The effect of molecular weight of hyaluronic acid on corneal cell viability

Hyaluronic acid (HA) is widely utilized in ophthalmology for its viscoelastic and wound-healing properties; however, its effects vary according to molecular weight (MW). This study evaluates the toxicity induced by HA across corneal epithelial cells, keratocytes, and endothelial cells to ensure its safe clinical application. Human corneal epithelial cells, keratocytes, and endothelial cells were cultured under standardized conditions. Viability was assessed using the Cell Counting Kit-8 (CCK-8) and the live/dead cell staining after exposure to HA of varying MW. The MW categories were very low (VLMW, MW range from 8000 to 15,000 Da), low (LMW, MW range from 130,000 to 150,000 Da), medium (MMW, MW range from 750,000 to 1,000,000 Da), and high (HMW, MW range over 1,000,000 Da)), at concentrations ranging from 0.025% to 0.5% for durations of 24, 48, and 72 h. LMW HA exhibited the highest toxicity across all layers of corneal cells, demonstrating a dose-dependent decrease in cell viability. In epithelial cells specifically, 0.5% LMW HA resulted in a reduction of viability by more than 50% within 24-72 h, with concentrations greater than or equal to 0.25% proving hazardous after 24 h. Keratocytes experienced toxicity across all HA MW, with LMW HA leading to the most significant reductions. In corneal endothelial cells, LMW HA decreased viability by more than 50% after 48 h. Conversely, VLMW HA and HMW HA showed minimal toxicity. These findings highlight the importance of selecting appropriate HA formulations based on MW to ensure both efficacy and safety in ophthalmic treatments.