Biomaterials-aided mandibular reconstruction using in vivo bioreactors.

Large mandibular defects are clinically challenging to reconstruct due to the complex anatomy of the jaw and the limited availability of appropriate tissue for repair. We envision leveraging current advances in fabrication and biomaterials to create implantable devices that generate bone within the patients themselves suitable for their own specific anatomical pathology. The in vivo bioreactor strategy facilitates the generation of large autologous vascularized bony tissue of customized geometry without the addition of exogenous growth factors or cells. To translate this technology, we investigated its success in reconstructing a mandibular defect of physiologically relevant size in sheep. We fabricated and implanted 3D-printed in vivo bioreactors against rib periosteum and utilized biomaterial-based space maintenance to preserve the native anatomical mandibular structure in the defect site before reconstruction. Nine weeks after bioreactor implantation, the ovine mandibles were repaired with the autologous bony tissue generated from the in vivo bioreactors. We evaluated tissues generated in bioreactors by radiographic, histological, mechanical, and biomolecular assays and repaired mandibles by radiographic and histological assays. Biomaterial-aided mandibular reconstruction was successful in a large superior marginal defect in five of six (83%) sheep. Given that these studies utilized clinically available biomaterials, such as bone cement and ceramic particles, this strategy is designed for rapid human translation to improve outcomes in patients with large mandibular defects.

Human Dental Pulp Stem Cells in Rat Mandibular Bone Defects.

This study aimed to evaluate the use of human dental pulp stem cells (hDPSCs) in non-critical-sized mandibular bone defects in rats. hDPSCs from permanent teeth were isolated and engrafted in mandibular bone defects in rats for 7, 14, and 28 days; bone defects without cells formed the control group. Samples were evaluated by scanning electron microscopy (SEM), light microscopy (hematoxylin and eosin staining), and the regeneration area was measured by the Image J program. Before surgery procedures, the human dental pulp cells were characterized as dental pulp stem cells: fusiform morphology, plastic-adherent; expression of CD105, CD73, and CD90; lack of expression of CD45 and CD34, and differentiated into osteoblasts, adipocytes, and chondroblasts. The results indicated that within 7 days the control group presented a pronounced bone formation when compared with the treated group (p < 0.05). After 14 days, the treated group showed an increase in bone formation, but with no statistical difference among the groups (p > 0.05). In the final evaluated period there was no difference between the control group and the treated group (p > 0.05). There was a significant difference between 7 and 14 days (p < 0.05) and between 7 and 28 days (p < 0.05) in the treated group. In conclusion, there is no evidence that the use of hDPSCs in the conditions of this study could improve bone formation in non-critical-sized mandibular bone defects.

Use of traction screw to aid in fracture reduction in bilateral parasymphysis fracture of mandible.

Treatment of bilateral parasymphysis fracture often requires special attention due to airway considerations and difficulty in achieving precise anatomic reduction. The central fracture fragment is often displaced posteriorly and inferiorly due to muscle pull, and this adds to difficulty in reduction and stabilization of the central fracture fragment during plate fixation. With this article, we advocate a technique using stainless steel screw and self-holding screwdriver to manipulate the central fragment and achieve an anatomic reduction. We have used this technique in 12 patients with bilateral parasymphysis fracture without any complications and have found it very effective.

[SOME REACTIONS OF THE REGIONAL LYMPH NODES OF RATS AFTER IMPLANTATION OF MULTIPOTENT STROMAL CELLS ADSORBED ON POLYHYDROXYALKANOATE INTO A BONE TISSUE DEFECT].

The reactions of the regional lymph nodes, caused by implantation of the autologous multipotent stromal cells of bone marrow origin (AMSCBMO) to accelerate the healing of mandibular bone defect were studied by fluorescent microscopy in inbred male Wag rats aged 6 months (n=62). After the introduction of polyhydroxyalkanoate transplant containing adsorbed AMSCBMO with a transfected Green Fluorescent Protein (GFP) gene into a damaged bone area, the lymphoid nodules in submandibular lymph nodes demonstrated the appearance of numerous large macrophages containing multiple oval fluorescent inclusions in the cytoplasm. The number of these macrophages increased within 2 weeks after surgery and then began to decline. Apparently, AMSCBMO introduced in this way, were partially absorbed by macrophages. After destruction of the structures formed from AMSCBMO, the debris was also phagocytized by macrophages. In either case, these macrophages appeared in the germinal centers of lymphoid nodules in lymph nodes, where the induction of immune responses against DNA and GFP protein was probable.

Regeneration of red bone marrow in rat lower jaw after transplantation of mesenchymal stem cells into the site of injury.

Regeneration processes in rat mandibular bone after transplantation of a suspension of autologous BM MSC in culture medium were studied by methods of light microscopy and X-ray densitometry. It was found that the structures of red BM in the callus after transplantation of autologous BM MSC formed earlier than in natural reparation. The formation of cavities containing BM determines lower tissue density at the site of injury after transplantation of autologous BM MSC on weeks 4 and 5 of observation than during spontaneous healing. These changes progressed throughout the observation period and attested to accelerated bone tissue reparation.

Bioplasty for vertebral fractures: preliminary results of a pre-clinical study on goats using autologous modified skin fibroblasts.

The debate is still ongoing about the long term effects of the mininvasive vertebral augmentation techniques and their usefulness in treating more complex cases where a bone inducing effect more than a merely bone substitution would be suitable, such as the vertebral fractures in young patients. We previously developed a clinically relevant gene therapy approach using modified dermal fibroblasts for inducing bone healing and bone formation in different animal models. The aim of this study is to show the feasibility of a minimally invasive percutaneous intrasomatic ex vivo gene therapy approach to treat thoracolumbar vertebral fractures and anterior column bone defects in a goat model.

[Regeneration of the damaged mandibular bone in rat after the injection of autologous mesenchymal stem cells of bone marrow origin adsorbed on the fibrin clot].

The processes of the repair of the damaged mandibular bone in rats were studied using light microscopy and x-ray densitometry at various time intervals after the local injection of the platelet-rich fibrin clot (PRFC), autologous mesenchymal (stromal) stem cells of bone marrow origin (AMSCBMO) or AMSCBMO, adsorbed on PRFC, into the damaged site. The best results were obtained after the application of PRFC with AMSCBMO. One week after the operation, the mandibular bone defect was largely filled with the newly formed bone tissue. It seems most probable that in this case the effects of fibrin and stem cells on the damaged bone were summarized or even amplified. Bone formation in these cases appeared to begin in the center, but not at the edges, of the defect. AMSCBMO were distributed over the whole volume of PRFC, filling all the defect more or less uniformly. As a result, maximally fast and successful restoration of bone tissue was reached in the area of the defect.

Comparative analysis of plasma-derived albumin scaffold, alveolar osteoblasts and synthetic membrane in critical mandibular bone defects: An experimental study on rats.

Repair of bone deficiencies in the craniofacial skeleton remains a challenging clinical problem. The aim of this study was to evaluate and compare the effects of a plasma-derived albumin scaffold, alveolar osteoblasts and synthetic membrane implanted into experimental mandibular defects. Bilateral mandibular defects were created in twelve immunodeficient rats. The bone defect was filled with serum scaffold alone in left sides and scaffold combined with human alveolar osteoblast in right side defects. Implanted areas were closed directly in Group 1 (n = 6) and covered by a resorbable polyglycolic-polylactic acid membrane in Group 2 (n = 6). Bone regeneration was determined at 12 weeks as measured by and exhaustive multiplanar computed tomography analysis and histological examination. No significant differences in bone density were observed between defects transplanted with scaffold alone or scaffold seeded with osteoblasts. The use of membrane did not result in a determining factor in the grade of bone regeneration between Groups 1 and 2. Based on these results, it could be concluded that the albumin scaffold alone has osteoinductive capacity but presence of seeded ostogenic cells accelerates defect repair without being significantly influenced by covering the defect with a resorbable membrane.

Leukocyte-platelet rich fibrin on the treatment of a large paradental cyst: a novel regenerative approach.

Leukocyte-platelet rich fibrin (PRF) is an autologous biomaterial formed by platelets, cytokines, growth factors and cells imprisoned on a fibrin mesh, produced according to Choukroun's protocol. The aim of the present article was to report the use of PRF, associated with a bone substitute, on the regenerative treatment of a large bone defect resulting from the enucleation of a paradental cyst involving the posterior mandible. The treatment resulted in the maintenance of the bone volume, and radiographic evaluation showed new bone formation after 40 days, suggesting an osteogenic and osteoinductive effect. Also, the current literature was reviewed.

An unusual case of bilateral anterior shoulder and mandible dislocations.

Unilateral anterior shoulder dislocation is the most common major joint dislocation seen by emergency physicians. Bilateral glenohumeral dislocations are rarely seen and almost always posterior after seizure or electrical shock. We present an unusual case of bilateral anterior dislocation of shoulder that had anterior dislocation of temporomandibular joint simultaneously. These problems occurred after a course of generalized tonic-clonic seizure. The coincidence of these dislocations is the first case published in the literature.

Bone regeneration of minipig mandibular defect by adipose derived mesenchymal stem cells seeded tri-calcium phosphate- poly(D,L-lactide-co-glycolide) scaffolds.

Reconstruction of bone defects represents a serious issue for orthopaedic and maxillofacial surgeons, especially in extensive bone loss. Adipose-derived mesenchymal stem cells (ADSCs) with tri-calcium phosphates (TCP) are widely used for bone regeneration facilitating the formation of bone extracellular matrix to promote reparative osteogenesis. The present study assessed the potential of cell-scaffold constructs for the regeneration of extensive mandibular bone defects in a minipig model. Sixteen skeletally mature miniature pigs were divided into two groups: Control group and scaffolds seeded with osteogenic differentiated pADSCs (n = 8/group). TCP-PLGA scaffolds with or without cells were integrated in the mandibular critical size defects and fixed by titanium osteosynthesis plates. After 12 weeks, ADSCs seeded scaffolds (n = 7) demonstrated significantly higher bone volume (34.8% ± 4.80%) than scaffolds implanted without cells (n = 6, 22.4% ± 9.85%) in the micro-CT (p < 0.05). Moreover, an increased amount of osteocalcin deposition was found in the test group in comparison to the control group (27.98 ± 2.81% vs 17.10 ± 3.57%, p < 0.001). In conclusion, ADSCs seeding on ceramic/polymer scaffolds improves bone regeneration in large mandibular defects. However, further improvement with regard to the osteogenic capacity is necessary to transfer this concept into clinical use.

Teriparatide (recombinant parathyroid hormone 1-34) enhances bone allograft integration in a clinically relevant pig model of segmental mandibulectomy.

Massive craniofacial bone loss poses a clinical challenge to maxillofacial surgeons. Structural bone allografts are readily available at tissue banks but are rarely used due to a high failure rate. Previous studies showed that intermittent administration of recombinant parathyroid hormone (rPTH) enhanced integration of allografts in a murine model of calvarial bone defect. To evaluate its translational potential, the hypothesis that rPTH would enhance healing of a mandibular allograft in a clinically relevant large animal model of mandibulectomy was tested. Porcine bone allografts were implanted into a 5-cm-long continuous mandible bone defect in six adult Yucatan minipigs, which were randomized to daily intramuscular injections of rPTH (1.75 µg/kg) and placebo (n = 3). Blood tests were performed on Day 56 preoperation, Day 0 and on Day 56 postoperation. Eight weeks after the surgery, bone healing was analyzed using high-resolution X-ray imaging (Faxitron and micro computed tomography [CT]) and three-point bending biomechanical testing. The results showed a significant 2.6-fold rPTH-induced increase in bone formation (p = 0.02). Biomechanically, the yield failure properties of the healed mandibles were significantly higher in the rPTH group (yield load: p < 0.05; energy to yield: p < 0.01), and the post-yield displacement and energy were higher in the placebo group (p < 0.05), suggesting increased mineralized integration of the allograft in the rPTH group. In contrast to similar rPTH therapy studies in dogs, no signs of hypercalcemia, hyperphosphatemia, or inflammation were detected. Taken together, we provide initial evidence that rPTH treatment enhances mandibular allograft healing in a clinically relevant large animal model.

Feline skull injuries: Treatment goals and recommended approaches.

PRACTICAL RELEVANCE: Skull trauma in cats, which includes fractures of the mandible and maxilla, as well as temporomandibular joint (TMJ) conditions, is frequently encountered in general practice. CLINICAL APPROACH: Head trauma requires immediate attention and the initial approach should be focused on stabilisation of the patient and evaluation of the major body systems, including respiratory and cardiovascular assessment, and neurological and ophthalmic examination. The head, oral occlusion and the patient's ability to open and close the mouth should be carefully evaluated. Once the cat is stable enough for anaesthesia, diagnostic imaging is essential to assess for skull injuries. Radiography may be helpful, although some conditions may be difficult to visualise due to soft tissue and bony structure superimposition. CT is a more sensitive technique for detecting skull injuries. TREATMENT GOALS AND TECHNIQUES: A variety of stabilisation techniques have been described in the feline patient, and repair goals focus on restoration of the animal's oral function, while ensuring adequate dental occlusion, minimal invasiveness and morbidity, and pain relief. Surgical repair of mandibular and maxillary fractures may variously involve interdental wiring, interarcade wiring or suture, use of interfragmentary wires, plate and screw fixation, external skeletal fixation and use of dental acrylic. Decision-making with regard to treatment options depends on dental occlusion, type and location of the fracture, fracture stability and pain. AIM: This review, directed at general practitioners working with cats, describes the relevant anatomy of the feline skull, the most common mandibular, maxillary and TMJ conditions, and their recommended management.

The effect of platelet-rich fibrin exudate addition to porous poly(lactic-co-glycolic acid) scaffold in bone healing: An in vivo study.

Bone grafting procedures have been widely utilized as the current state-of-the-art for bone regeneration, with autogenous bone graft being the gold-standard bone reconstructive option. However, the use of autografts may be limited by secondary donor-site comorbidities, a finite amount of donor supply, increased operating time, and healthcare cost impact. Synthetic materials, or alloplasts, such as the polymeric material, poly(lactic-co-glycolic acid) (PLGA) has previously been utilized as a transient scaffold to support healing of bone defects with the potential to locally delivery osteogenic additives. In this study a novel procedure was adopted to incorporate both the dissolved contents and mechanical components of leukocyte- and platelet-rich fibrin (L-PRF) into an PLGA scaffold through a two-step method: (a) extraction of the L-PRF membrane transudate with subsequent immersion of the PLGA scaffold in transudate followed by (b) delivering a fibrin gel as a low-viscosity component that subsequently polymerizes into a highly viscous, gel-like biological material within the pores of the PLGA scaffold. Two, ~0.40 cm3 , submandibular defects (n = 24) were created per side using rotary instrumentation under continuous irrigation in six sheep. Each site received a PLGA scaffold (Intra-Lock R&D, Boca Raton, FL), with one positive control (without L-PRF exudate addition [nL-PRF]), and one experimental (augmented with PLGA/L-PRF Blocks [L-PRF]). Animals were euthanized 6 weeks postoperatively and mandibles retrieved, en bloc, for histological analysis. Histomorphometric evaluation for bone regeneration was evaluated as bone area fraction occupancy (BAFO) within the region of interest of the cortical bone (with specific image analysis software) and data presented as mean values with the corresponding 95% confidence interval values. Qualitative evaluation of nondecalcified histologic sections revealed extensive bone formation for both groups, with substantially more bone regeneration for the L-PRF induced group relative nL-PRF group. Quantitative BAFO within the defect as function of the effect of L-PRF exudate on bone regeneration, demonstrated significantly (p = .018) higher values for the L-PRF group (38.26% ± 8.5%) relative to the nL-PRF group (~28% ± 4.0%). This in vivo study indicated that L-PRF exudate has an impact on the regeneration of bone when incorporated with the PLGA scaffold in a large translational model. Further studies are warranted in order to evaluate the L-PRF exudate added, as well as exploring the preparation methods, in order to facilitate bone regeneration.

Human amnion-derived mesenchymal stem cells promote osteogenic differentiation of human bone marrow mesenchymal stem cells via H19/miR-675/APC axis.

Bone volume inadequacy is an emerging clinical problem impairing the feasibility and longevity of dental implants. Human bone marrow mesenchymal stem cells (HBMSCs) have been widely used in bone remodeling and regeneration. This study examined the effect of long noncoding RNAs (lncRNAs)-H19 on the human amnion-derived mesenchymal stem cells (HAMSCs)-droved osteogenesis in HBMSCs. HAMSCs and HBMSCs were isolated from abandoned amniotic membrane samples and bone marrow. The coculture system was conducted using transwells, and H19 level was measured by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR). The mechanism was further verified. We here discovered that osteogenesis of HBMSCs was induced by HAMSCs, while H19 level in HAMSCs was increased during coculturing. H19 had no significant effect on the proliferative behaviors of HBMSCs, while its overexpression of H19 in HAMSCs led to the upregulated osteogenesis of HBMSCs in vivo and in vitro; whereas its knockdown reversed these effects. Mechanistically, H19 promoted miR-675 expression and contributed to the competitively bounding of miR-675 and Adenomatous polyposis coli (APC), thus significantly activating the Wnt/ß-catenin pathway. The results suggested that HAMSCs promote osteogenic differentiation of HBMSCs via H19/miR-675/APC pathway, and supply a potential target for the therapeutic treatment of bone-destructive diseases.

Role of multidetector row computed tomography in the management of mandible traumatic lesions.

Facial injuries are common and must be radiologically evaluated to detect fractures, to determine their morphology and topography, and to assess adjacent soft-tissue damage. Spiral multislice computed tomography is progressively replacing conventional films for mandible traumatic lesions because it reveals the multiplicity of fragments, the degree of dislocation and rotation, and the extent of skull base involvement. Computed tomography is also very useful in the evaluation of condylar fractures, to determine the best choice for surgical treatment, open or close. 3-dimensional (3D) computed tomography images can display condylar fractures, but also all mandibular fractures, accurately and directly, and are very useful for surgeons to select treating methods of condylar fractures. The demonstration by imaging of the involvement of key anatomic structures is essential to classify correctly the trauma and to select the best management.

Use of masseteric and deep temporal nerve blocks for reduction of mandibular dislocation.

A patient presented with a unilateral dislocated condyle that was resistant to reduction by simple manual manipulation because of elevator muscle spasm and severe muscle and temporomandibular joint pain. A technique involving a masseteric nerve block and a temporal nerve block was used, allowing a quick, safe, and minimally painful reduction. The method used for delivering these nerve blocks is described here.

Reconstruction of mandibular bone defects using biphasic calcium phosphate bone substitutes with simultaneous implant placement in mini-swine: A pilot in vivo study.

This study aimed to investigate implant osseointegration using a new strategy of biphasic calcium phosphate (BCP) bone substitutes with simultaneous implant placement in mandibular reconstruction. Additionally, the temporal transcriptional profile associated with the early biological processes during osseointegration was determined. BCP and hydroxyapatite (HA) bone substitutes with simultaneous implant placement were grafted into mandibular defects created in mini-swine. Radiographic, histological, and biochemical analyses were applied for evaluation of osseointegration effects at 4 months after the grafting procedure. Bone formation around the implant was assessed by the bone area percentage (BA%) and the bone-implant-contact percentage (BIC%). The biomechanical evaluation was performed by the implant pullout test and the removal torque test. Microarray technology was utilized for gene expression comparison analysis at day 14 postoperatively. Radiographic and histological observation indicated enhanced bone formation in the BCP group compared to the HA group. Histomorphometric analyses of BA% and BIC% as well as biochemical analyses of the maximal pull-out force and the ultimate shear strength were all significantly greater in the BCP group (p < 0.05). Transcriptional analysis at an early stage of osseointegration revealed that genes belonging to biological processes associated with cell proliferation, development, osteogenesis, angiogenesis, and neurogenesis as well as the osteogenesis-related TGF-ß/BMP and WNT signaling pathways were upregulated in the BCP group. In conclusion, the reconstruction of mandibular defects using BCP with simultaneous implant placement resulted in superior osseointegration effects. A number of candidate genes that were differentially expressed may contribute to the superior osseointegration effects. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2071-2079, 2019.

Quantifying Vascular Changes Surrounding Bone Regeneration in a Porcine Mandibular Defect Using Computed Tomography.

Angiogenesis is a critical process essential for optimal bone healing. Several in vitro and in vivo systems have been previously used to elucidate some of the mechanisms involved in the process of angiogenesis, and at the same time, to test potential therapeutic agents and bioactive factors that play important roles in neovascularization. Computed tomography (CT) is a noninvasive imaging technique that has recently allowed investigators to obtain a diverse range of high-resolution, three-dimensional characterization of structures, such as bone formation within bony defects. Unfortunately, to date, angiogenesis evaluation relies primarily on histology, or ex vivo imaging and few studies have utilized CT to qualitatively and quantitatively study the vascular response during bone repair. In the current study a clinical CT-based technique was used to evaluate the effects of rhBMP-2 eluting graft treatment on soft tissue vascular architecture surrounding a large segmental bone defect model in the minipig mandible. The objective of this study was to demonstrate the efficacy of contrast-enhanced, clinical 64-slice CT technology in extracting quantitative metrics of vascular architecture over a 12-week period. The results of this study show that the presence of rhBMP-2 had a positive effect on vessel volume from 4 to 12 weeks, which was explained by a concurrent increase in vessel number, which was also significantly higher at 4 weeks for the rhBMP-2 treatment. More importantly, analysis of vessel architecture showed no changes throughout the duration of the study, indicating therapeutic safety. This study validates CT analysis as a relevant imaging method for quantitative and qualitative analysis of morphological characteristics of vascular tissue around a bone healing site. Also important, the study shows that CT technology can be used in large animal models and potentially be translated into clinical models for the development of improved methods to evaluate tissue healing and vascular adaptation processes over the course of therapy. This methodology has demonstrated sensitivity to tracking spatial and temporal changes in vascularization and has the potential to be applied to studying changes in other high-contrast tissues as well. Impact Statement Tissue engineering solutions depend on the surrounding tissue response to support regeneration. The inflammatory environment and surrounding vascular supply are critical to determining if therapies will survive, engraftment occurs, and native physiology is restored. This study for the first time evaluates the blood vessel network changes in surrounding soft tissue to a bone defect site in a large animal model, using clinically available computed tomography tools and model changes in vessel number, size, and architecture. While this study focuses on rhBMP2 delivery impacting surrounding vasculature, this validated method can be extended to studying the vascular network changes in other tissues as well.

Sandwich-Like Nanofibrous Scaffolds for Bone Tissue Regeneration.

Advanced bone healing approaches included a wide range of biomaterials that mainly mimic the composition, structure, and properties of bone extracellular matrix with osteogenic activity. The present study aimed to develop a sandwich-like structure of electrospun nanofibers (NFs) based on polycaprolactone (PCL) and chitosan/polyethylene oxide (CS/PEO) composite to stimulate bone fracture healing. The morphology of the fabricated scaffolds was examined using scanning electron microscopy (SEM). Apatite deposition was evaluated using simulated body fluid (SBF). The physicochemical and mechanical properties of samples were analyzed by Fourier transform infrared, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and universal testing machine. SEM images exhibited a porous three-dimensional structure with NF diameters of 514-4745 nm and 68-786 nm for PCL NFs layer and the sandwich-like NFs scaffolds, respectively. Deposition of apatite crystal on scaffolds started at week 2 followed by heavy deposition at week 8. This was confirmed by measuring the consumption of calcium and phosphorous ions from SBF. Thermal stability of scaffolds was confirmed using DSC and TGA. Moreover, the PCL NF layer in the middle of the developed sandwich structure reinforced the scaffolds with bear load up to 12.224 ± 1.12 MPa and Young's modulus of 17.53 ± 3.24 MPa. The scaffolds' porous structure enhanced both cell propagation and proliferation. Besides, the presence of CS in the outer NF layers of the scaffolds increased the hydrophilicity, as evidenced by the reduction of contact angle from 116.6 to 57.6°, which is essential for cell attachment. Cell viability study on mesenchymal stem cells proved the cytocompatibility of the fabricated scaffolds. Finally, in vivo mandibular bone defect rabbit model was used to confirm the regeneration of a new healthy bone within 28 days. In conclusion, the developed scaffolds could be a promising solution to stimulate bone regeneration.