Non-Viral Gene Delivery to Hepatocellular Carcinoma via Intra-Arterial Injection

Component: Polymer; Description: Poly(beta-amino ester) (PBAE) 536 — B5-S3-E6: 1,5-pentanediol diacrylate backbone (B5) + 3-amino-1-propanol sidechain (S3) + 2-(3-aminopropylamino)ethanol endcap (E6)

Component: Other PBAEs Tested; Description: 446 (B4-S4-E6), 457 (B4-S5-E7)

Component: PBAE 536 Properties; Description: Molecular weight: 4370 g/mol; Polydispersity index: 2.40

Component: Nanoparticle Formulation; Description: PBAE + plasmid DNA in 25 mM sodium acetate (pH 5); polymer:DNA weight ratio 25:1 or 50:1

Component: Nanoparticle Size; Description: ~300 nm (hydrodynamic diameter)

Component: Zeta Potential; Description: 20-30 mV (positive; slightly reduced with sucrose)

Component: Cryoprotectant; Description: 90 mg/mL sucrose; NPs stable after freezing at -80°C (size unchanged)

Component: Payload; Description: • eGFP-N1 plasmid (in vitro)<br>• Firefly luciferase (fLuc) plasmid (in vivo)<br>• IRDye 800RS-labeled DNA (10% of mass; biodistribution)

Component: Delivery Route; Description: • Intra-arterial: hepatic artery via gastroduodenal artery (GDA) injection (500 μL, 100 μL/min)<br>• Intravenous: jugular vein injection (control)

Component: Cell Model; Description: N1-S1 rat hepatocellular carcinoma cells (ATCC)

Component: Animal Model; Description: RNU athymic rats (orthotopic HCC; liver capsule injection of N1-S1 cells)

Parameter: In Vitro Screening; Details: N1-S1 cells in adherent (laminin-coated) or suspension (round-bottom) culture; 300, 600, or 900 ng GFP DNA; 25 or 50 w/w ratios; 2 h incubation; assessed at 48 h

Parameter: In Vitro Readouts; Details: • Flow cytometry: % GFP-positive cells, geometric mean fluorescence<br>• MTS assay: cell viability (24 h post-transfection)<br>• Fluorescence microscopy (Axio Observer, 10×)

Parameter: Intra-Arterial Procedure; Details: Laparotomy; liver and duodenum externalized; GDA isolated and ligated distal end; common hepatic artery clamped; 27G needle inserted into GDA; 500 μL NPs injected at 100 μL/min; GDA ligated proximal; clamp removed

Parameter: In Vivo Groups; Details: • Healthy rats: IA (n=2) and IV (n=3)<br>• Tumor-bearing rats: IA (n=2) and IV (n=1)

Parameter: In Vivo Readouts; Details: IVIS imaging at 6 h post-injection: fluorescence (biodistribution; NIR dye) and bioluminescence (transfection; fLuc expression after D-luciferin injection)

Parameter: NP Characterization; Details: DLS (size); electrophoretic mobility (zeta potential); fresh vs. frozen (± sucrose)

Parameter: Statistics; Details: One-way ANOVA with Dunnett's post-test; GraphPad Prism

Analysis Category: Nanoparticle Characterization; Methods: DLS (Malvern Zetasizer Pro) — hydrodynamic diameter; electrophoretic mobility — zeta potential; GPC — molecular weight/PDI

Analysis Category: In Vitro Transfection; Methods: Flow cytometry (Attune NxT): % GFP+ cells, geometric mean; Fluorescence microscopy (Zeiss Axio Observer); MTS assay (Promega) for viability

Analysis Category: Surgical Procedure; Methods: Microsurgical hepatic artery injection via GDA; jugular vein injection for IV control; liver tumor implantation under liver capsule

Analysis Category: In Vivo Imaging; Methods: IVIS Spectrum; D-luciferin (150 mg/kg i.p.); fluorescence (NIR, ex/em: 778/794 nm) and bioluminescence; Living Image software; ROI analysis

Analysis Category: Image Analysis; Methods: Fold increase in average radiance over background (tumor ROI)

Parameter: Transfection efficiency (all PBAEs); Result: >50% GFP+ cells at various doses and w/w ratios

Parameter: Cell viability; Result: >70% for most formulations (lower for high dose/ratio of 457 and 536)

Parameter: Transfection pattern; Result: Higher w/w ratio (50 vs 25) = higher transfection

Parameter: Optimal PBAE selected; Result: 536 (intermediate efficacy, good viability; validated in prior human HCC work)

Formulation: Fresh (no sucrose); Size (nm): ~300; Zeta Potential (mV): 20-30

Formulation: Fresh + sucrose; Size (nm): ~300; Zeta Potential (mV): Modestly decreased (p=0.0288)

Formulation: Frozen (no sucrose); Size (nm): ~300; Zeta Potential (mV): ~20-30

Formulation: Frozen + sucrose; Size (nm): ~300; Zeta Potential (mV): Significantly decreased (p<0.0001)

Formulation: Stability; Size (nm): Size maintained across all conditions; Zeta Potential (mV): -

Route: Intravenous (n=3); NIR Fluorescence (Biodistribution): NPs in liver; Bioluminescence (Transfection): No transfection

Route: Intra-arterial (n=2); NIR Fluorescence (Biodistribution): NPs in liver; Bioluminescence (Transfection): No transfection

Route: Intravenous (n=1); NIR Fluorescence (Biodistribution): NPs in healthy liver; not in tumor; Bioluminescence (Transfection): No transfection in tumor or liver; Fold Increase (ROI over background): 1.61×

Route: Intra-arterial (n=2); NIR Fluorescence (Biodistribution): NPs in tumor and surrounding liver; Bioluminescence (Transfection): Transfection detected in tumor; Fold Increase (ROI over background): 27.9×

1. Small sample sizes: In vivo experiments used n=1-2 per group, limiting statistical power and generalizability. The authors acknowledge the preliminary nature of the study.

2. Off-target expression: "Off-target expression was observed in the surrounding liver tissue" after intra-arterial injection, indicating incomplete tumor selectivity. The authors note that "larger animal models may allow for more accurate simulation" of selective TACE-like catheterization.

3. Model limitations: The RNU athymic rat model was used due to spontaneous regression of N1-S1 tumors in syngeneic rats; this immunodeficient model does not recapitulate the immune microenvironment of HCC.

4. No therapeutic cargo: The study used reporter genes (GFP, fLuc) only; therapeutic efficacy with a functional gene (e.g., suicide gene, tumor suppressor) was not demonstrated.

5. No comparison to TACE or DEB-TACE: The study does not benchmark NP delivery against standard clinical procedures (TACE with chemotherapy or drug-eluting beads).

6. NP size relatively large: The ~300 nm nanoparticles may have limited diffusion into tumor tissue; the authors note that "systematic studies of NP size have shown improved intratumoral delivery with smaller (~100 nm) NPs."

7. Vascular model limitations: The authors acknowledge that "this preclinical model in rats enables effective NP delivery, it does not recapitulate the full selectivity of the TACE procedure, where specific branches feeding the tumor are selectively catheterized using real-time imaging."

8. No long-term safety assessment: The study assessed biodistribution and transfection at 6 h only; no evaluation of off-target expression, immunogenicity, or organ toxicity over time.

9. No active targeting: The NPs rely on passive delivery and the EPR effect; no tumor-specific targeting ligands were incorporated.

10. No in vivo luciferase expression kinetics: Expression was measured at a single time point (6 h); duration of transgene expression was not assessed.

11. Rat model not fully translational: While orthotopic, the rat model may not fully recapitulate human HCC vascularity, cirrhosis, or the complex tumor microenvironment.

12. Potential for embolism: The authors note that injections were performed at a rate of 100 μL/min "to minimize risk of embolism," but embolic complications were not systematically evaluated.

Report prepared based on the published International Journal of Nanomedicine article. For full experimental details, supplementary figures, and complete references, please refer to the original publication.