TABLE 2.

Catabolic and anabolic roles of exosomes in osteoarthritis.

Functions	Origins	Mechanisms
Catabolic effect	Synovial fluid (Gao et al., 2020), vascular endothelial cells (Yang et al., 2021a)	Recruit inflammatory cells (Gao et al., 2020), inhibit cartilage proliferation (Gao et al., 2020), promote joint degeneration (Gao et al., 2020), or induce chondrocyte apoptosis
Anabolic effect	MSCs (Tofiño-Vian et al., 2018), embryonic stem cells, dental pulp stem cells, monocytes (), amniotic fluid stem cells (Beretti et al., 2018), chondrogenic progenitor cells, chondrocytes (Zheng et al., 2019), PRP (), osteocytes	Reduce production of catabolic enzymes, promote chondrocytes to express cartilage ECM, (Guillén et al., 2021) promote chondrocyte differentiation (), promote proliferation of chondrocytes, inhibit chondrocyte apoptosis, (Lin et al., 2021)regulate immune response, or inhibit expression of inflammatory cytokines (Qiu et al., 2021)