Hydroxycamptothecin regulates scar formation of the filtration channel under scleral flap by inhibiting the proliferation of scleral fibroblasts

BACKGROUND: To investigate the inhibitory effect of a hyaluronic acid hydrogel loaded with hydroxycamptothecin (HCPT) on scar formation after filtration surgery in a rabbit model. METHODS: Scleral fibroblasts were isolated and extracted from rabbits’ eyes. After treatment with different concentrations of HCPT, cytotoxicity was detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and proliferation and extent of apoptosis were analysed using flow cytometry. Hydrogels loaded with different dosages of HCPT were prepared and placed under the scleral flap after the filtration surgery. One day, one week, and two weeks after surgery, follicular, conjunctival, corneal, and anterior chamber inflammation and iris and lens changes were observed. RESULTS: In vitro, compared with cells not treated with HCPT, cells treated with HCPT had decreased survival rate and proliferation, and the apoptosis level increased with increasing HCPT concentrations (p < 0.05). In vivo, the flattening time of filtering blebs in the three groups treated with different dosages of HCPT hydrogel was delayed. The degrees of oedema, inflammation, and bleeding were similar to those observed in the control group. The HCPT hydrogel effectively downregulated the expression of collagen 1 and 3 and tissue inhibitor of metalloproteinase 2 and upregulated the expression of matrix metalloproteinase 2 in a dose-dependent manner. CONCLUSIONS: HCPT significantly inhibited the growth of rabbits’ scleral fibroblasts and effectively inhibited scar formation after filtering surgery by accelerating the degradation of extracellular matrix deposition.