Intra-articular injection of loaded sPL sustained-release microspheres inhibits osteoarthritis and promotes cartilaginous repairs

BACKGROUND

Osteoarthritis is a chronic inflammatory disease of the joints associated with significant morbidity and lower quality of life. Current treatment strategies focus on reducing cartilage degeneration but fail to restore their proliferative ability. Super-activated platelet lysate (sPL) is an enhanced form of platelet-rich plasma that can be easily inactivated. The purpose of this study is to evaluate whether sPL-loaded PLGA/chitosan/gelatin microspheres can prevent and treat osteoarthritis.

METHODS

Features of biological microspheres were detected by SEM and ELISA. Osteoarthritis chondrocytes were co-cultured with hydrogel loaded with sPL. The effect of biological microspheres on chondrocyte proliferation was evaluated using a CCK-8 cell proliferation test. Cell morphology and cell necrosis were measured with a microscope. The gene expression levels of cartilage-related markers type 2 collagen, aggrecan (ACAN), and SRY type high mobility group box-9 (SOX9) were determined by real-time quantitative polymerase chain reaction (Rt-PCR). A rat osteoarthritis model was established. Micro-CT was used to characterize cartilaginous changes after the injection of biological microspheres. Histopathological HE staining, Safranin-O Fast Green staining and staining scores, type II collagen staining, and proteoglycan staining were used to evaluate the degree of cartilaginous repair.

RESULTS

Biological microspheres were able to continuously release biological factors. Exposure to loading sPL microspheres significantly increased chondrocyte proliferation, reduced cell necrosis, and increased the expression of cartilage markers type 2 collagen, ACAN, and SOX9 in osteoarthritic chondrocytes. In vivo experiments found that biological microspheres also smoothen cartilage surfaces, promote the expression of proteoglycan and type 2 collagen while also increasing cartilaginous integrity as evaluated using Safranin-O Fast Green staining.

CONCLUSIONS

PLGA/chitosan/gelatin hydrogel loaded with sPL is a promising tool for effective and non-invasive articular cartilage repair in osteoarthritis. Biological microspheres loaded with sPL release various biological factors to promote chondrocyte proliferation and upregulate chondrocyte functionalization genes (SOX9, CoX II, ACAN), leading to an overall enhanced cartilaginous matrix.

Hyper-activated platelet lysates prevent glucocorticoid-associated femoral head necrosis by regulating autophagy

Platelet Rich Plasma (PRP) can activate angiogenic and osteogenic pathways, making it a highly promising therapeutic agent for bone growth. Super active platelet lysate (sPL) is derived from platelet-rich plasma (PRP) through ultra-low temperature freeze-thawing. The aim of this study was to evaluate the potential therapeutic effect of sPL on glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH). sPL increased the proliferation of GC-treated osteoblasts and endothelial cells, and inhibited apoptosis in vitro. Furthermore, sPL promoted healing of necrotic bone tissues in a rat ONFH model by restraining GC-induced apoptosis and increase autophagy of the osteoblasts. Overall, the results of this study provide a theoretical basis for the clinical application of sPL in ONFH.