Graft Scaffold Research Articles

Mechanobiological optimization of scaffolds for bone tissue engineering.

Synthetic bone graft scaffolds aim to generate new bone tissue and alleviate the limitations of autografts and allografts. To meet that aim, it is essential to have a design approach able to generate scaffold architectures that will promote bone formation. Here, we present a topology-varying design optimization method, the "mixed-topology" approach, that generates new designs from a set of starting structures. This approach was used with objective functions focusing on improving the scaffold's local mechanical microenvironments to mechanobiologically promote bone formation within the scaffold and constraints to ensure manufacturability and achieve desired macroscale properties. The results demonstrate that this approach can successfully generate scaffold designs with improved microenvironments, taking into account different combinations of relevant stimuli and constraints.

Comparative Evaluation of the Differentiation and Proliferation Potential of Dental Pulp Stem Cells on Hydroxyapatite/Beta-Tricalcium Bone Graft and Bovine Bone Graft: An In Vitro Study.

Stem cells of mesenchymal origin have good proliferative capacity when compared to other stem cell types. Dental pulp stem cells (DPSCs) are a variety of mesenchymal cells obtained from the pulpal tissue of teeth and are abundantly available and easy to obtain. DPSCs facilitate and improve the formation of new bone using different bone graft scaffolds. This present study aims to evaluate and compare the osteogenic potential of DPSCs on alloplastic and xenogeneic bone grafts. Hydroxyapatite and beta-tricalcium bone graft and bovine bone graft were used in a triplicate manner in the laboratory. DPSCs were obtained from the pulpal tissue of extracted third molars in the laboratory. The cytotoxicity, osteogenic potential, and difference in the rate of proliferation of mesenchymal cells on the biomaterials were assessed. Darker purple staining was seen in the case of hydroxyapatite/beta-tricalcium bone graft on MTT colorimetric assay stating that there was an increase in cell viability in hydroxyapatite/beta-tricalcium bone graft as compared to the bovine bone graft. Hydroxyapatite/beta-tricalcium bone graft showed more osteogenic potential as compared to the bovine bone graft as a higher degree of red staining was seen in Alizarin staining. Higher cell viability and higher osteogenic proliferation and differentiation were seen on the hydroxyapatite/beta-tricalcium bone graft compared to the bovine bone scaffold.

Murine iPSC-Loaded Scaffold Grafts Improve Bone Regeneration in Critical-Size Bone Defects.

In certain situations, bones do not heal completely after fracturing. One of these situations is a critical-size bone defect where the bone cannot heal spontaneously. In such a case, complex fracture treatment over a long period of time is required, which carries a relevant risk of complications. The common methods used, such as autologous and allogeneic grafts, do not always lead to successful treatment results. Current approaches to increasing bone formation to bridge the gap include the application of stem cells on the fracture side. While most studies investigated the use of mesenchymal stromal cells, less evidence exists about induced pluripotent stem cells (iPSC). In this study, we investigated the potential of mouse iPSC-loaded scaffolds and decellularized scaffolds containing extracellular matrix from iPSCs for treating critical-size bone defects in a mouse model. In vitro differentiation followed by Alizarin Red staining and quantitative reverse transcription polymerase chain reaction confirmed the osteogenic differentiation potential of the iPSCs lines. Subsequently, an in vivo trial using a mouse model (n = 12) for critical-size bone defect was conducted, in which a PLGA/aCaP osteoconductive scaffold was transplanted into the bone defect for 9 weeks. Three groups (each n = 4) were defined as (1) osteoconductive scaffold only (control), (2) iPSC-derived extracellular matrix seeded on a scaffold and (3) iPSC seeded on a scaffold. Micro-CT and histological analysis show that iPSCs grafted onto an osteoconductive scaffold followed by induction of osteogenic differentiation resulted in significantly higher bone volume 9 weeks after implantation than an osteoconductive scaffold alone. Transplantation of iPSC-seeded PLGA/aCaP scaffolds may improve bone regeneration in critical-size bone defects in mice.

Airway disease decreases the therapeutic potential of epithelial stem cells

BackgorundTissue-engineered tracheal grafts (TETG) can be recellularized by the host or pre-seeded with host-derived cells. However, the impact of airway disease on the recellularization process is unknown.MethodsIn this study, we determined if airway disease alters the regenerative potential of the human tracheobronchial epithelium (hTBE) obtained by brushing the tracheal mucosa during clinically-indicated bronchoscopy from 48 pediatric and six adult patients.ResultsOur findings revealed that basal cell recovery and frequency did not vary by age or region. At passage 1, all samples produced enough cells to cellularize a 3.5 by 0.5 cm2 graft scaffold at low cell density (~ 7000 cells/cm2), and 43.75% could cellularize a scaffold at high cell density (~ 100,000 cells/cm2). At passage 2, all samples produced the number of cells required for both recellularization models. Further evaluation revealed that six pediatric samples (11%) and three (50%) adult samples contained basal cells with a squamous basal phenotype. These cells did not form a polarized epithelium or produce differentiated secretory or ciliated cells. In the pediatric population, the squamous basal cell phenotype was associated with degree of prematurity (< 28 weeks, 64% vs. 13%, p = 0.02), significant pulmonary history (83% vs. 34%, p = 0.02), specifically with bronchopulmonary dysplasia (67% vs. 19%, p = 0.01), and patients who underwent previous tracheostomy (67% vs. 23%, p = 0.03).ConclusionsIn summary, screening high-risk pediatric or adult population based on clinical risk factors and laboratory findings could define appropriate candidates for airway reconstruction with tracheal scaffolds.Level of evidence. Level III Cohort study.Graphical

Highly compliant biomimetic scaffolds for small diameter tissue-engineered vascular grafts (TEVGs) produced via melt electrowriting (MEW)

Biofabrication approaches toward the development of tissue-engineered vascular grafts (TEVGs) have been widely investigated. However, successful translation has been limited to large diameter applications, with small diameter grafts frequently failing due to poor mechanical performance, in particular mismatched radial compliance. Herein, melt electrowriting (MEW) of poly(ϵ-caprolactone) has enabled the manufacture of highly porous, biocompatible microfibre scaffolds with physiological anisotropic mechanical properties, as substrates for the biofabrication of small diameter TEVGs. Highly reproducible scaffolds with internal diameter of 4.0 mm were designed with 500 and 250 µm pore sizes, demonstrating minimal deviation of less than 4% from the intended architecture, with consistent fibre diameter of 15 ± 2 µm across groups. Scaffolds were designed with straight or sinusoidal circumferential microfibre architecture respectively, to investigate the influence of biomimetic fibre straightening on radial compliance. The results demonstrate that scaffolds with wave-like circumferential microfibre laydown patterns mimicking the architectural arrangement of collagen fibres in arteries, exhibit physiological compliance (12.9 ± 0.6% per 100 mmHg), while equivalent control geometries with straight fibres exhibit significantly reduced compliance (5.5 ± 0.1% per 100 mmHg). Further mechanical characterisation revealed the sinusoidal scaffolds designed with 250 µm pores exhibited physiologically relevant burst pressures of 1078 ± 236 mmHg, compared to 631 ± 105 mmHg for corresponding 500 µm controls. Similar trends were observed for strength and failure, indicating enhanced mechanical performance of scaffolds with reduced pore spacing. Preliminary in vitro culture of human mesenchymal stem cells validated the MEW scaffolds as suitable substrates for cellular growth and proliferation, with high cell viability (>90%) and coverage (>85%), with subsequent seeding of vascular endothelial cells indicating successful attachment and preliminary endothelialisation of tissue-cultured constructs. These findings support further investigation into long-term tissue culture methodologies for enhanced production of vascular extracellular matrix components, toward the development of the next generation of small diameter TEVGs.

Chondrocytes supplemented to bone graft-containing scaffolds expedite cranial defect repair

Critical maxillofacial bone fractures do not heal spontaneously, thus, often there is a need to facilitate repair via surgical intervention. Gold standard approaches, include the use of autologous bone graft, or devices supplemented with osteogenic growth factors and bone substitutes. This research aimed to employ a critical size calvaria defect model, to determine if the addition of chondrocytes to collagen-containing bone graft substitute, may expedite bone repair. As such, using a critical size rat calvaria defect, we implanted a collagen scaffold containing bone graft substitute (i.e., Bone graft scaffold, BG) or BG supplemented with costal chondrocytes (cBG). The rats were subjected to live CT imaging at 1, 6, 9, and 12 weeks following the surgical procedure and sacrificed for microCT imaging of the defect site. Moreover, serum markers and histological evaluation were assessed to determine osseous tissue regeneration and turnover. Live CT and microCT indicated cBG implants displayed expedited bone repair vs, BG alone, already at 6 weeks post defect induction. cBG also displayed a shorter distance between the defect edges and greater mineral apposition distance compared to BG. Summerizing, the data support the addition of chondrocytes to bone substitute, accelerates the formation of new bone within a critical size defect.

Structure, rheological properties, and biocompatibility of Laponite® cross-linked starch/polyvinyl alcohol hydrogels

Hydrogels, owing to their unique porous structures, hydrophilic properties, and biocompatibility, are being developed as scaffolds for bone grafts. However, the use of toxic initiators or cross-linking agents is a drawback. To overcome this, we developed Laponite®/cross-linked starch/polyvinyl alcohol (PVA) hydrogels prepared by one-step solution mixing. The structure, rheological properties, and biocompatibility of the hydrogels were investigated. Zeta potential, Fourier transform infrared, and X-ray diffraction analyses showed that hydrogen bonding and electrostatic interactions jointly maintained the structure of the cross-linked hydrogel systems. At a Laponite® concentration of 10 %, the hydrogel with a starch/PVA ratio of 2:2 exhibited a uniform porous structure, the highest storage modulus (G'), and the lowest degradation rate. At a starch/PVA ratio of 2:2, the G' increased; however, the degradation rate decreased with the increase in Laponite® content from 5 % to 20 %. These results indicate that the mechanical strength and degradation rate of the hydrogels could be adjusted by altering the starch/PVA ratio and the amount of Laponite®. In vitro cytotoxicity experiments showed that the Laponite®/starch/PVA (LSP) hydrogels were non-toxic to MC3T3-E1 cells. The starch/PVA ratio had no obvious effect on the proliferation of MC3T3-E1 cells, but an increase in Laponite® content significantly promoted cell proliferation. In summary, the results suggest that these LSP hydrogels have great potential for applications in bone tissue engineering.

Platelet-Rich Fibrin-Conditioned Medium as an Alternative to Fetal Bovine Serum Promotes Osteogenesis of Human Dental Pulp Stem Cells.

Human dental pulp stem cells (DPSCs) exhibit multilineage differentiation capabilities and superior clonogenic and proliferative properties. However, the use of animal-derived components such as FBS raises concerns regarding the clinical application of stem-cell-based therapies. Platelet-rich fibrin (PRF) derived from human blood is rich in fibrin, platelets, and growth factors and acts as a bioactive scaffold for grafting with biomaterials. In this study, we assessed the efficacy of PRF-conditioned medium (CM) in promoting DPSCs proliferation and osteogenic differentiation compared with the standard culture medium supplemented with FBS. A comparison of DPSCs cultured in FBS and PRF-CM revealed no differences in characteristics or morphology. However, cells cultured with PRF-CM exhibited inferior proliferation rates and cell numbers during passage in comparison with those cultured with FBS. In contrast, DPSCs cultured in PRF-CM showed significantly higher levels of calcification, and RT-PCR confirmed that the gene expression levels of markers associated with osteoblast differentiation were significantly increased. The PRF-CM approach offers a convenient, straightforward, and advantageous method for culturing DPSCs, without relying on animal-derived components. In summary, this study introduces a novel application of PRF-CM for enhancing the osteogenesis of DPSCs, which provides an alternative to FBS culture medium and addresses concerns associated with the use of animal-derived components in clinical settings.

Radiographic evaluation of alveolar ridge preservation using a chitosan/polyvinyl alcohol nanofibrous matrix: A randomized clinical study

The objective of this randomized clinical trial (RCT) was to assess the effectiveness of electrospun chitosan/polyvinyl alcohol (CS/PVA) nanofibrous scaffolds in preserving the alveolar ridge and enhancing bone remodeling following tooth extraction when compared to a control group. In this split RCT, 24 human alveolar sockets were randomly assigned to two groups, with 12 sockets receiving CS/PVA nanofibrous scaffold grafts (test group) and 12 left to heal by secondary intention as the control group. Cone-beam computed tomography (CBCT) was performed at two different time points: immediately after extraction (T0) and 4 months post-extraction (T4). After 4 months, linear vertical and horizontal radiographic changes and bone density of extraction sockets were assessed in both the test and control groups. The RCT included 12 patients (4 male and 8 female) with a mean age of 24 ± 3.37 years. The test group had a significantly lower mean vertical resorption vs the control group, with a mean difference of 1.1 mm (P < 0.05). Similarly, the control group's mean horizontal bone resorption was −2.01 ± 1.04 mm, while the test group had a significantly lower mean of −0.69 ± 0.41 mm, resulting in a mean difference of 1.35 mm (P < 0.05). Furthermore, the study group exhibited a significant increase in bone density (722.03 ± 131.17 HU) after 4 months compared to the control group (448.73 ± 93.23 HU). In conclusion, we demonstrated within the limitations of this study that CS/PVA nanofibrous scaffold significantly limited alveolar bone resorption horizontally and vertically and enhanced bone density in alveolar sockets after 4 months when compared to results in the control group (TCTR20230526005).

NexGen regen? Challenges and opportunities for growth factors and signaling agents in periodontal regeneration at intrabony defects

Regeneration of periodontal tissues that have been destroyed by inflammatory periodontitis involves the initiation of tissue engineering and wound healing of multiple tissues involved in the function of the teeth, including the periodontal ligament, cementum, and alveolar bone. Such regeneration is termed guided tissue regeneration and the unique challenges to reconstruct these tissues involves a complex interplay of cells, signaling molecules, and scaffolds. While traditional guided tissue regeneration treatments have involved cell occlusive membranes, bone replacement graft scaffolds, and endogenous multipotent mesenchymal stem cells, the use of adjunctive materials to enhance healing outcomes has been studied and many such adjunctive factors are in common current clinical use. This report will focus on the current and emerging adjunctive growth factors and signaling molecules that can be used to optimize periodontal regeneration in periodontal intrabony defects, their mechanisms of action, the challenges associated with periodontal regeneration, and future avenues for research.

Strategies for acellular graft scaffolds as alternatives to tissue regeneration

Autologous grafts represent the gold standard for regenerated tissues after diseases, trauma or defects. However, the main problems of this strategy are availability, donor site morbidity and postoperative complications. For this reason, a new approach in tissue engineering looks at scaffolds obtained through the decellularization of native extracellular matrices as an alternative technology to circumvent these limitations. Thus, this review aims to focus on the potential for use of acellular grafts, particularly on the methods of decellularization and recellularization, and continues with their application as part of the formulation of bioinks, which would represent a breakthrough in the field of biofabrication due to their naturally bioactive composition, preserving tissue architecture and structural integrity as a potential alternative for tissue regeneration.

Accelerated reconstruction of rat calvaria bone defect using 3D-printed scaffolds coated with hydroxyapatite/bioglass

Self-healing and autologous bone graft of calvaraial defects can be challenging. Therefore, the fabrication of scaffolds for its rapid and effective repair is a promising field of research. This paper provided a comparative study on the ability of Three-dimensional (3D) printed polycaprolactone (PCL) scaffolds and PCL-modified with the hydroxyapatite (HA) and bioglasses (BG) bioceramics scaffolds in newly bone formed in calvaria defect area. The studied 3D-printed PCL scaffolds were fabricated by fused deposition layer-by-layer modeling. After the evaluation of cell adhesion on the surface of the scaffolds, they were implanted into a rat calvarial defect model. The rats were divided into four groups with scaffold graft including PCL, PCL/HA, PCL/BG, and PCL/HA/BG and a non-explant control group. The capacity of the 3D-printed scaffolds in calvarial bone regeneration was investigated using micro computed tomography scan, histological and immunohistochemistry analyses. Lastly, the expression levels of several bone related genes as well as the expression of miR-20a and miR-17-5p as positive regulators and miR-125a as a negative regulator in osteogenesis pathways were also investigated. The results of this comparative study have showed that PCL scaffolds with HA and BG bioceramics have a great range of potential applications in the field of calvaria defect treatment.

Three-Dimensional Scaffolds for Bone Tissue Engineering.

Immobilization using external or internal splints is a standard and effective procedure to treat minor skeletal fractures. In the case of major skeletal defects caused by extreme trauma, infectious diseases or tumors, the surgical implantation of a bone graft from external sources is required for a complete cure. Practical disadvantages, such as the risk of immune rejection and infection at the implant site, are high in xenografts and allografts. Currently, an autograft from the iliac crest of a patient is considered the "gold standard" method for treating large-scale skeletal defects. However, this method is not an ideal solution due to its limited availability and significant reports of morbidity in the harvest site (30%) as well as the implanted site (5-35%). Tissue-engineered bone grafts aim to create a mechanically strong, biologically viable and degradable bone graft by combining a three-dimensional porous scaffold with osteoblast or progenitor cells. The materials used for such tissue-engineered bone grafts can be broadly divided into ceramic materials (calcium phosphates) and biocompatible/bioactive synthetic polymers. This review summarizes the types of materials used to make scaffolds for cryo-preservable tissue-engineered bone grafts as well as the distinct methods adopted to create the scaffolds, including traditional scaffold fabrication methods (solvent-casting, gas-foaming, electrospinning, thermally induced phase separation) and more recent fabrication methods (fused deposition molding, stereolithography, selective laser sintering, Inkjet 3D printing, laser-assisted bioprinting and 3D bioprinting). This is followed by a short summation of the current osteochondrogenic models along with the required scaffold mechanical properties for in vivo applications. We then present a few results of the effects of freezing and thawing on the structural and mechanical integrity of PLLA scaffolds prepared by the thermally induced phase separation method and conclude this review article by summarizing the current regulatory requirements for tissue-engineered products.

A tissue engineered 3D printed calcium alkali phosphate bioceramic bone graft enables vascularization and regeneration of critical-size discontinuity bony defects in vivo.

Introduction: Recently, efforts towards the development of patient-specific 3D printed scaffolds for bone tissue engineering from bioactive ceramics have continuously intensified. For reconstruction of segmental defects after subtotal mandibulectomy a suitable tissue engineered bioceramic bone graft needs to be endowed with homogenously distributed osteoblasts in order to mimic the advantageous features of vascularized autologous fibula grafts, which represent the standard of care, contain osteogenic cells and are transplanted with the respective blood vessel. Consequently, inducing vascularization early on is pivotal for bone tissue engineering. The current study explored an advanced bone tissue engineering approach combining an advanced 3D printing technique for bioactive resorbable ceramic scaffolds with a perfusion cell culture technique for pre-colonization with mesenchymal stem cells, and with an intrinsic angiogenesis technique for regenerating critical size, segmental discontinuity defects in vivo applying a rat model. To this end, the effect of differing Si-CAOP (silica containing calcium alkali orthophosphate) scaffold microarchitecture arising from 3D powder bed printing (RP) or the Schwarzwalder Somers (SSM) replica fabrication technique on vascularization and bone regeneration was analyzed in vivo. In 80 rats 6-mm segmental discontinuity defects were created in the left femur. Methods: Embryonic mesenchymal stem cells were cultured on RP and SSM scaffolds for 7d under perfusion to create Si-CAOP grafts with terminally differentiated osteoblasts and mineralizing bone matrix. These scaffolds were implanted into the segmental defects in combination with an arteriovenous bundle (AVB). Native scaffolds without cells or AVB served as controls. After 3 and 6months, femurs were processed for angio-µCT or hard tissue histology, histomorphometric and immunohistochemical analysis of angiogenic and osteogenic marker expression. Results: At 3 and 6months, defects reconstructed with RP scaffolds, cells and AVB displayed a statistically significant higher bone area fraction, blood vessel volume%, blood vessel surface/volume, blood vessel thickness, density and linear density than defects treated with the other scaffold configurations. Discussion: Taken together, this study demonstrated that the AVB technique is well suited for inducing adequate vascularization of the tissue engineered scaffold graft in segmental defects after 3 and 6months, and that our tissue engineering approach employing 3D powder bed printed scaffolds facilitated segmental defect repair.

Microneurotrophin BNN27 Reduces Astrogliosis and Increases Density of Neurons and Implanted Neural Stem Cell-Derived Cells after Spinal Cord Injury

Microneurotrophins, small-molecule mimetics of endogenous neurotrophins, have demonstrated significant therapeutic effects on various animal models of neurological diseases. Nevertheless, their effects on central nervous system injuries remain unknown. Herein, we evaluate the effects of microneurotrophin BNN27, an NGF analog, in the mouse dorsal column crush spinal cord injury (SCI) model. BNN27 was delivered systemically either by itself or combined with neural stem cell (NSC)-seeded collagen-based scaffold grafts, demonstrated recently to improve locomotion performance in the same SCI model. Data validate the ability of NSC-seeded grafts to enhance locomotion recovery, neuronal cell integration with surrounding tissues, axonal elongation and angiogenesis. Our findings also show that systemic administration of BNN27 significantly reduced astrogliosis and increased neuron density in mice SCI lesion sites at 12 weeks post injury. Furthermore, when BNN27 administration was combined with NSC-seeded PCS grafts, BNN27 increased the density of survived implanted NSC-derived cells, possibly addressing a major challenge of NSC-based SCI treatments. In conclusion, this study provides evidence that small-molecule mimetics of endogenous neurotrophins can contribute to effective combinatorial treatments for SCI, by simultaneously regulating key events of SCI and supporting grafted cell therapies in the lesion site.

Development and mechanical characterization of decellularized scaffolds for an active aortic graft.

Decellularized porcine aortas are proposed as scaffolds for revolutionary active aortic grafts. A change in the static and dynamic mechanical properties, associated with the microstructure of elastin and collagen fibers, corresponds to alteration in the cyclic expansion and perfusion, in addition to possible graft damage. Therefore, the present study thoroughly investigates the mechanical response of the decellularized scaffolds of human and porcine origin to static and dynamic mechanical loads. The responses of the native human and porcine aortas are also compared; this is unavailable in the literature. Because the aorta is subjected to pulsatile blood pressure, dynamical responses to cyclic loads and their associated viscoelastic properties are particularly relevant for advanced graft design. In parallel, this study examines the microstructure of the decellularized aorta. The resulting data are compared to the analogous data obtained for the native human and porcine tissues. The results indicate that by using an optimized decellularization protocol - based on sodium dodecyl sulfate (SDS) and DNase - that minimizes mechanical and structural changes of the tissue, layered scaffolds with static and dynamic properties very similar to natural human aortas are obtained. In particular, a decellularized porcine aorta is non-inferior to a decellularized human aorta. STATEMENT OF SIGNIFICANCE: About 55,000 patients undergo abdominal aortic aneurysm repair annually in the USA. The currently implanted grafts present a large mechanical mismatch with the native tissue. This increases the pulsatile nature of the blood flow with negative consequences to the organ perfusion. For this reason, biomimetic and mechanically compatible grafts for aortic repair are urgently needed and they can be obtained through tissue engineering. In this study, scaffolds from porcine and human aortas are obtained from an optimized decellularization protocol. They are accurately compared to the native tissue and present the ideal static and dynamic mechanical properties for developing innovative aortic grafts.

Creation and preclinical evaluation of a novel mussel-inspired, biomimetic, bioactive bone graft scaffold: direct comparison with Infuse bone graft using a rat model of spinal fusion.

Infuse bone graft is a widely used osteoinductive adjuvant; however, the simple collagen sponge scaffold used in the implant has minimal inherent osteoinductive properties and poorly controls the delivery of the adsorbed recombinant human bone morphogenetic protein-2 (rhBMP-2). In this study, the authors sought to create a novel bone graft substitute material that overcomes the limitations of Infuse and compare the ability of this material with that of Infuse to facilitate union following spine surgery in a clinically translatable rat model of spinal fusion. The authors created a polydopamine (PDA)-infused, porous, homogeneously dispersed solid mixture of extracellular matrix and calcium phosphates (BioMim-PDA) and then compared the efficacy of this material directly with Infuse in the setting of different concentrations of rhBMP-2 using a rat model of spinal fusion. Sixty male Sprague Dawley rats were randomly assigned to each of six equal groups: 1) collagen + 0.2 µg rhBMP-2/side, 2) BioMim-PDA + 0.2 µg rhBMP-2/side, 3) collagen + 2.0 µg rhBMP-2/side, 4) BioMim-PDA + 2.0 μg rhBMP-2/side, 5) collagen + 20 µg rhBMP-2/side, and 6) BioMim-PDA + 20 µg rhBMP-2/side. All animals underwent posterolateral intertransverse process fusion at L4-5 using the assigned bone graft. Animals were euthanized 8 weeks postoperatively, and their lumbar spines were analyzed via microcomputed tomography (µCT) and histology. Spinal fusion was defined as continuous bridging bone bilaterally across the fusion site evaluated via µCT. The fusion rate was 100% in all groups except group 1 (70%) and group 4 (90%). Use of BioMim-PDA with 0.2 µg rhBMP-2 led to significantly greater results for bone volume (BV), percentage BV, and trabecular number, as well as significantly smaller trabecular separation, compared with the use of the collagen sponge with 2.0 µg rhBMP-2. The same results were observed when the use of BioMim-PDA with 2.0 µg rhBMP-2 was compared with the use of the collagen sponge with 20 µg rhBMP-2. Implantation of rhBMP-2-adsorbed BioMim-PDA scaffolds resulted in BV and bone quality superior to that afforded by treatment with rhBMP-2 concentrations 10-fold higher implanted on a conventional collagen sponge. Using BioMim-PDA (vs a collagen sponge) for rhBMP-2 delivery could significantly lower the amount of rhBMP-2 required for successful bone grafting clinically, improving device safety and decreasing costs.

Lamellar keratoplasty using decellularised porcine cornea as an acellular scaffold graft for surgical management of deep corneal ulcer in a dog

Corneal ulcers are one of the most common eye affection in domestic animals, especially dogs. In preclinical studies, porcine corneas were used regularly as an animal model due to its relative similarity to human cornea and its availability in great numbers from slaughter houses. In the present study, decellularised porcine cornea was used for corneal grafting as an acellular scaffold graft material in a case presented with deep corneal ulcer. The efficiency of the graft material was analysed on the day of presentation, days 7, 14, 21 and 60 post grafting, based on corneal clarity, oedema, neovascularisation, pigmentation, visual function and scar tissue formation. Decellularised porcine corneas were found to be very convenient to handle during surgery, provided good tectonic support, had good tissue biocompatibility and produced only mild to moderate graft opacity.

Chitosan as Bone Scaffold and Graft Materials for Bone Regeneration: A Systematic Review

Chitosan is a natural biodegradable polymer made from crustacean exoskeletons (shrimp and crab). Recently, natural material is preferably used in order to prevent any side effects from synthetic material. Previous research showed that chitosan has anti-bacterial properties, which can act as a bone graft scaffold material to increase in bone regeneration process. This article discusses the antibacterial effect of chitosan in the bone regeneration process. Bone graft consists of many primary graft materials which focus on alloplastic graft composite type. Bone graft is related to bone regeneration which associated with the process of secondary/indirect bone healing. The main trait of bone graft material is that it is not toxic to the chitosan’s host cell. Chitosan’s anti-bacterial effects can be associated with one of the three phases of bone defect healing, which is inflammation phase that acts to prevent bacterial invasion as an infectious disease in bone injury. Because of this, it can accelerate the polarization of macrophage M1 (secrete pro-inflammatory cytokine) to macrophage M2 (secrete anti-inflammatory cytokine) that relates to osteoblastogenesis. Osteoblastogenesis relates to the increase of osteoblast synthesis, deposition and mineralization of extracellular matrix leading to the maturation of osteoblast become osteocyte called ossification process.

Chitosan, chondroitin sulfate, and hyaluronic acid based in-situ forming scaffold for efficient cell grafting

Current cell grafting techniques are majorly dependent on seeding cells on a pre-formed scaffold. However, cells grow in a 2-dimensional (2D) space in such constructs, not mimicking the tissue's 3-dimensional (3D) architecture. The present study evaluated a unique poly-electrolyte complexation (PEC) based strategy for the 3D engraftment of cells in a porous polymeric scaffold. The scaffold was synthesized using a positively charged polysaccharide chitosan (CH) and negatively charged glycosaminoglycans chondroitin sulfate (CS) and hyaluronic acid (HA). Two different scaffolds were synthesized, one using CH and CS [CH-CS] and another using CH and CS + HA [CH-(CS-HA)]. The physicochemical characterization of both the PECs confirmed electrostatic interactions, leading to a porous and viscoelastic PEC formation. Fibroblast cells were grafted and seeded in both scaffolds to evaluate the effect of different scaffold compositions and the difference between seeded and grafted cells. Imaging studies confirmed that grafting of the fibroblast cells supports cellular proliferation. The qPCR studies demonstrated increased expression of functional markers TGF-β, α-SMA, collagen-I, and fibronectin in the CH-(CS-HA) grafted cells. In summary, it was demonstrated that an in-situ forming PEC of CH, CS, and HA had good physicochemical properties for cell grafting and supported grafted cells with improved function.