Evaluating the influence of cholesterol content on the cellular uptake and formulation activity of nanoliposomal formulations against uveal melanoma

Introduction: Uveal melanoma (UM) is a rare but aggressive intraocular malignancy with limited responsiveness to current therapies. Nanoliposomal delivery systems can enhance intracellular drug transport, but their performance depends on lipid composition and the tumor's metabolic profile. UM exhibits dysregulated cholesterol metabolism driven by altered expression of enzymes such as SREBP2. Because cholesterol is a key structural membrane component that influences liposome properties, this study evaluated how cholesterol inclusion affects nanoliposome uptake and drug effects in UM cells. Methodology: MP41 uveal melanoma cells (ATCC®) were cultured in RPMI supplemented with 25% FBS. Cells (2×10⁴/mL) were seeded in vented centrifuge tubes and exposed to DPPE-rhodamine-labeled nanoliposomes containing 0, 5, 10, or 20 mol% cholesterol substituted for DOPC. Tubes were placed in an oscillating incubator at 37 °C for 60 minutes to promote liposome-cell interactions. Cellular uptake was quantified using a fluorescence microplate reader, and Quad Count™ was used for cell counting, viability, and growth-inhibition assessments. Result: At 1 hour, the inclusion of cholesterol decreased the uptake of nanoliposomes by MP41 uveal melanoma cells. DOPC consistently demonstrated the highest cellular uptake values (≈2594-4543 RFU), while 95/5 and 90/10 formulations displayed lower values (≈800-3451 RFU) by comparison. These findings reveal a reproducible inverse relationship between cholesterol content and cellular uptake, suggesting that the inclusion of cholesterol in nanoliposome diminishes cellular uptake. Ongoing studies will evaluate additional time points and conditions, and whether the findings correlate with cytotoxicity studies. Conclusion: Reduced cholesterol content in nanoliposomal formulations markedly enhanced cellular uptake by uveal melanoma cells. The consistently higher internalization observed with DOPC (100%) supports the use of relatively low-cholesterol (or cholesterol-free) preparations to enhance targeting. Cholesterol modulation could potentially enhance the effectiveness of therapeutics against uveal melanoma.