Two complementary molecular fragments improved the loading of protein cargo into small cellular vesicles. In the peer-reviewed cell-culture experiment, enzyme activity appeared in recipient cells without using a viral fusion protein. The work provides laboratory evidence of functional protein delivery by engineered vesicles. Intracellular release was not directly traced, and effectiveness in living animals or safety in people was not tested.
An enzyme carried by engineered extracellular vesicles remained active in recipient cells in a single peer-reviewed laboratory study. Vesicles are small membrane-bound packages released by cells. Researchers tested delivery using piggyBac, an enzyme that can remove a designated piece of DNA. Its activity increased the red fluorescence of a reporter called mCherry in the recipient cells.[1]
Complementary intein fragments named NpuN and NpuC formed the loading system. The NpuN fragment joined CD9, a protein associated with vesicle membranes, while NpuC accompanied the cargo. Compared with passive loading, the system improved protein loading by approximately 1.3-fold. The experiments used HEK293T cells, a human-derived laboratory cell line, without the viral fusion protein VSV-G.[1]
Stable producer cell lines performed better than transiently modified ones. Temporary introduction of DNA can also package plasmid DNA into vesicles, complicating interpretation of fluorescence in recipient cells. Stable cell lines helped the researchers distinguish active protein transfer from expression originating in carried DNA.[1]
Electron microscopy examined vesicle shape and light scattering measured size distributions. Characterization using natural vesicle markers remained limited with the engineered CD9-associated marker. The site of protein release and escape from intracellular compartments was not directly traced. The experiments did not examine tissue targeting. They also left efficacy in living animals and immune safety in humans untested.[1]
