Hybrid extracellular vesicles drive irreversible mitochondria damage and TCA metabolite deficiency-related chondrocyte senescence

Public summary

* Identifying hybrid extracellular vesicles in the joint fluid from osteoarthritis patients.

* Hybrid extracellular vesicles aggravates chondrocyte damage in osteoarthritis models.

* Hybrid extracellular vesicles drive irreversible mitochondria fragmentation and sustained cellular aging.

* Developing metabolically targeted combination strategies to treat osteoarthritis.

Abstract

Metabolic and inflammatory stresses play crucial roles in osteoarthritis (OA). However, the reasons behind the difficulty in correcting impaired metabolism and cellular dysfunction in OA chondrocytes remain unclear. Given the metabolic modulation effect of extracellular vesicles (EVs), we asked whether endogenous EVs play a critical role in OA. Here, we identified a subtype of hybrid extracellular vesicles (hEVs) enriched in the joint fluid from OA patients, correlating with OA severity. These hEVs exhibited dual markers from proinflammatory macrophages and chondrocytes, promoting chondrocyte uptake and enhancing metabolic regulatory capability. hEV administration increased chondrocyte damage, characterized by enhanced mitochondrial defects and cellular aging in OA models. Unlike the reversible metabolic damage induced by inflammation in cartilage stem/progenitor cells (CSPCs), hEVs induced irreversible mitochondrial fragmentation and sustained cellular aging, even after stimulus removal. Notably, while hEVs promoted a metabolic shift toward glycolysis in OA CSPCs, blocking glycolysis alone failed to restore CSPC dysfunction. Mechanistically, hEVs decreased the mitochondrial membrane potential (ΔΨm) in an ADP/ATP translocase 1 (ADT1)-dependent manner, contributing to irreversible mitochondria fragmentation. As a result, hEVs depleted tricarboxylic acid metabolites, particularly acetyl-CoA and α-ketoglutarate (α-KG), associated with altered histone acetylation and methylation in OA CSPCs. Thus, combination therapy with an ADT1 inhibitor, supplemented with acetyl-CoA and α-KG, corrected hEV-induced metabolic reprogramming and cellular fate changes, restoring impaired chondrogenesis and aging in OA CSPCs and OA models. This study reveals hEVs as unrecognized OA pathogenic drivers, linking EV-mediated irreversible mitochondria damage to chondrocyte aging, and opens a new avenue for OA treatment.