Researchers hope to use these RNA delivery particles to develop new treatments for cystic fibrosis and other lung diseases.
Engineers at the Massachusetts Institute of Technology (MIT) and the University of Massachusetts School of Medicine have designed a new type of nanoparticle that can be administered to the lung. The nanoparticles can deliver messenger RNA that encodes useful proteins.
With further development, these particles could provide an inhaled treatment for cystic fibrosis and other lung diseases, researchers say.
“This is the first demonstration of highly efficient delivery of RNA to the lungs of mice. said Daniel Anderson, professor of chemical engineering at MIT and a member of MIT’s Koch Institute for Integrative Cancer Research and Institute for Medical. Engineering and Science (IMES).
In mouse studies, Anderson and his colleagues used particles to deliver mRNAs encoding the machinery required for CRISPR/Cas9 gene editing. This may open the door to designing therapeutic nanoparticles that can excise and replace disease-causing genes.
Anderson is the senior author of the study, published today in Nature Biotechnology. Robert Langer, Professor of the David H. Koch Institute at the Massachusetts Institute of Technology. and Wen Xue, associate professor at the UMass Medical School RNA Therapeutics Institute. Bowen Li, a former MIT postdoc and current assistant professor at the University of Toronto. Rajith Singh Manan, MIT postdoc. And Shun-Qing Liang, a postdoc at UMass Medical School, is the first author of the paper.
target the lungs
Messenger RNA has great potential as a therapeutic to treat various diseases caused by defective genes. So far, one of the obstacles to its deployment has been the difficulty of delivering it to the right parts of the body without off-target effects. Since injected nanoparticles often accumulate in the liver, several clinical trials are currently underway evaluating potential mRNA therapeutics for liver diseases. RNA-based Covid-19 vaccines injected directly into muscle tissue have also proven effective.In many of these cases, the mRNA is encapsulated in lipid nanoparticles. These are fat globules that prevent mRNA from being prematurely degraded and help it enter target cells.
A few years ago, Anderson’s lab set out to design particles that could better transfect the epithelial cells that make up most of the lung’s lining. In 2019, his lab created nanoparticles that could deliver mRNAs encoding bioluminescent proteins to lung cells. These particles are made from polymers instead of lipids, making them easier to aerosolize for inhalation into the lungs. However, more work is needed on these particles to increase their effectiveness and maximize their usefulness.
In their new study, researchers set out to develop lung-targeted lipid nanoparticles. The particle is composed of a molecule containing two parts of him, a positively charged head group and a long lipid tail. The positive charge on the headgroup helps the particle interact with the negatively charged mRNA, and also helps it escape from cellular structures that engulf the particle once the mRNA enters the cell.
On the other hand, the lipid tail structure helps the particles to pass through the cell membrane. The researchers came up with 10 different chemical structures for the lipid tails, along with 72 different headgroups. By screening different combinations of these structures in mice, researchers were able to identify those most likely to reach the lungs.
efficient delivery
In further tests in mice, the researchers injected particles to deliver mRNAs encoding CRISPR/Cas9 components designed to block genetically encoded stop signals to the animal’s lung cells. showed that it can be used. When that stop signal is removed, the fluorescent protein gene is turned on. By measuring this fluorescent signal, researchers can determine the percentage of cells that successfully express the mRNA.
The researchers found that about 40% of lung epithelial cells were transfected after a single dose of mRNA. Levels were over 50% after 2 doses and up to 60% after 3 doses. The most important targets for treating lung disease are two types of epithelial cells called club cells and ciliated cells, each of which was transfected at approximately 15%.
“This means that the cells we were able to edit are really target cells for lung disease,” says Li. “This lipid allows mRNA to be delivered to the lung much more efficiently than other delivery systems reported to date.”
Also, new particles are rapidly degraded, so they are cleared from the lungs within days, reducing the risk of inflammation. Particles can also be delivered multiple times to the same patient if repeat doses are required. This is an advantage over alternative mRNA delivery approaches that use harmless modified versions of adenoviruses. Although these viruses are highly effective at delivering RNA, they cannot be administered repeatedly because they induce an immune response in the host.
“This work paves the way for promising therapeutic pulmonary gene delivery for a variety of pulmonary diseases,” says Dan Peer, director of the Institute for Precision Nanomedicine at Tel Aviv University. was not involved in this study. “This platform has several advantages compared to traditional vaccines and therapeutics, such as being cell-free, capable of rapid manufacturing, high versatility and a good safety profile. ”
To deliver the particles in this study, researchers used a method called intratracheal instillation. This is often used as a method to model drug delivery to the lung. They are now working on making the nanoparticles more stable so that they can be aerosolized and inhaled using a nebulizer.
The researchers also plan to test particles that deliver mRNAs capable of correcting genetic mutations found in the genes that cause cystic fibrosis in mouse models of the disease. They also hope to develop treatments for other lung diseases, such as idiopathic pulmonary fibrosis, and mRNA vaccines that can be delivered directly to the lungs.
Original: New nanoparticles can perform gene editing in the lung
Than: Massachusetts Institute of Technology | University of Massachusetts Medical School
