Flow cytometry quickly screens for the most useful nanoparticles for medicine

Recognizing that the way nanoparticles interact with the immune system remains unclear and unpredictable, restricting their potential use in medicine, researchers from the University of Geneva (UNIGE) and the University of Fribourg (UNIFR; both in Switzerland) used a flow cytometry method to select the most promising nanoparticles, thereby tracking the development of future treatments quickly.

In less than a week, the researchers were able to determine whether nanoparticles are compatible or not with the human body—an analysis that previously required several months of work. This discovery could lead to rapid, safe, and less expensive development of nanotechnology applied to medicine.

Related: Instrumentation advances add flexibility and quantitation to flow cytometry

Nanoparticles, which are small, virus-sized elements developed under laboratory conditions, measure between 1 and 100 nm. Their size allows potential use in a wide range of medical applications, including biomarkers for diagnosis or as a way to deliver therapeutic molecules to the exact spot in the body where the drug is intended to act. However, before being applied to the medicine, nanoparticles must prove that they are safe for the human body and that they are capable of bypassing the immune system so they can have an effect.

Until now, evaluating the biocompatibility of nanomaterials was a laborious task that took several months and posed reproducibility problems, since not all the tests were performed on the same batch of particles. So, Carole Bourquin, professor in the medicine and science faculties at UNIGE, and her research team used flow cytometry to reach a diagnosis on the three essential elements in a safe and standardized manner, and in record time.

"The macrophages are brought into contact with the nanoparticles for 24 hours, and are then passed in front of the laser beams," explains Inès Mottas, first author of a paper that describes the work. "The fluorescence emitted by the macrophages makes it possible to count them and characterize their activation levels. Since the particles themselves are fluorescent, we can also measure the amount ingested by the macrophages. Our process means we can test the three elements simultaneously, and we only need a very small amount of particles. We can obtain a comprehensive diagnosis of the nanoparticle submitted to us in two or three days."

The research team's method is part of the work being carried out within the National Centres of Competence in Research (NCCR), and is already successful with scientists striving to develop new particles. It focuses their work by enabling them to select the most promising particles quickly. As well as having a financial impact on the cost of research, the new approach also limits the use of animal testing.

Furthermore, the method opens the door to increasingly personalized treatment of certain pathologies. For example, by testing the nanoparticles on tumor cells isolated from a particular patient, it should theoretically be possible to identify the most effective treatment.

Full details of the work appear in the journal Nanoscale; for more information, please visit http://dx.doi.org/10.1039/c6nr08194k.