Modelling Intratumoral Treatment with miRNA Inhibitors: A Method to Analyze the Effect of miRNA Inhibitors on Tumor Growth in Murine Model

miRNA inhibitors are small, chemically modified single-stranded RNA molecules that bind to endogenous miRNA and repress its activity.

To model the effect of intratumoral treatment using miRNA inhibitors, begin by taking a suspension of bioluminescent enzyme-tagged cancer cells. Add a liquified basement membrane matrix to the cancer cell suspension.

Load the resulting mixture into a syringe. Inject it subcutaneously into the left flank of an immunodeficient nude mouse. Allow the cancer cells to grow and form a tumor.

Concomitantly, prepare a treatment mix by adding lipid nanoparticles - an in-vivo delivery agent - to the tube containing miRNA-inhibitor solution. Incubate the treatment mix to allow the encapsulation of miRNA-inhibitors into the lipid nanoparticles.

Inject the treatment mix directly into the tumor. Lipid nanoparticles deliver miRNA-inhibitors inside the tumor cell. Once inside, miRNA-inhibitors bind to specific oncogenic miRNAs, preventing them from hybridizing to their target mRNAs. This leads to the death of cancer cells.

Finally, inject a bioluminescent substrate solution subcutaneously into the mouse. In the presence of bioluminescence enzymes, the substrate in cancer cells oxidizes with subsequent light emission.

Visualize the mouse using a bioluminescence imaging chamber. Intratumorally injected miRNA-inhibitors significantly suppress tumor growth in the mouse.