Bilayer Scaffold Research Articles

Single-Stage Arthroscopic Cartilage Repair With Chondrectomy and Implantation of a Templated Membrane Collagen Scaffold With Bone Marrow Aspirate Concentrate Augmentation (AMIC Plus)

Single-staged cartilage repair techniques have shown great clinical efficacy in the treatment of articular cartilage defects of the knee, particularly when using bilayered acellular scaffolds augmented with bone marrow aspirate concentrate. We describe an all-arthroscopic approach to the single-staged cartilage repair procedure using a porcine-derived collagen I/III bilayered scaffold that is templated arthroscopically and augmented with bone marrow aspirate concentrate, in the treatment of critically sized articular defects of the knee.

Full-thickness osteochondral defect repair using a biodegradable bilayered scaffold of porous zinc and chondroitin sulfate hydrogel

The regeneration of osteochondral tissue necessitates the re-establishment of a gradient owing to the unique characteristics and healing potential of the chondral and osseous phases. As the self-healing capacity of hyaline cartilage is limited, timely mechanical support during neo-cartilage formation is crucial to achieving optimal repair efficacy. In this study, we devised a biodegradable bilayered scaffold, comprising chondroitin sulfate (CS) hydrogel to regenerate chondral tissue and a porous pure zinc (Zn) scaffold for regeneration of the underlying bone as mechanical support for the cartilage layer. The photocured CS hydrogel possessed a compressive strength of 82 kPa, while the porous pure Zn scaffold exhibited a yield strength of 11 MPa and a stiffness of 0.8 GPa. Such mechanical properties are similar to values reported for cancellous bone. In vitro biological experiments demonstrated that the bilayered scaffold displayed favorable cytocompatibility and promoted chondrogenic and osteogenic differentiation of bone marrow stem cells. Upon implantation, the scaffold facilitated the simultaneous regeneration of bone and cartilage tissue in a porcine model, resulting in (i) a smoother cartilage surface, (ii) more hyaline-like cartilage, and (iii) a superior integration into the adjacent host tissue. Our bilayered scaffold exhibits significant potential for clinical application in osteochondral regeneration.

Reactive Cell Electrospinning of Anisotropically Aligned and Bilayer Hydrogel Nanofiber Networks.

Structured hydrogels that incorporate aligned nanofibrous morphologies have been demonstrated to better replicate the structures of native extracellular matrices and thus their function in guiding cell responses. However, current techniques for nanofiber fabrication are limited in their ability to create hydrogel scaffolds with tunable directional alignments and cell types/densities, as required to reproduce more complex native tissue structures. Herein, we leverage a reactive cell electrospinning technique based on the dynamic covalent cross-linking of poly(ethylene glycol methacrylate (POEGMA) precursor polymers to fabricate aligned hydrogel nanofibers that can be directly loaded with cells during the electrospinning process. The scaffolds were found to support high C2C12 myoblast viabilities greater than 85% over 14 days, with changes in the electrospinning collector allowing for the single-step fabrication of nonaligned, aligned, or cross-aligned nanofibrous networks. Cell aspect ratios on aligned scaffolds were found on average to be 27% higher compared to those on nonaligned scaffolds; furthermore, cell-loaded bilayer scaffolds with perpendicular fiber alignments showed evidence of enabling localized directional cell responses to individual layer fiber directions while avoiding delamination between the layers. This fabrication approach thus offers potential for better mimicking the structure and thus function of aligned and multilayered tissues (e.g., smooth muscle, neural, or tendon tissues).

3D-printed biomimetic scaffolds with precisely controlled and tunable structures guide cell migration and promote regeneration of osteochondral defect

Untreated osteochondral defects will develop into osteoarthritis, affecting patients’ quality of life. Since articular cartilage and subchondral bone exhibit distinct biological characteristics, repairing osteochondral defects remains a major challenge. Previous studies have tried to fabricate multilayer scaffolds with traditional methods or 3D printing technology. However, the efficacy is unsatisfactory because of poor control over internal structures or a lack of integrity between adjacent layers, severely compromising repair outcomes. Therefore, there is a need for a biomimetic scaffold that can simultaneously boost osteochondral defect regeneration in both structure and function. Herein, an integrated bilayer scaffold with precisely controlled structures is successfully 3D-printed in one step via digital light processing (DLP) technology. The upper layer has both ‘lotus- and radial-’ distribution pores, and the bottom layer has ‘lotus-’ pores to guide and facilitate the migration of chondrocytes and bone marrow mesenchymal stem cells, respectively, to the defect area. Tuning pore sizes could modulate the mechanical properties of scaffolds easily. Results show that 3D-printed porous structures allow significantly more cells to infiltrate into the area of ‘lotus- and radial-’ distribution pores during cell migration assay, subcutaneous implantation, and in situ transplantation, which are essential for osteochondral repair. Transplantation of this 3D-printed bilayer scaffold exhibits a promising osteochondral repair effect in rabbits. Incorporation of Kartogenin into the upper layer of scaffolds further induces better cartilage formation. Combining small molecules/drugs and precisely size-controlled and layer-specific porous structure via DLP technology, this 3D-printed bilayer scaffold is expected to be a potential strategy for osteochondral regeneration.

Bioinspired 3D-printed scaffold embedding DDAB-nano ZnO/nanofibrous microspheres for regenerative diabetic wound healing

There is a constant demand for novel materials/biomedical devices to accelerate the healing of hard-to-heal wounds. Herein, an innovative 3D-printed bioinspired construct was developed as an antibacterial/regenerative scaffold for diabetic wound healing. Hyaluronic/chitosan (HA/CS) ink was used to fabricate a bilayer scaffold comprising a dense plain hydrogel layer topping an antibacterial/regenerative nanofibrous layer obtained by incorporating the hydrogel with polylactic acid nanofibrous microspheres (MS). These were embedded with nano ZnO (ZNP) or didecyldimethylammonium bromide (DDAB)-treated ZNP (D-ZNP) to generate the antibacterial/healing nano/micro hybrid biomaterials, Z-MS@scaffold and DZ-MS@scaffold. Plain and composite scaffolds incorporating blank MS (blank MS@scaffold) or MS-free ZNP@scaffold and D-ZNP@scaffold were used for comparison. 3D printed bilayer constructs with customizable porosity were obtained as verified by SEM. The DZ-MS@scaffold exhibited the largest total pore area as well as the highest water-uptake capacity and in vitro antibacterial activity. Treatment of Staphylococcus aureus-infected full thickness diabetic wounds in rats indicated superiority of DZ-MS@scaffold as evidenced by multiple assessments. The scaffold afforded 95% wound-closure, infection suppression, effective regulation of healing-associated biomarkers as well as regeneration of skin structure in 14 d. On the other hand, healing of non-diabetic acute wounds was effectively accelerated by the simpler less porous Z-MS@scaffold. Information is provided for the first-time on the 3D printing of nanofibrous scaffolds using non-electrospun injectable bioactive nano/micro particulate constructs, an innovative ZNP-functionalized 3D-printed formulation and the distinct bioactivity of D-ZNP as a powerful antibacterial/wound healing promotor. In addition, findings underscored the crucial role of nanofibrous-MS carrier in enhancing the physicochemical, antibacterial, and wound regenerative properties of DDAB-nano ZnO. In conclusion, innovative 3D-printed DZ-MS@scaffold merging the MS-boosted multiple functionalities of ZNP and DDAB, the structural characteristics of nanofibrous MS in addition to those of the 3D-printed bilayer scaffold, provide a versatile bioactive material platform for diabetic wound healing and other biomedical applications.

Development of a membrane and a bilayer of chitosan, gelatin, and polyhydroxybutyrate to be used as wound dressing for the regeneration of rat excisional wounds.

The skin is the largest organ in the human body that acts as a protective barrier from the outside environment. Certain dermatological pathologies or significant skin lesions can result in serious complications. Several studies have focused on the development of tissue-engineered skin substitutes. In this study, a new bilayer scaffold composed of a chitosan-gelatin membrane and a chitosan-polyhydroxybutyrate (PHB) porous matrix was synthesized and populated with human adipose-derived mesenchymal stem cells (hASCs) to be potentially used for wound dressing applications. By combining this membrane and porous matrix with the stem cells, we aimed to provide immunomodulation and differentiation capabilities for the wound environment, as well as mechanical strength and biocompatibility for the underlying tissue. The membrane was prepared from the mixture of chitosan and gelatin in a 2:1 ratio and the porous matrix was prepared from the mixture of chitosan and PHB, in equal proportions to form a final solution at 2.5% (m/v). Fourier transform infrared spectroscopy analysis showed the formation of blends, and micro-computed tomography, scanning electron microscopy and atomic force microscopy images demonstrated membrane roughness and matrix porosity. The MTT assay showed that the scaffolds were biocompatible with hASC. The membrane and the bilayer were used as dressing and support for cell migration in the dorsal excisional wound model in Wistar rats. Histological and gene transcriptional analyses showed that the animals that received the scaffolds regenerated the hair follicles in the deep dermis in the central region of the wound. Our results demonstrate the potential of these new biomaterials as dressings in wound healing studies, favoring tissue regeneration.

Structural and topological design of conformal bilayered scaffolds for bone tissue engineering

A fundamental outcome of bone tissue engineering is the regeneration of bone defects presenting large dimensions. A promising solution in biomedical practice is the implantation of biomimetic scaffolds, i.e. porous structures mimicking the natural shapes of healthy bone tissues, which are colonized by mesenchymal stem cells and that support the growth of the regenerating tissues, until the complete healing process is realized. This work presented a workflow for the geometrical modeling and the mechanical design of beam-based, bilayered, and conformal scaffolds, mimicking the human cortico-cancellous bone structure for filling a large dimension defect in the mandibular bone of an injured patient. An isotropic Voronoi topology built on a refined point set generated by a high-quality meshing algorithm was adopted for lattice generation, which led to an open-cell architecture characterized by full connectivity and uniform cell size. Such geometrical and structural features represent crucially important requirements for maximizing the osteointegration and the vascularization of the implanted scaffold. An irregular scaffold was modelled, including a cortical and a sponge layer. The beam radii of both layers were determined by matching the elastic properties of the corresponding bone tissues, thus minimizing the stress shielding effects. Interestingly, several scaffold properties deriving from the proposed procedure, such as the porosity and the pore size, were in good agreement with those reported in the literature.

3D Printing of Microenvironment-Specific Bioinspired and Exosome-Reinforced Hydrogel Scaffolds for Efficient Cartilage and Subchondral Bone Regeneration.

In clinical practice, repairing osteochondral defects presents a challenge due to the varying biological properties of articular cartilages and subchondral bones. Thus, elucidating how spatial microenvironment-specific biomimetic scaffolds can be used to simultaneously regenerate osteochondral tissue is an important research topic. Herein, a novel bioinspired double-network hydrogel scaffold produced via 3D printing with tissue-specific decellularized extracellular matrix (dECM) and human adipose mesenchymal stem cell (MSC)-derived exosomes is described. The bionic hydrogel scaffolds promote rat bone marrow MSC attachment, spread, migration, proliferation, and chondrogenic and osteogenic differentiation in vitro, as determined based on the sustained release of bioactive exosomes. Furthermore, the 3D-printed microenvironment-specific heterogeneous bilayer scaffolds efficiently accelerate the simultaneous regeneration of cartilage and subchondral bone tissues in a rat preclinical model. In conclusion, 3D dECM-based microenvironment-specific biomimetics encapsulated with bioactive exosomes can serve as a novel cell-free recipe for stem cell therapy when treating injured or degenerative joints. This strategy provides a promising platform for complex zonal tissue regeneration whilst holding attractive clinical translation potential.

Bi-layered nanofibers loaded with pomegranate flowers extract as a novel wound dressing: Fabrication, characterization, and in vivo healing promotion

Prolonged and impaired wound healing is a serious complication, and there is an emerging demand for strategies to overcome this problem. In this study, we developed electrospun bilayer nanofibers consisting of a chitosan/PVA active layer loaded with pomegranate flower extract (PFE) and a PCL inactive back layer. Structural, morphological, and physicochemical properties of nanofibers were characterized and wound healing effects of PFE-loaded nanofibers were assessed by in vitro and in vivo experiments, including antibacterial tests, wound closure measurements, and histological and immunohistochemical (IHC) analyses. Nanofibers with optimum formulation showed good hydrophilicity, a mean diameter of 404 nm, and an average roughness of 217 nm. TGA and FTIR studies exhibited typical absorption characteristics of PFE, PCL, and PVA and the compatibility of PFE with the components of bilayer nanofibers. The cumulative amount of PFE released from the monolayer and bilayer fibers after 6 h was measured to be 100% and 64%, respectively, indicating the more sustained release of PFE from bilayer scaffolds. Based on mechanical studies, a more ductile behavior was observed for bilayer fibers than monolayer fibers. The antibacterial assay for PFE-loaded nanofibers exhibited an inhibition zone with a diameter of 19.0 ± 0.5 mm and 15.8 ± 0.3 mm for S. aureus and P. aeruginosa, respectively. PFE-loaded nanofiber exposure contributed to faster wound closure (88% in 14 days) and a significant rise in the expression of α-SMA, CD31, collagen I, and vimentin, indicating a higher tissue regeneration rate for PFE-loaded nanofibers over other treatment groups. In conclusion, bilayer nanofibers containing PFE have a promising potential for wound healing acceleration.

Application of Menstrual Blood Derived Stromal (stem) Cells Exert Greater Regenerative Potency Than Fibroblasts/Keratinocytes in Chronic Wounds of Diabetic Mice.

In this study we differentially showed the effects of cell-seeded bilayer scaffold wound dressing in accelerating healing process in diabetic ulcers that still remains as a major clinical challenge. The aim of the study was to compare immunomodulatory and angiogenic activity, and regenerative effect differences between Menstrual blood-derived Stem Cells (MenSCs) and foreskin-derived keratinocytes/fibroblasts. The streptozotocin-induced diabetic mice model was developed in male C57/BL6 mice. A bilayer scaffold was fabricated by electrospining silk fibroin nano-fibers on human Amniotic Membrane (AM). Dermal fibroblasts and keratinocyte isolated from neonatal foreskin and MenSCs were isolated from the menstrual blood of healthy women. The diabetic mice were randomly divided into three groups including no treatment group, fibroblast/keratinocyte-seeded bilayer scaffold group (bSC+FK), and MenSCs-seeded bilayer scaffold group. The healing of full-thickness excisional wounds evaluations in the diabetic mice model in each group were evaluated at 3, 7, and 14 days after treatment. The gross and histological data sets significantly showed wound healing promotion via re-epithelialization and wound contraction along with enhanced regeneration in MenSCs-seeded bilayer scaffold group with the most similarity to adjacent intact tissue. Immunofluorescence staining of mouse skin depicted a descending trend of type III collagen along with the higher expression of involucrin as keratinocyte marker in the MenSCs-seeded bilayer nanofibrous scaffold group in comparison with other treatment groups from day 7 to day 14. Moreover, higher levels of CD31 and von Willebrand factor (VWF), and also a higher ratio of M2/M1 macrophages in association with higher levels of the neural marker were observed in the bSC+MenSCs group in comparison with bSC+FK and no treatment groups. Healing symptoms in wounds dressed with keratinocyte/fibroblast-seeded bilayer scaffold was significantly lower than MenSCs-seeded bilayer scaffold done on impaired diabetic wound chronicity.

Structural and biological investigation of alginate-nano-hydroxyapatite with chitosan-hyaluronic acid for potential osteochondral regeneration

Cartilage joint lesions have created a significant challenge in the field of durable reconstruction and recovery due to their limited long-term repair and reconstruction. In this study, a biphasic scaffold was obtained using chitosan (CS)-hyaluronic acid (HA) and alginate-nanohydroxyapatite (nHAP) for osteoarthritis diseases. The scaffolds revealed porous structures and hydrophilic chemical groups by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) methods, respectively. The resulting three-dimensional hydrogels were assembled by using fibrin glue and seeded with human chondrocytes cells (hCHCs) in the chondral layer and human adipose-derived mesenchymal stem cells (hAdMSCs) in the subchondral one. Then, the assessments including 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), SEM, compressive assay, weight loss, alizarin red staining, alkaline phosphatase (ALP) activity, alcian blue staining and Real-Time PCR were performed. The associated cell viability confirmed that there were no interventions between the cell types and SEM illustrated cell attachment and spreading. The subchondral and chondral layers were investigated separately to detect their ability for cellular commitment. Finally, the Real-time PCR was carried out on the bilayer scaffold and the related observations approved the osteogenic/chondrogenic differentiation of both cell types. Taken together, the Alg-nHAP/CS-HA scaffold provided an appropriate environment for cartilage and bone regenerations and could be recommended for all aspects of osteochondral tissue engineering.

Preparation and Characterization of a Novel Tissue-Engineered Blood Vessel of dECM/CS/Gel Bilayer Scaffolds

At present, decellularized extracellular matrix (dECM) has become a popular research material worldwide due to its good biocompatibility in the research of small-diameter tissue engineering blood vessels (diameter ≤6mm). In this study, the cells of porcine coronary artery were removed by acellular method to obtain dECM, which was coated with chitosan (CS)/gelatin (Gel) mixed hydrogels with different concentrations to bionic the natural blood vessel’s multilayer structure. The mechanical properties, microstructure, and biocompatibility of scaffolds were characterized. The experiment result showed that the bilayer scaffolds with different proportions were successfully constructed by this method, and the outer layers and inner layers of scaffolds were closely connected, and the pores were evenly distributed. The critical tension and elastic modulus of the five scaffolds showed no significant difference, and all scaffolds had good biocompatibility.

A Biomimetic, Bilayered Antimicrobial Collagen-Based Scaffold for Enhanced Healing of Complex Wound Conditions.

Chronic, nonhealing wounds in the form of diabetic foot ulcers (DFUs) are a major complication for diabetic patients. The inability of a DFU to heal appropriately leads to an open wound with a high risk of infection. Current standards of care fail to fully address either the underlying defective wound repair mechanism or the risk of microbial infection. Thus, it is clear that novel approaches are needed. One such approach is the use of multifunctional biomaterials as platforms to direct and promote wound healing. In this study, a biomimetic, bilayered antimicrobial collagen-based scaffold was developed to deal with the etiology of DFUs. An epidermal, antimicrobial collagen/chitosan film for the prevention of wound infection was combined with a dermal collagen-glycosaminoglycan scaffold, which serves to support angiogenesis in the wound environment and ultimately accelerate wound healing. Biophysical and biological characterization identified an 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide cross-linked bilayered scaffold to have the highest structural stability with similar mechanical properties to products on the market, exhibiting a similar structure to native skin, successfully inhibiting the growth and infiltration of Staphylococcus aureus and supporting the proliferation of epidermal cells on its surface. This bilayered scaffold also demonstrated the ability to support the proliferation of key cell types involved in vascularization, namely, induced pluripotent stem cell derived endothelial cells and supporting stromal cells, with early signs of organization of these cells into vascular structures, showing great promise for the promotion of angiogenesis. Taken together, the results indicate that the bilayered scaffold is an excellent candidate for enhancement of diabetic wound healing by preventing wound infection and supporting angiogenesis.

Cell-based wound dressing: Bilayered PCL/gelatin nanofibers-alginate/collagen hydrogel scaffold loaded with mesenchymal stem cells

Wound dressing is applied to promote the healing process, wound protection, and additionally regeneration of injured skin. In this study, a bilayer scaffold composed of a hydrogel and nanofibers was fabricated to improve the regeneration of injured skin. To this end, polycaprolactone/gelatin (PCL/Gel) nanofibers were electrospun directly on the prepared collagen/alginate (Col/Alg) hydrogel. The bilayer scaffold was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), mechanical properties, and swelling/degradation time. Cytotoxicity assays were evaluated using MTT assay. Then, the nanofiber and bilayer scaffolds were seeded with Adipose-derived stem cells (ADSCs). ADSCs were isolated from rat adipose tissue and analyzed using flow cytometry, in advance. Full-thickness wounds on the backs of rats were dressed with ADSCs-seeded bilayer scaffolds and nanofibers. Histopathological evaluations were performed after 14 and 21 days using H&E (hematoxylin and eosin) staining. The results indicated that re-epithelialization, angiogenesis, and collagen remodeling were enhanced in ADSCs-seeded bilayer scaffolds and nanofibers in comparison with the control group. In conclusion, the best re-epithelialization, collagen organization, neovascularization, and low presence of inflammation in the wound area were observed in the ADSCs-seeded bilayer scaffolds.

Biomimetic Bilayered Scaffolds for Tissue Engineering: From Current Design Strategies to MedicalApplications.

Tissue damage due to cancer, congenital anomalies, and injuries needs new efficient treatments that allow tissue regeneration. In this context, tissue engineering shows a great potential to restore the native architecture and function of damaged tissues, by combining cells with specific scaffolds. Scaffolds made of natural and/or synthetic polymers and sometimes ceramics play a key role in guiding cell growth and formation of the new tissues. Monolayered scaffolds, which consist of uniform material structure, are reported as not being sufficient to mimic complex biological environment of the tissues. Osteochondral, cutaneous, vascular, and many other tissues all have multilayered structures, therefore multilayered scaffolds seem more advantageous to regenerate these tissues. In this review, recent advances in bilayered scaffolds design applied to regeneration of vascular, bone, cartilage, skin, periodontal, urinary bladder, and tracheal tissues are focused on. After a short introduction on tissue anatomy, composition and fabrication techniques of bilayered scaffolds are explained. Then, experimental results obtained in vitro and in vivo are described, and their limitations are given. Finally, difficulties in scaling up production of bilayer scaffolds and reaching the stage of clinical studies are discussed when multiple scaffold components are used.

Accelular nanofibrous bilayer scaffold intrapenetrated with polydopamine network and implemented into a full-thickness wound of a white-pig model affects inflammation and healing process

Treatment of complete loss of skin thickness requires expensive cellular materials and limited skin grafts used as temporary coverage. This paper presents an acellular bilayer scaffold modified with polydopamine (PDA), which is designed to mimic a missing dermis and a basement membrane (BM). The alternate dermis is made from freeze-dried collagen and chitosan (Coll/Chit) or collagen and a calcium salt of oxidized cellulose (Coll/CaOC). Alternate BM is made from electrospun gelatin (Gel), polycaprolactone (PCL), and CaOC. Morphological and mechanical analyzes have shown that PDA significantly improved the elasticity and strength of collagen microfibrils, which favorably affected swelling capacity and porosity. PDA significantly supported and maintained metabolic activity, proliferation, and viability of the murine fibroblast cell lines. The in vivo experiment carried out in a domestic Large white pig model resulted in the expression of pro-inflammatory cytokines in the first 1–2 weeks, giving the idea that PDA and/or CaOC trigger the early stages of inflammation. Otherwise, in later stages, PDA caused a reduction in inflammation with the expression of the anti-inflammatory molecule IL10 and the transforming growth factor β (TGFβ1), which could support the formation of fibroblasts. Similarities in treatment with native porcine skin suggested that the bilayer can be used as an implant for full-thickness skin wounds and thus eliminate the use of skin grafts.

Integrated and Bifunctional Bilayer 3D Printing Scaffold for Osteochondral Defect Repair

AbstractBioinspired scaffolds with two distinct regions resembling stratified anatomical architecture provide potential strategies for osteochondral defect repair and are studied in preclinical animals. However, delamination of the two layers often causes tissue disjunction between the regenerated cartilage and subchondral bone, leading to few commercially available clinical applications. This study develops an integrated poly(ε‐caprolactone) (PCL)‐based scaffold for repairing osteochondral defects. An extracellular matrix (ECM)‐incorporated 3D printing composite scaffold (ECM/PCL) coated with ECM hydrogel (E‐co‐E/PCL) is fabricated as the upper layer, and magnesium oxide nanoparticles coated with polydopamine (MgO@PDA)‐incorporated composite scaffold (MD/PCL) is fabricated using 3D printing as the bottom layer. The physicochemical and mechanical properties of the bilayer scaffold meet the requirements in designing and fabricating the osteochondral scaffold, especially a strong interface possessed between the two layers. By in vitro study, the integrated scaffold stimulates proliferation, chondrogenic differentiation, and osteogenic differentiation of human bone mesenchymal stem cells. Moreover, the integrated bilayer scaffold exhibits well repair ability to facilitate simultaneous regeneration of cartilage and subchondral bone after implanting into the osteochondral defect in rats. In addition, cartilage “tidemarks” completely regenerated after 12 weeks of implantation of the bilayer scaffold, which indicates no tissue disjunctions formed between the regenerated cartilage and subchondral bone.

Self-healing hybrid hydrogels with sustained bioactive components release for guided bone regeneration

Guided bone regeneration (GBR) is widely used in treating oral bone defects to exclude the influence of non-osteogenic tissue on the bone healing process. The traditional method of GBR with a titanium mesh to treat large-area bone defects is limited by the deficiency of increased trauma and costs to patients. Herein, a bi-layered scaffold for GBR composed of a fiber barrier layer and a self-healing hydrogel repair layer is successfully fabricated. The barrier layer is a fibrous membrane material with specific porosity constructed by electrospinning, while the functional layer is a self-healing hydrogel material formed by multiple dynamic covalent bonds. The system can provide an osteogenic microenvironment by preventing the infiltration of connective tissue to bone defects, maintain the stability of the osteogenic space through the self-healing property, and regulate the release of bioactive substances in the dynamic physical condition, which is beneficial to osteoblast proliferation, differentiation, and bone regeneration. This study focused on exploring the effects of different crosslinkers and bonding methods on the comprehensive properties of hydrogels. and proved that the hybrid scaffold system has good biocompatibility, cell barrier function and can enhance bone regeneration activity. Thereby it could be a promising clinical strategy for bone regeneration.

Bilayer scaffold from PLGA/fibrin electrospun membrane and fibrin hydrogel layer supports wound healing in vivo

Hybrid scaffolds from natural and synthetic polymers have been widely used due to the complementary nature of their physical and biological properties. The aim of the present study, therefore, has been to analyze in vivo a bilayer scaffold of poly(lactide-co-glycolide)/fibrin electrospun membrane and fibrin hydrogel layer on a rat skin model. Fibroblasts were cultivated in the fibrin hydrogel layer and keratinocytes on the electrospun membrane to generate a skin substitute. The scaffolds without and with cells were tested in a full-thickness wound model in Wistar Kyoto rats. The histological results demonstrated that the scaffolds induced granulation tissue growth, collagen deposition and epithelial tissue remodeling. The wound-healing markers showed no difference in scaffolds when compared with the positive control. Activities of antioxidant enzymes were decreased concerning the positive and negative control. The findings suggest that the scaffolds contributed to the granulation tissue formation and the early collagen deposition, maintaining an anti-inflammatory microenvironment.

Electrospinning of ultrafine non‐hydrolyzed silk sericin/PEO fibers on PLA: A bilayer scaffold fabrication

AbstractWe report the feasibility of electrospinning of protein‐polymer multilayered scaffolds with selected materials such as non‐hydrolyzed silk sericin (SS), polyethylene oxide (PEO), and polylactic acid (PLA), with tuned fiber size and properties for each layer. We present a new innovative way for the electrospinning (ES) of non‐hydrolyzed SS mixed with PEO yielding fibers with an average diameter ranging between 120 and 150 nm. Different SS:PEO ratios have been electrospun to study the effect of the concentration of SS protein on the fibers size and shape, as well and their electrospinnability. Electrospun SS:PEO fibers display weak to no mechanical resistance (non‐measurable) and their deposition onto a sturdier scaffold is necessary to allow their use in biomedical and/or pharmaceutical fields. Therefore, bilayer scaffolds have been fabricated consisting of a PLA support and SS:PEO fibers obtained from the optimized SS:PEO ratio (1.2:4). They are composed of a sturdy hydrophobic layer of PLA fibers and a layer of sticky hydrophilic SS:PEO fibers. The scaffolds have been characterized extensively by Fourier transforms infra‐red (FTIR) spectroscopy, X‐ray diffraction (XRD), scanning electron microscopy (SEM), and their resistance to mechanical stress. Finally, hydrophobicity of both layers has been determined by measuring the contact angle of water droplets on the scaffolds, further proving the bilayer nature of the scaffolds.