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Inhaled Messenger RNA Developed, Tested

lung illustration

(Kai Stachowiak, Pixabay)

4 Jan. 2019. An academic-industry team developed an inhaled form of genetic material in nanoscale particles that enables lab mice to safely produce proteins in their lungs. The techniques, designed by researchers from Massachusetts Institute of Technology in Cambridge and the company Translate Bio Inc. in Lexington, Massachusetts, are described in today’s issue of the journal Advanced Materials (paid subscription required).

The team from the MIT lab of chemical engineering professor Daniel Anderson is seeking safe methods for delivering messenger RNA into the lungs to treat diseases such as cystic fibrosis. Messenger RNA or mRNA is a nucleic acid based on the genetic code from DNA, with instructions for cells to produce the amino acids in proteins for cellular functions, and an emerging platform for therapies. But ribonucleic acid, or RNA, by itself breaks down quickly in the body, thus it needs delivery methods that provide stability and durability. At the same time, even stable mRNA treatments would likely require multiple doses, thus the delivery materials need to be safe for frequent use.

Researchers led by former Anderson lab postdoctoral fellow Asha Patel, now at Imperial College London in the U.K., designed nanoscale particles of mRNA for delivery by inhalers, like those for drugs used by people with asthma. The delivery technique employs a biodegradable polymer, poly(beta-amino esters) or PBAEs, which Anderson’s lab used previously for delivery of gene therapies. To prove the concept, Patel and colleagues created particles about 150 nanometers in diameter — where 1 nanometer equals 1 billionth of a meter — combining PBAEs with mRNA that codes for luciferase, an enzyme triggering light-emitting reactions in cells.

The team suspended the particles in droplets to produce an inhalable mist, like those used in asthma inhalers. “Breathing is used as a simple but effective delivery route to the lungs,” says Patel in an MIT statement. “Once the aerosol droplets are inhaled, the nanoparticles contained within each droplet enter the cells and instruct it to make a particular protein from mRNA.”

The researchers tested the mist-delivered nanoparticles in lab mice. After 24 hours, say the authors, lung tissue in the test mice began illuminating from the mRNA. In addition, the team found the mRNA taken up by epithelial cells in tissue lining all 5 lobes of the lungs.The authors report the mice received multiple doses of the inhaled nanoparticles with no local or systemic toxic effects.

Malfunctioning epithelial cells are implicated in cystic fibrosis, a genetic disorder causing a build-up of thick mucus in the lungs and other organs. Translate Bio that helped fund the research is developing a treatment for cystic fibrosis with mRNA code-named MRT5005, now in an early- and mid-stage clinical trial. The company’s technology designs mRNA as therapies to correct missing or malfunctioning proteins, which it says restores functioning gene expression without entering the cell nucleus or changing a recipient’s genome. Michael Heartlein, Translate Bio’s chief scientist is a co-author of the paper.

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