Multilayer functional bionic fabricated polycaprolactone based fibrous membranes for osteochondral integrated repair.

Osteochondral defect repair is one of the challenging problems in orthopedics. In this study, a multilayer polycaprolactone (PCL) based fibrous membrane for osteochondral defect repair was biomimetically fabricated by combining self-induced crystallization, biomimetic mineralization and layer-by-layer electrospinning techniques. The multilayer functional bionic fibrous membrane consisted of cartilage repair layer, intermediate transition repair layer and subchondral bone repair layer. Glucosamine hydrochloride (GAH) encapsulated in core-shell structured PCL fibrous membrane (MGPCL) was suitable for cartilage repair. Shish-kebab (SK) structured PCL fibrous membrane with calcium phosphate coating (MSKPCL) was designed for subchondral bone repair. SK structured MGPCL fibrous membrane (SKMGPCL) was used as intermediate transition repair. The tensile modulus of MG/SKMG/MSKPCL fibrous membrane was 34.24 ± 2.39 MPa which met the requirements of cartilage and subchondral bone repair scaffolds, and in vitro culture results showed that MG/SKMG/MSKPCL fibrous membrane had good biological activity and osteogenic ability. These results showed that MG/SKMG/MSKPCL fibrous membrane provides a promising material basis for osteochondral integrated repair scaffold.

A facile method to fabricate high performance PVA/PAA-AS hydrogel via the synergy of multiple hydrogen bonding and Hofmeister effect.

Hydrogels are widely used in biomedical engineering, which often require matched mechanical properties to meet specific demands. Recently, numerous research studies have contributed to tissue engineering hydrogels by soaking strategies to obtain designed properties. Herein, a strategy to fabricate poly(vinyl alcohol)/poly(acrylic acid)-ammonium sulfate (PVA/PAA-AS) hydrogel by successively soaking an aqueous PAA solution and (NH4)2SO4 solution based on the synergy of multiple hydrogen bonding and Hofmeister effect is reported, which exhibits remarkable comprehensive mechanical properties: rigidity (elastic modulus: 0.7-3.6 MPa), strength at break (tensile stress: 3.2-12.0 MPa; strain 320-650%), and toughness (fracture energy: 4.5-30.0 MJ m-3). Besides, PVA/PAA-AS hydrogel with unique spring-like microstructure exhibited super-resilience in 30% strain range by energy-transforming mechanism. Compared with pure PVA hydrogel, PVA/PAA-AS hydrogel has the equal excellent cytocompatibility. Therefore, PVA/PAA-AS hydrogel with high strength, modulus, toughness, super-resilience and excellent biocompatibility has potential applications in the soft tissue engineering field such as muscles, tendons, and ligaments.

Gelatin-glucosamine hydrochloride/crosslinked-cyclodextrin metal-organic frameworks@IBU composite hydrogel long-term sustained drug delivery system for osteoarthritis treatment.

Osteoarthritis (OA) is a disease of articular cartilage degradation and inflammation of the joint capsule. Combining anti-inflammatory therapy with nutritional supplement is an effective means for the treatment of OA. In this study, we prepared gelatin (Gel)-glucosamine hydrochloride (GH) mixed crosslinked-cyclodextrin metal-organic framework (G-GH/CL-CD-MOF) composite hydrogel. Polyethylene glycol diglycidyl ether was the crosslinking agent of GH and Gel to solve the problem of poor mechanical properties and water solubility at 37 °C. CL-CD-MOF was fabricated through a simple one-step chemical reaction to crosslink the hydrophilic hydroxyl groups in CD-MOF with diphenyl carbonate. Electron microscopy and x-ray diffraction analysis of CL-CD-MOF showed perfect porous morphology with a chaotic internal structure. CL-CD-MOF@IBU was prepared by immersing CL-CD-MOF in high-concentration ibuprofen (IBU) solution. CL-CD-MOF@IBU was uniformly dispersed in Gel and GH mixed solution to prepare G-GH/CL-CD-MOF@IBU composite hydrogel long-term sustained drug delivery system. The compression curve of G-GH/CL-CD-MOF composite hydrogel showed a non-linear elastic behavior. The cyclic loading-unloading compression showed that the shape of the G-GH/CL-CD-MOF composite hydrogel can be kept intact under 50% strain. On the day 14, the G-GH/CL-CD-MOF@IBU composite hydrogel was degraded by 87.1%, 61% of IBU was released. G-GH/CL-CD-MOF@IBU exhibited good biocompatibility during co-culture with MC3T3-E1 cells. Briefly, the certain mechanical properties, sustained drug release behavior, and good biocompatibility of G-GH/CL-CD-MOF@IBU composite hydrogel showed that it has potential application in OA treatment of long-term sustained nutritional supplement and anti-inflammatory synchronously.

Application of electrospun nanofibers in bone, cartilage and osteochondral tissue engineering.

Tissue damage related to bone and cartilage is a common clinical disease. Cartilage tissue has no blood vessels and nerves. The limited cell migration ability results in low endogenous healing ability. Due to the complexity of the osteochondral interface, the clinical treatment of osteochondral injury is limited. Tissue engineering provides new ideas for solving this problem. The ideal tissue engineering scaffold must have appropriate porosity, biodegradability and specific functions related to tissue regeneration, especially bioactive polymer nanofiber composite materials with controllable biodegradation rate and appropriate mechanical properties have been getting more and more research. The nanofibers produced by electrospinning have high specific surface area and suitable mechanical properties, which can effectively simulate the natural extracellular matrix (ECM) of bone or cartilage tissue. The composition of materials can affect mechanical properties, plasticity, biocompatibility and degradability of the scaffold, thereby further affect the repair efficiency. This article reviews the characteristics of polymer materials and the application of its electrospun nanofibers in bone, cartilage and osteochondral tissue engineering.

Core-Shell Nanofibers with a Shish-Kebab Structure Simulating Collagen Fibrils for Bone Tissue Engineering.

The repair of bone defects is one of the great challenges facing modern orthopedics clinics. Bone tissue engineering scaffold with a nanofibrous structure similar to the original microstructure of a bone is beneficial for bone tissue regeneration. Here, a core-shell nanofibrous membrane (MS), MS containing glucosamine (MS-GLU), MS with a shish-kebab (SK) structure (SKMS), and MS-GLU with a SK structure (SKMS-GLU) were prepared by micro-sol electrospinning technology and a self-induced crystallization method. The diameter of MS nanofibers was 50-900 nm. Contact angle experiments showed that the hydrophilicity of SKMS was moderate, and its contact angle was as low as 72°. SK and GLU have a synergistic effect on cell growth. GLU in the core of MS was demonstrated to obviously promote MC3T3-E1 cell proliferation. At the same time, the SK structure grown on MS-GLU nanofibers mimicked natural collagen fibers, which facilitated MC3T3-E1 cell adhesion and differentiation. This study showed that a biomimetic SKMS-GLU nanofibrous membrane was a promising tissue engineering scaffold for bone defect repair.