; Bone Substitutes ; chemistry ; pharmacology ; Calcium Sulfate ; chemistry ; pharmacology ; Cell Proliferation ; drug effects ; Mice ; Osteoblasts ; cytology ; drug effects ; metabolism ; Osteocalcin ; metabolism ; Strontium ; chemistry

OBJECTIVETo explore whether strontium ranelate (Sr) promotes osteoblast lineage differentiation of rat bone mesenchymal stem cells (BMSCs) through the bone morphogenetic protein-2 (BMP-2)/Smad signaling pathway.

METHODSCultured rat BMSCs were exposed to different concentrations of Sr, noggin (an inhibitor of BMP-2) or Smad1 siRNA. The activity of alkaline phosphatase (ALP) in the exposed cells was detected by colorimetry, and the formation of mineralized nodules was observed with alizarin red staining. The expressions of phosphorylated (p) Smad1/5/8 and Runt-related transcription factor 2 (Runx2) in the cells were detected by Western blotting.

RESULTSExposure to Sr at 0.1 to 10 mmol/L for 1 h markedly increased the expression of p-Smad1/5/8 in the BMSCs, and the increment was the most obvious following 1 mmol/L Sr exposure. Preconditioning with 100 ng/ml noggin for 2 h inhibited Sr-induced up-regulation of p-Smad1/5/8 expressions. Exposure of the cells to 0.1 to 5 mmol/L Sr for 6 h significantly enhanced Runx2 expression, and the peak enhancement occurred following 1 mmol/L Sr exposure. Transfection of the BMSCs with Smad1 siRNA decreased the basal level of Smad1/5/8 protein expression, and also inhibited Sr-induced up-regulation of p-Smad1/5/8 and Runx2 expressions as well as Sr-induced enhancement of ALP activity and formation of mineralized nodules.

CONCLUSIONThe BMP-2/Smad pathway is involved in Sr-induced osteoblast differentiation of rat BMSCs.

Alkaline Phosphatase ; metabolism ; Animals ; Bone Marrow Cells ; cytology ; Bone Morphogenetic Protein 2 ; metabolism ; Cell Differentiation ; drug effects ; Cells, Cultured ; Mesenchymal Stromal Cells ; cytology ; Osteogenesis ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Smad1 Protein ; metabolism ; Strontium ; pharmacology ; Thiophenes ; pharmacology

OBJECTIVETo establish a suitable protocol for activating mouse somatic cell nuclear transfer embryos with strontium chloride (SrCl2).

METHODSWe constructed and identified mouse nuclear transfer (NT) embryos. After nuclear injection, we activated the NT embryos using the following chemical activation methods: exposing the NT embryos to 5 and 10 mmol/L SrCl2 strontium for 1 -8 h, activating the NT embryos with 1-20 mmol/L SrCl2 strontium at 4 and 6 h, treating the NT embryos with 10 mmol/L SrCl2 strontium in different activating media, and exposing the NT embryos to 10 mmol/L SrCl2 strontium combined with 6-dimethylaminopurine (6-DMAP) and cytochalasin B (CB). After activation, the NT embryos were cultured in vitro in the cleavage medium.

RESULTSWhen the NT embryos were treated with SrCl2 at the concentration of 5 mmol/L, the cleavage rate was remarkably higher at 6 h (38.9%) than at 1 h (6.7%), 2 h (22.8%), 3 h (22.8%) and 4 h (25.6%) (P < 0.05), but with no significant differences from those at 5 h (28.9%), 7 h (34.4%) and 8 h (28.9%) (P > 0.05). When the NT embryos were treated with SrCl2 for 6 h, the rates of cleavage and blastulation were 68.9% and 7.2% at 10 mmol/L, markedly higher than at 1 mmol/L (28.3% and 0%), 2.5 mmol/L (35.6% and 0%), 5 mmol/L (37.8% and 1.1%), 7.5 mmol/L (60.6% and 2.2%), 15 mmol/L (51.7% and 1.1%), and 20 mmol/L (41.7% and 1.1%) (P < 0.05). The cleavage rate of the NT embryos cultured in the Ca2+ and Mg2+ KSOM medium was 27.8%, significantly lower than in the Ca(2+)-free KSOM (69.4%), Ca2+/Mg(2+)-free KSOM (66.1%), and Ca2+/Mg(2+)-free + EDTA KSOM (68.3%) (P < 0.05). The total cell blastocyst number was significantly larger in the NT embryos treated with SrCl2 + CB (45.40 +/- 2.23) than in those treated with SrCl2 (30.15 +/- 1.12), 6-DMAP (34.95 +/- 1.38), and 6-DMAP + CB (37.45 +/- 1.43) (P < 0.05).

CONCLUSIONSix-hour treatment with 10 mmol/L SrCl2 in Ca2+ alone or in combination with CB can well activate NT embryos in mice.

Animals ; Blastocyst ; cytology ; drug effects ; Embryo Culture Techniques ; Embryo, Mammalian ; cytology ; drug effects ; Embryonic Development ; drug effects ; Female ; Mice ; Mice, Inbred C57BL ; Nuclear Transfer Techniques ; Oocytes ; cytology ; drug effects ; Strontium ; pharmacology

OBJECTIVESr-HA, a new type of hydroxyapatite biomaterial, was implanted into animals to study the bioreaction and character, which would be helpful for the further clinical applications in the future.

METHODSTotally 24 rabbits were divided into 3 groups. The bone defect of 6 mm x 12 mm x 4 mm was made at both mandibular angles of rabbits and Sr-HA of different proportion (10%, 5%, 0) was applied to reform the defects. One group of animals were killed randomly at 1, 3 and 6 months after operation to evaluate the material biological compatibility using anatomic, X-ray examination, histological and ECT methods.

RESULTSThe histological photographs showed that Sr-HA caused little infection around implanted area and, almost was not repulsed by hosts. With the degradation of biomaterial, there was more apparent new bone growth in the area around Sr-HA than that around HA and some ossification can be found in soft tissue nearby. Also a tight osteointegrity was gradually got after the operation, according to the results of X-ray and, the border between Sr-HA and bone was hardly discovered at the 6th month after the operation. A more obvious nuclide assembling was observed at the side of Sr-HA by ECT images. With the biodegradation of Sr-HA, more new bone was intruded into the spare space of the biomaterial.

CONCLUSIONSr-HA has better biocompatibility and higher biodegradation than that of pure HA. It holds an excellent osteoinductivity and fair osteoconductivity to some degree too. So a more satisfying effect of bone defect rehabilitation was gained with the increasing new bone depositing in the free space of the material, when it degraded gradually.

Animals ; Biocompatible Materials ; Biodegradation, Environmental ; Bone Substitutes ; Hydroxyapatites ; chemistry ; pharmacology ; Implants, Experimental ; Mandible ; surgery ; Osteogenesis ; physiology ; Rabbits ; Strontium ; chemistry ; pharmacology