Nanotherapy for leishmaniasis
doi:10.1038/nindia.2011.74 Published online 30 May 2011
Researchers have devised a novel way of delivering an anti-leishmanial drug that overcomes drug-induced toxicity. The drug carrier, made of a multiwalled carbon nanotube, enhances the drug's efficacy for inhibiting the growth of Leishmania donovani, a parasite that causes visceral leishmaniasis.
Treating leishmaniasis with first-line drugs such as amphotericin B (AmB), paromomycin and miltefosine is a challenge because such treatments are toxic and expensive. Furthermore, many Leishmania parasites are now resistant to these drugs. Liposomal formulation of AmB, although effective and only slightly toxic, is expensive.
Such drawbacks encouraged the researchers to look for suitable alternatives. They selected carbon nanotube (CNT) for its ability to bind to biomolecules and deliver them to target tissues. Modified CNT has been shown to permeate cell membranes and deliver biomolecules into cells — an attribute that makes them attractive as drug-delivery vehicles.
The researchers attached AmB to functionalized CNTs (f-CNTs) to yield AmB-f-CNTs. They then compared the toxicity and efficacy of AmB-f-CNTs with AmB and f CNTs in lab and animal studies.
In lab studies with mice macrophage cell lines, AmB-f CNT was around 14 times more potent than AmB for inhibiting the growth of amastigotes, the form of Leishmania parasites that cause leishmaniasis in humans. In addition, AmB-f CNT showed no toxicity to kidney and liver in mice. The percentage suppression of parasites in the spleen of mice was significantly higher with AmB-f CNT (89.8%) than with AmB (68.9%).
"This new formulation using carbon nanotubes as a therapeutic vector has shown promising results in experiments, and could therefore become an alternative option for the treatment of visceral leishmaniasis in the future," says lead researcher Shyam Sundar.
The authors of this work are from: Infectious Disease Research Laboratory, Department of Medicine, Institute of Medical Sciences, and Department of Physics, Banaras Hindu University, Varanasi, India.