Magnetic Delivery of Paclitaxel by Magnetic Anionic Liposome/Atelocollagen Complexes for Targeted Cancer Therapy.

Magnetic drug carriers are a valuable tool for site-specific drug delivery, utilizing both passive targeting via the enhanced permeability and retention effect and active targeting through magnetic forces. We previously developed magnetic anionic liposome (Mag-AL)/atelocollagen (ATCOL) complexes and demonstrated their efficient accumulation at the targeted tissue through magnetic attraction and electrostatic interactions. To assess the usefulness of Mag-AL/ATCOL complexes as tumor-targeted drug delivery carriers, we herein prepared paclitaxel (PTX)-loaded Mag-AL/ATCOL complexes and examined their cellular association and cytotoxicity in C26 murine colon adenocarcinoma cells. The biodistribution of the complexes and their antitumor efficacy were also investigated in C26-bearing mice. PTX-Mag-AL/ATCOL complexes exhibited significant binding to C26 cells under an external magnetic field and released PTX in a sustained manner. Consequently, cytotoxic effects against C26 cells were achieved by PTX-Mag-AL/ATCOL complexes with the application of a magnetic field. Moreover, PTX-Mag-AL/ATCOL complexes preferentially distributed in the spleen and liver after their intravenous administration into C26 tumor-bearing mice, while tumor accumulation showed an approximately 2.9-fold augmented by the application of an external magnetic field to the tumor. Due to this magnetic guidance, PTX-Mag-AL/ATCOL complexes significantly inhibited C26 tumor growth. These results indicate that Mag-AL/ATCOL complexes have the potential to improve the therapeutic efficacy of anticancer drugs as magnetic drug carriers.