Tropoelastin improves adhesion and migration of intra-articular injected infrapatellar fat pad MSCs and reduces osteoarthritis progression.

Intra-articular injection of mesenchymal stem cells (MSCs) is a promising strategy for osteoarthritis (OA) treatment. However, more and more studies reveal that the injected MSCs have poor adhesion, migration, and survival in the joint cavity. A recent study shows that tropoelastin (TE) regulates adhesion, proliferation and phenotypic maintenance of MSCs as a soluble additive, indicating that TE could promote MSCs-homing in regenerative medicine. In this study, we used TE as injection medium, and compared it with classic media in MSCs intra-articular injection such as normal saline (NS), hyaluronic acid (HA), and platelet-rich plasma (PRP). We found that TE could effectively improve adhesion, migration, chondrogenic differentiation of infrapatellar fat pad MSCs (IPFP-MSCs) and enhance matrix synthesis of osteoarthritic chondrocytes (OACs) in indirect-coculture system. Moreover, TE could significantly enhance IPFP-MSCs adhesion via activation of integrin ß1, ERK1/2 and vinculin (VCL) in vitro. In addition, intra-articular injection of TE-IPFP MSCs suspension resulted in a short-term increase in survival rate of IPFP-MSCs and better histology scores of rat joint tissues. Inhibition of integrin ß1 or ERK1/2 attenuated the protective effect of TE-IPFP MSCs suspension in vivo. In conclusion, TE promotes performance of IPFP-MSCs and protects knee cartilage from damage in OA through enhancement of cell adhesion and activation of integrin ß1/ERK/VCL pathway. Our findings may provide new insights in MSCs intra-articular injection for OA treatment.

Intra-articular injection of anti-inflammatory peptide-loaded glycol chitosan/fucoidan nanogels to inhibit inflammation and attenuate osteoarthritis progression.

Glycol chitosan/fucoidan nanogels loaded with anti-inflammatory peptide KAFAK (GC/Fu@KAFAK NGs) were fabricated based on the electrostatic interaction and genipin cross-linking methods. The prepared NGs had an average size of 286.3 ± 5.0 nm and positive surface charge of 14.0 ± 0.2 mV. The anti-inflammatory and chondro-protective effects of GC/Fu@KAFAK NGs were evaluated on interlecukin-1ß (IL-1ß)-stimulated rat chondrocytes. We found that GC/Fu@KAFAK NGs not only inhibited the expression of inflammatory factors interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), but also enhanced the expression of chondrogenic markers type II collagen, aggrecan, and Sox9. More importantly, in rat osteoarthritis (OA) model, the intra-articular (IA) injection of GC/Fu@KAFAK NGs reduced glycosaminoglycan loss and diminished inflammatory cytokine release. In addition, GC/Fu@KAFAK NGs showed good biocompatibility both in vitro and in vivo. In conclusion, IA inject-able GC/Fu@KAFAK NGs might have great potential in OA treatment.

Asiatic acid attenuates hypertrophic and fibrotic differentiation of articular chondrocytes via AMPK/PI3K/AKT signaling pathway.

BACKGROUND: Osteoarthritis (OA), the most common joint disorder, is characterized by a progressive degradation of articular cartilage. Increasing evidence suggests that OA is closely associated with cartilage pathologies including chondrocyte hypertrophy and fibrosis. METHODS: In this study, we showed that asiatic acid (AA) treatment reduced chondrocyte hypertrophy and fibrosis. First, the cytotoxicity of AA (0, 5, 10, and 20 µM) to chondrocytes was evaluated, and 5 µM was selected for subsequent experiments. Then, we detected the gene and protein level of chondrocyte hypertrophic markers including type X collagen (COL-X), matrix metalloproteinase-13 (MMP-13), alkaline phosphatase (ALP), and runt-related transcription factor 2 (Runx2); chondrocyte fibrosis markers including type I collagen (COL-Ι) and alpha-smooth muscle actin (α-SMA); and chondrogenic markers including SRY-related HMG box 9 (SOX9), type II collagen (COL-II), and aggrecan (ACAN). Further, we tested the mechanism of AA on inhibiting chondrocyte hypertrophy and fibrosis. Finally, we verified the results in an anterior cruciate ligament transection (ACLT) rat OA model. RESULTS: We found that AA treatment inhibited the hypertrophic and fibrotic phenotype of chondrocytes, without affecting the chondrogenic phenotype. Moreover, we found that AA treatment activated AMP-activated protein kinase (AMPK) and inhibited phosphoinositide-3 kinase/protein kinase B (PI3K/AKT) signaling pathway in vitro. The results in an ACLT rat OA model also indicated that AA significantly attenuated chondrocyte hypertrophy and fibrosis. CONCLUSION: AA treatment could reduce hypertrophic and fibrotic differentiation and maintain the chondrogenic phenotype of articular chondrocytes by targeting the AMPK/PI3K/AKT signaling pathway. Our study suggested that AA might be a prospective drug component that targets hypertrophic and fibrotic chondrocytes for OA treatment.

Preparation and characterization of methacrylated gelatin/bacterial cellulose composite hydrogels for cartilage tissue engineering.

Methacrylated gelatin (GelMA)/bacterial cellulose (BC) composite hydrogels have been successfully prepared by immersing BC particles in GelMA solution followed by photo-crosslinking. The morphology of GelMA/BC hydrogel was examined by scanning electron microscopy and compared with pure GelMA. The hydrogels had very well interconnected porous network structure, and the pore size decreased from 200 to 10 µm with the increase of BC content. The composite hydrogels were also characterized by swelling experiment, X-ray diffraction, thermogravimetric analysis, rheology experiment and compressive test. The composite hydrogels showed significantly improved mechanical properties compared with pure GelMA. In addition, the biocompatility of composite hydrogels were preliminarily evaluated using human articular chondrocytes. The cells encapsulated within the composite hydrogels for 7 days proliferated and maintained the chondrocytic phenotype. Thus, the GelMA/BC composite hydrogels might be useful for cartilage tissue engineering.

Intra-articular injection of etoricoxib-loaded PLGA-PEG-PLGA triblock copolymeric nanoparticles attenuates osteoarthritis progression.

The current pharmacological therapies for osteoarthritis (OA) are mainly focused on symptomatic relief of pain and inflammation through the use of nonsteroidal anti-inflammatory drugs (NSAIDs). Etoricoxib is a cyclooxygenase-2 (COX-2) selective NSAID with a higher cyclooxygenase-1 (COX-1) to COX-2 selectivity ratio than the other COX-2 selective NSAIDs and a lower risk of gastrointestinal toxicity compared to traditional NSAIDs. In this study, we first evaluated the anti-inflammatory and chondro-protective effects of etoricoxib on interlecukin-1ß-stimulated human osteoarthritic chondrocytes. We found that etoricoxib not only inhibited the expression of inflammation mediators COX-2, prostaglandin E2 (PGE2), and nitric oxide, but also had a similar chondro-protective effect to celecoxib through down-regulating matrix degrading enzymes matrix metalloproteinase-13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS-5). We then used PLGA-PEG-PLGA triblock copolymeric nanoparticles (NPs) as a drug delivery system to locally deliver etoricoxib into the articular cavity to reduce the risk of cardiovascular toxicity of etoricoxib when administered systemically or orally. The etoricoxib-loaded NPs showed a sustained drug release over 28 days in vitro; in rat OA model, the intra-articular injection of etoricoxib-loaded NPs alleviated the symptoms of subchondral bone, synovium, and cartilage. In conclusion, our study confirmed the chondro-protective role of etoricoxib in OA, and proved the curative effects of etoricoxib-loaded PLGA-PEG-PLGA NPs in vivo.