Docetaxel prodrug and hematoporphyrin co-assembled nanoparticles for anti-tumor combination of chemotherapy and photodynamic therapy

Abstract

To realize the synergistic anti-tumor effect of chemotherapy and photodynamic therapy, the mono sulfide-modified docetaxel (DTX) prodrugs (DSD) provided by our laboratory and hematoporphyrin (HP) were used to physically prepare co-assembled nanoparticles (DSD/HP NPs) by nano-precipitation. For the first time, this study showed its characteristics, in vitro anti-tumor activity, pharmacokinetic behavior in rats, in vivo distribution, and pharmacodynamic effects on 4T1 tumor-bearing Bal b/c mice. DSD/HP NPs optimized by single-factor and response surface optimization had several distinct characteristics. First, it had dark purple appearance with particle size of 105.16 ± 1.24 nm, PDI of 0.168 ± 0.15, entrapment efficiency and drug loading of DSD and HP in DSD/HP NPs of 96.27 ± 1.03% and 97.70 ± 0.20%, 69.22 ± 1.03% and 20.03 ± 3.12%, respectively. Second, it had good stability and could release DTX and HP slowly in the media of pH 7.4 PBS with 10 mM DTT (H₂O₂). Moreover, DSD/HP NPs along with NiR treatment significantly inhibited 4T1 cells proliferation, and induced more reactive oxygen species and cells apoptosis. In vivo pharmacokinetic and pharmacodynamic studies showed that DSD/HP NPs could prolong the drug circulation time in rats, increase drug distribution in tumor site, obviously inhibit tumor growth, and decrease the exposure of drug to normal tissues. Therefore, DSD/HP NPs as a promising co-assembled nano-drug delivery system could potentially improve the therapeutic efficiency of chemotherapeutic drug and achieve better anti-tumor effects due to the combination of chemotherapy and photodynamic therapy.

Keywords: Docetaxel prodrug; chemotherapy; co-assembled nanoparticles; hematoporphyrin; photodynamic therapy.

Scheme 1.

Schematic illustration of DSD/HP co-assembled nano-drug delivery system for the combination of nanotechnology, chemotherapy, and photodynamic therapy. I DSD and HP were successfully prepared to be as co-assembled nanoparticles (DSD/HP NPs) using the method of nanoprecipitation. II DSD/HP NPs were administered to rats intravenously to prolong the drugs circulated time in blood. III The designed DSD/HP NPs improved the accumulation of drugs in tumor site, produced more ROS to induce 4T1 cells apoptosis, and initiated the antitumor efficiency of chemotherapy and locoregional photodynamic therapy.

Figure 1.

Three-dimensional effect diagram of three factors (DSD concentration, molar ratio of HP to DSD, and stabilizer) on the particle size (Size), PDI, EE of DD (EE₁), and EE of HP (EE₂) of DSD/HP NPs.

Figure 2.

The appearance picture (A), TEM image (B), particle size distribution (C), physical stability (D), and long-term storage stability (E) of DSD/HP NPs. In vitro release profiles of DTX (F) and HP (G) released from DSD/HP NPs under different media. The plasma concentration time curves of DTX after intravenous injection of DTX-Inj, DSD NPs, and DSD/HP NPs at the dose of 0.01 mmol DTX/kg in rats (H) (n = 6, mean ± SD; **p < 0.01vs PBS group; ^##p < 0.01vs H₂O₂ group).

Figure 3.

The effects of DTX-Sol (A), DSD NPs (B), MIX-Sol (C), MIX-Sol + NiR (D), DSD/HP NPs (E), and DSD/HP NPs + NiR (F) groups on cell viability in 4T1 cells after 24 h and 48 h incubation at different concentrations of DTX (n = 3).

Figure 4.

The ROS fluorescence images (A) and relative fluorescence values (B) of Control, Control + NiR, DTX-Sol, DSD NPs, HP-Sol + NiR, MIX-Sol, MIX-Sol + NiR, DSD/HP NPs, and DSD/HP NPs + NiR groups in 4T1 cells (** p < 0.01 vs Control group, ## p < 0.01 vs DTX-Sol group, bb p < 0.01 vs DSD/HP NPs group, n = 3).

Figure 5.

The effects of Control, Control + NiR, DTX-Sol, DSD NPs, HP-Sol + NiR, MIX-Sol, MIX-Sol + NiR, DSD/HP NPs, and DSD/HP NPs + NiR groups on 4T1 cells apoptosis. The quantitative result of Annexin V-FITC/PI double staining apoptosis assays by flow cytometry (A and B). The qualitative analysis result of DAPI staining (C) (** p < 0.01 vs Control group, ## p < 0.01 vs DTX-Sol group, bb p < 0.01 vs DSD/HP NPs group, n = 3).

Figure 6.

The changes of body weight (A), tumor volume (B), and H&E staining image (C) of tissues of 4T1 tumor-bearing mice treated with Saline, DTX-Inj, HP-Sol + NiR, DSD NPs, MIX-Sol + NiR, DSD/HP NPs, DSD/HP NPs-10 + NiR, DSD/HP NPs-5 + NiR, and DSD/HP NPs-3 + NiR (** p < 0.01 vs Saline, ## p < 0.01 vs DTX-Inj, b p < 0.05, bb p < 0.01 vs DSD NPs, cc p < 0.01 vs DSD/HP NPs).