The effect of adding hyaluronic acid to calcium phosphate on periapical tissue healing following periradicular surgery in dogs

The optimal dosage of hyaluronic acid for bone regeneration in rat calvarial defects

PURPOSE

Hyaluronic acid (HA) affects angiogenesis and promotes the migration and differentiation of mesenchymal cells, thereby activating the osteogenic ability of osteoblasts. Although studies on the action of HA during bone regeneration are being actively conducted, the optimal dose of HA required for bone regeneration remains unclear. Therefore, the purpose of this study was to elucidate the most effective HA dose for bone formation using a rat critical-size defect model.

METHODS

Thirty rats were randomly divided into 5 groups, with 6 rats in each group. An absorbable collagen sponge soaked with HA or saline was used to fill an 8-mm defect, which was then covered with a collagen membrane. Different treatments were performed for each group as follows: (1) saline control, (2) 1 mg/mL HA, (3) 25 mg/mL HA, (4) 50 mg/mL HA, or (5) 75 mg/mL HA. After a healing period of 4 weeks, micro-computed tomography and histological analysis were performed. The obtained values were analyzed using analysis of variance and the Tukey test (P<0.05).

RESULTS

At week 4, the 75 mg/mL HA group had the highest bone volume/total volume ratio, new bone, and bone fill among the 5 groups, and these values were significantly different from those observed in the control group (P<0.01) and 1 mg/mL HA group (P<0.001). More active bone formation was observed in the higher-dose HA groups (25 mg/mL, 50 mg/mL, and 75 mg/mL HA), which included a large amount of woven bone.

CONCLUSIONS

The 75 mg/mL HA group showed better bone formation than the other groups (1, 25, and 50 mg/mL HA and control).

Local delivery of hydrogel encapsulated vascular endothelial growth factor for the prevention of medication-related osteonecrosis of the jaw

The anti-angiogenic effects of bisphosphonates have been hypothesized as one of the major etiologic factors in the development of medication-related osteonecrosis of the jaw (MRONJ), a severe debilitating condition with limited treatment options. This study evaluated the potential of a gelatine-hyaluronic acid hydrogel loaded with the angiogenic growth factor, vascular endothelial growth factor (VEGF), as a local delivery system to aid in maintaining vascularization in a bisphosphonate-treated (Zoledronic Acid) rodent maxillary extraction defect. Healing was assessed four weeks after implantation of the VEGF-hydrogel into extraction sockets. Gross examination and histological assessment showed that total osteonecrosis and inflammatory infiltrate was significantly reduced in the presence of VEGF. Also, total vascularity and specifically neovascularization, was significantly improved in animals that received VEGF hydrogel. Gene expression of vascular, inflammatory and bone specific markers within the defect area were also significantly altered in the presence of VEGF. Furthermore, plasma cytokine levels were assessed to determine the systemic effect of locally delivered VEGF and showed similar outcomes. In conclusion, the use of locally delivered VEGF within healing extraction sockets assists bone healing and prevents MRONJ via a pro-angiogenic and immunomodulatory mechanism.

Injectable silanized hyaluronic acid hydrogel/biphasic calcium phosphate granule composites with improved handling and biodegradability promote bone regeneration in rabbits

Biphasic calcium phosphate (BCP) granules are osteoconductive biomaterials used in clinics to favor bone reconstruction. Yet, poor cohesivity, injectability and mechanical properties restrain their use as bone fillers. In this study, we incorporated BCP granules into in situ forming silanized hyaluronic acid (Si-HA) and hydroxypropylmethylcellulose (Si-HPMC) hydrogels. Hydrogel composites were shown to be easily injectable (F < 30 N), with fast hardening properties (<5 min), and similar mechanical properties (E∼ 60 kPa). In vivo, both hydrogels were well tolerated by the host, but showed different biodegradability with Si-HA gels being partially degraded after 21d, while Si-HPMC gels remained stable. Both composites were easily injected into critical size rabbit defects and remained cohesive. After 4 weeks, Si-HPMC/BCP led to poor bone healing due to a lack of degradation. Conversely, Si-HA/BCP composites were fully degraded and beneficially influenced bone regeneration by increasing the space available for bone ingrowth, and by accelerating BCP granules turnover. Our study demonstrates that the degradation rate is key to control bone regeneration and that Si-HA/BCP composites are promising biomaterials to regenerate bone defects.

Integrated Oxidized-Hyaluronic Acid/Collagen Hydrogel with β-TCP Using Proanthocyanidins as a Crosslinker for Drug Delivery

The susceptibility of guided bone regeneration (GBR) material to infection by pathogens at wound sites during bone healing has often been overlooked. The objective of this study was the synthesis and characterization of a potential material for antibacterial GBR application. In the current study, the mechanical strength and biocompatibility of a composite restoration material-made of oxidized hyaluronic acid (HA)/type I collagen hydrogel integrated with tricalcium phosphate (β-TCP) using a natural crosslinking agent, oligomeric proanthocyanidins (OPCs)-were evaluated. The suitability of the material as a carrier matrix for antibacterial applications was evaluated by following the drug-release profile of tetracycline loaded within the composite. Results indicated that this composite material had a high swelling ratio of 420% and mechanical strength of 25 kPa while remaining at more than 60% of the weight after 30 days of an in vitro degradation test with good biocompatibility in promoting the proliferation of MG-63 cells. Drug release studies further showed that 93% of the tetracycline was released after 5 days, which supports this GBR material's capability to release antibacterial drugs while keeping other required GBR material design functions.