Povidone-Iodine Has a Profound Effect on In Vitro Osteoblast Proliferation and Metabolic Function and Inhibits Their Ability to Mineralize and Form Bone.

STUDY DESIGN A study examining the clinical protocol of scoliosis wound irrigation, demonstrating povidone-iodine's (PVI) effect on human osteoblast cells. Primary and immortal cell line osteoblasts were treated with 0.35% PVI for 3 minutes, and analyzed for proliferation rate, oxidative capacity, and mineralization. OBJECTIVE To model spinal wound irrigation with dilute PVI in vitro, in order to investigate the effect of PVI on osteoblast proliferation, metabolism, and bone mineralization. SUMMARY OF BACKGROUND DATA Previously PVI irrigation has been proposed as a safe and effective practice to avoid bacterial growth after spinal surgery. However, recent evidence in multiple cell types suggests that PVI has a deleterious effect on cellular viability and cellular function. METHODS Primary and immortal human osteoblast cells were exposed to either phosphate buffered saline control or with 0.35% PVI for 3 minutes. Cellular proliferation was measured over the duration of 7 days by MTS assay. Oxygen consumption rate, extracellular acidification rate, and proton production rate were analyzed using a Seahorse XF24 Bioanalyzer. Protein expression of the electron transport chain subunits CII-SDHB, CIII-UQRCR2, and CV-ATP5A was measured via Western blotting. Mineralized bone nodules were stained with alizarin red. RESULTS Expressed as a percentage of normal osteoblast proliferation, osteoblasts exposed to 0.35% PVI exhibited a significant 24% decrease in proliferation after 24 hours. This was a sustained response, resulting in a 72% decline in cellular proliferation at 1 week. There was a significant reduction in oxygen consumption rate, extracellular acidification rate, and proton production rate (P < 0.05), in osteoblasts that had been exposed to 0.35% PVI for 3 minutes, coupled with a marked reduction in the protein expression of CII-SDHB. Osteoblasts exposed to 0.35% PVI exhibited reduced bone nodule mineralization compared to control phosphate buffered saline exposed osteoblasts (P < 0.01). CONCLUSION PVI has a rapid and detrimental effect on human osteoblast cellular proliferation, metabolic function, and bone nodule mineralization. LEVEL OF EVIDENCE NA.