Scientists from the Technical University of Munich (TUM) and Helmholtz Zentrum Munchen demonstrated the dark skin pigment melanin as an effective tool in tumor diagnosis and treatment.
Melanin acts as a protection against the damaging rays of the sun through light energy absorption and heat conversion. The researchers demonstrated that the nanoparticles derived from cell membrane loaded with melanin "improved tumor imaging in an animal model while slowing the growth of the tumor," according to Phys.
Treatment against tumors can have the potential to be treated using nanoparticles as the tumor tissue is more absorbent compared to healthy cells because of their permeable vascular system. Outer membrane vesicles (OMVs) which are 20-to 200-nanometer particles are examples. they can be produced cheaply in bacteria and are biocompatible and biodegradable. Nanoparticles are easy to administer once loaded with medicinal active agents.
Prof. Vasilis Ntziachristos, team leader and Professor of Biological Imaging at TUM, showed the potential of OMVs in tumor diagnosis and treatment. Their study focused on the characteristics of OMVs and melanin.
Dr. Vipul Gujrati, first author of the study, explains the principle: "Melanin absorbs light very readily-even in the infrared spectrum. We use this light in our optoacoustic imaging technique for tumor diagnosis. It simultaneously converts this absorbed energy into heat, which is then emitted. Heat is also a way to combat tumors-other researchers are currently exploring this method in clinical trials."
Optoacoustics integrates ultrasound technology and optical imaging. Tissues are heated by weak laser pulses that briefly expand. The tissue contraction produces ultrasound signals. The tissue type dictates the measured signals and these signals recorded by sensors.
OMVs resolve the problem of the water insolubility of melanin. The scientists genetically engineered bacteria in order to produce melanin and store this in their membrane-derived nanoparticles. Mice who had tumors in their lower back region were subjected to the black nanoparticles.
Tumor cancer cells are killed when the tumor tissue is subjected to heat with stronger laser pulses by OMVs.
"Our melanin nanoparticles fit into the new medical field of theranostics-where therapy and diagnostics are combined. This makes them a highly interesting option for use in clinical practice," says Ntziachristos. The scientists will now develop their OMVs further to bring them into clinical use in the future.
