Lipid Nanoparticle Packaging Is an Effective and Nontoxic mRNA Delivery Platform in Embryonic Zebrafish

Lipid nanoparticles (LNPs) are an attractive platform for the delivery of therapeutic RNA molecules because LNPs are versatile, have been validated in clinical trials, and are well tolerated. Here, we test whether LNPs can be used to deliver a reporter green fluorescent protein (gfp) mRNA to different tissues in zebrafish embryos. We show that LNP-packaged gfp mRNA can be delivered, through injection, and taken up by cells in multiple tissues in zebrafish embryos without any apparent detrimental effects on embryonic health or survival. Zebrafish embryos injected with LNP-packaged gfp mRNA show subsequent GFP expression in neural, vascular, cardiac, and skeletal muscle tissue, depending on injection site. In contrast, comparable naked (nonpackaged) gfp mRNA injections lead to little or no GFP expression. This study shows that LNPs can be used as an mRNA delivery platform in zebrafish and thus provides a basis for testing the therapeutic functions of LNP-packaged candidate mRNAs in the increasingly diverse array of zebrafish disease models.