Hybrid and Composite Scaffolds Based on Extracellular Matrices for Cartilage Tissue Engineering

Cartilage consists of chondrocytes and a special extracellular matrix (ECM) having unique biochemical, biophysical, and biomechanical properties that play a critical role in the proliferation and differentiation of cells inherent to cartilage functions. Cartilage tissue engineering (CTE) requires recreating these microenvironmental physicochemical conditions to lead to chondrocyte differentiation from stem cells. ECM-derived hybrid scaffolds based on chondroitin sulfate, hyaluronic acid, collagen, and cartilage ECM analogs provide environments conducive to stem cell proliferation. In this review, we describe hybrid scaffolds based on these four cartilage ECM derivatives; we also categorize these scaffolds based on the methods used for their preparation. The use of hybrid scaffolds is increasing in CTE to address the complexity of cartilage tissue. Thus, a comprehensive review on the topic should be a useful guide for future research. Scaffolds fabricated from extracellular matrix (ECM) derivatives are composed of conducive structures for cell attachment, proliferation, and differentiation, but generally do not have proper mechanical properties and load-bearing capacity. In contrast, scaffolds based on synthetic biomaterials demonstrate appropriate mechanical strength, but the absence of desirable biological properties is one of their main disadvantages. To integrate mechanical strength and biological cues, these ECM derivatives can be conjugated with synthetic biomaterials. Hence, hybrid scaffolds comprising both advantages of synthetic polymers and ECM derivatives can be considered a robust vehicle for tissue engineering applications. © Copyright 2019, Mary Ann Liebert, Inc., publishers 2019

Bioprinting Via a Dual-Gel Bioink Based on Poly(Vinyl Alcohol) and Solubilized Extracellular Matrix towards Cartilage Engineering

Various hydrogel systems have been developed as biomaterial inks for bioprinting, including natural and synthetic polymers. However, the available biomaterial inks, which allow printability, cell viability, and user-defined customization, remains limited. Incorporation of biological extracellular matrix materials into tunable synthetic polymers can merge the benefits of both systems towards versatile materials for biofabrication. The aim of this study was to develop novel, cell compatible dual-component biomaterial inks and bioinks based on poly(vinyl alcohol) (PVA) and solubilized decellularized cartilage matrix (SDCM) hydrogels that can be utilized for cartilage bioprinting. In a first approach, PVA was modified with amine groups (PVA-A), and mixed with SDCM. The printability of the PVA-A/SDCM formulations cross-linked by genipin was evaluated. On the second approach, the PVA was functionalized with cis-5-norbornene-endo-2,3-dicarboxylic anhydride (PVA-Nb) to allow an ultrafast light-curing thiol-ene cross-linking. Comprehensive experiments were conducted to evaluate the influence of the SDCM ratio in mechanical properties, water uptake, swelling, cell viability, and printability of the PVA-based formulations. The studies performed with the PVA-A/SDCM formulations cross-linked by genipin showed printability, but poor shape retention due to slow cross-linking kinetics. On the other hand, the PVA-Nb/SDCM showed good printability. The results showed that incorporation of SDCM into PVA-Nb reduces the compression modulus, enhance cell viability, and bioprintability and modulate the swelling ratio of the resulted hydrogels. Results indicated that PVA-Nb hydrogels containing SDCM could be considered as versatile bioinks for cartilage bioprinting

Plastination of decalcified bone by a new resin technique

Background: The scope of this study was to preserve whole detailed structure of dissected and decalcified bones, taken from used cadavers, by a new plastination technique. Materials and Methods: Specimens we used in this study were sheep femurs and human bones including pelvis, femur, tibia, and fibula. Bones, at first, fixed with 5% formalin and were decalcified with 5% nitric acid, and then were fixed again and washed under the tap water. The resulted flexible bones were dehydrated in -25΀C acetone and degreased them in +25΀C acetone. Then, the experimental and control specimen were placed in the vacuum chamber for forced impregnation with our new flexible unsaturated polyester resin (UP 89 method) and silicon resin (S 10 method), respectively. Finally, the strength and flexibility of plastinated decalcified specimens were investigated by tensometer, and the weight diversity was measured by digital balance. Results: Plastinated bones prepared by this technique were found to be dried, non-fragile, durable, odorless, non-greasy, and demonstrating all detailed structures of the bones. Tensile and weight tests results indicated that plastinated decalcified femurs have owned higher flexibility and strength but lesser weight than plastinated undecalcified femurs. The characteristics of both experimental and control groups of plastinated decalcified specimens were found to have no significant difference. Conclusions: Our synthesized resin found to be much more economical than conventional plastination method. In more details, properties of these new products were the same as, S 10 method, from points of strength, flexibility and weight, but, since the money cost for producing them was about one fifth that of S 10 method

A Review on Antibacterial Biomaterials in Biomedical Applications: From Materials Perspective to Bioinks Design

In tissue engineering, three-dimensional (3D) printing is an emerging approach to producing functioning tissue constructs to repair wounds and repair or replace sick tissue/organs. It allows for precise control of materials and other components in the tissue constructs in an automated way, potentially permitting great throughput production. An ink made using one or multiple biomaterials can be 3D printed into tissue constructs by the printing process; though promising in tissue engineering, the printed constructs have also been reported to have the ability to lead to the emergence of unforeseen illnesses and failure due to biomaterial-related infections. Numerous approaches and/or strategies have been developed to combat biomaterial-related infections, and among them, natural biomaterials, surface treatment of biomaterials, and incorporating inorganic agents have been widely employed for the construct fabrication by 3D printing. Despite various attempts to synthesize and/or optimize the inks for 3D printing, the incidence of infection in the implanted tissue constructs remains one of the most significant issues. For the first time, here we present an overview of inks with antibacterial properties for 3D printing, focusing on the principles and strategies to accomplish biomaterials with anti-infective properties, and the synthesis of metallic ion-containing ink, chitosan-containing inks, and other antibacterial inks. Related discussions regarding the mechanics of biofilm formation and antibacterial performance are also presented, along with future perspectives of the importance of developing printable inks