To evaluate the therapeutic efficacy of dexamethasone (DM) and methotrexate (MTX) entrapped within polysialic acid (PSA)-trimethyl chitosan (TMC) nanoparticles using an in vitro model of rheumatoid arthritis (RA).The loading capacity of the PSA-TMC nanoparticles was determined. An RA in vitro model was developed by stimulating a synovial cell line with a proinflammatory mediator. Multiplex immunoassay was used to determine changes in the secretion of interleukin-6 (IL-6), interleukin-8 (IL-8), and granulocyte-macrophage colony-stimulating factor (GM-CSF) by the in vitro model following administration of the DM- and MTX-loaded nanoparticles.The loading capacity of the PSA-TMC nanoparticles was approximately 0.1 mg of drug/mg of nanoparticle. When applied to our in vitro model of RA, there were no significant differences in the concentrations of IL-6 and IL-8 when comparing the free drugs and drug-loaded nanoparticles, administered at concentration of 0.1 mg/ml and 1.0 mg/ml, respectively.The present study verified that MTX and DM are able to retain bioactivity when loaded into PSA-TMC nanoparticles. Although in vitro efficacy was not increased, the in vivo efficacy will likely be enhanced by the site-specific targeting conferred by nanoparticle entrapment.
