Osteoarthritis (OA) is a degenerative disease that induces
pain, cartilage deformation, and joint
inflammation. Mesenchymal stem cells (MSCs) are potential therapeutic agents for treatment of OA. However, MSC
therapy can cause excessive
inflammation.
Signal transducer and activator of transcription 3 (STAT3) modulates secretion of many proinflammatory
cytokines. Experimental OA was induced by intra-articular (IA) injection of
monosodium iodoacetate (MIA) to the right knee of rats. MSCs from OA patients (OA-MSCs) were treated with STA21, a small molecule that blocks STAT3 signaling, by IA or intravenous (IV) injection after MIA injection.
Pain severity was quantified by assessment of secondary
tactile allodynia using the von Frey assessment test. Cartilage degradation was measured by microcomputed tomography image analysis, histological analysis, and the Mankin score.
Protein and gene expression was evaluated by
enzyme-linked
immunosorbent assay, immunohistochemistry, and real-time polymerase chain reaction. MSCs increased production of proinflammatory
cytokines under inflammatory conditions. STA21 significantly decreased expression of these proinflammatory molecules via inhibition of STAT3 activity but increased gene expression of molecules related to migration potential and
immunomodulation in OA-MSCs. STAT3-inhibited OA-MSCs administrated by IV or IA injection decreased
pain severity and cartilage damage in rats with MIA-induced OA rats by decreasing proinflammatory
cytokines in the joints. Combined IA and IV-injected STAT3-inhibited OA-MSCs had an additive effect of
pain relief in MIA-induced OA rats. STAT3 inhibition may optimize the therapeutic activities of MSCs for treating OA by attenuating
pain and progression of MIA by inhibiting
inflammation and cartilage damage.