Researchers from the Shenzhen Institute of Advanced Technology have developed a nanofluidic device that can prepare exosome-based drug delivery vehicles with greater efficiency while maintaining exosome integrity.
To ensure that drugs are carried to target cells that require them, there is a need to design safe and precise delivery systems. Many delivery vehicles have been developed in recent years, such as nanoparticles, liposomes, and viral vectors. These vectors have been employed in the treatment of cancer, neurodegenerative disease, and cardiovascular disease, etc. However, the use of these is not without side effects.
Exosomes are biological nanocarriers that are naturally secreted by various cell types (e.g. tumour cells) and function as a communication tool between cells. As such, exosomes prove more advantageous than existing delivery systems as they have lower immunogenicity, longer circulation times, non-toxicity, optimal biocompatibility, strong tissue penetration, improved targeting effect, and strong ability to cross the blood-brain barrier. Given this edge, why are they not more widely used? It appears that current methods of loading exosomes with target drugs lacks efficiency, takes a long time to incubate, and induces excessive damage on both exosomes and their cargos.
Taking these limitations into considerations, a team of researchers led by Professor Yang Hui from the Shenzhen Institute of Advanced Technology (SIAT) of the Chinese Academy of Sciences developed a novel nanofluidic device that can process high-throughput samples to prepare exosome-based drug delivery vehicles. This device is named “exosome-nanoporator” or ENP, which utilises nanofluidic technology to accurately control the characteristics of fluids in nanoscale to obtain highly controllable conditions for the preparation of exosome-based drug delivery vehicles.
Previous studies have reported that mechanically compressing cells to form transient pores of different sizes on the membranes can facilitate the loading of external macromolecules. Based on this work, the research team assembled 21 parallel microfluidic channels on a polydimethylsiloxane (PDMS) layer with 10 channels connected to the inlet and 11 channels connected to the outlet. The team further added 1,500 parallel nanochannels on a glass substrate before bonding the PDMS layer to the glass substrate. This way, each pair of inlet and outlet microchannels are bridged by 1,500 parallel nanochannels, which collectively makes 30,000 nanochannels on their novel ENP device, ensuring high sample throughput.
To test the performance and applicability of the ENP, purified exosomes and a chemotherapeutic drug doxorubicin hydrochloride (DOX HCl) were introduced into the device via the inlet and processed. As the exosomes pass through the nanochannels, their membranes are mechanically deformed, increasing their permeability as transient nanopores are formed. The drug DOX HCl enters the exosomes from the surrounding buffer and the treated exosomes are collected at the outlet of the device.
After accounting for background noise, the absolute dosage that was loaded into the exosomes by the team’s nanofluidic device exceeds the loading amount of other previously published works and meets the requirements for use in animal models.
To test the targeting effect of the newly treated exosomes, the team incubated human non-small cell lung cancer cells with the ENP-treated exosomes for 24 hours. “We f[ound] that the exosomes treated by the ENP can deliver their drug cargos to human non-small cell lung cancer cells and induce cell death. This indicates potential opportunities [for] the device [in] developing new exosome-based delivery vehicles for medical and biological applications,” said Prof. Yang.
Future work would involve increasing the amount of treated exosomes so that clinical drugs, nucleic acids, proteins, etc. loaded in these extracellular vesicles will reach the actual level for clinical applications. The success of this new strategy would not only advance the field of nanofluidic technology but also open new doors for developing exosome-based delivery vehicles for biological research.
Source: Liao et al. (2021). Antisense ribosomal siRNAs inhibit RNA polymerase I-directed transcription in C. elegans. Nucleic Acids Research, 49(16), 9194-9210.