A March 2025 study published in the journal Precision Clinical Medicine (1) wrote: “exosomes from stem cell sources have led to some breakthroughs in the treatment of osteoarthritis and have important clinical significance.” In discussing the possible role of exosomes in helping patients with osteoarthritis, the authors suggest that throughout the development of osteoarthritis, multiple pathological features are commonly observed. These include the death of hyperactive chondrocytes (cartilage cells that go from healthy and vibrant to degenerative and eventually die), degradation of the extracellular matrix (a secretion that acts as a binder or scaffold to build new cells on), inflammation of the synovial membrane, formation of new blood vessels (neovascularization), nerve invasion, and remodeling of the subchondral bone. Each of these changes plays a significant role in promoting the progression of osteoarthritis, and their interactions further exacerbate the condition.

Exosomes, which are small extracellular vesicles released by various cells, have emerged as important mediators in the pathology of osteoarthritis. Exosomes derived from different cellular sources can have either beneficial or detrimental effects on osteoarthritis. For example, exosomes from stem cells and chondrocytes may exert protective or regenerative effects, while those originating from immune cells, inflamed synoviocytes (a source of inflammation), or diseased subchondral osteoblasts can worsen the disease and contribute to its chronic progression.

Although the precise mechanisms by which regenerative or reparative exosomes act in osteoarthritis treatment remain unclear, research has shown that these vesicles can slow the advancement of osteoarthritis. They achieve this by modulating pathological responses through molecular communication between chondrocytes. Specifically, exosomes can reduce inflammation, regulate ECM metabolism, protect chondrocytes from excessive cell death, modulate immune responses, inhibit abnormal blood vessel formation, promote cell migration and proliferation, and alleviate osteoarthritis-related pain.

In February 2026, a paper in the Current pharmaceutical design (2) further explains that exosomes derived from Mesenchymal Stem Cells can influence chondrocyte (cells that secrete collagen (mainly type II) and proteoglycans (cells that provide structural support to form new cartilage) that form the cartilage matrix) behavior in several key ways. These vesicles are capable of modulating chondrocyte proliferation, reducing apoptosis (cell death), regulating autophagy (removal of dead and dying cells), and attenuating inflammation. Such abilities position exosomes as important mediators in the maintenance of cartilage health and the progression of osteoarthritis.

Further, emerging evidence highlights the significant role of exosomal non-coding RNAs (cells that manage and regulate other cells), in the regulation of cartilage degradation and subchondral bone remodeling. These non-coding RNAs can influence the pathogenesis of osteoarthritis.

Numbers of exosomes and their role in joint break down and regeneration

A March 2026 study in the journal Biomedicine & Pharmacotherapy (3) noted the abundance of extracellular vesicles (of which exosomes are a specific type) in joint fluid seems to be more closely linked to the activity level of cells rather than the total number of cells present. This idea is backed by evidence indicating a weak correlation between extracellular vesicles counts and the overall cell numbers in the joint fluid. Therefore, cellular activity may be the main factor driving the increased production of extracellular vesicles in these pathological conditions.

This indicates they good / bad aspect of exosomes. In a degenerative joint environment exosomes increase and deliver “toxic” messages increasing inflammation and disease. However, researchers suggest that the introduction of extracellular vesicles from “healthy” exosomes derived from stem cells can also turn off inflammation and the degenerative processes happening in a diseased joint. This is a controversial issue.

References

1 Wang X, Xu L, Wu Z, Lou L, Xia C, Miao H, Dai J, Fei W, Wang J. Exosomes of stem cells: a potential frontier in the treatment of osteoarthritis. Precision Clinical Medicine. 2024 Nov 26;8(1):pbae032-.
2 Bagherifard A, Talebi S, Hemmatyar A, Mokhtari K, Yahyazedeh H, Tanzadehpanah H. Exosomes in Osteoarthritis: Emerging Roles in Pathogenesis, Diagnosis, and Therapeutic Potential. Current Pharmaceutical Design. 2026.
3 Leng Y, Gao Y, Zhang J, Qi X. The dual role of extracellular vesicles in OA: Pathological mediators, diagnostic biomarkers, and therapeutic targets. Biomedicine & Pharmacotherapy. 2026 Mar 1;196:119064.