Bacterial magnetosomes (BMs) are commonly used as vehicles for certain enzymes, nucleic acids and antibodies, although they have never been considered drug carriers. To evaluate the clinical potential of BMs extracted from Magnetospirillum gryphiswaldense in cancer therapy, doxorubicin (DOX) was loaded onto the purified BMs at a ratio of 0.87 +/- 0.08 mg/mg using glutaraldehyde. The DOX-coupled BMs (DBMs) and BMs exhibited uniform sizes and morphology evaluated by TEM. The diameters of DBMs and BMs obtained by AFM were 71.02 +/- 6.73 and 34.93 +/- 8.24 nm, respectively. The DBMs released DOX slowly into serum and maintained at least 80% stability following 48 h of incubation. In vitro cytotoxic tests showed that the DBMs were cytotoxic to HL60 and EMT-6 cells, manifested as inhibition of cell proliferation and suppression in c-myc expression, consistent with DOX. These observations depicted in vitro antitumor property of DBMs similar to DOX. The approach of coupling DOX to magnetosomes may have clinical potential in anti-tumor drug delivery.
Bacterial magnetosomes (BMs) have drawn great interest as novel magnetic targeted carriers and have been widely used as carriers for enzymes, nucleic acids and antibodies experimentally. However, BMs have rarely been employed as drug carriers in vivo mainly due to the unclear biocompatibility and pharmacokinetics of BMs. In this study, we provided a unique effective method for purification and sterilization of BMs. The BMs obtained exhibited sterility, high purity, narrowed size-distribution, uniformity in morphology, intact membrane and abundant amino groups in BMs membrane. To elucidate the in vivo body distribution of BMs and if BMs displayed any rejection by animals when they are delivered into the vascular system, the BMs were injected into the sublingual vena of Sprague-Dawley (SD) rats and the tissue distribution of BMs in dejecta, urine, serum and main organs was examined. A target distribution of BMs in SD rats was observed. After injected into the sublingual vena, BMs were only found in livers and there was no obvious evidence to indicate the existence of BMs in the dejecta and urine within 72 h following the intravenous administration.
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