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Trypanosome parasites are infecting mammals in Sub-Saharan Africa and are transmitted between hosts through bites of the tsetse fly. The transmission from the insect vector to the mammal host causes a number of metabolic and physiological changes. A fraction of the population continuously adapt to the immune system of the host, indicating heterogeneity at the population level. Yet, the cell to cell variability in populations is mostly unknown. We develop here an analytical method for quantitative measurements at the single cell level based on encapsulation and cultivation of single-cell Trypanosoma brucei in emulsion droplets. We first show that mammalian stage trypanosomes survive for several hours to days in droplets, with an influence of droplet size on both survival and growth. We unravel various growth patterns within a population and find that droplet cultivation of trypanosomes results in 10-fold higher cell densities of the highest dividing cell variants compared to standard cultivation techniques. Some variants reach final cell titers in droplets closer to what is observed in nature than standard culture, of practical interest for cell production. Droplet microfluidics is therefore a promising tool for trypanosome cultivation and analysis with further potential for high-throughput single cell trypanosome analysis., (© 2021. The Author(s).)

We demonstrate an accurate and sensitive quantification of mutated KRAS oncogene in genomic DNA, using droplet-based microfluidics and digital PCR.

We describe a droplet microfluidics method to screen for multiple mutations of a same oncogene in a single experiment using passive droplet fusion. Genomic DNA from H1573 cell-line was screened for the presence of the six common mutations of the KRAS oncogene as well as wild-type sequences with a detection efficiency of 98 %. Furthermore, the mutant allelic fraction of the cell-line was also assessed correctly showing that the technique is quantitative.

Polymerase chain reaction based techniques have been widely used in laboratory settings. Several applications in oncology, virology or prenatal diagnosis require highly sensitive detection methods, which cannot be achieved with conventional techniques. Digital PCR (dPCR) was developed from the association of PCR and limiting dilution procedures. It is based on the compartmentalization of DNA molecules in small volumes. Controlling the size and the content of each compartment is crucial to obtain a high sensitivity with a single molecule resolution. Microfluidics offers promising tools to isolate DNA fragments such as microdroplets, microchambers or microwells with volumes ranging from few picoliters to nanoliters. The review provides an overview of recent developments of microfluidics dPCR platforms and how this technology can influence the management of cancer patients., (© 2015 médecine/sciences – Inserm.)