A fast, reliable and cost-effective method to generate tumor organs for therapy screening in vivo

Multi-walled carbon nanotubes complement the anti-tumoral effect of 5-Fluorouracil

Multiple-drug resistance in human cancer is a major problem. To circumvent this issue, clinicians combine several drugs. However, this strategy could backfire resulting in more toxic or ineffective treatments. Carbon nanotubes (CNTs), and particularly multi-walled nanotubes (MWCNTs), display intrinsic properties against cancer interfering with microtubule dynamics and triggering anti-proliferative, anti-migratory and cytotoxic effects in vitro that result in tumor growth inhibition in vivo. Remarkably, these effects are maintained in tumors resistant to traditional microtubule-binding chemotherapies such as Taxol^®.

In the view of these properties, we investigate the use of MWCNTs in the development of active-by-design nanocarriers, attempting to enhance the effect of broadly-used chemotherapies. We compare the cytotoxic and the anti-tumoral effect of 5-Fluorouracil (5-FU) -an antimetabolite treatment of various forms of cancer- with that of the drug physisorbed onto MWCNTs. Our results demonstrate how the total effect of the drug 5-FU is remarkably improved (50% more effective) when delivered intratumorally coupled to MWCNTs both in vitro and in vivo in solid tumoral models. Our results demonstrate how using MWCNTs as anti-cancer drug delivery platforms is a promising approach to boost the efficacy of traditional chemotherapies, while considerably reducing the chances of resistance in cancer cells.

Biodegradable multi-walled carbon nanotubes trigger anti-tumoral effects

Carbon nanotubes are of huge biotechnological interest because they can penetrate most biological barriers and, inside cells, can biomimetically interact with the cytoskeletal filaments, triggering anti-proliferative and cytotoxic effects in highly dividing cells. Unfortunately, their intrinsic properties and bio-persistence represent a putative hazard that relapses their application as therapies against cancer. Here we investigate mild oxidation treatments to improve the intracellular enzymatic digestion of MWCNTs, but preserving their morphology, responsible for their intrinsic cytotoxic properties. Cell imaging techniques and confocal Raman spectroscopic signature analysis revealed that cultured macrophages can degrade bundles of oxidized MWCNTs (o-MWCNTs) in a few days. The isolation of nanotubes from these phagocytes 96 hours after exposure confirmed a significant reduction of approximately 30% in the total length of these filaments compared to the control o-MWCNTs extracted from the cell culture medium, or the intracellular pristine MWCNTs. More interestingly, in vivo single intratumoral injections of o-MWCNTs triggered ca. 30% solid melanoma tumour growth-inhibitory effects while displaying significant signs of biodegradation at the tumoral/peri-tumoral tissues a week after the therapy has had the effect. These results support the potential use of o-MWCNTs as antitumoral agents and reveal interesting clues of how to enhance the efficient clearance of in vivo carbon nanotubes.