A USF Health preclinical study indicates nanoparticles containing a micro-RNA switch offers promising biotechnology to advance the fight against atherosclerotic cardiovascular disease

Illustration of angioplasty with a stent

Tampa, FL (Feb. 9, 2021) – Percutaneous coronary intervention (PCI), commonly known as angioplasty with a stent, opens clogged arteries and saves lives. Despite its benefit in treating atherosclerosis that causes coronary artery disease, this common minimally invasive procedure still poses severe complications for some patients.

Angioplasty involves inflating a balloon at the tip of a catheter to compress fatty deposits (plaques) against the artery wall, thereby restoring blood flow to the narrowed or blocked vessels. The image-guided procedure is often combined with the placement of either uncoated stents — tiny expandable mesh devices– or stents coated with slowly-released antiproliferative drugs. The drug-eluting stents help avert the growth of scar tissue (smooth muscle cell proliferation) in the artery so that the vessel does not eventually close again, known as restenosis.

However, current antiproliferative drugs indiscriminately inhibit the growth of all nearby cells, including the layer of endothelial cells lining the blood vessels. These endothelial cells prevent blood clots (thrombosis) within the stent and the formation of more plaques (neoatherosclerosis), which can trigger a heart attack or sudden cardiac death.

Focused on tackling this treatment complication, University of South Florida Health (USF Health) Morsani College of Medicine researchers recently developed a next-generation nanotherapy. Their preclinical findings are detailed in a study published Feb. 2 in Molecular Therapy.

Hana Totary-Jain, PhD, USF Health associate professor of molecular pharmacology and physiology, was principal investigator for the nanotherapy study.

The nanotherapy comprised of a nontoxic peptide known as p5RHH and a synthetic messenger RNA (mRNA) that carries the genetic instructions, or code, needed by cells to make proteins. By simply mixing up the p5RHH with the mRNA, they spontaneously self assemble into compacted nanoparticles that specifically target the injured regions of the arteries in mouse models mimicking angioplasty. The nanoparticles contain an microRNA switch added to the mRNA.

“One of the main challenges of cardiovascular disease remains the delivery of targeted therapies specifically to the plaque regions and the cells that form plaques, including the smooth muscle cells and inflammatory cells — without affecting the endothelial cells or the healthy regions,” said the study’s principal investigator Hana Totary-Jain, PhD, an associate professor of molecular pharmacology physiology at USF Health Morsani College of Medicine.

To do this, the researchers used mRNA that encodes for p27 protein, which blocks cell growth, and added to the mRNA an endothelial cell-specific microRNA to generate a microRNA switch. The design of this microRNA switch allowed the researchers to turn on the mRNA in smooth muscle cells to inhibit their growth and the formation of restenosis. It also enabled them to turn off the mRNA in endothelial cells so these cells could grow uninhibited and quickly heal the damaged blood vessel.

John Lockhart, PhD, was the paper’s lead author.

“If we can come up with an antiproliferative therapy that specifically targets the cardiovascular smooth muscles cells and the infiltrating inflammatory cells but spares the endothelial cells – which we’ve done with the design of our microRNA switches – then we should be able to achieve the therapeutic effects of drug-eluting stents without the downside of thrombosis and neoatherosclerosis,” said the paper’s lead author John Lockhart, PhD, who worked on the study as a doctoral student at USF Health Molecular Pharmacology and Physiology. Dr. Lockhart is continuing his postdoctoral training at Moffitt Cancer Center.

The latest study builds upon previous research by Dr. Totary-Jain, indicating that a microRNA-based therapy worked better than drug-eluting stents in a rat model of angioplasty. That work used an adenovirus vector to carry the cell-selective therapy to injured arteries. In this study the viral vector was replaced with a nanoparticle alternative – a change needed to avoid safety concerns and advance the therapy toward use in patients.

The investigational nanoparticles were injected into mice with arteries mimicking post-angioplasty vessel injury every three days for two weeks (5 doses total). Mice treated with the nanoparticles containing the miRNA switch had significantly reduced restenosis and completely restored endothelial cell growth in the injured artery, compared to animals treated with nanoparticles containing mRNA without the miRNA switch, the researchers report.

Above: Injured control artery treated with near infrared florescent protein, depicts restenosis in center. Below: Injured artery treated with the microRNA switch nanotherapy shows open artery (no restenosis) and clear endothelial cell layer marked in green. | Images courtesy of Hana Totary-Jain, USF Health

In addition, the nanoparticles efficiently delivered its mRNA cargo, without degradation, solely to regions of the artery where endothelial cells were damaged. The particles did not toxically accumulate either in the cells of healthy organs (the liver, spleen. lungs or kidneys), or in uninjured arteries adjacent to those requiring treatment. The researchers observed no adverse reactions or outcomes in mice treated with the nanoparticles.

Overall, the findings suggest that the miRNA-switch nanoparticles could be applied clinically to selectively prevent restenosis after PCI by specifically targeting areas of endothelial cell damage to allow quicker cell regrowth and repair of injured arteries.

The USF Health researchers next plan to investigate the potential of the microRNA-switch nanoparticles to directly treat atherosclerotic plaques, thereby eliminating the need for PCI.

“Cardiovascular disease is still the number one cause of death,” said Dr. Totary-Jain, a member of the USF Health Heart Institute. “This research offers promise for the development of novel biomolecular therapies to advance the fight against coronary artery disease and peripheral artery disease,”

One person dies of cardiovascular disease every 36 seconds in the U.S., according to the Centers for Disease Control and Prevention.

The USF Health research was supported by grants from the National Institutes of Health. Samuel Wickline, MD, director of the USF Health Heart Institute, and Hua Pan, PhD, assistant professor at the Heart Institute, collaborated on the study.

Preclinical study shows microRNA approach inhibited re-narrowing while healing vessels

Tampa, FL (Aug. 18, 2014) — A new therapy developed by researchers at the University of South Florida (USF) Morsani College of Medicine and Columbia University Medical Center (CUMC) may help reduce the life-threatening complications of interventional cardiovascular disease treatment.

The researchers demonstrated in a rat model that the novel molecular therapy could selectively inhibit blood vessel re-narrowing and simultaneously promote vessel healing following a medical procedure using a balloon catheter to open narrowed or blocked arteries.

Their preclinical study was published in Sept. 2, 2014 in the Journal of Clinical Investigation.

Hana Totary-Jain, PhD, assistant professor of molecular pharmacology and physiology at the USF Health Morsani College of Medicine, was principal investigator for the study.

“This innovative microRNA-based strategy can be used to combine anti-proliferative and pro-healing mechanisms for improved repair of coronary arteries,” said the study’s principal investigator Hana Totary-Jain, PhD, assistant professor of molecular pharmacology and physiology at the USF Health Morsani College of Medicine, who came to USF Health from CUMC last year to join the USF Health Heart Institute.

“The most significant finding of our study is that for the first time we were able to achieve in one fell swoop both the inhibition of cells responsible for re-narrowing of the vessel, and preserving the ‘good’ endothelial cells that protect against thrombosis,” said lead author Gaetano Santulli, MD, PhD, a cardiologist working at CUMC’s College of Physicians & Surgeons.

Angioplasty, the world’s most common medical procedure, opens a narrowed or blocked artery by inserting a small balloon into the blood vessel. If the artery is blocked, a tiny wire-mesh tube, known as a stent, is mounted on the end of the balloon to leave in the vessel when the balloon is removed. The stent holds the artery open and maintains blood flow after angioplasty clears the vessel of fatty deposits. Physicians performed 560,500 angioplasties in the United States in 2011, according to a recent report by the Agency for Healthcare Research and Quality,and, Dr. Santulli said, 70 to 90 percent of all angioplasty patients receive one or more stents.

Together, angioplasty and stenting have helped advance the field of interventional cardiology and save lives.

Drug-eluting stents, first approved for use in the United States in 2003, dramatically reduced rates of restenosis compared to earlier bare metal stents. Medications coating these stents thwart the development of scar tissue causing the treated coronary artery to re-narrow, a complication often requiring another procedure.

While the drug-eluting stent overcame the obstacle of restenosis, research eventually showed that the medications released by the device were not specific — meaning they failed to discriminate between destructive and beneficial cells. The drugs blocked proliferation and migration of vascular smooth muscle cells leading to artery re-narrowing, but they also blocked regrowth of endothelial cells indispensable to healing blood vessel walls disrupted by stent implantation.

Formation of blood clots several months or even years after initial implantation remains a severe, though rare, increased risk associated with the lack of endothelium covering the treated vessel. This risk for late stent clotting, or thrombosis, requires patients to stay on prolonged dual antiplatelet therapy to help prevent life-threatening heart attacks — but not without increasing the odds of major bleeding.

Gaetano Santulli, MD, PhD, of Columbia University Medical Center, was lead author.

With this history in mind, researchers at USF and CUMC harnessed the intrinsic power of microRNAs — master regulators of gene expression affecting many biological processes including cell proliferation — to create a more selective therapy.

Their goal was to inhibit blood vessel re-narrowing and, at the same time, allow endothelial cells to regrow and heal the vessel. They tested the experimental therapy in a rat model of balloon angioplasty injury, and discovered it worked.

Among the findings:

–          As soon as two weeks following arterial injury induced by balloon angioplasty, the injured arteries in the rats receiving microRNA-based therapy were 80 percent covered with new endothelium. In the group receiving a molecular therapy that mimicked drug-eluting stents, endothelial cell coverage remained below 30 percent even after one month. “The difference was quite amazing,” Dr. Totary-Jain said.

–          Measures of blood clotting in the microRNA-based therapy group at two weeks post-injury were reduced to the same levels as in the uninjured control animals.

–          In addition to helping protect against thrombosis-associated clotting, the endothelial cells restored in the treated group appeared to work as well in helping dilate blood vessels as endothelial cells in the vessels of the healthy, untreated control group. “From a clinical point of view, reduced thrombosis and functional vascular responses represent the most promising aspects of the whole study,” Dr. Santulli said.

Dr. Totary-Jain works with Jamie Chilton, PhD, one of the study’s co-authors.

More studies are needed, including implanting stents to test the therapy in other models of atherosclerosis and diabetes.

“This is just the first step, but we are working on tailoring the strategy to be more effective,” Dr. Totary-Jain said. “The combination of this selective therapy with a better stent platform and biodegradable polymer has the potential to revolutionize the future of vascular interventional medicine.”

The USF/CUMC study was supported by the American Heart Association and the National Institutes of Health/National Heart, Lung and Blood Institute.

Article citation: Gaetano Santulli, Anetta Wronska, Kunihiro Uryu, Thomas G. Diacovo, Melanie Gao, Steven O. Marx, Jan Kitajewski, Jamie M. Chilton, Kemal Marc Akat, Thomas Tuschl, Andrew R. Marks, Hana Totary-Jain; “A selective microRNA-based strategy inhibits restenosis while preserving endothelial function;”Journal of Clinical Investigation: 2014;124 (9):4102-4114. DOI: 10.1172/JCI76069.

-USF Health-

USF Health’s mission is to envision and implement the future of health. It is the partnership of the USF Health Morsani College of Medicine, the College of Nursing, the College of Public Health, the College of Pharmacy, the School of Biomedical Sciences and the School of Physical Therapy and Rehabilitation Sciences; and the USF Physician’s Group. The University of South Florida is a Top 50 research university in total research expenditures among both public and private institutions nationwide, according to the National Science Foundation. For more information, visit www.health.usf.edu