The effects of gelatin, fibrin-platelet glue and their combination on healing of the experimental critical bone defect in a rat model: radiological, histological, scanning ultrastructural and biomechanical evaluation

The Effect of Mineralized Plasmatic Matrix and Chitosan on the Healing of Critical-Sized Mandibular Bone Defects in a Rabbit Model

Background: In maxillofacial surgery, critical size mandibular defects remain a challenging issue. There have been numerous attempts to improve mandibular defect healing. Recently, bone tissue engineering has provided many benefits in improving bone healing. Herein, we tried to investigate the effect of Mineralized plasmatic matrix (MPM) and Chitosan to enhance tissue healing and regeneration in mandibular bone defect. Methods: A mandibular bone defect of critical size was created in 45 New Zealand rabbits. There were three groups of rabbits: the MPM group, the Chitosan group, and the control group. Radiographical, histological, and immune histochemical evaluations were performed at 4, 8, and 12 post-operative weeks. Results: The MPM group demonstrated the highest degree of bone formation with uniform radio-opacity nearly like that of adjacent healthy parent tissue. While in the chitosan group, most of the defect area was filled with radio-opaque bone with persistent small radiolucent areas. The control group showed less bone formation than the MPM and chitosan group, with more radiolucent areas. Sections stained with (H&E) demonstrated an increase in osseous tissue formation in both the MPM and chitosan groups. Staining with Masson’s trichrome revealed an increase in fibrous connective tissue proliferation in both the MPM and chitosan groups. In both the MPM and chitosan groups, nuclear factor kappa p65 was downregulated, and matrix metalloproteinase-9 was upregulated. Conclusion: According to the current study, MPM and Chitosan may have beneficial effects on the healing of critical-sized mandibular bone defects.

Novel Techniques and Future Perspective for Investigating Critical-Size Bone Defects

A critical-size bone defect is a challenging clinical problem in which a gap between bone ends will not heal and will become a nonunion. The current treatment is to harvest and transplant an autologous bone graft to facilitate bone bridging. To develop less invasive but equally effective treatment options, one needs to first have a comprehensive understanding of the bone healing process. Therefore, it is imperative to leverage the most advanced technologies to elucidate the fundamental concepts of the bone healing process and develop innovative therapeutic strategies to bridge the nonunion gap. In this review, we first discuss the current animal models to study critical-size bone defects. Then, we focus on four novel analytic techniques and discuss their strengths and limitations. These four technologies are mass cytometry (CyTOF) for enhanced cellular analysis, imaging mass cytometry (IMC) for enhanced tissue special imaging, single-cell RNA sequencing (scRNA-seq) for detailed transcriptome analysis, and Luminex assays for comprehensive protein secretome analysis. With this new understanding of the healing of critical-size bone defects, novel methods of diagnosis and treatment will emerge.

Effects of Combination of BMP7, PFG, and Autograft on Healing of the Experimental Critical Radial Bone Defect by Induced Membrane (Masquelet) Technique in Rabbit

Background

Healing of large segmental bone defects can be challenging for orthopedic surgeons. This research was conducted to provide further insight into the effects of BMP7 in combination with autograft and platelet fibrin glue (PFG) on bone regeneration by Masquelet technique (MT).

Methods

Twenty five domestic male rabbits, more than 6 months old, weighing 2.00±0.25 kg were randomly divided into five equal groups as follows: MT-blank cavity (without any biological or synthetic materials) (1), blank cavity (2), MT-autograft (3), MT-autograft-BMP7 (4), and MT-BMP7-PFG (5). A 20 mm segmental defect was made in radial bone in both forelimbs. The Masquelet technique was done in all groups except group 2. The study was evaluated by radiology, biomechanics, histopathology and scanning electron microscopy.

Results

The results showed that Masquelet technique enhanced the healing process, as, the structural and functional criteria of the injured bone showed significantly improved bone healing (P<0.05). Treatment by PFG-BMP7, Autograft-BMP7, and autograft demonstrated beneficial effects on bone healing. However, Autograft-BMP7 was more effective than autograft in healing of the radial defect in rabbits.

Conclusion

Our findings introduce the osteogenic materials in combination with Masquelet technique as an alternative for reconstruction of the big diaphyseal defects in the long bones in animal models. Our findings may be useful for clinical application in future.

Metformin-Incorporated Gelatin/Hydroxyapatite Nanofiber Scaffold for Bone Regeneration

Tissue engineering and regenerative medicine has gradually evolved as a promising therapeutic strategy to the modern health care of aging and diseased population. In this study, we developed a novel nanofibrous scaffold and verified its application in the critical bone defect regeneration. The metformin-incorporated nano-gelatin/hydroxyapatite fibers (NGF) was produced by electrospinning, cross-linked, and then characterized by X-ray powder diffractometer and Fourier-transform infrared spectroscopy. Cytotoxicity, cell adhesion, cell differentiation, and quantitative osteogenic gene and protein expression were analyzed by bone marrow stem cells (BMSCs) from rat. Rat forearm critical bone defect model was performed for the in vivo study. The NGF were characterized by their porous structures with proper interconnectivity without significant cytotoxic effects; the adhesion of BMSCs on the NGF could be enhanced. The osteogenic gene and protein expression were upregulated. Postimplantation, the new regenerated bone in bone defect was well demonstrated in the NGF samples. We demonstrated that the metformin-incorporated NGF greatly improved healing potential on the critical-size bone defect. Although metformin-incorporated NGF had advantageous effectiveness during bone regeneration, further validation is required before it can be applied to clinical applications. Impact statement Bone is the structure that supports the rest of the human body. Critical-size bone defect hinders the regeneration of damaged bone tissues and compromises the mechanical strength of the skeletal system. Characterized by their porous structures with proper interconnectivity, the electrospinning nano-gelatin/hydroxyapatite fibrous scaffold developed in this study can greatly improve the healing potential on the critical-size bone defect. Further validation can validate its potential clinical applications.

Designing Hydrogel-Based Bone-On-Chips for Personalized Medicine

The recent development of bone-on-chips (BOCs) holds the main advantage of requiring a low quantity of cells and material, compared to traditional In Vitro models. By incorporating hydrogels within BOCs, the culture system moved to a three dimensional culture environment for cells which is more representative of bone tissue matrix and function. The fundamental components of hydrogel-based BOCs, namely the cellular sources, the hydrogel and the culture chamber, have been tuned to mimic the hematopoietic niche in the bone aspirate marrow, cancer bone metastasis and osteo/chondrogenic differentiation. In this review, we examine the entire process of developing hydrogel-based BOCs to model In Vitro a patient specific situation. First, we provide bone biological understanding for BOCs design and then how hydrogel structural and mechanical properties can be tuned to meet those requirements. This is followed by a review on hydrogel-based BOCs, developed in the last 10 years, in terms of culture chamber design, hydrogel and cell source used. Finally, we provide guidelines for the definition of personalized pathological and physiological bone microenvironments. This review covers the information on bone, hydrogel and BOC that are required to develop personalized therapies for bone disease, by recreating clinically relevant scenarii in miniaturized devices.

In vitro and in vivo assessment of glucose cross-linked gelatin/zein nanofibrous scaffolds for cranial bone defects regeneration

The purpose of this study was to evaluate the glucose cross-linked gelatin/zein scaffolds for bone regeneration in vitro and in vivo. The nanofibrous scaffolds exhibited fast mineralization in the concentrated simulated body fluid with the deposited octacalcium phosphate and dicalcium phosphate dehydrate. The nanofibrous scaffolds exhibited no cytotoxic effect on MC3T3e1 cells in a CCK-8 test. Additionally, scanning electron microscope and confocal laser scanning microscopy images revealed that all the scaffolds were biocompatible and showed excellent support for MC3T3e1 cells. In the osteogenesis characterizations, Alizarin Red staining experiments indicated the improved calcium deposits on the cross-linked scaffolds, while the alkaline phosphatase activity showed no difference. Furthermore, the in vivo cranial bone regeneration results suggested that the cross-linked gelatin/zein scaffolds presented a strong positive effect on the cranial bone regeneration with the increased new bone volume and connective tissue formation, but the incorporation of zein in the gelatin scaffolds did not favor the bone regeneration. Moreover, the cross-linked gelatin scaffold retarded the bone resorption as indicated by the higher levels of IFN-γ and lower levels of IL-6, which restricted the differentiation of osteoclasts.