Highly efficient exosome purification from human plasma by tangential flow filtration based microfluidic chip

Exosomes play an important role in microenvironmental regulation, cellular communication, tumor progression/metastasis and prognosis. A key challenge in the study of exosomes is the isolation and purification of exosomes from contaminants. In this study, we develop a size-dependent microfluidic chip to isolate and purify exosomes from human blood by tangential flow filtration. The microfluidic chip combines symmetrically two polymethyl methacrylate (PMMA) layers with serpentine channels and a nanoporous polycarbonate track etched (PCTE) membrane in between. Due to the uniform pore size (similar to 100 nm in diameter) of the nanoporous PCTE membrane, protein contaminants can be cleaned with high efficiency (97%), and exosomes trapped in the microfluidic chip can be collected by reverse elution with high recovery (>80%). The collected exosomes are subjected to matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) analysis. Based on the fingerprint peaks of exosomes, it is demonstrated that plasma proteins are largely cleaned and only exosome proteins dominate the mass spectra. Compared to ultracentrifugation (UC) that is considered as the gold standard for exosome isolation and purification, the size-dependent microfluidic chip-based protocol shows higher protein cleaning efficiency and exosome recovery rate. The whole process takes <3 h, shorter than UC. Considering that microfluidic based methods can be automatically controlled, the current method is promising in large-cohort clinical usage.

Automated summary

A size-dependent microfluidic chip was developed to efficiently isolate and purify exosomes from human blood, showing high protein cleaning efficiency and exosome recovery rate compared to traditional ultracentrifugation. The method uses symmetric layers of PMMA with a nanoporous PCTE membrane, allowing for quick and automated large-cohort clinical usage.