Engineering of lipid prodrug-based, hyaluronic acid-decorated nanostructured lipid carriers platform for 5-fluorouracil and cisplatin combination gastric cancer therapy

Purpose: 5-Fluorouracil (5-FU) plus cisplatin (CDDP) is a first-line gastric cancer chemotherapy regimen, but it causes substantial toxicity and 5-FU has poor biopharmaceutical properties. A targeted nanoparticle platform could codeliver both drugs, improve synergy, and reduce systemic toxicity.

Hypothesis: If 5-FU is converted into a lipid prodrug (5-FU–stearic acid) and co-encapsulated with CDDP into hyaluronic acid (HA)-coated nanostructured lipid carriers (NLCs), then the formulation will selectively target CD44-overexpressing gastric cancer cells, produce synergistic antitumor activity, and reduce systemic toxicity compared with free drugs or uncoated NLCs.

Aims: Synthesize and characterize a 5-FU–stearic acid lipid prodrug. - Prepare 5-FU prodrug/CDDP-loaded NLCs (FU/C-NLC) and HA-coated NLCs (HA-FU/C-NLC). - Optimize HA coating concentration by evaluating zeta potential, particle size, and encapsulation efficiency. - Evaluate in vitro cytotoxicity and drug synergy in BGC823 gastric cancer cells. - Assess in vivo antitumor efficacy and systemic toxicity in BGC823 xenograft-bearing mice.

Delivery system: Platform: Nanostructured lipid carriers (NLCs). - Lipid matrix: Glyceryl monostearate, soya lecithin, soybean oil (2:1:1, w/w/w). - Surfactants/stabilizers: Tween 80 and dimethyldioctadecylammonium bromide. - Payload: 5-FU–stearic acid prodrug and cisplatin (CDDP). - Targeting ligand: Hyaluronic acid (HA) coating for CD44-mediated targeting. - Optimized formulation: HA-FU/C-NLC; size 181.6 ± 3.2 nm, PDI 0.21 ± 0.04, zeta potential +26.3 ± 2.4 mV; encapsulation efficiency 89.8 ± 2.9% for 5-FU and 89.1 ± 2.1% for CDDP. - Route: Intravenous tail-vein injection.

Approach: In vitro: Human gastric cancer BGC823 cells; MTT cytotoxicity assay; combination index (CI) analysis at various 5-FU:CDDP weight ratios. - In vivo: BALB/c nude mice bearing BGC823 xenografts; eight groups (n = 6): saline, HA-FU/C-NLC, FU/C-NLC, FU-NLC, C-NLC, free 5-FU–stearic acid + CDDP solution, free 5-FU–stearic acid solution, and free CDDP solution. - Dosing: 20 mg 5-FU/kg and 1 mg CDDP/kg; tail-vein injection once weekly for 21 days. - Monitoring: Tumor volume and body weight measured every 3 days.

Key methods: ¹H NMR for prodrug structure confirmation. - TEM for nanoparticle morphology. - Photon correlation spectroscopy / Zetasizer for particle size, PDI, and zeta potential. - HPLC for 5-FU–stearic acid quantification; graphite furnace atomic absorption spectroscopy for CDDP. - Dialysis method for in vitro drug release. - MTT assay for cytotoxicity; CI calculation for synergy. - Tumor volume and body weight measurements for in vivo efficacy/toxicity.

Key results: Optimal HA coating concentration was 0.2% (w/v); higher concentrations (0.3–0.4%) decreased encapsulation efficiency and increased particle size. - HA-FU/C-NLC showed sustained release: >80% 5-FU release at 48 h vs 36 h for FU/C-NLC and 24 h for FU-NLC; >80% CDDP release at 48 h vs 12 h for FU/C-NLC and C-NLC. - Synergy was strongest at a 5-FU:CDDP weight ratio of 20:1; HA-FU/C-NLC had the lowest CI₅₀ (0.31), indicating synergism. - In vivo, HA-FU/C-NLC produced the greatest tumor growth inhibition among all groups (P < 0.05 vs free drugs and uncoated NLC). - HA-FU/C-NLC showed no significant body weight loss, whereas free drug groups had noticeable weight loss.

Interpretation: HA-coated NLCs codelivering a 5-FU lipid prodrug and CDDP provide synergistic antitumor activity with reduced systemic toxicity in a gastric cancer model. The authors propose this as a promising targeted combination nanomedicine platform for gastric cancer and potentially other antitumor drug combinations.

Limitations: Only one gastric cancer cell line (BGC823) and one xenograft model were used. - No survival study; efficacy was monitored for only 21 days. - No biodistribution or CD44-blocking/competitive targeting validation. - No long-term toxicity or repeated-dose safety evaluation. - HA targeting is inferred from CD44 expression but not directly proven in this study. - No comparison with clinical standard regimens or other nanocarrier systems. - No large-animal validation.