Abstract 2004: Selective cytotoxicity of multiple myeloma using novel cell membrane lipid-extracted nanoliposomes
Authors: Amorin Matthew , Daley Peter , Smullen William , Campbell Robert 
Published: April 2023

Background: Multiple Myeloma (MM) is a highly malignant hematologic disease that originates in the bone marrow from tumorigenic plasma cells that rapidly proliferate and often metastasize before detection or symptom manifestation. Due to the enhanced anaerobic metabolism of cancer vis-a-vis normal cells, elevated media levels of LDH following cell death can serve as a reliable benchmark for in-vitro targeted MM treatment efficacy. Cell membrane Lipid Extracted Nanoliposomes (CLENs) are novel drug delivery vehicles that demonstrate preferential uptake by neoplastic cells. By varying the composition of CLENs, they can be tailored to optimize liposomal uptake by MM cells. This study evaluates the degree to which optimized in-vitro cellular uptake of CLENs translates to cytotoxicity by comparing the attrition rate of doxorubicin hydrochloride (DOX)-loaded MM CLENs compared to relevant liposomal and cellular controls.

Methods: The RPMI 8226 cell line was this study’s cellular model for MM. RPMI-8226 cells were seeded at 10,000 cells/mL in 48 well plates. The Y79 (retinoblastoma) cell line served as the negative control for all in vitro experiments. Both cell lines were exposed to two different liposome preparations loaded with 3 mol% doxorubicin hydrochloride (DOX), a MM targeted CLENs preparation of 95% DOPC and 5 mol% RPMI-8226 cell lipid extract (LE) and a non-specific, 100 % DOPC liposome. Liposome preparations were separated from free drug by centrifugation and overnight dialysis. Following overnight liposome exposure, the CyQUANTTM LDH Cytotoxicity Assay Kit (Invitrogen) was utilized to assess extracellular LDH activity and evaluate cytotoxicity of DOX-loaded RPMI-8226 LE in vitro.

Results: The mean diameter for the DOX-loaded DOPC (100%) and DOPC/LE (95/5) nanoliposomes was 203 ± 24.3 nm (n=4) and 235 ± 24.6 nm (n=4), respectively. The average zeta potential was -15.79 ± 0.33 mV (n=2) and 0.26 ± 0.19 mV (n=2) for DOPC (100%) and DOPC/LE (95/5), respectively. The mean percent of doxorubicin incorporated into DOPC (100%) and DOPC/LE (95/5) was 72% (n=4) and 84% (n=4), respectively. Following overnight exposure of RPMI 8226 cells to DOX-loaded DOPC (100%) and DOX-loaded DOPC/LE (95/5) at 50 nM and 150 nM, preliminary results showed that the inclusion of LE significantly improved cytotoxicity when compared to the DOX-loaded DOPC control. Additionally, DOX-loaded DOPC/LE (95/5) displayed enhanced extracellular LDH activity compared to the DOX-loaded DOPC control, indicated by higher red formazan fluorescence intensity. There was no difference in LDH activity or cytotoxicity between the two DOX-loaded preparations against Y79 (negative control) cells.

Conclusions: Preliminary results suggest that RPMI 8226-CLENs represent an improvement over the use of more conventional nanoliposome preparations. Future studies will evaluate additional drug-loaded CLENs in vitro.

Citation Format: Matthew Amorin, Peter Daley, William Smullen, Robert Campbell. Selective cytotoxicity of multiple myeloma using novel cell membrane lipid-extracted nanoliposomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2004.