SOX9 functionalized scaffolds as a barrier to against cartilage fibrosis.

Hyaline cartilage regeneration will bring evangel to millions of people suffered from cartilage diseases. However, uncontrollable cartilage fibrosis and matrix mineralization are the primary causes of cartilage regeneration failure in many tissue engineering scaffolds. This study presents a new attempt to avoid endochondral ossification or fibrosis in cartilage regeneration therapy by establishing biochemical regulatory area. Here, SOX9 expression plasmids are assembled in cellulose gels by chitosan gene vectors to fabricate SOX9+ functionalized scaffolds. RT-qPCR, western blot and biochemical analysis all show that the SOX9 reinforcement strategy can enhance chondrogenic specific proteins expression and promote GAG production. Notably, the interference from SOX9 has resisted osteogenic inducing significantly, showing an inhibition of COL1, OPN and OC production, and the inhibition efficiency was about 58.4 %, 22.8 % and 76.9 % respectively. In vivo study, implantation of these scaffolds with BMSCs can induce chondrogenic differentiation and resist endochondral ossification effectively. Moreover, specific SOX9+ functionalized area of the gel exhibited the resistance to matrix mineralization, indicating the special biochemical functional area for cartilage regeneration. These results indicate that this strategy is effective for promoting the hyaline cartilage regeneration and avoiding cartilage fibrosis, which provides a new insight to the future development of cartilage regeneration scaffolds.

Physically cross-linked chitosan gel with tunable mechanics and biodegradability for tissue engineering scaffold.

Chitosan, a cationic polysaccharide, exhibits promising potential for tissue engineering applications. However, the poor mechanical properties and rapid biodegradation have been the major limitations for its applications. In this work, an effective strategy was proposed to optimize the mechanical performance and degradation rate of chitosan gel scaffolds by regulating the water content. Physical chitosan hydrogel (HG, with 93.57 % water) was prepared by temperature-controlled cross-linking, followed by dehydration to obtain xerogel (XG, with 2.84 % water) and rehydration to produce wet gel (WG, with 56.06 % water). During this process, changes of water content significantly influenced the water existence state, hydrogen bonding, and the chain entanglements of chitosan in the gel network. The mechanical compression results showed that the chitosan gel scaffolds exhibited tunable compressive strength (0.3128-139 MPa) and compressive modulus (0.2408-1094 MPa). XG could support weights exceeding 65,000 times its own mass while maintaining structural stability. Furthermore, in vitro and in vivo experiments demonstrated that XG and WG exhibited better biocompatibility and resistance to biodegradation compared with HG. Overall, this work contributes to the design and optimization of chitosan scaffolds without additional chemical crosslinkers, which has potential in tissue engineering and further clinical translation.

Double network microcrystalline cellulose hydrogels with high mechanical strength and biocompatibility for cartilage tissue engineering scaffold.

Cartilage tissue regeneration is tremendously tough, it has become a major clinical challenge for the orthopedic medical community. Because of their bionic structure, high water content, biocompatibility, and biodegradability, hydrogels derived from natural polysaccharide are excellent candidates for cartilage tissue engineering. However, these materials often face problems such as poor mechanical strength and excessive swelling, which limit their clinical application. This study used a chemical-physical multi-step cross-linking strategy to create double-network (DN) microcrystalline cellulose (MCC) hydrogels. The hydrogels' intrinsic biomimetic macroporous shape and high water content made them ideal for chondrocyte adhesion and proliferation. The performance requirements for cartilage tissue engineering scaffolds are met by DN hydrogels, which have a sufficiently high compressive strength (4.53 MPa), superior compression recovery, and fatigue resistance, compared to single-network (SN) hydrogels. According to in vitro findings, DN hydrogels could boost cell adhesion and proliferation due to their safe and non-toxic nature. Hydrogels were demonstrated to be stable over the long-term performance, to degrade slowly, and to have strong histocompatibility by in vivo implantation. To construct cartilage tissue engineering scaffold and conduct three-dimensional cell culture, DN hydrogels have significant potential.

Advances in surface modification of tantalum and porous tantalum for rapid osseointegration: A thematic review.

After bone defects reach a certain size, the body can no longer repair them. Tantalum, including its porous form, has attracted increasing attention due to good bioactivity, biocompatibility, and biomechanical properties. After a metal material is implanted into the body as a medical intervention, a series of interactions occurs between the material's surface and the microenvironment. The interaction between cells and the surface of the implant mainly depends on the surface morphology and chemical composition of the implant's surface. In this context, appropriate modification of the surface of tantalum can guide the biological behavior of cells, promote the potential of materials, and facilitate bone integration. Substantial progress has been made in tantalum surface modification technologies, especially nano-modification technology. This paper systematically reviews the progress in research on tantalum surface modification for the first time, including physicochemical properties, biological performance, and surface modification technologies of tantalum and porous tantalum.