Bone marrow mesenchymal stromal cell-derived exosomes in knee osteoarthritis: Bridging mechanistic understanding to clinical applications

Table 2 Comparative features of exosomes from mesenchymal stromal cell sources in osteoarthritis models

Source	Main advantages in osteoarthritis context	Principal limitations or concerns
Bone marrow[59-61]	Strong chondrogenic lineage; rich ECM-related proteome; extensive mechanistic data and historical use in cartilage repair	Donor age dependence; invasive harvest; intermediate performance in comparative exosome meta-analysis; variable outcomes in MSC trials
Adipose tissue[63,64]	Abundant, minimally invasive harvest; high cell yield; strong immunomodulatory profile; good pain relief in MSC trials	Some preparations favour fibrocartilage over hyaline repair; structural regeneration less consistent; potential influence of donor metabolic status
Umbilical cord[65]	Neonatal cells with high proliferative capacity; off-the-shelf allogeneic banking; robust anti-inflammatory and chondroprotective actions; early clinical data in KOA	Fewer long-term joint safety data; regulatory complexity of allogeneic products
Synovium/synovial fluid[34,60]	Joint-specific tissue origin; excellent targeting and regenerative potency, especially with miR-140-5p enrichment; top rankings in rodent network analyses	Arthroscopic retrieval for autologous use; scalability challenges; limited clinical-grade products

ECM: Extracellular matrix; MSC: Mesenchymal stromal cell; KOA: Knee osteoarthritis.