Osteoarthritis (OA) has generally been introduced as a degenerative disease; however, it has recently been understood as a low-grade chronic inflammatory process that could promote symptoms and accelerate the progression of OA. Current treatment strategies, including corticosteroid injections, have no impact on the OA disease progression. Mesenchymal stem cells (MSCs) based therapy seem to be in the spotlight as a disease-modifying treatment because this strategy provides enlarged anti-inflammatory and chondroprotective effects. Currently, bone marrow, adipose derived, synovium-derived, and Wharton’s jelly-derived MSCs are the most widely used types of MSCs in the cartilage engineering. MSCs exert immunomodulatory, immunosuppressive, antiapoptotic, and chondrogenic effects mainly by paracrine effect. Because MSCs disappear from the tissue quickly after administration, recently, MSCs-derived exosomes received the focus for the next-generation treatment strategy for OA. MSCs-derived exosomes contain a variety of miRNAs. Exosomal miRNAs have a critical role in cartilage regeneration by immunomodulatory function such as promoting chondrocyte proliferation, matrix secretion, and subsiding inflammation. In the future, a personalized exosome can be packaged with ideal miRNA and proteins for chondrogenesis by enriching techniques. In addition, the target specific exosomes could be a gamechanger for OA. However, we should consider the off-target side effects due to multiple gene targets of miRNA.

Background: Intraarticular injection of tranexamic acid (IA-TXA) plus drain-clamping is a preferred method of reducing bleeding after total knee arthroplasty (TKA). However, no consensus had been reached regarding the timing of clamping. The purpose of this study was to determine the optimum duration of drain-clamping after TKA with IA-TXA.Methods: We retrospectively reviewed 151 patients that underwent unilateral TKA with IA-TXA plus drain-clamping for 30 minutes (Group A, 60 patients), 2 hours (Group B, 42 patients), or 3 hours (Group C, 49 patients). Total drained volumes, hematocrit (Hct) reductions, estimated blood losses (EBLs), transfusion rates, and wound complications were reviewed.Results: Mean total drained volume, Hct reduction, EBL, and transfusion rate were significantly less in group C than in groups A or B (p < 0.01). No significant intergroup difference was found for wound-related complications. No surgical site infection or deep vein thrombosis was observed.Conclusion: IA-TXA plus drain-clamping for 3 hours is optimal for reducing blood loss with minimal complications after TKA.