Fragmented adipose tissue graft for bone healing: histological and histometric study in rabbits' calvaria

Comparison of the Effect of Platelet-rich Plasma (PRP) and Fat Graft on Autologous Bone Grafting in a Randomized-controlled Experimental Skull Model

Gold standard method for the treatment of critical-sized bone defects is the autogenous bone grafting procedure. A number of new and potentially useful adjuncts currently are being investigated to enhance the success of bone grafting. We propose to evaluate the effect of the most known and easily obtained 2 biological materials, fat graft and platelet-rich plasma (PRP), on bone graft healing. Twenty-seven New Zealand male rabbits were included in this randomized, controlled study. Two-sided 15-mm diameter bone defects were created in the parietal bones and the bones taken were replaced right-to-left and vice versa with 1 control group, 1 fat graft applied group, and the last one PRP applied group. Histologic evaluation and 3-dimensional maxillofacial computerized tomography were performed and bone density was calculated. In radiologic analysis, bone density was significantly different in the PRP group compared with the control and fat graft group in the 12th week ( P <0.05). In histologic scoring analysis, the PRP group had a better score than the control and fat graft group, while the fat graft group was worse than the control group in the 6th week ( P <0.05). The addition of PRP had a positive effect whereas fat graft had a negative effect on bone graft healing compared with the control group.

Rabbit calvarial and mandibular critical-sized bone defects as an experimental model for the evaluation of craniofacial bone tissue regeneration

INTRODUCTION

Many studies have aimed to investigate the regeneration potential of bone substitutes through animal models at different defect sites, where the bone healing mechanism varies due to developmental, structural and functional differences. This study aims to develop a rabbit model with two functionally different (non-load-bearing calvarias and load-bearing mandibular) critical-sized defects (CSD) in one rabbit.

MATERIAL & METHOD

The comparison of the "gold standard" autograft to a sham (no graft) control was undertaken in order to validate this model; at the same time, a 3D-printed biphasic calcium phosphate scaffold was implanted to test its utility in the evaluation of new bone substitute materials. Twenty rabbits were selected with both a 10 mm calvaria defect and a 11 mm bicortical semi-cylindrical mandibular defect. The animals were euthanized at 4 and 12 weeks once surgery, microcomputed tomography and histological analysis had been performed.

RESULTS

In the case of the calvaria, the results for the non-healing sham group compared with the healing of those that had undergone the autograft validated the CSD model. But the mandibular defect was not validated, due to the particularity of mandible high mechanical stress and infectious risk.

DISCUSSION

This study showed for the first time that rabbits have a high tolerance for the bilateral double-site CSD model under consideration; and further studies are essential to modify and improve the design of mandibular CSD.

Buccal fat pad as a sealant in palatal mucosa tearing: technical note

For patients with a dentofacial deformity undergoing a planned segmentation of the maxilla for the management of a transverse maxillary arch discrepancy, palatal mucosa tearing may occur during sawing or palatal expansion traction, giving rise to an oronasal communication. This technical note describes the covering of a tear in the palatal mucosa using a buccal fat pad (BFP) flap, in the context of maxillary segmentation during Le Fort I osteotomy. Through the limited buccal incision used for the Le Fort I osteotomy, a small incision is made in the right periosteum posteriorly, and a supraperiosteal dissection is performed to access the BFP. After a sufficient amount of flap is made available, it is gently introduced through the osteotomy gap until it reaches the palatal mucosa defect and is then sutured. In the patient case presented, the palatal mucosa healed fully within 18 days, and the patient reported no nasal regurgitation of food, defective speech, fetid odour, bad taste, or upper respiratory tract or ear infection during the postoperative period. This technique using a BFP flap should therefore be considered in the context of unexpected tearing of the palatal mucosa in patients undergoing a segmented Le Fort I osteotomy.

Adipose tissue in bone regeneration - stem cell source and beyond

Adipose tissue (AT) is recognized as a complex organ involved in major home-ostatic body functions, such as food intake, energy balance, immunomodulation, development and growth, and functioning of the reproductive organs. The role of AT in tissue and organ homeostasis, repair and regeneration is increasingly recognized. Different AT compartments (white AT, brown AT and bone marrow AT) and their interrelation with bone metabolism will be presented. AT-derived stem cell populations - adipose-derived mesenchymal stem cells and pluripotent-like stem cells. Multilineage differentiating stress-enduring and dedifferentiated fat cells can be obtained in relatively high quantities compared to other sources. Their role in different strategies of bone and fracture healing tissue engineering and cell therapy will be described. The current use of AT- or AT-derived stem cell populations for fracture healing and bone regenerative strategies will be presented, as well as major challenges in furthering bone regenerative strategies to clinical settings.

Comparative Evaluation of Bone Repair with Four Different Bone Substitutes in Critical Size Defects

This study evaluated the osteoconductive potential of four biomaterials used to fill bone defects. For this, 24 male Albino rabbits were submitted to the creation of a bilateral 8 mm calvarial bone defect. The animals were divided into four groups-bovine hydroxyapatite, Bio-Oss® (BIO); Lumina-Bone Porous® (LBP); Bonefill® (BFL); and an alloplastic material, Clonos® (CLN)-and were euthanized at 14 and 40 days. The samples were subjected to histological and histometric analysis for newly formed bone area. Immunohistochemical analysis for Runt-related transcription factor 2 (Runx2), vascular endothelial growth factor (VEGF), and osteocalcin (OC) was performed. After statistical analysis, the CLN group showed greater new bone formation (NB) in both periods analyzed (p < 0.05). At 14 days, the NB showed greater values in BIO in relation to LBP and BFL groups; however, after 40 days, the LBP group surpassed the results of BIO (p < 0.001). The immunostaining showed a decrease in Runx2 intensity in BIO after 40 days, while it increased for LBP (p < 0.05). The CLN showed increased OC compared to the other groups in both periods analyzed (p < 0.05). Therefore, CLN showed the best osteoconductive behavior in critical defects in rabbit calvaria, and BFL showed the lowest osteoconductive property.

Copaiba oil effect on experimental jaw defect in Wistar rats

PURPOSE

To evaluate the effects of copaiba oil on jaw defects repair in Wistar rats treated with bioglass or adipose tissue.

METHODS

A jaw defect was randomly created in forty-two rats and filled with bioglass or adipose tissue. The two groups (Gbio and Gcell) were subdivided in three subgroups with seven animals each according to gavage administration: control (distillated water), oil (copaiba oil) and melox (meloxicam). Euthanasia was performed after forty post-operative days. The bone formation was analyzed regarding the histological aspects.

RESULTS

The osteoclasts activity was observed only in four subgroups (p=0.78). Regarding the osteoblasts presence, it was very similar between the subgroups, the difference was due to Gcell-melox (p=0.009) that presented less osteoblastic activity. The inflammatory cells were more evident in Gcell-melox subgroup, however, there was no difference in comparison with the other subgroups (p=0.52). Bone formation was observed in all subgroups, just two animals showed no bone formation even after 40 days. More than 50% of bone matrix mineralization was observed in 56% (23 animals) of the analyzed areas. The bone matrix mineralization was not different between subgroups (p=0.60).

CONCLUSIONS

The subgroups that received copaiba oil showed bone repair, although not statistically significant in comparison to subgroups treated with meloxicam or controls. Copaiba oil administered by gavage had no effect on bone repair in this experimental model.

Osteocalcin Immunohistochemical Expression During Repair of Critical-Sized Bone Defects Treated with Subcutaneous Adipose Tissue in Rat and Rabbit Animal Model

The aim of this study was to evaluate the osteocalcin immunoexpression during the bone repair treated with subcutaneous adipose tissue in rats and rabbits. Fourteen rats and 14 rabbits were used in the study. A critical-sized calvarial defect was created in each animal. The animals were divided into 4 experimental groups: RC (rat control), RbC (rabbit control), RAT (rat adipose tissue), RbAT (rabbit adipose tissue). In the groups RC and RbC the defect was filled with a blood clot. In groups RAT and RbAT, the defect was filled with macerated subcutaneous adipose tissue. The euthanasia was performed at 30 days (RC and RAT) and 40 days (RbC and RbAT). Histological analysis and immunohistochemical analysis of osteocalcin protein expression were performed. Data were submitted to descriptive statistical analysis (mode). Osteocalcin immunoexpression was detected in the experimental models. Notwithstanding, RbAT showed higher positivity, especially in the adipocytes, than the group RAT group. In groups RC and RbC, the surgical wound was filled by collagen fibers. In Group RAT, the defect was composed by collagen fibers and adipocytes in the reparative sites. Similarly, in RbAT, the defect also was partially filled by collagen fibers and presence of adipocytes dispersed among the fibers. Additionally, chronic inflammatory process and areas of bone matrix deposition were observed. It may be concluded that in both animal models the adipose tissue demonstrated low osteogenic capacity. However, the rabbit animal model exhibited a more evident osteocalcin immunoexpression and a greater amount of newly formed bone matrix.