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Bone regeneration involves multiple factors such as tissue interactions, an inflammatory response, and vessel formation. In the event of diseases, old age, lifestyle, or trauma, bone regeneration can be impaired which could result in a prolonged healing duration or requiring an external intervention for repair. Currently, bone grafts hold the golden standard for bone regeneration. However, several limitations hinder its clinical applications, e.g., donor site morbidity, an insufficient tissue volume, and uncertain post-operative outcomes. Bone tissue engineering, involving stem cells seeded onto scaffolds, has thus been a promising treatment alternative for bone regeneration. Adipose-derived mesenchymal stem cells (AD-MSCs) are known to hold therapeutic value for the treatment of various clinical conditions and have displayed feasibility and significant effectiveness due to their ease of isolation, non-invasive, abundance in quantity, and osteogenic capacity. Notably, in vitro studies showed AD-MSCs holding a high proliferation capacity, multi-differentiation potential through the release of a variety of factors, and extracellular vesicles, allowing them to repair damaged tissues. In vivo and clinical studies showed AD-MSCs favoring better vascularization and the integration of the scaffolds, while the presence of scaffolds has enhanced the osteogenesis potential of AD-MSCs, thus yielding optimal bone formation outcomes. Effective bone regeneration requires the interplay of both AD-MSCs and scaffolds (material, pore size) to improve the osteogenic and vasculogenic capacity. This review presents the advances and applications of AD-MSCs for bone regeneration and bone tissue engineering, focusing on the in vitro, in vivo, and clinical studies involving AD-MSCs for bone tissue engineering.
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Tecido Adiposo , Regeneração Óssea , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Osteogênese , Engenharia Tecidual , Alicerces Teciduais , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Tecido Adiposo/citologia , Animais , Transplante de Células-Tronco Mesenquimais/métodos , Engenharia Tecidual/métodos , Alicerces Teciduais/química , Diferenciação CelularRESUMO
OBJECTIVES: The aim of this study was to present key findings from the 2019 national adult oral health survey in Singapore (NAOHS). METHODS: A multi-stage stratified sampling method was used to recruit participants for a representative national adult oral health survey. A total of 12 212 households were randomly selected from the National Database on Dwellings in Singapore. Within each household eligible persons aged ≥65 years were automatically invited to participate while a Kish selection method was used to invite those between 21 and 64 years old. The survey comprised a face-to-face interview questionnaire and a clinical examination which recorded details of tooth loss, DMFT, DMFS and prevalence of periodontal disease according to the CPITN and the US CDC-AAP classifications. Weighted analysis was performed to adjust for oversampling, non-response and post-stratification. Multivariate regression with backward stepwise selection was carried out to identify predictors of chronic periodontal disease and untreated dental caries. RESULTS: Six hundred and sixty-three participants completed both the questionnaires and the clinical examination. The prevalence of edentulousness was 2.7%. Of participants, 34.8% presented with untreated dental caries with a higher proportion found in those who were aged ≥60 years, of Malay ethnicity, living in 1-2-room public housing and who only visited the dentist when there was a problem. Mean DMFS and DMFT indices were 24.7 and 7.9 respectively. Based on the CDC-AAP classification, the prevalence of moderate-severe chronic periodontitis was 56.9% and increased with age, with a higher proportion in males. Participants with untreated dental caries were more likely to have moderate or severe periodontal disease. CONCLUSIONS: Survey findings showed high prevalence of dental caries and periodontal disease, at 34.8% and 77.6% respectively. A clear socio-economic gradient in the distribution of tooth loss, untreated dental caries and moderate-to-severe periodontitis was observed.
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Cárie Dentária , Inquéritos de Saúde Bucal , Humanos , Singapura/epidemiologia , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Prevalência , Cárie Dentária/epidemiologia , Adulto , Doenças Periodontais/epidemiologia , Adulto Jovem , Índice CPO , Perda de Dente/epidemiologia , Saúde Bucal/estatística & dados numéricosRESUMO
OBJECTIVES: Prevention complements the curative management of oral diseases. Effective preventive interventions involve the adoption of oral health promoting behaviours. Little is known about the awareness of oral disease and its prevention among Singaporean adults as well as their prevailing oral health attitudes and behaviours. The aim of the study was to describe the oral health knowledge, attitudes and behaviours of adults in Singapore. METHODS: A random sample of adults (≥21 years old) in Singapore was selected to complete an interviewer-administered questionnaire. The questionnaire gathered information about their knowledge of the aetiology, signs and symptoms as well as prevention of dental caries and periodontal disease; attitudes about the value of teeth, locus of control in maintaining oral health and oral health behaviours including toothbrushing, flossing and dental attendance. RESULTS: A total of 1196 adults of weighted mean age 48 years old with almost equal proportions of males and females responded to the questionnaire. Participants were more unaware about the causes of periodontal disease (25.7%) than dental caries (4%). While more than 90% of participants felt that healthy teeth were important and could affect their overall health, many (67.0%) felt it was natural to lose their teeth with old age. Among the participants, 83.5% brushed their teeth twice a day; 41.9% flossed their teeth and 53.9% visited the dentist at least once a year. CONCLUSIONS: The study findings showed good knowledge around dental caries but some gaps around periodontal disease. It also found that participants perceived having limited control over preventing tooth loss. Irregular dental attendance and poor denture wearing habits were also noted. The findings shed light on key areas to focus on through oral health promotion to improve overall oral health.
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Comportamentos Relacionados com a Saúde , Conhecimentos, Atitudes e Prática em Saúde , Saúde Bucal , Humanos , Singapura/epidemiologia , Masculino , Feminino , Pessoa de Meia-Idade , Adulto , Saúde Bucal/estatística & dados numéricos , Idoso , Doenças Periodontais/epidemiologia , Doenças Periodontais/prevenção & controle , Inquéritos e Questionários , Cárie Dentária/epidemiologia , Cárie Dentária/prevenção & controle , Inquéritos de Saúde Bucal , Adulto Jovem , Escovação Dentária/estatística & dados numéricos , Assistência Odontológica/estatística & dados numéricosRESUMO
Dental restorations are in increasing demand, yet their success rate strongly decreases after 5-10 years post-implantation, attributed in part to mismatching properties with the surrounding buccal environment that causes failures and wear. Among current research to address this issue, biomimetic approaches are promising. Nacre-like ceramic composites are particularly interesting because they combine multiple antagonistic properties making them more resistant to failure in harsh environment than other materials. With the rapid progress in 3D printing producing nacre-like structures has open up new opportunities not yet realised. In this paper, nacre-like composites of various compositions are reviewed in the context of hypothetical biomimetic dental restorations. Their structural, functional and biological properties are compared with those of dentin, enamel, and bone to determine which composition would be the most suitable for each of the 3 mineralized regions found in teeth. The role of complex microstructures and mineral orientations are discussed as well as 3D printing methods that allow the design and fabrication of such complex architectures. Finally, usage of these processes and anticipated prospects for next generation biomimetic dental replacements are discussed to suggest future research directions in this area. STATEMENT OF SIGNIFICANCE: With the current ageing population, dental health is a major issue and current dental restorations still have shortcomings. For the next generation of dental restorations, more biomimetic approaches would be desirable to increase their durability. Among current materials, nacre-like ceramic composites are interesting because they can approach the various structural properties found in the different parts of our teeth. Furthermore, it is also possible to embed self-sensing functionalities to enable monitoring of oral health. Finally, new recent 3D printing technologies now permit the fabrication of complex shapes with local compositions and local microstructures. With this current status of the research, we anticipate new dental restorations designs and highlight the remaining gaps and issues to address.
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Nácar , Impressão Tridimensional , Cerâmica/química , Biomimética , MineraisRESUMO
Alveolar ridge augmentation is an important dental procedure to increase the volume of bone tissue in the alveolar ridge before the installation of a dental implant. To meet the high demand for bone grafts for alveolar ridge augmentation and to overcome the limitations of autogenous bone, allografts, and xenografts, researchers are developing bone grafts from synthetic materials using novel fabrication techniques such as 3D printing. To improve the clinical performance of synthetic bone grafts, stem cells with osteogenic differentiation capability can be loaded into the grafts. In this pilot study, we propose a novel bone graft which combines a 3D-printed polycaprolactone-tricalcium phosphate (PCL-TCP) scaffold with adipose-derived mesenchymal stem cells (AD-MSCs) that can be harvested, processed and implanted within the alveolar ridge augmentation surgery. We evaluated the novel bone graft in a porcine lateral alveolar defect model. Radiographic analysis revealed that the addition of AD-MSCs to the PCL-TCP scaffold improved the bone volume in the defect from 18.6% to 28.7% after 3 months of healing. Histological analysis showed the presence of AD-MSCs in the PCL-TCP scaffold led to better formation of new bone and less likelihood of fibrous encapsulation of the scaffold. Our pilot study demonstrated that the loading of AD-MSCs improved the bone regeneration capability of PCL-TCP scaffolds, and our novel bone graft is suitable for alveolar ridge augmentation.
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OBJECTIVE: The asymmetric mandible presents the clinician with unique anatomic challenges in orthognathic surgery correction. This study aims to investigate these characteristics of the asymmetric mandible: mandible bone thickness, soft tissue thickness, and the proximity of the bone cortex to the inferior alveolar nerve (IAN) canal. STUDY DESIGN: Three-dimensional virtual models were created of 35 participants of Asian descent with mandibular asymmetry. Mandibular bone thicknesses and soft tissue thicknesses were measured at certain landmarks. Statistical analysis of the thicknesses of both sides of the mandible was performed. Comparison of thicknesses between patients with minor and major asymmetry were also performed. RESULTS: The bone was significantly thinner at the longer side at all 4 mandible landmarks (P < .001). The bone lateral to the IAN was significantly thinner at the longer side, as well (P < .001). The soft tissue thickness did not differ significantly across sides, except at 1 landmark. These findings were even more exaggerated in the major asymmetry group. CONCLUSIONS: The longer side of the asymmetric mandible bone was thinner, and the bone lateral to the IAN was also thinner as a result. This asymmetric thinness was exaggerated in patients with severe asymmetry, which may predispose the longer side to IAN injury and unfavorable fractures. The differences in bone thickness in the asymmetric mandible may also result in residual postoperative asymmetry.
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Assimetria Facial , Má Oclusão Classe III de Angle , Cirurgia Ortognática , Humanos , Mandíbula/anatomia & histologia , Imageamento TridimensionalRESUMO
Tooth loss greatly affects a person's quality of life and many turn to dental implants to replace lost teeth. The success of a dental implant depends on the amount of alveolar bone supporting the implant, and thus, bone augmentation is often necessary to preserve or build up bone volume in the alveolar ridge. Bone can be augmented with autogenous bone, allografts, or xenografts, but the limitations of such natural bone grafts prompt researchers to develop synthetic scaffolds supplemented with cells and/or bioactive agents as alternative bone grafts. The translation of these combination scaffolds from the laboratory to the clinic requires reliable experimental models that can simulate the clinical conditions in human patients. In this article, we describe the use of a porcine alveolar defect model as a platform to evaluate the efficacy of a novel combination of a three-dimensional-printed polycaprolactone-tricalcium phosphate (PCL-TCP) scaffold and adipose-derived mesenchymal stem cells (AD-MSCs) in lateral alveolar augmentation. The surgical protocol for the defect creation and regenerative surgery, as well as analytical methods to determine the extent of tissue regeneration, are described and discussed.
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Aumento do Rebordo Alveolar , Células-Tronco Mesenquimais , Tecido Adiposo , Aumento do Rebordo Alveolar/métodos , Animais , Regeneração Óssea , Transplante Ósseo/métodos , Humanos , Qualidade de Vida , SuínosRESUMO
Additive manufacturing has proven to be a viable alternative to conventional manufacturing methodologies for metallic implants due to its capability to customize and fabricate novel and complex geometries. Specific to its use in dental applications, various groups have reported successful outcomes for customized root-analog dental implants in preclinical and clinical studies. However, geometrical accuracy of the fabricated samples has never been analyzed. In this article, we studied the geometric accuracy of a 3D printed titanium dental implant design against the tooth root of the monkey maxilla incisor. Monkey maxillas were scanned using cone-beam computed tomography, then segmentation of the incisor tooth roots was performed before the fabrication of titanium dental implants using a laser powder bed fusion (PBF) process. Our results showed 68.70% ± 5.63 accuracy of the 3D printed dental implant compared to the actual tooth (n = 8), where main regions of inaccuracies were found at the tooth apex. The laser PBF fabrication process of the dental implants showed a relatively high level of accuracy of 90.59% ± 4.75 accuracy (n = 8). Our eventual goal is to develop an accurate workflow methodology to support the fabrication of patient-specific 3D-printed titanium dental implants that mimic patients' tooth anatomy and fit precisely within the socket upon tooth extraction. This is essential for promoting primary stability and osseointegration of dental implants in the longer term.
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Reconstruction of bone due to surgical removal or disease-related bony defects is a clinical challenge. It is known that the immune system exerts positive immunomodulatory effects on tissue repair and regeneration. In this study, we evaluated the in vivo efficacy of autologous neutrophils on bone regeneration using a rabbit calvarial defect model. Methods: Twelve rabbits, each with two surgically created calvarial bone defects (10 mm diameter), were randomly divided into two groups; (i) single application of neutrophils (SA-NP) vs. SA-NP control, and (ii) repetitive application of neutrophils (RA-NP) vs. RA-NP control. The animals were euthanized at 4 and 8 weeks post-operatively and the treatment outcomes were evaluated by micro-computed tomography, histology, and histomorphometric analyses. Results: The micro-CT analysis showed a significantly higher bone volume fraction (bone volume/total volume) in the neutrophil-treated groups, i.e., median interquartile range (IQR) SA-NP (18) and RA-NP (24), compared with the untreated controls, i.e., SA-NP (7) and RA-NP (14) at 4 weeks (p < 0.05). Similarly, new bone area fraction (bone area/total area) was significantly higher in neutrophil-treated groups at 4 weeks (p < 0.05). Both SA-NP and RA-NP had a considerably higher bone volume and bone area at 8 weeks, although the difference was not statistically significant. In addition, immunohistochemical analysis at 8 weeks revealed a higher expression of osteocalcin in both SA-NP and RA-NP groups. Conclusions: The present study provides first hand evidence that autologous neutrophils may have a positive effect on promoting new bone formation. Future studies should be performed with a larger sample size in non-human primate models. If proven feasible, this new promising strategy could bring clinical benefits for bone defects to the field of oral and maxillofacial surgery.
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Regeneração Óssea , Neutrófilos/metabolismo , Crânio/fisiologia , Animais , Doenças Ósseas/terapia , Modelos Animais de Doenças , Masculino , Neutrófilos/transplante , Osteocalcina/metabolismo , Coelhos , Crânio/diagnóstico por imagem , Crânio/patologia , Microtomografia por Raio-XRESUMO
PURPOSE: One of the key approaches to minimize the risk of COVID-19 transmission would be to reduce the titres of SARS-CoV-2 in the saliva of infected COVID-19 patients. This is particularly important in high-risk procedures like dental treatment. The present randomized control trial evaluated the efficacy of three commercial mouth-rinse viz. povidone-iodine (PI), chlorhexidine gluconate (CHX) and cetylpyridinium chloride (CPC), in reducing the salivary SARS-CoV-2 viral load in COVID-19 patients compared with water. METHODS: A total of 36 SARS-CoV-2-positive patients were recruited, of which 16 patients were randomly assigned to four groups-PI group (n = 4), CHX group (n = 6), CPC group (n = 4) and water as control group (n = 2). Saliva samples were collected from all patients at baseline and at 5 min, 3 h and 6 h post-application of mouth-rinses/water. The samples were subjected to SARS-CoV-2 RT-PCR analysis. RESULTS: Comparison of salivary Ct values of patients within each group of PI, CHX, CPC and water at 5 min, 3 h and 6 h time points did not show any significant differences. However, when the Ct value fold change of each of the mouth-rinse group patients were compared with the fold change of water group patients at the respective time points, a significant increase was observed in the CPC group patients at 5 min and 6 h and in the PI group patients at 6 h. CONCLUSION: The effect of decreasing salivary load with CPC and PI mouth-rinsing was observed to be sustained at 6 h time point. Within the limitation of the current study, as number of the samples analyzed, the use of CPC and PI formulated that commercial mouth-rinses may be useful as a pre-procedural rinse to help reduce the transmission of COVID-19. ISRCTN (ISRCTN95933274), 09/09/20, retrospectively registered.
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Anti-Infecciosos Locais/uso terapêutico , Tratamento Farmacológico da COVID-19 , Antissépticos Bucais/uso terapêutico , SARS-CoV-2/efeitos dos fármacos , Saliva/virologia , Carga Viral/efeitos dos fármacos , Adulto , COVID-19/prevenção & controle , COVID-19/transmissão , COVID-19/virologia , Cetilpiridínio/análise , Cetilpiridínio/uso terapêutico , Clorexidina/análogos & derivados , Clorexidina/análise , Clorexidina/uso terapêutico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Antissépticos Bucais/química , Povidona-Iodo/análise , Povidona-Iodo/uso terapêutico , Singapura , Resultado do Tratamento , Adulto JovemRESUMO
The emergence of the highly infectious novel coronavirus SARS-CoV-2 has led to a global COVID-19 pandemic. Since the outbreak of COVID-19, worldwide healthcare systems have been severely challenged. The rapid and explosive surge of positive cases has significantly increased the demand for medical care. Herein we provide a perspective on the role dentists can play in voluntary medical assistance and future preparedness for a similar pandemic. Though dentists and physicians have different scopes of practice, their trainings share many similarities. Hence, dental professionals, with their knowledge of basic human science and sterile surgical techniques, are an invaluable resource in the COVID-19 pandemic response. Overall, it is commendable that many dentists have risen to the challenge in the fight against COVID-19. For example, in Singapore, National Dental Centre Singapore (NDCS) deployed dental clinicians as well as volunteers from research laboratories to screen for suspected cases, provide consultations as well as conduct swabbing operations. Dental practice will be considerably changed in the post-COVID-19 era. There is a greater need to have refresher courses for practicing dentists on new infection control strategies. Moreover, the curriculum in dental schools should be expanded to include competencies in pandemic and disaster relief. In addition, voluntary medical work should be made a part of the community dentistry curriculum. This volunteerism will leave a positive impact on developing the careers of young dentists. Hence, the contribution of dentists beyond dental practice in this pandemic situation will be appreciated by future generations.
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Decellularized bovine and porcine tissues have been used as scaffolds to support tissue regeneration but inherit religious restrictions and risks of disease transmission to humans. Decellularized marine tissues are seen as attractive alternatives due to their similarity to mammalian tissues, reduced biological risks, and less religious restrictions. The aim of this study was to derive an acellular scaffold from the skin of tilapia and evaluate its suitability as a tissue engineering scaffold. Tilapia skin was treated with a series of chemical and enzymatic treatments to remove cellular materials. The decellularized tilapia skin (DTS) was then characterized and evaluated in vitro and in vivo to assess its biological compatibility. The results indicated that the decellularization process removed 99.6% of the DNA content from tilapia skin. The resultant DTS was shown to possess a high denaturation temperature of 68.1 ± 1.0°C and a high Young's modulus of 56.2 ± 14.4 MPa. The properties of DTS were also compared against those of crosslinked electrospun tilapia collagen membrane, another form of tilapia-derived collagen scaffold. In vitro studies revealed that both DTS and crosslinked electrospun tilapia collagen promoted cellular metabolic activity, differentiation, and mineralization of murine preosteogenic MC3T3-E1 cells. The rat calvarial defect model was used to evaluate the in vivo performance of the scaffolds, and both scaffolds did not induce hyperacute rejections. Furthermore, they enhanced bone regeneration in the critical defect compared with the sham control. This study suggests that tilapia-derived scaffolds have great potential in tissue engineering applications.
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Pele/citologia , Tilápia/anatomia & histologia , Engenharia Tecidual/métodos , Alicerces Teciduais/química , Animais , Linhagem Celular , Colágeno/metabolismo , DNA/metabolismo , Módulo de Elasticidade , Camundongos , Crânio/patologia , Resistência à TraçãoRESUMO
IMPACT STATEMENT: Cells need a home to proliferate and remodel; biomimicry of the microarchitecture and microenvironment is important, and with 10 years of history in more than 20,000 clinical applications of 3D printed medical grade polycaprolactone scaffolds, we present the lessons learnt and project the future.
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Regeneração Óssea/fisiologia , Poliésteres/química , Impressão Tridimensional , Alicerces Teciduais/química , Animais , Humanos , Neovascularização Fisiológica , OsteogêneseRESUMO
Corneal opacities are a leading cause of global blindness. They are conventionally treated by the transplantation of donor corneal tissue, which is, restricted by a worldwide donor material shortage and allograft rejection. Autologous adult stem cells with a potential to differentiate into corneal stromal keratocytes (CSKs) could offer a suitable choice of cells for regenerative cell therapy. Postnatal periodontal ligament (PDL) contains a population of adult stem cells, which has a similar embryological origin as CSK, that is cranial neural crest. We harvested PDL cells from young adult teeth extracted because of non-functional or orthodontic reason and differentiated them towards CSK phenotype using a two-step protocol with spheroid formation followed by growth factor and cytokine induction in a stromal environment (human amnion stroma and porcine corneal stroma). Our results showed that the PDL-differentiated CSK-like cells expressed CSK markers (CD34, ALDH3A1, keratocan, lumican, CHST6, B3GNT7 and Col8A2) and had minimal expression of genes related to fibrosis and other lineages (vasculogenesis, adipogenesis, myogenesis, epitheliogenesis, neurogenesis and hematogenesis). Introduction of PDL spheroids into the stroma of porcine corneas resulted in extensive migration of cells inside the host stroma after 14-day organ culture. Their quiescent nature and uniform cell distribution resembled to that of mature CSKs inside the native stroma. Our results demonstrated the potential translation of PDL cells for regenerative corneal cell therapy for corneal opacities.
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Células-Tronco Adultas/transplante , Doenças da Córnea/terapia , Ligamento Periodontal/transplante , Medicina Regenerativa , Células-Tronco Adultas/citologia , Animais , Diferenciação Celular/genética , Linhagem da Célula/genética , Movimento Celular/genética , Córnea/crescimento & desenvolvimento , Córnea/patologia , Ceratócitos da Córnea/citologia , Humanos , Crista Neural/citologia , Crista Neural/transplante , Ligamento Periodontal/citologia , SuínosRESUMO
Repair and regeneration of critical-sized bone defects remain a major challenge in orthopaedic and craniomaxillofacial surgery. Until now, attempts to bioengineer bone tissue have been hindered by the inability to establish proper angiogenesis and osteogenesis in the tissue construct. In the present study, we established a novel triple cell co-culture model consisting of osteoblasts, endothelial cells, and neutrophils and conducted a systematic investigation of the effects of neutrophils on angiogenesis and osteogenesis. Neutrophils significantly increased angiogenesis in the tissue construct, evidenced by the formation of microvessel-like structures with an extensive lattice-like, stable tubular network in the co-culture model. Moreover, neutrophils significantly induced the expression of pro-angiogenic markers, such as VEGF-A, CD34, EGF, and FGF-2 in a dose- and time-dependent manner. Subsequently, PCR arrays corroborated that neutrophils upregulate the important angiogenic markers and MMPs. Moreover, neutrophils also enhanced osteogenic markers, such as ALP, OCN, OPN, and COL-1 compared with the controls. As shown by the osteogenic gene arrays, neutrophils significantly regulated major osteogenic markers such as BMP2, BMP3, BMP4, BMP5, TGF-ß2, RUNX2, and ECM proteins. Significantly higher mineralization was observed in triple cell co-culture compared with controls. Foregoing data indicate that the triple cell co-culture model can be used to stimulate the growth of microvasculature within a bone bioengineering construct to improve cell viability. Neutrophil-mediated enhancement of angiogenesis and osteogenesis could be a viable, clinically relevant tissue engineering strategy to obtain optimal bone growth in defect sites, in the field of oral and maxillofacial surgery.
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Técnicas de Cocultura/métodos , Células Endoteliais da Veia Umbilical Humana/citologia , Neovascularização Fisiológica , Neutrófilos/citologia , Osteoblastos/citologia , Osteogênese , Adulto , Biomarcadores/metabolismo , Matriz Óssea/metabolismo , Calcificação Fisiológica , Forma Celular , Feminino , Regulação da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Neovascularização Fisiológica/genética , Neutrófilos/metabolismo , Osteogênese/genética , Fatores de Tempo , Migração Transendotelial e Transepitelial , Fator A de Crescimento do Endotélio Vascular/metabolismo , Adulto JovemRESUMO
Recombinant human bone morphogenetic protein (BMP)-2 is an FDA-approved therapy for nonunion tibia fracture, though it has a number of biological and practical disadvantages. Our research group has developed a novel tissue engineering strategy termed antibody-mediated osseous regeneration. This entails application of anti-BMP-2 monoclonal antibodies (mAbs) to capture endogenous BMP's to mediate in vivo bone formation. This has been documented in a number of animal models. The present exploratory study sought to investigate the application of antibody-mediated osseous regeneration for repair of nonunion tibia defect in a nonhuman primate model. A 20 mm segmental osteotomy was performed in tibia of 6 Macaca fascicularis and was implanted with absorbable collagen sponge that was functionalized with chimeric anti-BMP-2 or isotype matched control mAb. Cone beam computed tomography (CBCT), histologic and histomorphometric analyses were performed 12 weeks post-operatively. CBCT analyzed by quantitative 3D volumetric analysis revealed that sites implanted with absorbable collagen sponge functionalized with anti-BMP-2 mAb demonstrated numerically higher mineralized tissue (408 ± 127 mm3) compared with sites implanted with isotype matched control mAb (214 ± 81 mm3), though the difference was not statistically significant ( p = 0.09). Histologic and histomorphometric analysis showed de novo bone formation with greater ( p < 0.01) percentage of bone volume in sites implanted with anti-BMP-2 (41.3 ± 4.4%), compared with isotype matched control mAb (14.6 ± 5.6%). Results from the present exploratory study provide evidence for the potential of anti-BMP-2 mAb to mediate repair of a large segmental tibia defects in a nonhuman primate model. Therapeutic antibodies have generally been shown to have great safety and efficacy profile, though their application in tissue engineering has been limited in the past. Following further investigation, anti-BMP-2 mAbs immobilized on appropriate scaffold may have application in repair of large skeletal defects without the need for exogenous growth factors.
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Anticorpos Monoclonais/farmacologia , Proteína Morfogenética Óssea 2/imunologia , Colágeno/química , Tíbia/fisiopatologia , Fator de Crescimento Transformador beta/imunologia , Animais , Regeneração Óssea , Humanos , Macaca , Masculino , Osteogênese , Proteínas Recombinantes/imunologia , Alicerces TeciduaisRESUMO
Antibody-mediated osseous regeneration (AMOR) has been introduced by our research group as a tissue engineering approach to capture of endogenous growth factors through the application of specific monoclonal antibodies (mAbs) immobilized on a scaffold. Specifically, anti-Bone Morphogenetic Protein- (BMP-) 2 mAbs have been demonstrated to be efficacious in mediating bone repair in a number of bone defects. The present study sought to investigate the application of AMOR for repair of mandibular continuity defect in nonhuman primates. Critical-sized mandibular continuity defects were created in Macaca fascicularis locally implanted with absorbable collagen sponges (ACS) functionalized with chimeric anti-BMP-2 mAb or isotype control mAb. 2D and 3D analysis of cone beam computed tomography (CBCT) imaging demonstrated increased bone density and volume observed within mandibular continuity defects implanted with collagen scaffolds functionalized with anti-BMP-2 mAb, compared with isotype-matched control mAb. Both CBCT imaging and histologic examination demonstrated de novo bone formation that was in direct apposition to the margins of the resected bone. It is hypothesized that bone injury may be necessary for AMOR. This is evidenced by de novo bone formation adjacent to resected bone margins, which may be the source of endogenous BMPs captured by anti-BMP-2 mAb, in turn mediating bone repair.
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Anticorpos Monoclonais/uso terapêutico , Proteína Morfogenética Óssea 2/imunologia , Mandíbula/crescimento & desenvolvimento , Doenças Mandibulares/terapia , Engenharia Tecidual , Animais , Anticorpos Monoclonais/imunologia , Proteína Morfogenética Óssea 2/uso terapêutico , Regeneração Óssea/efeitos dos fármacos , Regeneração Óssea/genética , Colágeno/uso terapêutico , Modelos Animais de Doenças , Humanos , Macaca fascicularis , Mandíbula/efeitos dos fármacos , Mandíbula/patologia , Doenças Mandibulares/fisiopatologia , Osteogênese/efeitos dos fármacos , Osteogênese/genética , Alicerces Teciduais , CicatrizaçãoRESUMO
Collagen has been used extensively in tissue engineering applications. However, the source of collagen has been primarily bovine and porcine. In view of the potential risk of zoonotic diseases and religious constraints associated with bovine and porcine collagen, fish collagen was examined as an alternative. The aim of this study is to use tilapia fish collagen to develop a cross-linked electrospun membrane to be used as a barrier membrane in guided bone regeneration. As there is limited data available on the cytotoxicity and immunogenicity of cross-linked tilapia collagen, in vitro and in vivo tests were performed to evaluate this in comparison to the commercially available Bio-Gide® membrane. In this study, collagen was extracted and purified from tilapia skin and electrospun into a nanofibrous membrane. The resultant membrane was cross-linked to obtain a cross-linked electrospun tilapia collagen (CETC) membrane, which was characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), degradation studies, cytotoxicity studies, and cell proliferation studies. The membranes were also implanted subcutaneously in rats and the host immune responses were examined. The DSC data showed that cross-linking increased the denaturation temperature of tilapia collagen to 58.3°C ± 1.4°C. The in vitro tests showed that CETC exhibited no cytotoxicity toward murine fibroblast L929 cells, and culture of murine preosteoblast MC3T3-E1 cells demonstrated better proliferation on CETC as compared to Bio-Gide. When implanted in rats, CETC caused a higher production of interleukin IL-6 at early time points as compared to Bio-Gide, but there was no long-term inflammatory responses after the acute inflammation phase. This finding was supported with histology data, which clearly illustrated that CETC has a decreased inflammatory response comparable to the benchmark control group. In all, this study demonstrated the viability for the use of CETC as a tissue engineering scaffold and provides an insight on the in vivo immune responses toward xenogenic collagen scaffolds.
Assuntos
Colágeno/farmacologia , Reagentes de Ligações Cruzadas/farmacologia , Membranas Artificiais , Tilápia/metabolismo , Engenharia Tecidual/métodos , Animais , Adesão Celular/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Citocinas/metabolismo , Módulo de Elasticidade , Implantes Experimentais , Masculino , Camundongos , Osteogênese/efeitos dos fármacos , Ratos Sprague-Dawley , Tela Subcutânea/efeitos dos fármacos , Resistência à TraçãoRESUMO
The aim of the current study was to evaluate bone formation and tissue response to porous poly(methyl methacrylate) (PMMA) cement with or without hydroxyapatite (HA) in a rabbit mandibular model. Therefore, 14 New Zealand White rabbits were randomly divided into two groups of seven according to the designed study end points of 4 and 12 weeks. For each rabbit, two decorticated defects (6 mm in height and 10 mm in width for each) were prepared at both sides of the mandible. Subsequently, the defects were filled with, respectively, porous PMMA and porous PMMA-HA cement. After reaching the designated implantation period, the rabbits were euthanized and the mandibles were retrieved for histological analysis. Results showed that both porous PMMA and porous PMMA-HA supported bone repair. Neither of the bone cements caused significant inflammation to nerve or other surrounding tissues. After implantation of 12 weeks, majority of the porosity was filled with newly formed bone for both cements, which supports the concept that a porous structure within PMMA can enhance bone ingrowth. Histomorphometrical evaluation, using histological grading scales, demonstrated that, at both implantation times, the presence of HA in the PMMA enhanced bone formation. Bone was always in direct contact with the HA particles, while intervening fibrous tissue was present at the PMMA-bone interface. On the basis of results, it was concluded that injectable porous PMMA-HA cement might be a good candidate for craniofacial bone repair, which should be further evaluated in a more clinically relevant large animal model.
Assuntos
Materiais Biocompatíveis/química , Cimentos Ósseos/química , Durapatita/química , Mandíbula/citologia , Teste de Materiais , Osteogênese/fisiologia , Polimetil Metacrilato/química , Animais , Masculino , Modelos Animais , Porosidade , CoelhosRESUMO
[This corrects the article DOI: 10.1155/2017/8094152.].