Simvastatin prevents articular chondrocyte dedifferentiation induced by nitric oxide by inhibiting the expression of matrix metalloproteinases 1 and 13

Simvastatin and fluvastatin attenuate trauma-induced cell death and catabolism in human cartilage

Joint injuries are known to induce pathomechanisms that might lead to posttraumatic osteoarthritis (PTOA). In this regard, statins with their pleiotropic effects could represent potential therapeutic agents in preventing the development of PTOA. Therefore, we investigated the effects of simvastatin and fluvastatin in a drop-tower-based human ex vivo cartilage trauma model. After 7 days, a mechanical impact (0.59 J) resulted in a decrease of the cell viability and increased expression of catabolic enzymes in cartilage explants. Simvastatin and fluvastatin treatment of impacted cartilage demonstrated cell protective effects in a concentration dependent manner. Moreover, statin therapy exhibited chondroprotective effects as demonstrated by attenuated expression of MMP-2 and MMP-13 as well as subsequent breakdown of collagen type II (after impact). Further analysis indicated antioxidative properties of the statins by upregulating the gene expression of SOD2 and suppression that of NOX2 and NOX4. Despite its protective effects, simvastatin impaired the biosynthesis of collagen type II, which was confirmed during chondrogenic redifferentiation of high passage chondrocytes. However, while long-term administration of statins for 4 weeks impaired chondrogenic redifferentiation, addition of simvastatin at low concentrations for 1 week exhibited a slightly promoting effect. In conclusion, our data imply that simvastatin and fluvastatin are suitable in terms of initial harm reduction after cartilage trauma.

S-Equol Protects Chondrocytes against Sodium Nitroprusside-Caused Matrix Loss and Apoptosis through Activating PI3K/Akt Pathway

Osteoarthritis (OA) is a common chronic disease with increasing prevalence in societies with more aging populations, therefore, it is causing more concern. S-Equol, a kind of isoflavones, was reported to be bioavailable and beneficial to humans in many aspects, such as improving menopausal symptoms, osteoporosis and prevention of cardiovascular disease. This study investigated the effects of S-Equol on OA progress in which rat primary chondrocytes were treated with sodium nitroprusside (SNP) to mimic OA progress with or without the co-addition of S-Equol for the evaluation of S-Equol's efficacy on OA. Results showed treatment of 0.8 mM SNP caused cell death, and increased oxidative stress (NO and H₂O₂), apoptosis, and proteoglycan loss. Furthermore, the expressions of MMPs of MMP-2, MMP-3, MMP-9, and MMP-13 and p53 were increased. The addition of 30 μM S-Equol could lessen those caused by SNP. Moreover, S-Equol activates the PI₃K/Akt pathway, which is an upstream regulation of p53 and NO production and is associated with apoptosis and matrix degradation. As a pretreatment of phosphoinositide ₃-kinases (PI₃K) inhibitor, all S-Equol protective functions against SNP decrease or disappear. In conclusion, through PI₃K/Akt activation, S-Equol can protect chondrocytes against SNP-induced matrix degradation and apoptosis, which are commonly found in OA, suggesting S-Equol is a potential for OA prevention.

Small molecule compounds promote the proliferation of chondrocytes and chondrogenic differentiation of stem cells in cartilage tissue engineering

The application of tissue engineering to generate cartilage is limited because of low proliferative ability and unstable phenotype of chondrocytes. The sources of cartilage seed cells are mainly chondrocytes and stem cells. A variety of methods have been used to obtain large numbers of chondrocytes, including increasing chondrocyte proliferation and stem cell chondrogenic differentiation via cytokines, genes, and proteins. Natural or synthetic small molecule compounds can provide a simple and effective method to promote chondrocyte proliferation, maintain a stable chondrocyte phenotype, and promote stem cell chondrogenic differentiation. Therefore, the study of small molecule compounds is of great importance for cartilage tissue engineering. Herein, we review a series of small molecule compounds and their mechanisms that can promote chondrocyte proliferation, maintain chondrocyte phenotype, or induce stem cell chondrogenesis. The studies in this field represent significant contributions to the research in cartilage tissue engineering and regenerative medicine.