Novel injectable adhesive hydrogel loaded with exosomes for holistic repair of hemophilic articular cartilage defect

Hemophilic articular cartilage damage presents a significant challenge for surgeons,characterized by recurrent intraarticular bleeding,a severe inflammatory microenvironment,and limited self-repair capability of cartilage tissue.Currently,there is a lack of tissue engineering-based integrated therapies that address both early hemostasis,anti-inflammation,and long-lasting chondrogenesis for hemophilic articular cartilage defects.Herein,we developed an adhesive hydrogel using oxidized chondroitin sulfate and gelatin,loaded with exosomes derived from bone marrow stem cells(BMSCs)(Hydrogel-Exos).This hydrogel demonstrated favorable injectability,self-healing,biocompatibility,biodegradability,swelling,frictional and mechanical properties,providing a comprehensive approach to treating hemophilic articular cartilage defects.The adhesive hydrogel,featuring dynamic Schiff base bonds and hydrogen bonds,exhibited excellent wet tissue adhesiveness and hemostatic properties.In a pig model,the hydrogel could be smoothly injected into the knee joint cartilage defect site and gelled in situ under fluid-irrigated arthroscopic conditions.Our in vitro and in vivo experiments confirmed that the sustained release of exosomes yielded anti-inflammatory effects by modulating macrophage M2 polarization through the NF-κB pathway.This immunoregulatory effect,coupled with the extracellular matrix components provided by the adhesive hydrogel,enhanced chondrogenesis,promoted the cartilage repair and joint function restoration after hemophilic articular cartilage defects.In conclusion,our results highlight the significant application potential of Hydrogel-Exos for early hemostasis,immunoregulation,and long-term chondrogenesis in hemophilic patients with cartilage injuries.This innovative approach is well-suited for application during arthroscopic procedures,offering a promising solution for addressing the complex challenges associated with hemophilic articular cartilage damage.

Advanced hydrogels for the repair of cartilage defects and regeneration

Cartilage defects are one of the most common symptoms of osteoarthritis(OA),a degenerative disease that affects millions of people world-wide and places a significant socio-economic burden on society.Hydrogels,which are a class of biomaterials that are elastic,and display smooth surfaces while exhibiting high water content,are promising candidates for cartilage regeneration.In recent years,various kinds of hydrogels have been developed and applied for the repair of cartilage defects in vitro or in vivo,some of which are hopeful to enter clinical trials.In this review,recent research findings and developments of hydrogels for cartilage defects repair are summarized.We discuss the principle of cartilage regeneration,and outline the requirements that have to be fulfilled for the deployment of hydrogels for medical applications.We also highlight the development of advanced hydrogels with tailored properties for different kinds of cartilage defects to meet the requirements of cartilage tissue engineering and precision medicine.

Expression of Transforming Growth Factor β_(1) in Mesenchymal Stem Cells: Potential Utility in Molecular Tissue Engineering for Osteochondral Repair

The feasibility of using gene therapy to treat full-thickness articular cartilage defects was investigated with respect to the transfection and expression of exogenous transforming growth factor(TGF)-β_(1)genes in bone marrow-derived mesenchymal stem cells(MSCs)in vitro.The full-length rat TGF-β_(1)cDNA was transfected to MSCs mediated by lipofectamine and then selected with G418,a synthetic neomycin analog.The transient and stable expression of TGF-β_(1)by MSCs was detected by using immunohistochemical staining.The lipofectamine-mediated gene therapy efficiently transfected MSCs in vitro with the TGF-β_(1)gene causing a marked up-regulation in TGF-β_(1)expression as compared with the vector-transfected control groups,and the increased expression persisted for at least 4 weeks after selected with G418.It was suggested that bone marrow-derived MSCs were susceptible to in vitro lipofectamine mediated TGF-β_(1)gene transfer and that transgene expression persisted for at least 4 weeks.Having successfully combined the existing techniques of tissue engineering with the novel possibilities offered by modern gene transfer technology,an innovative concept,i.e.molecular tissue engineering,are put forward for the first time.As a new branch of tissue engineering,it represents both a new area and an important trend in research.Using this technique,we have a new powerful tool with which:(1)to modify the functional biology of articular tissue repair along defined pathways of growth and differentiation and(2)to affect a better repair of full-thickness articular cartilage defects that occur as a result of injury and osteoarthritis.

Molecular Tissue Engineering: Applications for Modulation of Mesenchymal Stem Cells Proliferation by Transforming Growth Factor β_1 Gene Transfer

The effect of transforming growth factor β 1 (TGF β 1 ) gene transfection on the proliferation of bone marrow derived mesenchymal stem cells (MSC S ) and the mechanism was investigated to provide basis for accelerating articular cartilage repairing using molecular tissue engineering technology. TGF β 1 gene at different doses was transduced into the rat bone marrow derived MSCs to examine the effects of TGF β 1 gene transfection on MSCs DNA synthesis, cell cycle kinetics and the expression of proliferating cell nuclear antigen (PCNA). The results showed that 3 μl lipofectamine mediated 1 μg TGF β 1 gene transfection could effectively promote the proliferation of MSCs best; Under this condition (DNA/Lipofectamine=1μg/3μl), flow cytometry and immunohistochemical analyses revealed a significant increase in the 3 H incorporation, DNA content in S phase and the expression of PCNA. Transfection of gene encoding TGF β 1 could induce the cells at G0/G1 phase to S1 phase, modulate the replication of DNA through the enhancement of the PCNA expression, increase the content of DNA at S1 phase and promote the proliferation of MSCs. This new molecular tissue engineering approach could be of potential benefit to enhance the repair of damaged articular cartilage, especially those caused by degenerative joint diseases.