In vitro and in vivo evaluation of actively targetable nanoparticles for paclitaxel delivery

https://doi.org/10.1016/j.ijpharm.2004.10.009Get rights and content

Abstract

The aim of the present work was to assess the merits of an actively targetable nanoparticles (ATN), PEG-coated biodegradable polycyanoacrylate nanoparticles (PEG-nanoparticles) conjugated to transferrin, for paclitaxel delivery. PEG-nanoparticles loading paclitaxel were prepared by solvent evaporation technique in advance. ATN were prepared by coupling of transferrin to PEG-nanoparticles. The results showed that the average encapsulation efficiency of ATN was 93.4 ± 3.6% with particle size (101.4 ± 7.2 nm) and zeta-potential (−13.6 ± 1.1 mV). The paclitaxel loaded ATN exhibited a low burst effect with about only 16.2% drug release within the first phase. Subsequently, paclitaxel release profiles displayed a sustained release phase. The amount of cumulated paclitaxel release over 30 days was 81.6%. ATN exhibited a markedly delayed blood clearance in mice, and the paclitaxel level from ATN remained much higher at 24 h compared with that of free drug from paclitaxel injection. The distribution profiles of ATN in S-180 solid tumor-bearing mice after intravenous administration showed the tumor accumulation of paclitaxel increase with time, and the paclitaxel concentration in tumor was about 4.8 and 2.1 times higher than those from paclitaxel injection and PEG-nanoparticles at 6 h after intravenous injection. For mice treated with 20 mg/kg × 5 of ATN, the decrease in body weight was limited within 4% of the initial weight at 5 days after the final administration, and tumor regression was significantly observed with complete tumor regression for five out of nine mice. The tumor burden with ATN-treated mice was much smaller compared with free paclitaxel or NTN-treated mice. In addition, the life span of tumor-bearing mice was significantly increased when they were treated with ATN, in particular, three mice survived over 60 days. Thus, PEG-coated biodegradable polycyanoacrylate nanoparticles conjugated to transferrin could be an effective carrier for paclitaxel delivery.

Introduction

Paclitaxel has demonstrated significant activity in clinical trials against a wide variety of tumors, especially, ovarian and breast cancer in the past 10–20 years. However, due to its high hydrophobicity, an adjuvant such as Cremophor EL has to be used to prepare injection as its clinical dosage form. Unfortunately, Cremophor EL causes serious side-effects and leads to hypersensitivity reactions in many patients (Panchagnula, 1998, Dhanikula and Panchagnula, 1999, Singla et al., 2002). In order to increase therapeutic efficiency and reduce side-effects, much effort has been devoted to the development of tumor-targetable DDS of paclitaxel such as liposomes (Sampedro et al., 1993, Sharma and Straubinger, 1994, Crosasso et al., 2000), nanoparticles (Suh et al., 1998, Fonseca et al., 2002, Mu and Feng, 2002, Mu and Feng, 2003, Kim et al., 2003, Mitra and Lin, 2003, Potineni et al., 2003), parenteral emulsion (Lundberg, 1997, Kan et al., 1999), water-soluble prodrugs and conjugates (Rodrigues et al., 1995, Dosio et al., 1997, Pendri et al., 1998, Safavy et al., 2003). So far, the different approaches investigated have shown a lot of promise to replace the Cremophor EL-based vehicle for paclitaxel delivery, but except liposomes, the final product for human use is still far away.

In general, solid tumors show hypervascular permeability and impaired lymphatic drainage. Due to such effects, macromolecules or nanoparticles (<200 nm) can significantly accumulate in tumor, however, this behavior belongs to passive mechanism and lacks go-aheadism to recognize and bind to tumor cell or tissue. It has been reported that the membrane transferrin receptor-mediated endocytosis of the complex of transferrin bound iron and transferrin receptor is the major route of cellular iron uptake, and the efficient cellular uptake pathway has been exploited for the site-specific delivery of anti-tumor drugs, protein and therapeutic gene into proliferating cells including erythroblasts and cancer cells that overexpress transferrin receptor (Wagner et al., 1994, Li and Qian, 2002). The conjugation of transferrin with drugs is usually performed either directly by chemical conjugation or genetically by infusion of peptides/proteins into the structure of transferrin. Although direct coupling methods are easy to carry out, they show some disadvantages, such as polymeric products are likely to be formed during the preparation, and the resulting conjugates are chemically poorly defined with respect to the chemical link between drugs and carrier proteins (Kratz and Beyer, 1998, Singh, 1999). In addition, it has shown that transferrin-coupled liposomes significantly enhanced uptake of free doxorubicin or α-IFN via the receptor-mediated mechanism (Liao et al., 1998, Eavarone et al., 2000). So, the design of PEG-coated biodegradable polycyanoacrylate nanoparticles conjugated to transferrin (transferrin-PEG nanoparticles), an actively targetable nanoparticles (ATN) as paclitaxel carriers could be one of the ideal solutions to deliver paclitaxel to tumor because ATN has double effect from passive and active mechanism.

Previously, we prepared nanoparticles bearing polyethylene glycol-coupled transferrin for delivery of pDNA, and the cells association assay showed that the degree of target cell binding of this nanoparticles was much greater than that of common PEG-nanoparticles without bearing transferrin in vitro (Li et al., 2003). In this study, we selected paclitaxel as model drug and compared ATN's pharmacokinetics behavior, distribution, toxicity and anti-tumor efficacy in animal models with non-actively targeted PEG-nanoparticles (NTN) and current clinical formulation (paclitaxel injection). The result showed that this new formulation achieved a lot of advantages, especially, more effectively tumor regression through remarkably enhanced tumor accumulation of paclitaxel.

Section snippets

Materials

Paclitaxel (purity, >99%) and paclitaxel injection (No. 030911, 30 mg/5 ml) were purchased from Shanghai Hualian Pharmaceutical Co. Ltd. t-Boc-HNPEG 3400 was purchased from Shearwater Polymers Inc. (Huntsville, AL). Cyanoacetic acid (purity, 99%) and polyvinylalcohol (MW = 16,000) was obtained from Fluka (Buches, Switzerland). n-Hexadecanol, trifluoroacetic acid and human transferrin were purchased from Sigma (St. Louis, MO,USA). Mouse-anti-human transferrin antibody (MAB 033-19/1) and

Characteristics of ATN loading paclitaxel

The characteristics of ATN loading paclitaxel were summarized in Table 1. The paclitaxel was incorporated in ATN and NTN with a little different encapsulation efficiency by emulsion technique. ATN showed slightly low encapsulation efficiency than that of NTN. This result could be from that some paclitaxel was unadsorbed during transferrin was conjugated with NTN. In general, some of the drug could be adsorbed onto the surface of the nanoparticles by various forces such as Vander Wals forces

Acknowledgements

The work was partly supported by the National Natural Science Foundation of China, No. 30371691, and the National Basic Research Program of China (973 Program), No. 2004CB518802. Authors thank Prof. Zuming Shen and Dr. Yafang Wang for their excellent technical assistance in animal experiment.

References (30)

  • M. Rodrigues et al.

    Synthesis and β-lactamase-mediated activation of cephalosporin-taxol prodrug

    Chem. Biol.

    (1995)
  • A.K. Singla et al.

    Paclitaxel and its formulations

    Int. J. Pharm.

    (2002)
  • B. Stella et al.

    Design of folic acid-conjugated nanoparticles for drug targeting

    J. Pharm. Sci.

    (2000)
  • F. Dosio et al.

    Preparation and characterization and properties in vitro and in vivo of a paclitaxel-albumin conjugates

    J. Control. Release

    (1997)
  • D.A. Eavarone et al.

    Targeted drug delivery to C6 glioma by transferrin-coupled liposomes

    J. Biomed. Mater. Res.

    (2000)
  • Cited by (143)

    • Taxane anticancer formulations: challenges and achievements

      2020, Advances in Medical and Surgical Engineering
    • Engineered Hydrogels in Cancer Therapy and Diagnosis

      2017, Trends in Biotechnology
      Citation Excerpt :

      The unique features of hydrogels highlight them as broadly applicable biomaterials (Figure 3 and Table 1) [18]. Previous studies have demonstrated the feasibility of the use of hydrogel vehicles as smart and/or local delivery of multiple cargos [24,47,87]. Hydrogels also have the capability to carry nanoparticles that potentially could play a role as on/off molecular nanoswitches triggered by tumor hallmarks [53].

    View all citing articles on Scopus
    View full text