A novel type of nanoparticle that can be injected into the lungs and deliver messenger RNA encoding useful proteins has been developed by scientists at MIT and the University of Massachusetts Medical School.
These particles may eventually provide an inhalable treatment for cystic fibrosis and other lung conditions, according to the researchers.
The delivery of RNA to mice’s lungs in this study was shown to be extremely effective for the first time. According to Daniel Anderson, a professor in the MIT Department of Chemical Engineering and a member of the Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science (IMES), “We are optimistic that it can be used to treat or repair a range of genetic diseases, including cystic fibrosis.”.
“This is the first example of highly effective RNA transport to the lungs in mice. We want to utilize it to treat or mend a variety of hereditary illnesses, including cystic fibrosis.”
Daniel Anderson, a professor in MIT’s Department of Chemical Engineering.
Anderson and his associates delivered mRNA encoding the equipment required for CRISPR/Cas9 gene editing using the particles in a study on mice. This might make it possible to create therapeutic nanoparticles that can cut out and replace disease-causing genes.
Anderson, Robert Langer, and the David H. Koch Institute’s David H. Koch are the senior authors of the study, which was published in Nature Biotechnology today. Koch Institute Professor at MIT; Wen Xue, an associate professor at the RNA Therapeutics Institute at the University of Massachusetts Medical School. The paper’s lead authors are Bowen Li, a former postdoc at MIT who is now an assistant professor at the University of Toronto; Rajith Singh Manan, a postdoc at MIT; and Shun-Qing Liang, a postdoc at the UMass Medical School.
Lung area as a target.
A number of diseases brought on by faulty genes may be successfully treated using messenger RNA as a therapeutic. Its deployment has so far been hampered by the challenge of getting it to the right part of the body without having any off-target effects. There are currently several clinical trials evaluating potential mRNA treatments for liver diseases because injected nanoparticles frequently build up in the liver. Direct injections into muscle tissue of RNA-based COVID-19 vaccines have also demonstrated efficacy. In many of those instances, mRNA is encased in a lipid nanoparticle—a fatty sphere that prevents mRNA from being prematurely degraded and aids in its entry into target cells.
With the goal of better transfecting the epithelial cells that make up the majority of the lining of the lungs, Anderson’s lab set out to create particles a number of years ago. To deliver mRNA encoding a bioluminescent protein to lung cells in 2019, his lab developed nanoparticles. Those particles were made of polymers rather than lipids, making it simpler to aerosolize them for inhalation into the lungs. To boost their effectiveness and make the most of them, more work must be done on those particles.
In their latest research, the scientists sought to create lipid nanoparticles that could specifically target the lungs. A positively charged headgroup and a long lipid tail are the two components that make up the molecules that make up the particles. The headgroup’s positive charge facilitates interactions with mRNA’s negative charge as well as mRNA’s escape from the cellular structures that enclose the particles once they enter cells.
In the meantime, the lipid tail structure facilitates the particles’ passage through the cell membrane. The scientists developed 72 different headgroups and 10 different chemical structures for the lipid tails. The scientists were able to determine which of these structures were most likely to reach the lungs by screening various combinations of these structures in mice.
Delivery that is quick
In follow-up experiments in mice, the researchers demonstrated that they could use the particles to deliver mRNA-encoding CRISPR/Cas9 components intended to sever a stop signal that was genetically encoded into the lung cells of the animals. A gene for a fluorescent protein activates when that stop signal is eliminated. The amount of cells that successfully expressed the mRNA can be calculated by measuring this fluorescent signal, according to the study’s authors.
The researchers discovered that after a single dose of mRNA, about 40% of lung epithelial cells were transfected. The level increased to more than 50% after two doses and to 60% after three doses. Two epithelial cell types called club cells and ciliated cells, each of which was transfected at about 15%, are the most crucial targets for treating lung disease.
This indicates that the cells that we were able to edit are the ones that are most relevant to lung disease, claims Li. More effectively than any other delivery method previously reported, this lipid can help us deliver mRNA to the lung.”.
The risk of inflammation is decreased because the new particles degrade quickly, allowing for quick removal from the lung. If repeated doses are required, it is also possible to administer the particles to the same patient more than once. They have an advantage over a different method of mRNA delivery that makes use of harmless adenoviruses that have been modified. Although those viruses are very good at delivering RNA, they can’t be used repeatedly because they make the host’s immune system react.
The researchers used an approach known as intratracheal instillation to administer the particles in this study. This technique is frequently used to simulate medication delivery to the lungs. They are currently focusing on improving the stability of their nanoparticles so they can be nebulized and inhaled as aerosols.
In a mouse model of the illness, the researchers also intend to test the ability of the particles to deliver mRNA to correct the genetic mutation discovered in the gene that causes cystic fibrosis. Additionally, they want to create mRNA vaccines that could be given directly to the lungs, as well as treatments for other lung conditions like idiopathic pulmonary fibrosis.
More information: Wen Xue, Combinatorial design of nanoparticles for pulmonary mRNA delivery and genome editing, Nature Biotechnology (2023). DOI: 10.1038/s41587-023-01679-x. www.nature.com/articles/s41587-023-01679-x
