Advances in the Treatment of Partial-Thickness Cartilage Defect

Injectable Bioadhesive Photocrosslinkable Hydrogels with Sustained Release of Kartogenin to Promote Chondrogenic Differentiation and Partial-Thickness Cartilage Defects Repair

Partial-thickness cartilage defect (PTCD) is a common and formidable clinical challenge without effective therapeutic approaches. The inherent anti-adhesive characteristics of the extracellular matrix within cartilage pose a significant impediment to the integration of cells or biomaterials with the native cartilage during cartilage repair. Here, an injectable photocrosslinked bioadhesive hydrogel, consisting of gelatin methacryloyl (GM), acryloyl-6-aminocaproic acid-g-N-hydroxysuccinimide (AN), and poly(lactic-co-glycolic acid) microspheres loaded with kartogenin (KGN) (abbreviated as GM/AN/KGN hydrogel), is designed to enhance interfacial integration and repair of PTCD. After injected in situ at the irregular defect, a stable and robust hydrogel network is rapidly formed by ultraviolet irradiation, and it can be quickly and tightly adhered to native cartilage through amide bonds. The hydrogel exhibits good adhesion strength up to 27.25 ± 1.22 kPa by lap shear strength experiments. The GM/AN/KGN hydrogel demonstrates good adhesion, low swelling, resistance to fatigue, biocompatibility, and chondrogenesis properties in vitro. A rat model with PTCD exhibits restoration of a smoother surface, stable seamless integration, and abundant aggrecan and type II collagen production. The injectable stable adhesive hydrogel with long-term chondrogenic differentiation capacity shows great potential to facilitate repair of PTCD.

Injectable microspheres adhering to the cartilage matrix promote rapid reconstruction of partial-thickness cartilage defects

An effective treatment for the irregular partial-thickness cartilage defect in the early stages of osteoarthritis (OA) is lacking. Cartilage tissue engineering is effective for treating full-thickness cartilage defects with limited area. In this study, we designed an injectable multifunctional poly(lactic-co-glycolic acid) (PLGA) microsphere to repair partial-thickness cartilage defects. The microsphere was grafted with an E7 peptide after loading the microsphere with kartogenin (KGN) and modifying the outer layer through dopamine self-polymerization. The microsphere could adhere to the cartilage defect, recruit synovial mesenchymal stem cells (SMSCs) in situ, and stimulate their differentiation into chondrocytes after injection into the articular cavity. Through in vivo and in vitro experiments, we demonstrated the ability of multifunctional microspheres to adhere to cartilage matrix, recruit SMSCs, and promote their differentiation into cartilage. Following treatment, the cartilage surface of the model group with partial-thickness cartilage defect showed smooth recovery, and the glycosaminoglycan content remained normal; the untreated control group showed significant progression of OA. The microsphere, a framework for cartilage tissue engineering, promoted the expression of SMSCs involved in cartilage repair while adapting to cell migration and growth. Thus, for treating partial-thickness cartilage defects in OA, this innovative carrier system based on stem cell therapy can potentially improve therapeutic outcomes. STATEMENT OF SIGNIFICANCE: Mesenchymal stem cells (MSCs) therapy is effective in the repair of cartilage injury. However, because of the particularity of partial-thickness cartilage injury, it is difficult to recruit enough seed cells in situ, and there is a lack of suitable scaffolds for cell migration and growth. Here, we developed polydopamine surface-modified PLGA microspheres (PMS) containing KGN and E7 peptides. The adhesion ability of the microspheres is facilitated by the polydopamine layer wrapped in them; thus, the microspheres can adhere to the injured cartilage and recruit MSCs, thereby promoting their differentiation into chondrocytes and accomplishing cartilage repair. The multifunctional microspheres can be used as a safe and potential method to treat partial-thickness cartilage defects in OA.

Porcine platelet lysates exert the efficacy of chondroregeneration and SMAD2-mediated anti-chondrofibrosis on knee osteoarthritis

BACKGROUND

The lack of self-repairability in cartilage and the formation of fibrocartilage pose significant challenges in treating knee osteoarthritis, and there is still no ideal solution. Autologous platelet lysates have been clinically applied to treat kOA and exert satisfactory cartilage-repair efficacy, but the preparation of human PL brings damage to patients and is hardly standardized.

METHODS

In this study, porcine PL was developed to replace hPL, and its chondroregenerative and anti-chondrofibrosis effects were explored. Enzyme-Linked Immunosorbent Assay was applied to qualify the PL products. In vivo, partial-thickness cartilage defects were created on rats as a kOA model, and the von Frey test, histopathological observation, immunohistochemical analysis, and western blot analysis were conducted. In vitro, CCK-8 assay, real-time PCR analysis, immunofluorescence test, and WB analysis were conducted for the mechanism study of pPL.

RESULTS

The in vivo data showed that pPL significantly repaired the cartilage defect by improving matrix synthesis and also ameliorated the pain response in the kOA model of rats. In addition, pPL exerted an anti-fibrosis effect on cartilage by suppressing the expressions of COL1, COL3, α-SMA, VIMENTIN, SMAD2, p-SMAD2, and CTGF in cartilage. The in vitro data verified these effects and indicated that the SMAD2 pathway mediated the anti-fibrosis mechanism of pPL. Moreover, the comparable effects between pPL and rat PL indicate that there is no immune rejection from pPL.

CONCLUSIONS

This study firstly demonstrated the anti-kOA effects of pPL on both cartilage-repair and anti-chondrofibrosis. It developed pPL as a promising alternative to autologous PL for clinical applications.