Bioengineered neo-corneal endothelium using collagen type-I coated silk fibroin film

Therapeutic potential of silkworm sericin in wound healing applications

Chronic wounds are characterised by an imbalance between pro and anti-inflammatory signals, which result in permanent inflammation and delayed re-epithelialization, consequently hindering wound healing. They are associated with bacterial infections, tissue hypoxia, local ischemia, reduced vascularization, and MMP-9 upregulation. The global prevalence of chronic wounds has been estimated at 40 million in the adult population, with an alarming annual growth rate of 6.6%, making it an increasingly significant clinical problem. Sericin is a natural hydrophilic protein obtained from the silkworm cocoon. Due to its biocompatibility, biodegradability, non-immunogenicity, and oxidation resistance, coupled with its excellent affinity for target biomolecules, it holds great potential in wound healing applications. The silk industry discards 50,000 tonnes of sericin annually, making it a readily available material. Sericin increases cell union sites and promotes cell proliferation in fibroblasts and keratinocytes, thanks to its cytoprotective and mitogenic effects. Additionally, it stimulates macrophages to release more therapeutic cytokines, thus improving vascularization. This review focuses on the biological properties of sericin that contribute towards enhanced wound healing process and its mechanism of interaction with important biological targets involved in wound healing. Emphasis is placed on diverse wound dressing products that are sericin based and the utilisation of nanotechnology to design sericin nanoparticles that aid in chronic wound management.

Sustainable Bombyx mori's silk fibroin for biomedical applications as a molecular biotechnology challenge: A review

Silk is a natural engineering material with a unique set of properties. The major constituent of silk is fibroin, a protein widely used in the biomedical field because of its mechanical strength, toughness and elasticity, as well as its biocompatibility and biodegradability. The domestication of silkworms allows large amounts of fibroin to be extracted inexpensively from silk cocoons. However, the industrial extraction process has drawbacks in terms of sustainability and the quality of the final medical product. The heterologous production of fibroin using recombinant DNA technology is a promising approach to address these issues, but the production of such recombinant proteins is challenging and further optimization is required due to the large size and repetitive structure of fibroin's DNA and amino acid sequence. In this review, we describe the structure-function relationship of fibroin, the current extraction process, and some insights into the sustainability of silk production for biomedical applications. We focus on recent advances in molecular biotechnology underpinning the production of recombinant fibroin, working toward a standardized, successful and sustainable process.

Approaches for corneal endothelium regenerative medicine

The state of the art therapy for treating corneal endothelial disease is transplantation. Advances in the reproducibility and accessibility of surgical techniques are increasing the number of corneal transplants, thereby causing a global deficit of donor corneas and leaving 12.7 million patients with addressable visual impairment. Approaches to regenerate the corneal endothelium offer a solution to the current tissue scarcity and a treatment to those in need. Methods for generating corneal endothelial cells into numbers that could address the current tissue shortage and the possible strategies used to deliver them have now become a therapeutic reality with clinical trials taking place in Japan, Singapore and Mexico. Nevertheless, there is still a long way before such therapies are approved by regulatory bodies and become clinical practice. Moreover, acellular corneal endothelial graft equivalents and certain drugs could provide a treatment option for specific disease conditions without the need of donor tissue or cells. Finally, with the emergence of gene modulation therapies to treat corneal endothelial disease, it would be possible to treat presymptomatic patients or those presenting early symptoms, drastically reducing the need for donor tissue. It is necessary to understand the most recent developments in this rapidly evolving field to know which conditions could be treated with which approach. This article provides an overview of the current and developing regenerative medicine therapies to treat corneal endothelial disease and provides the necessary guidance and understanding towards the treatment of corneal endothelial disease.

Potential of a novel scaffold composed of human platelet lysate and fibrin for human corneal endothelial cells

Cell-based therapies have been emerged to find innovative solutions for corneal endothelial dysfunction. The aim of this study is to investigate the suitability of a blended scaffold containing human platelet lysate (HPL) and fibrin not only for cultivating human corneal endothelial cells (HCECs) but also for serving as a scaffold for the respected cells. We isolated HCECs from human donors and encapsulated the cells with three concentrations of HPL/Fibrin scaffold, namely HPL/Fibrin 1, HPL/Fibrin 2 and HPL/Fibrin 3, by adding 28.9, 57.8 and 86.7 mg/dl of fibrinogen to HPL to obtain a final percentage of 10, 20 and 30 % of fibrinogen, respectively. SEM imaging and swelling test were done to characterize the scaffolds. Cell viability assay and cell counting were performed on the cells. HCECs were characterized by morphology and immunocytochemistry. SEM imaging on freeze-dried scaffolds showed higher porosity of HPL/Fibrin 1 and HPL/Fibrin 2 than HPL/Fibrin 3, but larger pores were observed only in HPL/Fibrin 1. Cellular attachment and morphology on HPL/Fibrin 1 were appropriate by SEM imaging. A higher swelling rate was observed in HPL/Fibrin 1. After 3 and 5 days, higher numbers of cells were observed specifically in HPL/Fibrin 1. A higher expression of Na+/K+-ATPase, ZO-1 and vimentin proteins was detected in the HPL/Fibrin 1-cultured HCECs as compared with control (no scaffold). HPL/Fibrin can be used as a suitable scaffold for HCECs while preserving the cells viability. Further investigations are necessitated to approve the beneficial effects of the suggested scaffold for delivering and transplantation of cultivated HCECs into the anterior chamber of the eye.

Silk Film Stiffness Modulates Corneal Epithelial Cell Mechanosignaling

Silk fibroin films are excellent candidate biomaterials for corneal tissue engineering due to their optical transparency, biocompatibility, and mechanical strength. Their tunable chemical and mechanical properties open the possibility of engineering cellular microenvironments that can both mimic native corneal tissue and provide stimuli to actively promote wound regeneration. While silk film mechanical properties, such as surface topography, have demonstrated the ability to control corneal epithelial cell wound regenerating behavior, few studies have explored the stiffness tunability of these films and its cellular effects. Cells are known actively sense the stiffness of their surroundings and processes such as cell adhesion, migration, proliferation, and expression of stem markers can be strongly influenced by matrix stiffness. This study develops technical solutions that allow for both the fabrication of films with stiffnesses similar to corneal tissue and also for their characterization in an aqueous, native-like environment at a scale relevant to cellular forces. Physiological evidence demonstrates that corneal epithelial cells are mechanosensitive to films of different stiffnesses and show that cell spreading, cytoskeletal tension, and molecular mechanotransducer localization are associated with film stiffness. These results indicate that silk film stiffness can be used to regulate cell behavior for the purposes of ocular surface repair.

Current development of alternative treatments for endothelial decompensation: Cell-based therapy

Current treatment for corneal endothelial dysfunction consists in the replacement of corneal endothelium by keratoplasty. Owing to the scarcity of donor corneas and the increasing number of transplants, alternative treatments such as cell-based therapies are necessary. In this article, we highlight the biological aspects of the cornea and the corneal endothelium, as well as the context that surrounds the need for new alternatives to conventional keratoplasty. We then review some of those experimental treatments in more detail, focusing on the development of the in vitro and preclinical phases of two cell-based therapies: tissue-engineered endothelial keratoplasty (TE-EK) and cell injection. In the case of TE-EK graft construction, we analyse the current progress, considering all the requirements it must meet in order to be functional. Moreover, we discuss the inherent drawbacks of endothelial keratoplasties, which TE-EK grafts should overcome in order to make surgical intervention easier and to improve the outcomes of current endothelial keratoplasties. Finally, we analyse the development of preclinical trials and their limitations in terms of performing an optimal functional evaluation of cell-based therapy, and we conclude by discussing early clinical trials in humans.

Biomaterials for corneal endothelial cell culture and tissue engineering

The corneal endothelium is the posterior monolayer of cells that are responsible for maintaining overall transparency of the avascular corneal tissue via pump function. These cells are non-regenerative in vivo and therefore, approximately 40% of corneal transplants undertaken worldwide are a result of damage or dysfunction of endothelial cells. The number of available corneal donor tissues is limited worldwide, hence, cultivation of human corneal endothelial cells (hCECs) in vitro has been attempted in order to produce tissue engineered corneal endothelial grafts. Researchers have attempted to recreate the current gold standard treatment of replacing the endothelial layer with accompanying Descemet's membrane or a small portion of stroma as support with tissue engineering strategies using various substrates of both biologically derived and synthetic origin. Here we review the potential biomaterials that are currently in development to support the transplantation of a cultured monolayer of hCECs.

Corneal endothelium tissue engineering: An evolution of signaling molecules, cells, and scaffolds toward 3D bioprinting and cell sheets

Cornea is an avascular and transparent tissue that focuses light on retina. Cornea is supported by the corneal-endothelial layer through regulation of hydration homeostasis. Restoring vision in patients afflicted with corneal endothelium dysfunction-mediated blindness most often requires corneal transplantation (CT), which faces considerable constrictions due to donor limitations. An emerging alternative to CT is corneal endothelium tissue engineering (CETE), which involves utilizing scaffold-based methods and scaffold-free strategies. The innovative scaffold-free method is cell sheet engineering, which typically generates cell layers surrounded by an intact extracellular matrix, exhibiting tunable release from the stimuli-responsive surface. In some studies, scaffold-based or scaffold-free technologies have been reported to achieve promising outcomes. However, yet some issues exist in translating CETE from bench to clinical practice. In this review, we compare different corneal endothelium regeneration methods and elaborate on the application of multiple cell types (stem cells, corneal endothelial cells, and endothelial precursors), signaling molecules (growth factors, cytokines, chemical compounds, and small RNAs), and natural and synthetic scaffolds for CETE. Furthermore, we discuss the importance of three-dimensional bioprinting strategies and simulation of Descemet's membrane by biomimetic topography. Finally, we dissected the recent advances, applications, and prospects of cell sheet engineering for CETE.

Influence of the Casting Concentration on the Mechanical and Optical Properties of FA/CaCl2-Derived Silk Fibroin Membranes

In this study, we describe the manufacturing and characterization of silk fibroin membranes derived from the silkworm Bombyx mori. To date, the dissolution process used in this study has only been researched to a limited extent, although it entails various potential advantages, such as reduced expenses and the absence of toxic chemicals in comparison to other conventional techniques. Therefore, the aim of this study was to determine the influence of different fibroin concentrations on the process output and resulting membrane properties. Casted membranes were thus characterized with regard to their mechanical, structural and optical assets via tensile testing, SEM, light microscopy and spectrophotometry. Cytotoxicity was evaluated using BrdU, XTT, and LDH assays, followed by live-dead staining. The formic acid (FA) dissolution method was proven to be suitable for the manufacturing of transparent and mechanically stable membranes. The fibroin concentration affects both thickness and transparency of the membranes. The membranes did not exhibit any signs of cytotoxicity. When compared to other current scientific and technical benchmarks, the manufactured membranes displayed promising potential for various biomedical applications. Further research is nevertheless necessary to improve reproducible manufacturing, including a more uniform thickness, less impurity and physiological pH within the membranes.

Mussel-inspired polydopamine-coated silk fibroin as a promising biomaterial

Silk fibroin (SF) is one of the natural biomaterials with promising and growing potential in different clinical applications such as corneal transplantation, donor site skin substitute and tympanic membrane. Some of the SFs that are extracted from mulberry silkworm do not have the arginyl–glycyl–aspartic acid (RGD) sequence for properly supporting cell adhesion and proliferation. Therefore, in the current study, polydopamine (PDA)-coated SFs were prepared to provide an RGD sequence, and the effect of PDA coating on different properties of SF was investigated. The results are also compared with those of an amniotic membrane (AM) that is a commercially available natural biomaterial for the mentioned applications. The Raman spectra showed characteristic peaks at 1581 and 1370 cm−1, which demonstrate the formation of the coating layer on the surface of the films. The results showed that coating led to no significant difference in surface hydrophilicity; a smoother surface; and improved cell attachment and distribution; and a little decrease in membrane transparency, but the membrane still being transparent enough to provide vivid vision through it.

Characterization of surface modified glycerol/silk fibroin film for application to corneal endothelial cell regeneration

Corneal endothelial cells (CEnCs) play a fundamental role in maintaining the transparency of the cornea. CEnCs lose their full proliferating capacity when tissue damages occur. The loss in proliferation rate is associated with corneal edema and decrease in visual acuity, leading in severe cases, to blindness. In these situations, a corneal transplant is usually needed to restore the original tissue functions. Tissue engineering is an efficient alternative for the production of implantable films, which can regenerate the tissue functions regulating at the same time the immune-response. In this study, we proposed a stable and transparent film, composed of silk fibroin modified with glycerol (G/SF), as a potential substrate for corneal endothelial cells regeneration. Our results confirmed that G/SF films have a uniform structure, rougher surface and lower thickness respect to the SF film. In vitro tests show that G/SF films can induce a slight increase in CEnCs initial adhesion and proliferation rate if compared with the SF film. Morphology and gene expression evaluations demonstrated that the bioactive effects of silk fibroin were not affected by the presence of glycerol. For this reason, the G/SF films are suitable as CEnCs carrier and promising for the corneal damages treatments.

Quercetin Inlaid Silk Fibroin/Hydroxyapatite Scaffold Promotes Enhanced Osteogenesis

There is a significant rise in the bone grafts demand worldwide to treat bone defects owing to continuous increase in conditions such as injury, trauma, diseases, or infections. Therefore, development of three-dimensional scaffolds has evolved as a reliable technology to address the current limitations for bone tissue regeneration. Mimicking the natural bone, in this study, we have designed a silk fibroin/hydroxyapatite scaffold inlaid with a bioactive phytochemical (quercetin) at different concentrations for promoting osteogenesis, especially focusing on quercetin ability for enhancing bone health. Characterization of the quercetin/silk fibroin/hydroxyapatite (Qtn/SF/HAp) scaffolds showed an increased pore size and irregular porous microstructure with good mechanical strength. The Qtn (low-content)/SF/HAp scaffold was found to be an efficient cell carrier facilitating cellular growth, osteogenic differentiation, and proliferation as compared to SF/HAp and Qtn (high-content)/SF/HAp scaffolds. However, Qtn (high-content)/SF/HAp was observed to inhibit cell proliferation without any effects on cell viability. In vitro and in vivo outcomes studied using bone marrow-derived mesenchymal stem cells (rBMSCs) confirm the cytocompatibility, osteogenic differentiation ability, and prominent upregulation of the bone-specific gene expressions for the rBMSCs-seeded Qtn/SF/HAp scaffolds. In particular, the implanted Qtn (low-content)/SF/HAp scaffolds at the bone defect site were found to be well-attached and amalgamated with the surrounding tissues with approximately 80% bone volume recovery at 6 weeks after surgery as compared with other groups. Based on the aforementioned observations highlighting the quercetin efficiency for bone regeneration, the as-synthesized Qtn (low-content)/SF/HAp scaffolds can be envisioned to provide a biomimetic bone-like microenvironment promoting rBMSCs differentiation into osteoblast, thus suggesting a potential alternative graft for high-performance regeneration of bone tissues.

Natural Biomaterials for Corneal Tissue Engineering, Repair, and Regeneration

Corneal blindness is a major cause of vision loss, estimated to affect over 10 million people worldwide. Once impaired through clouding or shape change, the best treatment option for restoring vision is corneal transplantation using full or partial thickness cadaveric grafts. However, donor corneas are globally limited and face rejection and graft failure, similar to other transplanted organs. Thus, there is a need for viable alternatives to donor corneas in order to increase supply, reduce rejection, and to minimize variability in tissue quality. To address this, researchers have developed new materials and strategies to tissue engineer full or partial thickness cornea grafts in order to repair, regenerate, or replace the diseased cornea. This progress report first reviews the anatomy and physiology of the cornea to frame the biological requirements and discuss the injuries and diseases that necessitate the need fortransplantation, as well as the requirements for a suitable donor tissue alternative. This is followed by recent progress using naturally derived biomaterials including silk, collagen, amniotic membranes, and decellularized corneas. Finally, remaining challenges in the field as they relate to the biomaterials discussed are identified, and the future research directions that should result in further advances in restoring corneal vision are highlighted.

Biofunctionalized Lysophosphatidic Acid/Silk Fibroin Film for Cornea Endothelial Cell Regeneration

Cornea endothelial cells (CEnCs) tissue engineering is a great challenge to repair diseased or damaged CEnCs and require an appropriate biomaterial to support cell proliferation and differentiation. Biomaterials for CEnCs tissue engineering require biocompatibility, tunable biodegradability, transparency, and suitable mechanical properties. Silk fibroin-based film (SF) is known to meet these factors, but construction of functionalized graft for bioengineering of cornea is still a challenge. Herein, lysophosphatidic acid (LPA) is used to maintain and increase the specific function of CEnCs. The LPA and SF composite film (LPA/SF) was fabricated in this study. Mechanical properties and in vitro studies were performed using a rabbit model to demonstrate the characters of LPA/SF. ATR-FTIR was characterized to identify chemical composition of the films. The morphological and physical properties were performed by SEM, AFM, transparency, and contact angle. Initial cell density and MTT were performed for adhesion and cell viability in the SF and LPA/SF film. Reverse transcription polymerase chain reactions (RT-PCR) and immunofluorescence were performed to examine gene and protein expression. The results showed that films were designed appropriately for CEnCs delivery. Compared to pristine SF, LPA/SF showed higher biocompatibility, cell viability, and expression of CEnCs specific genes and proteins. These indicate that LPA/SF, a new biomaterial, offers potential benefits for CEnCs tissue engineering for regeneration.

Vascular Cell Co-Culture on Silk Fibroin Matrix

Silk fibroin (SF), a natural polymer material possessing excellent biocompatibility and biodegradability, and has been widely used in biomedical applications. In order to explore the behavior of vascular cells by co-culturing on regenerated SF matrix for use as artificial blood vessels, human aorta vascular smooth muscle cells (HAVSMCs) were co-cultured with human arterial fibroblasts (HAFs) or human umbilical vein endothelial cells (HUVECs) on SF films and SF tubular scaffolds (SFTSs). Analysis of cell morphology and deoxyribonucleic acid (DNA) content showed that HUVECs, HAVSMCs and HAFs adhered and spread well, and exhibited high proliferative activity whether cultured alone or in co-culture. Immunofluorescence and scanning electron microscopy (SEM) analysis showed that HUVECs and HAFs co-existed well with HAVSMCs on SF films or SFTSs. Cytokine expression determined by reverse transcription-polymerase chain reaction (RT-PCR) indicated that the expression levels of α-smooth muscle actin (α-SMA) and smooth muscle myosin heavy chain (SM-MHC) in HAVSMCs were inhibited on SF films or SFTSs, but expression could be obviously promoted by co-culture with HUVECs or HAFs, especially that of SM-MHC. On SF films, the expression of vascular endothelial growth factor (VEGF) and platelet endothelial cell adhesion molecule-1 (CD31) in HUVECs was promoted, and the expression levels of both increased obviously when co-cultured with HAVSMCs, with the expression levels of VEGF increasing with increasing incubation time. The expression levels of VEGF and CD31 in cells co-cultured on SFTSs improved significantly from day 3 compared with the mono-culture group. These results were beneficial to the mechanism analysis on vascular cell colonization and vascular tissue repair after in vivo transplantation of SFTSs.

Functionalized silk fibroin film scaffold using β-Carotene for cornea endothelial cell regeneration

Design of corneal endothelium substitute is important for replacement of cadaveric cornea tissue. Our previous study has shown the suitability of silk fibroin (SF) as a biomaterial for cornea scaffold. In this study, we used β-Carotene (β-C) to enhance the regeneration of corneal endothelial cells (CEnCs) and maintain CEnC specific function. The fabricated film scaffolds showed desired transparency and hydrophilic properties which are crucial factors for vision recovery. The cell viability, phenotype and gene expression was examined using MTT assay, immunofluorescence and reverse transcription polymerase chain reactions. Compared with pristine SF scaffold, proper amount of β-C incorporated with SF scaffolds showed higher initial cell attachment, cell viability and mRNA expression. The results indicate that the fabricated SF film scaffold incorporated with small amount of β-C might be the suitable alternative corneal endothelium substitute for transplantation.

Multi-layered silk film coculture system for human corneal epithelial and stromal stem cells

With insufficient options to meet the clinical demand for cornea transplants, one emerging area of emphasis is on cornea tissue engineering. In the present study, the goal was to combine the corneal stroma and epithelium into one coculture system, to monitor both human corneal stromal stem cell (hCSSC) and human corneal epithelial cell (hCE) growth and differentiation into keratocytes and differentiated epithelium in these three-dimensional tissue systems in vitro. Coculture conditions were first optimized, including the medium, air-liquid interface culture, and surface topography and chemistry of biomaterial scaffold films based on silk protein. The silk was used as scaffolding for both stromal and epithelial tissue layers because it is cell compatible, can be surface patterned, and is optically clear. Next, the effects of proliferating and differentiating hCEs and hCSSCs were studied in this in vitro system, including the effects on cell proliferation, matrix formation by immunochemistry, and gene expression by quantitative reverse transcription-polymerase chain reaction. The incorporation of both cell types into the coculture system demonstrated more complete differentiation and growth for both cell types compared to the corneal stromal cells and corneal epithelial cells alone. Silk films for corneal epithelial culture were optimized to combine a 4.0-μm-scale surface pattern with bulk-loaded collagen type IV. Differentiation of each cell type was in evidence based on increased expression of corneal stroma and epithelial proteins and transcript levels after 6 weeks in coculture on the optimized silk scaffolds.

Regulating the gaps between folds on the surface of silk fibroin membranes via LBL deposition for improving their biomedical properties

Silk fibroin (SF) has become a promising biomaterial in guided bone regeneration (GBR). In an attempt to modify the size of the gaps on the surface of SF barrier membrane and improve its antibacterial activity, biological and mechanical properties, positively charged Lysozyme (LY)-Collagen Type-I (COL) composites and negatively charged SF were introduced to the negatively charged surface of SF substrates utilizing the electrostatic layer-by-layer (LBL) self-assembly technique. The morphology, chemical structures and element content of the LBL structured membranes were investigated. The results suggested that LY and COL were successfully assembled and the gaps between the folds on the surface of the membranes became smaller gradually with the increase of coated film numbers. Besides, the content of β-sheets of the membranes increased after deposition, which indicated the improvement of their mechanical properties. Moreover, the results of the measurement of immobilized LY and antibacterial assay not only revealed that the enzymatic catalysis and antibacterial activity of the samples enhanced with the increase of coated bilayer numbers but also implied that LBL modified membranes had better antibacterial activity when LY-COL was on the outermost layer. Furthermore, CCK-8 assay certified both SF membrane and LBL structured membranes could facilitate cell growth and proliferation, and the introduction of COL could further promote this ability. Finally, cell attachment and morphology examination provided intuitional evidence that SF membrane and LBL modified membranes have excellent biocompatibility.

Optimization of Corneal Epithelial Progenitor Cell Growth on Bombyx mori Silk Fibroin Membranes

Scaffolds prepared from silk fibroin derived from cocoons of the domesticated silkworm moth Bombyx mori have demonstrated potential to support the attachment and growth of human limbal epithelial (HLE) cells in vitro. In this study, we attempted to further optimize protocols to promote the expansion of HLE cells on B. mori silk fibroin- (BMSF-) based scaffolds. BMSF films were initially coated with different extracellular matrix proteins and then analysed for their impact on corneal epithelial cell adhesion, cell morphology, and culture confluency. Results showed that collagen I, collagen III, and collagen IV consistently improved HCE-T cell adherence, promoted an elongated cell morphology, and increased culture confluency. By contrast, ECM coating had no significant effect on the performance of primary HLE cells cultured on BMSF films. In the second part of this study, primary HLE cells were grown on BMSF films in the presence of medium (SHEM) supplemented with keratinocyte growth factor (KGF) and the Rho kinase inhibitor, Y-27632. The results demonstrated that SHEM medium supplemented with KGF and Y-27632 dramatically increased expression of corneal differentiation markers, keratin 3 and keratin 12, whereas expression of the progenitor marker, p63, did not appear to be significantly influenced by the choice of culture medium.

Nature-Derived Aloe Vera Gel Blended Silk Fibroin Film Scaffolds for Cornea Endothelial Cell Regeneration and Transplantation

The goal of this study was to fabricate an appropriate replacement for cadaveric corneas to overcome a shortage of cadaveric corneas for transplantation. In this study, we fabricated transparent ultrathin film scaffolds with nature-derived aloe vera (AV) gel and silk fibroin (SF) for corneal endothelial cells (CECs). The scaffolds were subjected to analysis of transparency and contact angle using field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy to determine their physical and chemical properties. FESEM images revealed that the critical morphology of CECs was formed on the AV gel in the blend with SF rather than in the scaffold with SF alone. The cell proliferation, phenotype, and specific gene marker expressions for CECs were determined by MTT assays, immunofluorescence, and reverse transcription polymerase chain reactions. Incorporation of a small amount of AV gel increased the cell viability and maintained its functions well. The scaffolds were easily handled for transplantation into rabbit eyes with small incisions and examined by their transparency after transplantation and histological staining. The scaffolds attached to the surface of the corneal stroma and integrated with surrounding corneal tissue without a significant inflammatory reaction. These results indicate that AV blended SF film scaffolds might be a suitable substitute for alternative corneal grafts for transplantation.

Elastomers in vascular tissue engineering

Elastomers are popular in vascular engineering applications, as they offer the ability to design implants that match the compliance of native tissue. By mimicking the natural tissue environment, elastic materials are able to integrate within the body to promote repair and avoid the adverse physiological responses seen in rigid alternatives that often disrupt tissue function. The design of elastomers has continued to evolve, moving from a focus on long term implants to temporary resorbable implants that support tissue regeneration. This has been achieved through designing chemistries and processing methodologies that control material behavior and bioactivity, while maintaining biocompatibility in vivo. Here we review the latest developments in synthetic and natural elastomers and their application in cardiovascular treatments.