Intracellular delivery of targeted lipid nanoparticles across three resistant tumour models

Introduction

Lipid nanoparticles are now a practical carrier for several nucleic-acid medicines, yet intracellular delivery into resistant tumour cell populations is still poorly standardised. Papers often report a single model, a single ligand and an incomplete account of the lipid mixture, which makes the next laboratory’s attempt to reproduce the result unnecessarily hard.

This study was designed as a three-model comparison under one manufacturing protocol. The aim was not to identify a clinical candidate, but to show whether ligand targeting still moved uptake once formulation variables were held still.¹

A delivery paper that cannot be rerun from the methods is a demonstration, not a method.

Editorial standard used for this sample record

Materials and Methods

Formulation

Four lots were prepared: one untargeted control and three ligand-targeted lots (LNP-01, LNP-02, LNP-03). The ionisable lipid, helper phospholipid, cholesterol and PEG-lipid molar ratios were identical across lots. Ligands were conjugated after particle formation. Size and polydispersity were recorded by dynamic light scattering immediately after dialysis and again after 72 hours at 4 °C.

1. Lipid film hydration and microfluidic mixing under a fixed flow-rate ratio.
2. Dialysis against phosphate buffer, then sterile filtration at 0.22 µm.
3. Ligand conjugation on the targeted lots only, with an unconjugated control retained.
4. Encapsulation measured against a calibration curve prepared the same day.

Models and endpoints

Three resistant tumour models (A, B and C) were used for uptake. Plasma exposure was measured in a separate pharmacokinetic cohort. Endpoints, exclusion rules and the analysis set were written down before the first animal was dosed. The decay of concentration after the distribution phase was summarised as

Results

All targeted lots remained below 100 nm after dialysis. Encapsulation was above 90% in each targeted lot. Figure 1 places the particles against the three cell-model outlines used for uptake; it is a schematic, not a micrograph.

Figure 1

Placement of targeted lipid nanoparticles against the three resistant tumour models used for uptake. Geometric outlines stand for cell models. Schematic prepared for this sample article record.

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Relative uptake was higher for every targeted lot than for the untargeted control. LNP-03 produced the largest increase. The values in Table 1 and Figure 2 are specimen numbers for the layout; they are not a claim about a real experiment.

Figure 2

Relative uptake by lot. Heights are sample values prepared so the figure component can be reviewed. Schematic prepared for this sample article record.

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Discussion

Holding the lipid ratios constant and varying only the ligand made the uptake differences easier to read. That is a design choice, not proof that ligand targeting will survive a change in lipid identity or in a tumour that was not tested.

The pharmacokinetic cohort was small. Plasma exposure is reported as a descriptive profile, not as a bioequivalence argument. Off-target uptake was not mapped, and the models do not represent a clinical population.

• The study does not identify a preferred clinical formulation.
• No survival or tumour-growth endpoint was collected.
• Reproducibility depends on the lipid lots and ligand batches, which must be stated in any follow-up.

Conclusion

Under a shared manufacturing protocol, ligand-targeted lots increased relative uptake across three resistant tumour models without leaving the intended size band. The useful product of the work is the comparison itself: formulation, model and endpoint written down together so another group can disagree in public.