Carnegie Mellon Researchers Create Biohybrid Nanoparticles That Could Revolutionize Drug Delivery

An international team of scientists led by Carnegie Mellon University researchers has engineered novel hybrid exosomes with polymer surfaces that can be used to precisely and consistently deliver therapeutics. The research has been published in the “Proceedings of the National Academy of Sciences.”

The genesis of this research came over drinks several years ago, according to Sushil Lathwal, a postdoctoral researcher at MIT, who received his Ph.D. in chemistry from Mellon College of Science in 2020, and Saigopalakrishna “Sai” Yerneni, a biomedical engineering doctoral student in the College of Engineering.

Yerneni had been working on understanding cell-to-cell communication and developing synthetic exosomes — miniscule extracellular vesicles that can transport a variety of cargo from cell-to-cell like mail carriers.

“What is unique about these ‘mail carriers’ is that they are optimized to travel in the body without attracting undue attention from the immune system, making them an ideal drug delivery vehicle,” Yerneni said.

In recent years, scientists have been working to harness these natural nanoparticles to deliver therapeutics, such as cancer drugs. However, natural exosomes are very unstable in storage and when circulating in the body, limiting their potential effectiveness for medical uses.

That’s where Lathwal came in.

In his research, Lathwal had been working on automating the synthesis of polymer biohybrids using atom transfer radical polymerization (ATRP), the groundbreaking and robust method of controlled polymerization developed by CMU’s J.C. Warner University Professor of Natural Sciences Krzysztof Matyjaszewski in 1994.

“As we were watching the bubbles in our beer that resembled exosomes that night, we thought ‘could we combine polymer chemistry with exosomes to create a unique class of exosome-polymer hybrids for drug delivery applications?’” Lathwal said. That idea sparked a collaboration that came to involve researchers from Mellon College of Science, the College of Engineering and institutions in three other countries.

The latest research from this scientific team builds on work published last year in the journal “ACS Nano,” which demonstrated the creation of an all-purpose platform for easily producing synthetic exosomes with a DNA-cholesterol tether that could be used to carry a wide variety of cargo to cells. In their study, the researchers harnessed the power of ATRP to create exosomes with thousands of polymer chains on their surfaces, known as exosome polymer hybrids. These biocompatible surface polymers serve as a protective shell for the exosome, making them more stable.

“We were able to improve the shelf life of exosomes from weeks to months,” Yerneni said. “But more importantly, we increased their circulation time in the blood by severalfold to provide them enough time to reach the target tissue.” While native exosomes are cleared from blood circulation in three hours, exosome-polymer hybrids remain in circulation for 12 hours post-injection.