Advances in guided bone regeneration membranes: a comprehensive review of materials and techniques.

Guided tissue/bone regeneration (GTR/GBR) is a widely used technique in dentistry to facilitate the regeneration of damaged bone and tissue, which involves guiding materials that eventually degrade, allowing newly created tissue to take its place. This comprehensive review the evolution of biomaterials for guided bone regeneration that showcases a progressive shift from non-resorbable to highly biocompatible and bioactive materials, allowing for more effective and predictable bone regeneration. The evolution of biomaterials for guided bone regeneration GTR/GBR has marked a significant progression in regenerative dentistry and maxillofacial surgery. Biomaterials used in GBR have evolved over time to enhance biocompatibility, bioactivity, and efficacy in promoting bone growth and integration. This review also probes into several promising fabrication techniques like electrospinning and latest 3D printing fabrication techniques, which have shown potential in enhancing tissue and bone regeneration processes. Further, the challenges and future direction of GTR/GBR are explored and discussed.

Development of a PVA/PCL/CS-Based Nanofibrous Membrane for Guided Tissue Regeneration and Controlled Delivery of Doxycycline Hydrochloride in Management of Periodontitis: In Vivo Evaluation in Rats.

Antibiotic administration is an adjacent therapy to guided tissue regeneration (GTR) in the management of periodontitis. This is due to the major role of pathogen biofilm in aggravating periodontal defects. This study aimed to fabricate a GTR membrane for sustained delivery of doxycycline hydrochloride (DOX) while having a space-maintaining function. The membranes were prepared using a polymeric blend of polycaprolactone/polyvinyl alcohol/chitosan by the electrospinning technique. The obtained membranes were characterized in terms of physicochemical and biological properties. Nanofibers showed a mean diameter in the submicron range of < 450 nm while having uniform randomly aligned morphology. The obtained membranes showed high strength and flexibility. A prolonged in vitro release profile during 68 h was observed for manufactured formulations. The prepared membranes showed a cell viability of > 70% at different DOX concentrations. The formulations possessed antimicrobial efficacy against common pathogens responsible for periodontitis. In vivo evaluation also showed prolonged release of DOX for 14 days. The histopathological evaluation confirmed the biocompatibility of the GTR membrane. In conclusion, the developed nanofibrous DOX-loaded GTR membranes may have beneficial characteristics in favour of both sustained antibiotic delivery and periodontal regeneration by space-maintaining function without causing any irritation and tissue damage.

Healing outcomes of open versus closed flap procedures for collagen membrane coverage following immediate dental implant placements with simultaneous guided tissue regeneration.

OBJECTIVE: To compare the outcomes of open healing to complete closure for collagen membrane coverage for immediate implant placements with simultaneous guided bone regeneration (GBR) in two retrospective cohorts. METHODS: The subjects included 118 patients who received Bio-Gide® collagen membrane coverage for immediate implant placements and GBR in 20 anterior and 98 posterior teeth. For 58 patients, gingival flaps were released to achieve full coverage of collagen membrane (CC group). For 60 patients, no efforts were made to release the gingival flaps and collagen membrane was left exposed for open healing (OH group). Antibiotics and analgesics were prescribed for 7 days after surgery. The width of crestal open wounds were measured after surgery (W0), and at 1, 2 and 16 weeks (W16). Changes in bone mass were assessed by cone-beam computed tomography after implant placement and again at W16. Gingival and bone tissues over the implant cover screws were harvested and assessed for 16 patients in the OH group at W16. RESULTS: No wound dehiscence occurred in the CC group from W0 to W16. Both the vertical and horizontal bone dimension changes were not significantly different between the OH and CC group. For the OH group, soft tissue was completely healed at W16 when the initial wound widths were ≤6 mm. For those with initial wound widths ≥ 7 mm, the cover screws were exposed in 5/16 patients at W16 but did not affect the final restorations. Tissue staining showed keratinized mucosa and new bone formation above the dental implant in the OH group. CONCLUSION: Open healing achieved healing outcomes similar to those of complete closure for collagen membrane coverage following immediate implant placements. CLINICAL SIGNIFICANCE: For immediate implant placement requiring bone grafting and collagen membrane coverage, it is unnecessary to release the gingival flaps or use tissue grafts to achieve full coverage of the crestal wounds. Open healing with exposed membrane could achieve similar outcomes with less pain and swelling.

Electrospun Nanofibrous Conduit Filled with a Collagen-Based Matrix (ColM) for Nerve Regeneration.

Traumatic nerve defects result in dysfunctions of sensory and motor nerves and are usually accompanied by pain. Nerve guidance conduits (NGCs) are widely applied to bridge large-gap nerve defects. However, few NGCs can truly replace autologous nerve grafts to achieve comprehensive neural regeneration and function recovery. Herein, a three-dimensional (3D) sponge-filled nanofibrous NGC (sf@NGC) resembling the structure of native peripheral nerves was developed. The conduit was fabricated by electrospinning a poly(L-lactide-co-glycolide) (PLGA) membrane, whereas the intraluminal filler was obtained by freeze-drying a collagen-based matrix (ColM) resembling the extracellular matrix. The effects of the electrospinning process and of the composition of ColM on the physicochemical performance of sf@NGC were investigated in detail. Furthermore, the biocompatibility of the PLGA sheath and ColM were evaluated. The continuous and homogeneous PLGA nanofiber membrane had high porosity and tensile strength. ColM was shown to exhibit an ECM-like architecture characterized by a multistage pore structure and a high porosity level of over 70%. The PLGA sheath and ColM were shown to possess stagewise degradability and good biocompatibility. In conclusion, sf@NGC may have a favorable potential for the treatment of nerve reconstruction.

Regeneração óssea guiada para aumento horizontal de rebordo utilizando fibrina rica em plaquetas associada a enxertos ósseos: revisão de literatura / Guided bone regenerationfor horizontal bone augmentation using platelet- rich fibrin associated with bone grafts: literature review

Objetivo: revisar a literatura sobre os diferentes tipos de derivados de plaquetas autólogas e o desempenho clínico do uso do sticky bone para aumento ósseo horizontal de rebordo. Materiais e métodos: Para realização dessa revisão foram realizadas buscas nas bases de dados PubMed, Google Scholar e Web of Science, utilizando os seguintes descritores: "platelet-rich fibrin" AND "sticky bone" OR "alveolar bone grafting" AND "sticky bone" OR "guided bone regeneration" AND "sticky bone" AND "alveolar ridge augmentation" OR "Alveolar ridge augmentation" AND "sticky bone". Foram incluídos artigos publicados em inglês, que abordavam conceitos relacionados aos agregados plaquetários e a regeneração óssea guiada para aumento ósseo horizontal de rebordo utilizando fibrina rica em plaquetas associada à enxertos ósseos (sticky bone). Resultados: Após avaliação dos estudos encontrados foram selecionados 11 artigos sobre o uso do sticky bone para aumento horizontal de rebordo. Para compor este trabalho foram selecionados também 14 estudos de revisão e artigos associados ao tema. Por ser de fácil aplicação e obtenção, muitos autores têm estudado as aplicações cirúrgicas do sticky bone e os resultados demonstram que o aumento horizontal do rebordo utilizando essa técnica pode ser realizado de forma previsível. Conclusão: apesar de haver estudos promissores sobre o uso do sticky bone, falta evidência na literatura sobre seu sucesso clínico. Assim, para compreender o potencial regenerativo desta técnica são necessários um maior número de estudos randomizados, com diferentes materiais de enxerto e protocolos padronizados de obtenção do sticky bone.(AU)

Objective: to review the literature on the different types of autologous platelet derivatives and the clinical performance of using sticky bone for horizontal bone ridge augmentation. Materials and methods: In order to conduct this review, it was conducted searches in the PubMed, Google Scholar, and Web of Science databases using the following descriptors: "platelet-rich fibrin" AND "sticky bone" OR "alveolar bone grafting" AND "sticky bone" OR "guided bone regeneration" AND "sticky bone" AND "alveolar ridge augmentation" OR "Alveolar ridge augmentation" AND "sticky bone". It included articles published in English that addressed concepts related to platelet aggregates and guided bone regeneration for horizontal bone augmentation using platelet-rich fibrin associated with bone grafts (sticky bone). Results: After evaluating the studies found, were selected 11 articles on the use of sticky bone for horizontal ridge augmentation. To compose this work, 14 review studies and articles associated with the topic were also selected. Due to its ease of application and availability, many authors have explored the surgical applications of sticky bone, and the results indicate that horizontal ridge augmentation using this technique can be predictably performed. Conclusion: while there are promising studies on the use of sticky bone, the literature lacks evidence regarding its clinical success. Therefore, to fully understand the regenerative potential of this technique, further randomized studies are needed, involving different graft materials and standardized protocols for obtaining sticky bone.(AU)

Tissue-Engineered Core-Shell Silk-Fibroin/Poly-l-Lactic Acid Nerve Guidance Conduit Containing Encapsulated Exosomes of Human Endometrial Stem Cells Promotes Peripheral Nerve Regeneration.

Nerve guide conduits (NGCs) have been shown to be less efficient than nerve autografts in peripheral nerve regeneration. To address this issue, we developed for the first time a novel tissue-engineered nerve guide conduit structure encapsulated with human endometrial stem cell (EnSC) derived exosomes, which promoted nerve regeneration in rat sciatic nerve defects. In this study, we initially indicated the long-term efficacy and safety impacts of newly designed double layered SF/PLLA nerve guide conduits. Then the regeneration effects of SF/PLLA nerve guide conduits containing exosomes derived from human EnSCs were evaluated in rat sciatic nerve defects. The human EnSC derived exosomes were isolated from the supernatant of human EnSC cultures and characterized. Subsequently, the human EnSC derived exosomes were encapsulated in constructed NGCs by fibrin gel. For in vivo studies, entire 10 mm peripheral nerve defects were generated in rat sciatic nerves and restored with NGC encapsulated with human EnSC derived exosomes (Exo-NGC group), nerve guide conduits, and autografts. The efficiency of the NGCs encapsulated with human EnSCs derived exosomes in assisting peripheral nerve regeneration was investigated and compared with other groups. The in vivo results demonstrated that encapsulated human EnSC derived exosomes in NGC (Exo-NGC) significantly benefitted nerve regeneration based on motor function, sensory reaction, and electrophysiological results. Furthermore, immunohistochemistry with histopathology results showed the formation of regenerated nerve fibers, along with blood vessels that newly were developed, as a result of the exosome functions in the Exo-NGC group. These outcomes illustrated that the newly designed core-shell SF/PLLA nerve guide conduit encapsulated with human EnSC derived exosomes enhanced the regeneration process of axons and improved the functional recovery of rat sciatic nerve defects. So, encapsulated human EnSC-derived exosomes in a core-shell SF/PLLA nerve guide conduit are a potential therapeutic cell-free treatment for peripheral nerve defects.

Biodegradable polyurethane-incorporating decellularized spinal cord matrix scaffolds enhance Schwann cell reprogramming to promote peripheral nerve repair.

Decellularized extracellular matrix (dECM) nerve guide conduits (NGCs) are a promising strategy to replace autogenous nerve grafting for the treatment of peripheral nerve system (PNS) injury. However, dECM conduits with mechanical properties that match those of peripheral nerves are yet to be well developed. Herein, we developed polyurethane-based NGCs incorporating decellularized spinal cord (BWPU-DSC NGCs) to repair peripheral nerves. BWPU-DSC NGCs have an inner three-dimensional micro-nanostructure. The mechanical properties of BWPU-DSC NGCs were similar to those of polyurethane NGCs, which were proven to promote peripheral nerve regeneration. An in vitro study indicated that BWPU-DSC NGCs could boost the proliferation and growth of cell processes in Schwann and neuron-like cells. In a rat sciatic nerve transected injury model, BWPU-DSC NGCs exhibited a dramatic increase in nerve repair, similar to that obtained by the current gold standard autograft implantation at only 6 weeks post-implantation, whereas polyurethane NGCs still displayed incomplete nerve repair. Histological analysis revealed that BWPU-DSC NGCs could induce the reprogramming of Schwann cells to promote axon regeneration and remyelination. Moreover, reprogrammed Schwann cells together with BWPU-DSC NGCs had anti-inflammatory effects and altered the activation state of macrophages to M2 phenotypes to enhance PNS regeneration. In this study, we provided a strategy to prepare polyurethane-based dECM NGCs enriched with bioactive molecules to promote PNS regeneration.

Osteo-Immunomodulatory Role of Interleukin-4-Immobilized Plasma Immersion Ion Implantation Membranes for Bone Regeneration.

Barrier membranes for guided tissue regeneration are essential for bone repair and regeneration. The implanted membranes may trigger early inflammatory responses as a foreign material, which can affect the recruitment and differentiation of bone cells during tissue regeneration. The purpose of this study was to determine whether immobilizing interleukin 4 (IL4) on plasma immersion ion implantation (PIII)-activated surfaces may alter the osteo-immunoregulatory characteristics of the membranes and produce pro-osteogenic effects. In order to immobilize IL4, polycaprolactone surfaces were modified using the PIII technology. No discernible alterations were found between the morphology before and after PIII treatment or IL4 immobilization. IL4-immobilized PIII surfaces polarized macrophages to an M2 phenotype and mitigated inflammatory cytokine production under lipopolysaccharide stimulation. Interestingly, the co-culture of macrophages (on IL4-immobilized PIII surfaces) and bone marrow-derived mesenchymal stromal cells enhanced the production of angiogenic and osteogenic factors and triggered autophagy activation. Exosomes produced by PIII + IL4-stimulated macrophages were also found to play a role in osteoblast differentiation. In conclusion, the osteo-immunoregulatory properties of bone materials can be modified by PIII-assisted IL4 immobilization, creating a favorable osteoimmune milieu for bone regeneration.

Additive manufacturing of Schwann cell-laden collagen/alginate nerve guidance conduits by freeform reversible embedding regulate neurogenesis via exosomes secretion towards peripheral nerve regeneration.

Peripheral nerve injury is a common clinical problem that could be debilitating to one's quality of life. The complex nerve guidance conduits (NGCs) with cells in order to improve nerve regeneration. Therefore, we used freeform reversible embedding of suspended hydrogels to fabricate Schwann cells (SCs)-laden collagen/alginate (Col/Alg) NGCs. First, we evaluated Col influence on the characteristics of NGCs. After which, Wharton's jelly mesenchymal stem cells (WJMSC) are seeded onto the inner channel of NGCs and evaluated neural regeneration behaviors. Results indicated the SCs-laden NGCs with 2.5 % Col found the highest proliferation and secretion of neurotrophic protein. Furthermore, co-culture of SCs promoted differentiation of WJMSC as seen from the increased neurogenic-related protein in NGCs. To determine the molecular mechanism between SCs and WJMSC, we demonstrated the neurotrophic factors secreted by SCs act on tropomyosin receptor kinase A (TrkA) receptors of WJMSC to promote nerve regeneration. In addition, our study demonstrated SCs-derived exosomes had a critical role in regulating neural differentiation of WJMSC. Taken together, this study demonstrates the fabrication of SCs-laden Col/Alg NGCs for nerve regeneration and understanding regarding the synergistic regenerative mechanisms of different cells could bring us a step closer for clinical treatment of large nerve defects.

Multifaceted polymeric nerve guidance conduits with distinctive double-layered architecture and plasma-induced inner chemistry gradient for the repair of critical-sized defects.

Despite tissue engineering advances, current nerve guidance conduits (NGCs) are still failing in repairing critical-sized defects. This study aims, therefore, at tackling large nerve gaps (2 cm) by designing NGCs possessing refined physicochemical properties enhancing the activity of Schwann cells (SCs) that support nerve regeneration over long distances. As such, a combinatorial strategy adopting novel plasma-induced surface chemistry and architectural heterogeneity was considered. A mechanically suitable copolymer (Polyactive®) was electrospun to produce nanofibrous NGCs mimicking the extracellular matrix. An innovative seamless double-layered architecture consisting of an inner wall comprised of bundles of aligned fibers with intercalated random fibers and an outer wall fully composed of random fibers was conceived to synergistically provide cell guidance cues and sufficient nutrient inflow. NGCs were subjected to argon plasma treatments using a dielectric barrier discharge (DBD) and a plasma jet (PJ). Surface chemical changes were examined by advanced X-ray photoelectron spectroscopy (XPS) micro-mappings. The DBD homogeneously increased the surface oxygen content from 17 % to 28 % on the inner wall. The PJ created a gradient chemistry throughout the inner wall with an oxygen content gradually increasing from 21 % to 30 %. In vitro studies revealed enhanced primary SC adhesion, elongation and proliferation on plasma-treated NGCs. A cell gradient was observed on the PJ-treated NGCs thus underlining the favorable oxygen gradient in promoting cell chemotaxis. A gradual change from circular to highly elongated SC morphologies mimicking the bands of Büngner was visualized along the gradient. Overall, plasma-treated NGCs are promising candidates paving the way towards critical nerve gap repair.

Metformin-Incorporated Gelatin/Nano-Hydroxyapatite Scaffolds Promotes Bone Regeneration in Critical Size Rat Alveolar Bone Defect Model.

In this study, we fabricated gelatin/nano-hydroxyapatite/metformin scaffold (GHMS) and compared its effectiveness in bone regeneration with extraction-only, Sinbone, and Bio-Oss Collagen® groups in a critical size rat alveolar bone defect model. GHMS was synthesized by co-precipitating calcium hydroxide and orthophosphoric acid within gelatin solution, incorporating metformin, and cross-linked by microbial transglutaminase. The morphology, characterization, and biocompatibility of scaffold were examined. The in vitro effects of GHMS on osteogenic gene and protein expressions were evaluated. In vivo bone formation was assessed in a critical size rat alveolar bone defect model with micro-computed tomography and histological examination by comparing GHMS with extraction-only, Sinbone, and Bio-Oss Collagen®. The synthesized GHMS had a highly interconnected porous structure with a mean pore size of 81.85 ± 13.8 µm. GHMS exhibited good biocompatibility; promoted ALPL, RUNX2, SP7, BGLAP, SPARC and Col1a1 gene expressions; and upregulated the synthesis of osteogenic proteins, including osteonectin, osteocalcin, and collagen type I. In critical size rat alveolar bone defects, GHMS showed superior bone regeneration compared to extraction-only, Sinbone, and Bio-Oss Collagen® groups as manifested by greater alveolar ridge preservation, while more bone formation with a lower percentage of connective tissue and residual scaffold at the defect sites grafted with GHMS in histological staining. The GHMS presented in this study may be used as a potential bone substitute to regenerate alveolar bone. The good biocompatibility, relatively fast degradation, interconnected pores allowing vascularization, and higher bioactivity properties of the components of the GHMS (gelatin, nHA, and metformin) may contribute to direct osteogenesis.

Low-intensity pulsed ultrasound enhances bone marrow-derived stem cells-based periodontal regenerative therapies.

BACKGROUND: Alveolar bone loss is one of the most common consequence for periodontitis, which is a major obstacle in periodontal regeneration. Bone marrow stromal cells (BMSCs) have shown significant promise in the treatment of various disease, which also contribute to the natural bone repair process. Low-intensity pulsed ultrasound (LIPUS) is a therapeutic ultrasound used in our previous studies to promotes alveolar bone regeneration. In addition, LIPUS was found to be a promising method to enhance mesenchymal stromal cell-based therapies. In the current study, we have investigated the effects of LIPUS combined with BMSCs therapies on BMSCs homing and its potential to promote alveolar bone regeneration. METHODS: BMSCs were isolated from rat and characterized by multilineages differentiation assay. Then these cells were labeled with luciferase and green fluorescent protein (GFP) by lentivirus in vitro. Periodontal bone defect was made on the mesial area of the maxillary first molar in rats. A total of 1 × 106 Luc-GFP labeled BMSCs were injected into rat tail vein. Bioluminescence imaging was utilized to track BMSCs in vivo. The rats were sacrificed eight weeks after surgery and the samples were harvested. Micro-computed tomography (Micro-CT) was performed to evaluate alveolar bone regeneration. Paraffin sections were made and subject to hematoxylin-eosin staining, masson staining and immunohistochemistry staining. RESULTS: BMSCs display a fibroblast-like morphology and can differentiate into adipocytes or osteoblasts under appropriate condition. The transfected BMSCs are strongly positive for GFP express. Bioluminescence imaging showed that most of BMSCs were trapped in the lung. A small portion BMSCs were homed to the alveolar bone defect area in BMSCs group, while more cells were observed in BMSCs/LIPUS group compare to other groups on day 3 and 7. Micro-CT results showed that BMSCs/LIPUS group resulted in more new bone formation than other groups. Immunohistochemical results showed higher expression of COL-I and osteopontin in BMSCs/LIPUS group compared with the other groups. CONCLUSIONS: These results suggested that LIPUS can enhance BMSCs-based periodontal alveolar bone regeneration. This study provides new insights into how LIPUS might provide therapeutic benefits by promoting BMSCs homing.

A Brief Review of In Vitro Models for Injury and Regeneration in the Peripheral Nervous System.

Nerve axonal injury and associated cellular mechanisms leading to peripheral nerve damage are important topics of research necessary for reducing disability and enhancing quality of life. Model systems that mimic the biological changes that occur during human nerve injury are crucial for the identification of cellular responses, screening of novel therapeutic molecules, and design of neural regeneration strategies. In addition to in vivo and mathematical models, in vitro axonal injury models provide a simple, robust, and reductionist platform to partially understand nerve injury pathogenesis and regeneration. In recent years, there have been several advances related to in vitro techniques that focus on the utilization of custom-fabricated cell culture chambers, microfluidic chamber systems, and injury techniques such as laser ablation and axonal stretching. These developments seem to reflect a gradual and natural progression towards understanding molecular and signaling events at an individual axon and neuronal-soma level. In this review, we attempt to categorize and discuss various in vitro models of injury relevant to the peripheral nervous system and highlight their strengths, weaknesses, and opportunities. Such models will help to recreate the post-injury microenvironment and aid in the development of therapeutic strategies that can accelerate nerve repair.

Regenerative Neurology and Regenerative Cardiology: Shared Hurdles and Achievements.

From the first success in cultivation of cells in vitro, it became clear that developing cell and/or tissue specific cultures would open a myriad of new opportunities for medical research. Expertise in various in vitro models has been developing over decades, so nowadays we benefit from highly specific in vitro systems imitating every organ of the human body. Moreover, obtaining sufficient number of standardized cells allows for cell transplantation approach with the goal of improving the regeneration of injured/disease affected tissue. However, different cell types bring different needs and place various types of hurdles on the path of regenerative neurology and regenerative cardiology. In this review, written by European experts gathered in Cost European action dedicated to neurology and cardiology-Bioneca, we present the experience acquired by working on two rather different organs: the brain and the heart. When taken into account that diseases of these two organs, mostly ischemic in their nature (stroke and heart infarction), bring by far the largest burden of the medical systems around Europe, it is not surprising that in vitro models of nervous and heart muscle tissue were in the focus of biomedical research in the last decades. In this review we describe and discuss hurdles which still impair further progress of regenerative neurology and cardiology and we detect those ones which are common to both fields and some, which are field-specific. With the goal to elucidate strategies which might be shared between regenerative neurology and cardiology we discuss methodological solutions which can help each of the fields to accelerate their development.

Design and optimization of 3D-bioprinted scaffold framework based on a new natural polymeric bioink.

OBJECTIVES: This aimed at the design and production of engineered 3D scaffold prototypes using a natural polymeric bioink made of chitosan and poly-γ-glutamic acid with a specific focus on 3D-bioprinting process and on 3D framework geometry. METHODS: Prototypes were produced using a 3D bioprinter exploiting layer-by-layer deposition technology. The 3D scaffold prototypes were fully characterized concerning pore size and size distribution, stability in different experimental conditions, swelling capability, and human dermal fibroblasts viability. KEY FINDINGS: Hexagonal framework combined with biopaper allowed stabilizing the 3-layers structure during process manufacturing and during incubation in cell culture conditions. The stability of 3-layers structure was well preserved for 48 h. Crosslinking percentages of 2-layers and 3-layers prototype were 88.2 and 68.39, respectively. The swelling study showed a controlled swelling capability for 2-layers and 3-layers prototype, ∼5%. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay results showed good biocompatibility of 3-layers prototype and their suitability for preserving 48 h cell viability in 3D cultures. Moreover, a significant increment of absorbance value was measured after 48 h, demonstrating cell growth. CONCLUSIONS: Bioink obtained combining chitosan and poly-γ-glutamic acid represents a good option for 3D bioprinting. A stable 3D structure was realized by layer-by-layer deposition technology; compared with other papers, the present study succeeded in using medical healthcare-grade polymers, no-toxic crosslinker, and solvents according to ICH Topic Q3C (R4).

Bio-mimicked guided tissue regeneration/guided bone regeneration membranes with hierarchical structured surfaces replicated from teak leaf exhibits enhanced bioactivity.

Bio-mimicked GTR/GBR membranes with hierarchical structured surfaces were developed by direct and indirect replication of teak leaf surface. The membranes were fabricated using solvent casting method with customized templates. The surfaces obtained were those with micro-trichomes (MTS) and micro-depression (MDS) that resembled a whorling pattern. Structural details of the fabricated membrane surfaces were studied under stereomicroscope and scanning electron microscopy. Surface roughness, water wetting angle, water uptake, and degradation properties of the membranes were examined. The effects of the micro-patterned hierarchical structure on in vitro bioactivities of human osteoblast-like cells (MG63) and human gingival fibroblast cells HGF1-RT1 were studied. In vivo study carried out on rat skulls to assess the response of surrounding tissues for 4 weeks showed that the bio-mimicked MTS and MDS membrane surfaces enhanced the cell proliferation. The proliferation significantly increased with increasing surface roughness and decreasing contact angle. There was also an evidence of rapid new bone maturation with membranes with MTS. It is thus suggested that the teak leaf mimicked whorling patterned hierarchical structured surface is an important design for enhancing bioactivity.

Modern Approaches to Acellular Therapy in Bone and Dental Regeneration.

An approach called cell-free therapy has rapidly developed in regenerative medicine over the past decade. Understanding the molecular mechanisms and signaling pathways involved in the internal potential of tissue repair inspires the development of new strategies aimed at controlling and enhancing these processes during regeneration. The use of stem cell mobilization, or homing for regeneration based on endogenous healing mechanisms, prompted a new concept in regenerative medicine: endogenous regenerative medicine. The application of cell-free therapeutic agents leading to the recruitment/homing of endogenous stem cells has advantages in overcoming the limitations and risks associated with cell therapy. In this review, we discuss the potential of cell-free products such as the decellularized extracellular matrix, growth factors, extracellular vesicles and miRNAs in endogenous bone and dental regeneration.

Clinical management of endo-perio lesion through guided tissue regeneration: a 5 year follow-Up / Manejo clínico de una lesión endo-perio a través de la regeneración tisular guiada: control post-operatorio de 5 años

ABSTRACT: Progressive periodontal disease causes loss of supporting structures of teeth resulting in deep bony defects. In this case a report of 22-year old female patient is being presented with clinical findings of vertical bone loss in two adjacent teeth, on distal surface of 2nd upper right premolar and mesial surface of upper right 1st molar. Root canal treatment, non-surgical periodontal therapy followed by guided tissue regeneration was carried out using decalcified freeze-dried bone allograft (DFDBA) and collagen membrane. Analysis of clinical and radiographic findings showed marked reduction in pocket depth up to 12mm with hard tissue repair on 3-month, 2-year and 5- year follow ups.

RESUMEN: La enfermedad periodontal progresiva provoca la pérdida de las estructuras de soporte de los dientes, lo que resulta en defectos óseos profundos. En este caso clínico se presenta un informe de una paciente de 22 años con pérdida ósea vertical en la superficie distal del segundo premolar superior derecho y en la superficie mesial del primer molar superior derecho. El tratamiento del conducto radicular, la terapia periodontal no quirúrgica seguida de la regeneración tisular guiada se llevó a cabo utilizando aloinjerto óseo liofilizado descalcificado (DFDBA) y membrana de colágeno. El análisis de los hallazgos clínicos y radiográficos mostró una marcada reducción en la profundidad de la bolsa de hasta 12 mm con reparación de tejido duro en seguimientos de 3 meses, 2 años y 5 años.

Extracellular vesicles fail to trigger the generation of new cardiomyocytes in chronically infarcted hearts.

Background: Extracellular vesicles (EV) mediate the therapeutic effects of stem cells but it is unclear whether this involves cardiac regeneration mediated by endogenous cardiomyocyte proliferation. Methods: Bi-transgenic MerCreMer/ZEG (n = 15/group) and Mosaic Analysis With Double Markers (MADM; n = 6/group) mouse models underwent permanent coronary artery ligation and received, 3 weeks later, 10 billion EV (from human iPS-derived cardiovascular progenitor cells [CPC]), or saline, injected percutaneously under echo guidance in the peri-infarcted myocardium. Endogenous cardiomyocyte proliferation was tracked by EdU labeling and biphoton microscopy. Other end points, including cardiac function (echocardiography and MRI), histology and transcriptomics were blindly assessed 4-6 weeks after injections. Results: There was no proliferation of cardiomyocytes in either transgenic mouse strains. Nevertheless, EV improved cardiac function in both models. In MerCreMer/ZEG mice, LVEF increased by 18.3 ± 0.2% between baseline and the end-study time point in EV-treated hearts which contrasted with a decrease by 2.3 ± 0.2% in the PBS group; MADM mice featured a similar pattern as intra-myocardial administration of EV improved LVEF by 13.3 ± 0.16% from baseline whereas it decreased by 14.4 ± 0.16% in the control PBS-injected group. This functional improvement was confirmed by MRI and associated with a reduction in infarct size, the decreased expression of several pro-fibrotic genes and an overexpression of the anti-fibrotic miRNA 133-a1 compared to controls. Experiments with an anti-miR133-a demonstrated that the cardio-reparative effects of EV were partly abrogated. Conclusions: EV-CPC do not trigger cardiomyocyte proliferation but still improve cardiac function by other mechanisms which may include the regulation of fibrosis.

Molecular Mechanisms of Mesenchymal Stem Cell-Based Therapy in Acute Kidney Injury.

Acute kidney injury (AKI) causes a lot of harm to human health but is treated by only supportive therapy in most cases. Recent evidence shows that mesenchymal stem cells (MSCs) benefit kidney regeneration through releasing paracrine factors and extracellular vesicles (EVs) to the recipient kidney cells and are considered to be promising cellular therapy for AKI. To develop more efficient, precise therapies for AKI, we review the therapeutic mechanism of MSCs and MSC-derived EVs in AKI and look for a better understanding of molecular signaling and cellular communication between donor MSCs and recipient kidney cells. We also review recent clinical trials of MSC-EVs in AKI. This review summarizes the molecular mechanisms of MSCs' therapeutic effects on kidney regeneration, expecting to comprehensively facilitate future clinical application for treating AKI.