Purpose: Hepatocellular carcinoma (HCC) has poor survival and standard therapies are limited by off-target toxicity to healthy hepatocytes and drug resistance. Gene therapy is promising, but non-viral vectors often suffer from poor intracellular delivery and lack of cancer specificity. A biodegradable polymeric nanoparticle system is needed to deliver DNA preferentially to HCC cells while sparing healthy liver cells.
Hypothesis: If biodegradable poly(beta-amino ester) (PBAE) nanoparticles are optimized for DNA delivery, then a specific formulation—536 at a 25 polymer-to-DNA w/w ratio—will effectively transfect heterogeneous human HCC cell lines, maintain high hepatocyte viability, and selectively deliver DNA to cancer cells over healthy hepatocytes in co-culture and in vivo.
Aims: Synthesize and screen a library of end-modified PBAE polymers for DNA transfection and cytotoxicity. - Evaluate transfection efficacy and viability across nine human HCC lines and a healthy human hepatocyte line. - Identify a cancer-selective PBAE nanoparticle formulation. - Validate cancer specificity in an HCC/hepatocyte co-culture model. - Test in vivo DNA delivery in a subcutaneous human HCC xenograft mouse model.
Delivery system:
Component: Polymer class; Details: Poly(beta-amino ester)s (PBAEs); biodegradable, cationic
Component: Lead polymer; Details: 536: 2-((3-aminopropyl)amino)ethanol end-modified poly(1,5-pentanediol diacrylate-co-3-amino-1-propanol)
Component: Nanoparticle type; Details: Polymeric nanoparticles formed by electrostatic complexation with DNA
Component: Payload; Details: Plasmid DNA: eGFP-N1 for in vitro; luciferase-pcDNA3 for in vivo
Component: Polymer:DNA ratios; Details: 25, 50, 75 w/w; lead formulation 536 at 25 w/w
Component: DNA dose; Details: 600 ng/well in vitro
Component: Size / zeta; Details: ~157 ± 3 nm hydrodynamic size; zeta potential ~18 ± 0.3 mV in PBS
Component: Targeting ligand; Details: None
Component: Key feature; Details: Biomaterial-mediated cancer-specific DNA delivery; no synthetic targeting ligand
Approach: In vitro: Nine human HCC lines (Huh-7, Hep3b, HepG2, C3A, SK-HEP-1, PLC/PRF/5, SNU-387, SNU-423, SNU-475) and healthy human hepatocyte line THLE-3. - Transfection: eGFP DNA; 2 h incubation; flow cytometry at 48 h; MTS viability at 24 h. - Controls: Lipofectamine 2000, jetPRIME, 25 kDa branched PEI. - Co-culture: RFP-positive Huh-7 HCC cells + RFP-negative THLE-3 hepatocytes; eGFP transfection; flow cytometry and microscopy. - Electroporation control: eGFP plasmid electroporated without polymer to test transcription/translation differences. - In vivo: Subcutaneous Huh-7 xenografts in athymic nude mice; intratumoral injection of 536 25 w/w NPs carrying luciferase plasmid; bioluminescence imaging at 6, 24, 48 h. n = 4 for PBAE NP and n = 3 for PBS. - No orthotopic liver tumor model; no therapeutic gene; no survival endpoint.
Key methods: Polymer/NP characterization: GPC, ¹H NMR, DLS, zeta potential, TEM. - Transfection: Flow cytometry for eGFP-positive % and geometric mean fluorescence. - Viability: MTS assay. - Cellular uptake: Cy5-labeled DNA; flow cytometry. - Co-culture specificity: RFP/Huh-7 vs THLE-3; flow cytometry and fluorescence microscopy. - Electroporation: Control for plasmid transcription/translation. - In vivo: Bioluminescence imaging (IVIS) after intratumoral NP injection. - Statistics: Student’s t-test, one-way ANOVA with Dunnett’s/Bonferroni post hoc; p < 0.05.
Key results: Lead formulation: 536 at 25 w/w was the only PBAE that effectively transfected all nine HCC lines while maintaining THLE-3 viability >80%. - Transfection efficacy: eGFP expression ranged from 36.9% ± 0.4 to 83.5% ± 0.5 in HCC cells; approximately 20% in healthy THLE-3 hepatocytes. Each HCC line had significantly higher expression than hepatocytes (p < 0.01). - Comparison to PEI: PEI 25 kDa 2 w/w only achieved comparable transfection in 2 of 9 HCC lines; slow-dividing HCC lines were poorly transfected by PEI but well transfected by 536. - Co-culture specificity: 536 25 w/w NPs preferentially transfected Huh-7 HCC cells: 95.37% ± 0.5 eGFP-positive Huh-7 vs 35.6% ± 0.26 THLE-3 hepatocytes (p < 0.01). - Mechanism: Cancer selectivity was not due to cell growth rate or transcription/translation differences; cellular uptake of 536 NPs was significantly lower in THLE-3 hepatocytes than in HCC lines. - In vivo: Intratumoral 536 25 w/w NPs produced significant luciferase expression in subcutaneous Huh-7 xenografts at 24 h compared with PBS (p < 0.05).
Interpretation: The authors claim that PBAE-based nanoparticles, especially 536 at 25 w/w, enable high and preferential DNA delivery to heterogeneous human HCC cells while sparing healthy hepatocytes. The formulation maintained viability, showed cancer-selective uptake, and achieved in vivo transfection in a subcutaneous HCC model. These biodegradable, liver cancer–selective NPs are proposed as a promising non-viral platform for therapeutic gene delivery to liver cancer.
Limitations: In vivo model: Subcutaneous Huh-7 xenograft only; no orthotopic liver tumor or systemic/transarterial delivery. - No therapeutic efficacy: Only reporter genes (eGFP, luciferase); no tumor growth inhibition, survival, or therapeutic gene testing. - Small in vivo sample size: n = 4 for PBAE NP, n = 3 for PBS. - No biodistribution or long-term safety data. - No targeting ligand: Cancer specificity relies on biomaterial-mediated uptake, mechanism not fully resolved. - No large-animal or human validation. - Limited mechanistic insight: Uptake differences observed, but full pathway/mechanism not established. - No evaluation of repeat dosing, immunogenicity, or clearance. - Co-culture model: Only one HCC line (Huh-7) paired with hepatocytes; not fully representative of HCC heterogeneity.
