Nebulized nanolipid-RNA is a key step in improving cystic fibrosis treatment

Researchers at Oregon State University and Oregon Health and Science University have taken a critical step
in improving and extending the lives of people with cystic fibrosis.
Patients with cystic fibrosis have long-term blockages of the airways and their life expectancy has been greatly reduced
.
A team of scientists and clinicians designed inhalable lipid nanoparticles that can efficiently deliver messenger RNA to the lungs, prompting lung cells to make disease-inhibiting proteins
.

The findings were published in
ACS Nano.
The study was led by postdoctoral scholars Jeonghwan Kim and Gaurav Sahay
.
Gaurav Sahay is an associate professor of pharmacy sciences at Oregon State University's College of Pharmacy, where he studies lipid nanoparticles (LNPs) as a gene delivery vector with a focus on cystic fibrosis
.
Lipids are fatty acids and similar organic compounds, including many natural oils and waxes, while nanoparticles are tiny substances ranging in size from billionths of a meter to billionths of a meter
.

Cystic fibrosis is a progressive genetic disorder that causes persistent lung infections that affects 30,000 people in the United States and confirms about 1,000 new cases each year
.
More than three-quarters of patients are diagnosed before the age of 2, and despite steady progress in mitigating complications, the average life expectancy is still only 40 years
.

Cystic fibrosis transmembrane conduction regulator (CFTR) is a defective gene that causes the disease and is characterized by lung dehydration and mucus buildup
that blocks the airways.

In 2018, Sahay and other scientists and clinicians at Oregon State University and Oregon Health and Science University demonstrated a proof-of-concept for a new therapy that loads chemically modified CFTR messenger RNA into LNPs, opening the door
to molecular drugs that can be inhaled at home.

Nanoparticles carrying messenger RNA allow cells to properly synthesize proteins needed to regulate chloride ions and water transport, which is essential
for healthy respiratory function.

In the current mouse model study, Sahay and collaborators, including OHSU doctor Kelvin MacDonald, who treats cystic fibrosis patients, designed and fabricated nanoparticles with special functions that allow them to more efficiently deliver molecular payloads to lung cells
.

"Lipid nanoparticles have successfully delivered messenger RNA in vaccines, but inhalation-based messenger RNA therapy remains a challenge," Sahay said
.
"During atomization, LNPs tend to break due to shear stress, which leads to ineffective conveying
.
"

What is needed, he explains, is that LNPs are tough enough to withstand atomization and penetrate viscous mucus, while being flexible enough to perform critical actions once inside the cell—they must escape from the compartments of endosomes into the cytoplasm, where the transmitted genes can perform their intended functions
.

A 2020 paper co-authored by Sahay showed that LNPs containing phytosterols (plant-based molecules chemically similar to cholesterol) are dozens to hundreds of times better at performing endosomal escape; Plant sterols change the shape of the nanoparticles from spherical to polyhedral and make them move faster
.

In the latest study, the researchers used cholesterol mimics sitosterol and macrogol lipids to address the challenges of
persistence and mobility.

"The increased concentration of PEG in LNPs gives it better resistance to shear and mucus penetration, and β-sitosterol forms a polyhedral shape that aids escape from endosomes
," Sahay said.
Inhalation of LNPs resulted in local protein production in the lungs of mice without toxicity, either in the lungs or systemically, and repeated administration resulted in sustained protein
production in the lungs.
”

Jeonghwan Kim, Antony Jozic, Yuxin Lin, Yulia Eygeris, Elissa Bloom, Xiaochen Tan, Christopher Acosta, Kelvin D.
MacDonald, Kevin D.
Welsher, Gaurav Sahay.
Engineering Lipid Nanoparticles for Enhanced Intracellular Delivery of mRNA through Inhalation.
ACS Nano, 2022; 16 (9): 14792