Effect of bone morphogenic protein-2 and desferoxamine on distraction osteogenesis

The effect of Hypoxia-Inducible Factor-1a stabilization on bone regeneration during distraction osteogenesis: A systematic review of animal studies

OBJECTIVE

This systematic review described Hypoxia-Inducible Factor-1a stabilization or upregulation approaches along with underlying signaling pathways and assessed bone regeneration, angiogenesis, and consolidation time during DO in animal models.

DESIGN

A comprehensive and systematic search of electronic databases including PubMed, Scopus, and ScienceDirect was performed till December 26, 2023. The search was limited to English articles, and no time restrictions were applied.

RESULTS

A total of 14 studies met the inclusion criteria and were included for final review. Four methods have been shown to activate the HIF pathway including genetic, pharmacological, mechanical, and cell preconditioning approaches. Deferoxamine (DFO) was administered as a pharmacological hypoxia-mimicking agent in many studies reporting acceptable outcomes on bone regeneration and acceleration of bone consolation. Applying mechanical loads at the optimal rate and amplitude serves as a minimally invasive approach with acceptable results. HIF-related signaling pathways increase osteogenesis and angiogenesis during DO, potentially through VHL/HIF-1a/VEGF, Wnt/β-catenin, and Mesenchymal-Epithelial transition (MET) signaling pathways.

CONCLUSION

Activation of HIF-related signaling pathways enhances and accelerates bone regeneration during the consolidation phase of distraction osteogenesis. The most feasible approach with the least side effects must be selected for further clinical studies.

The role of rhBMP-2 in mandibular bone regeneration following tooth extraction through HIF-1α and VEGF-A expression: An Immunohistochemical study

Background

Dentists frequently conduct tooth extractions when there is damage to the tooth or the tissue that supports it. When a tooth is extracted, the alveolar bone will sustain injury. Most of the initial bone volume is lost following the healing phase after extraction. Rehabilitation must start as soon as a tooth is missing, mainly because the alveolar bone is severely damaged during the tooth extraction, particularly in the buccal region where the tooth is removed. Dental implant is one method of replacing lost teeth. One of the most important elements influencing the clinical result of dental implants is a change in the dimension of the alveolar bone. Several bone-grafting techniques, such as socket preservation techniques, have been developed to increase the volume of bone throughout the healing phase after tooth extraction. This study aims to assess the impact rhBMP-2 on creating bone regeneration through VEGF and HIF-1α in the mandibular socket post-extraction in Wistar rats.

Method

On the anterior side of the mandible, in the socket area where the tooth was extracted, rhBMP-2 was injected into the socket, and the xenograft material was applied with a syringe. Male, 9-week-old Wistar rats were chosen (n = 30).

Result

Our statistical evaluations have revealed a significantly higher VEGF-A and HIF-1α expression post-extraction of the rhBMP-2 and xenograft group compared to other group treatments. These findings are significant as they provide a deeper understanding of the mechanisms involved in bone regeneration post-extraction.

Conclusion

Our study suggests that injecting rhBMP-2 into the grafted material and socket extraction during GBR dramatically increases the expression of VEGF-A and HIF-1α. These findings have the potential to significantly impact oral surgery and regenerative dentistry, opening up new possibilities for enhancing bone regeneration techniques.

The initial implementation of the transverse bone transport technique in the post-radiation region of the mandible. A pre-clinical in vivo study

BACKGROUND

To link the treatment of radiation injury with angiogenesis, and to design and seek a new therapeutic technique for the prevention and treatment of radiation injury.

METHODS

The transverse bone transport device for rabbit mandible was designed and manufactured. Eighteen New Zealand white rabbits were randomly divided into a radiotherapy group and a normal group. The radiotherapy group received 18 Gy of radiation, and the device was implanted two weeks later. After a 7-day incubation period, transverse transportation was performed at a speed of 0.5 circles (0.4 mm) per day, with an 8-day cycle and a total traction distance of 3.2 mm. CBCT, Micro CT, and histological staining were employed to assess the dynamics of movement, osteogenesis, and angiogenesis.

RESULTS

The transverse bone transport model of rabbit mandible was successfully established. CBCT revealed that the transport height in the normal and radiotherapy groups were 3.24 ± 0.17 mm and 3.22 ± 0.19 mm respectively. Micro CT analysis showed an increase in BV/TV and Tb.N over time, while Tb.Sp decreased; differences in BV/TV existed at 2 weeks but disappeared thereafter; differences in Tb.N and Tb.Sp persisted at 2 and 4 weeks. Histological staining using HE, Masson, and IHC demonstrated good bone maturity accompanied by rich neovascularization, and this was also confirmed by ImageJ software analysis.

CONCLUSIONS

The transverse bone transport was employed for the first time in the radiation-induced mandibular damage, thereby establishing a basis for further investigation into its clinical efficacy, application value, and underlying mechanisms. This breakthrough offers novel prospects for clinical interventions.

Exploring calcium-free alternatives in endochondral bone repair tested on In vivo trials - A review

Bone repair via endochondral ossification is a complex process for the critical size reparation of bone defects. Tissue engineering strategies are being developed as alternative treatments to autografts or allografts. Most approaches to bone regeneration involve the use of calcium composites. However, exploring calcium-free alternatives in endochondral bone repair has emerged as a promising way to contribute to bone healing. By analyzing researches from the last ten years, this review identifies the potential benefits of such alternatives compared to traditional calcium-based approaches. Understanding the impact of calcium-free alternatives on endochondral bone repair can have profound implications for orthopedic and regenerative medicine. This review evaluates the efficacy of calcium-free alternatives in endochondral bone repair through in vivo trials. The findings may guide future research to develop innovative strategies to improve endochondral bone repair without relying on calcium. Exploring alternative approaches may lead to the discovery of novel therapies that improve bone healing outcomes.

Bio-integrated scaffold facilitates large bone regeneration dominated by endochondral ossification

Repair of large bone defects caused by severe trauma, non-union fractures, or tumor resection remains challenging because of limited regenerative ability. Typically, these defects heal through mixed routines, including intramembranous ossification (IMO) and endochondral ossification (ECO), with ECO considered more efficient. Current strategies to promote large bone healing via ECO are unstable and require high-dose growth factors or complex cell therapy that cause side effects and raise expense while providing only limited benefit. Herein, we report a bio-integrated scaffold capable of initiating an early hypoxia microenvironment with controllable release of low-dose recombinant bone morphogenetic protein-2 (rhBMP-2), aiming to induce ECO-dominated repair. Specifically, we apply a mesoporous structure to accelerate iron chelation, this promoting early chondrogenesis via deferoxamine (DFO)-induced hypoxia-inducible factor-1α (HIF-1α). Through the delicate segmentation of click-crosslinked PEGylated Poly (glycerol sebacate) (PEGS) layers, we achieve programmed release of low-dose rhBMP-2, which can facilitate cartilage-to-bone transformation while reducing side effect risks. We demonstrate this system can strengthen the ECO healing and convert mixed or mixed or IMO-guided routes to ECO-dominated approach in large-size models with clinical relevance. Collectively, these findings demonstrate a biomaterial-based strategy for driving ECO-dominated healing, paving a promising pave towards its clinical use in addressing large bone defects.

Effect of rh-BMP-2 in the Initiation of Neovascularization in Human Gingival Tissue: A Split-Mouth Clinical Study

The aim of this study is to evaluate the effect on the initiation of new blood vessel formation of rh-BMP-2 administration in the human gingival tissue during bone regeneration surgery.

MATERIAL AND METHODS

The randomized controlled clinical trial included twenty patients with bilateral partial edentulous of the mandibular premolar and molar region. Each patient received one implants on each side. Only one side received a 0.25 µg injection of rhBMP-2 into the gingival flap and grafted material during guided bone regeneration (GBR) for dental implantation. And the other side received GBR without injection. Three samples were collected from each patient as follows: one from the anterior area of the mandible (control group #1) collected at the time of all implant surgeries, and the two other samples during the placement of healing abutments at 4 months of follow-up, from treated side with rh-BMP-2 (test group) and untreated ones (control group #2). A total of 60 gingival samples were collected. Samples were stained with hematoxylin-eosin, and immunohistochemistry was performed with a vascular endothelial growth factor marker. The number of new vessels in each sample was counted.

RESULT

Statistical analyses showed a significantly higher number of new vessels in the gingival tissue of the test group.

CONCLUSIONS

Rh-BMP-2 injections into the gingival flap significantly improved new blood vessel formation.