In vitro osteogenesis of rat bone marrow mesenchymal cells on PEEK disks with heat-fixed apatite by CO2 laser bonding

Naringin promotes osteogenic potential in bone marrow-derived mesenchymal stem cells via mediation of miR-26a/Ski axis

Background

Osteonecrosis of the femoral head (ONFH) is a common orthopedic disease, which seriously affects the quality of life of patients. Naringin has protective effect on ONFH. In present study, we aimed to investigate the mechanism of Naringin regulating miR-26a in ONFH.

Methods

Two sequencing datasets (GSE89587 for micro-RNA, GSE123568 for mRNA) related to ONFH were obtained from the GEO database for bioinformatics analysis. Bone marrow-derived mesenchymal stem cells (BMSCs) were treated with adipogenic medium (AM) or osteogenic medium (OM), and then treated with 10 μM, 100 μM or 1000 μM Naringin. Gene and protein levels were detected by RT-qPCR and Western blotting. ALP activity and alizarin red staining (ARS) were applied to investigate the osteogenic differentiation of BMSCs. Oil red O staining was performed to test adipogenic differentiation. The content of triglycerides (TG) in BMSCs was detected by TG detection kit. Double luciferase reporter gene measured the interaction between miR-26a and Ski.

Results

Bioinfomatic analyses indicated a significant downregulation of miR-26a and a significant upregulation of Ski in the peripheral blood of patients with ONFH. Naringin significantly promoted the osteogenic differentiation, and increased the ALP activity and ARS. Meanwhile, it decreased the adipogenic differentiation and inhibited TG levels. In addition, miR-26a was downregulated and Ski was increased in AM-treated BMSCs, while miR-26a was upregulated and Ski was decreased in OM-treated BMSCs. Furthermore, miR-26a promoted the osteogenic differentiation and suppressed the adipogenic differentiation in BMSCs. Moreover, Naringin enhanced osteogenic potential in BMSCs was reversed by knockdown of miR-26a or overexpression of Ski.

Conclusion

Naringin could promote osteogenic differentiation of BMSCs via mediation of miR-26a/Ski axis. Thereby, Naringin might be a new agent for ONFH treatment.

MgO-enhanced β-TCP promotes osteogenesis in both in vitro and in vivo rat models

Allogeneic bone grafts are used to treat bone defects in orthopedic surgery, but the osteogenic potential of artificial bones remains a challenge. In this study, we developed a β-tricalcium phosphate (β-TCP) formulation containing MgO, ZnO, SrO, and SiO2 and compared its bone-forming ability with that of β-TCP without biological elements. We prepared β-TCP discs with 60% porosity containing 1.0 wt% of these biological elements. β-TCP scaffolds were loaded with bone marrow-derived mesenchymal stem cells (BMSC) from 7-week-old male rats and cultured for 2 weeks. ALP activity and mRNA expression of osteogenic markers were evaluated. In addition, scaffolds were implanted subcutaneously in rats and analyzed after 7 weeks. In vitro, the MgO group showed lower Ca concentrations and higher osteogenic marker expression compared to controls. In vivo, the MgO group showed higher ALP activity compared to controls, and RT-qPCR analysis showed significant expression of BMP2 and VEGF. Histopathology, fluorescent immunostaining, and micro-CT also showed relatively better bone formation in the MgO group. β-TCP with MgO may enhance bone morphology in vitro and in vivo and improve the prognosis of patients with substantial and refractory bone defects.

A novel injectable hydrogel containing polyetheretherketone for bone regeneration in the craniofacial region

Polyetheretherketone (PEEK) is an organic material introduced as an alternative for titanium implants. Injectable hydrogels are the most promising approach for bone regeneration in the oral cavity to fill the defects with irregular shapes and contours conservatively. In the current study, injectable Aldehyde-cellulose nanocrystalline/silk fibroin (ADCNCs/SF) hydrogels containing PEEK were synthesized, and their bone regeneration capacity was evaluated. Structure, intermolecular interaction, and the reaction between the components were assessed in hydrogel structure. The cytocompatibility of the fabricated scaffolds was evaluated on human dental pulp stem cells (hDPSCs). Moreover, the osteoinduction capacity of ADCNCs/SF/PEEK hydrogels on hDPSCs was evaluated using Real-time PCR, Western blot, Alizarin red staining and ALP activity. Bone formation in critical-size defects in rats' cranial was assessed histologically and radiographically. The results confirmed the successful fabrication of the hydrogel and its osteogenic induction ability on hDPSCs. Furthermore, in in vivo phase, bone formation was significantly higher in ADCNCs/SF/PEEK group. Hence, the enhanced bone regeneration in response to PEEK-loaded hydrogels suggested its potential for regenerating bone loss in the craniofacial region, explicitly surrounding the dental implants.

Silicate/zinc-substituted strontium apatite coating improves the osteoinductive properties of β-tricalcium phosphate bone graft substitute

Background

β-Tricalcium phosphate (β-TCP) is a popular synthetic bone graft substitute with excellent osteoconductive properties and bioabsorbability. However, its osteoinductive properties are inferior to those of autologous or allogeneic bone. Trace elements such as strontium (Sr), silica (Si), and zinc (Zn) have been reported to promote osteogenesis in materials. In this study, we aimed to determine whether a Si/Zn-substituted Sr apatite coating of β-TCP could enhance osteoinductive properties.

Methods

The apatite-coated β-TCP disks were prepared using nanoparticle suspensions of silicate-substituted Sr apatite (SrSiP) or silicate- and Zn-co-substituted Sr apatite (SrZnSiP).

Bone marrow mesenchymal cells (BMSCs) from rat femur were cultured and subsequently seeded at a density of 1.0 × 10⁶/cm² onto apatite-coated and non-coated β-TCP disks.

In vitro, the β-TCP disks were then placed in osteogenic medium, and lactate dehydrogenase (LDH) activity was measured from supernatants after culture for 2 days. Additionally, after culture for 14 days, the mRNA expression of genes encoding osteocalcin (OC), alkaline phosphatase (ALP), bone morphogenetic protein-2 (BMP-2), and vascular endothelial growth factor (VEGF) was evaluated by qRT-PCR. In vivo, the β-TCP disks were transplanted subcutaneously into rats that were sacrificed after 4 weeks. Then, the harvested disks were evaluated biochemically (ALP activity, OC content, mRNA expression of OC, ALP, BMP-2, and VEGF measured by qRT-PCR), radiologically, and histologically.

Results

Significantly higher mRNA expression of almost all evaluated osteogenic and angiogenic genes was observed in the SrZnSiP and SrSiP groups than in the non-coated group, with no significant cytotoxicity elicited by the apatite coating in vitro. Moreover, in vivo, the SrZnSiP and SrSiP groups showed significantly higher osteogenic and angiogenic gene expression and higher ALP activity and OC content than the non-coated group (P < 0.05). Radiological and histopathological findings revealed abundant bone formation in the apatite-coated group.

Conclusions

Our findings indicate that apatite coating of β-TCP improves osteoinductive properties without inducing significant cytotoxicity.