Toxic effects of povidone–iodine on synovial cell and articular cartilage

The objective of this study was to investigate the toxic effects of povidone–iodine (PVI). A series of MTT assay of cultured synovial cells stimulated by PVI have been made. Test for assay of membrane-toxic effect of PVI and lactate dehydrogenase (LDH) has also been carried out. After making intraarticular injection into rats’ hind knee joints with 0.1 ml of PVI every day for 1 week, we have extracted the knee joints and blood from rats in four divided groups on the 0, 1st, 3rd, and 7th day. Our microscopic analysis was performed that cartilage and synovium membrane were stained with hematoxylin, toluidine blue, and safranin O. Iodine, glutamic oxaloacetic transminase, creatine phosphokinase (CPK), and LDH in rat sera have been measured. We were able to confirm cytotoxicity in the synovial cells placed in PVI concentration of more than 6.25×10⁻²%. In comparison with the positive control, LDH, in this case, was released at the concentration level of 33.3%. Independent of period of stimulation, LDH was released the most in the PVI concentration of 6.25×10⁻². The histopathological analysis of articular cartilage has indicated clear morphological alterations in rats’ synovium; especially, toluidine blue staining and safranin O staining were seen in the metachromasia of articular cartilage. However, no fissures or erosive changes in the articular cartilage, which were usually observable in the case of osteoarthritis, were observed. In the synovium inflammatory cells, which were mainly plasma cells and lymphoid cells, no neutrophils were infiltrated. The degree of infiltration has increased steadily day by day. Fibrin deposition has been observed even in the synovium of 1-day stimulation. On the 7th day, a serum total iodine concentration has been 544 μg/dl, 4,440 IU/ml for CPK concentration, and 2,049 IU/ml for LDH concentration, while the control concentrations have been 7.1 μg/dl, 491 IU/ml, and 700 IU/ml, respectively. Our experiment has disclosed that PVI preparation is strongly cytotoxic to synovial cell and articular cartilage.