Developing An Ex Vivo Tumor Slice Platform For Lipid Nanoparticle Screening

Abstract

Messenger RNA (mRNA) therapeutics are rapidly emerging as a promising approach for the treatment of a wide range of diseases, including cancer. This is exemplified and reinforced by the recent clinical approval of three nucleic acid-based therapeutics. The type of delivery system plays a pivotal role in the therapeutic efficacy of mRNA-based therapeutics. Among these, lipid nanoparticles (LNPs) have emerged as a highly potential and extensively-studied delivery system. The use of precision-cut tumor slices (PCTS) presents an interesting approach for the evaluation of LNPs in a more native context, as it addresses the translational gap between in vitro and in vivo studies. We present an ex vivo tumor slice platform for the efficient screening of a mRNA-LNP library. Tumor slices were prepared from MC38 tumors grown in C57BL/6J mice and subsequently cultured in vitro. Viability and (endothelial & lymphocyte) cell populations were evaluated over a 48-hour period using a metabolic activity assay, microscopy and flow cytometry. In addition, firefly luciferase (Fluc) mRNA LNPs were generated, characterized and evaluated for efficacy using a 2D in vitro model and the tumor slices. The cultured slices remain viable up to 5 days with endothelial and lymphocyte populations surviving up to 48 hours. Ultimately, tumor slices can be used to successfully screen mRNA LNP libraries. This presents a versatile approach for screening LNP libraries in a reproducible manner within a biologically relevant context, paving the way for more personalized strategies, in for example, cancer therapy.