The system, described in a new study, relies on tiny vesicles harvested from HEK293T cell cultures. These naturally occurring nanoscale sacs, measuring roughly 125 nanometers in diameter, have attracted growing interest as drug carriers because of their low immunogenicity, excellent biocompatibility and ability to shield fragile cargoes from degradation. Yet despite these advantages, sEVs have struggled in ischemic heart disease because they accumulate poorly in the heart. The culprit is the tight endothelium lining cardiac capillaries, a barrier that is often overlooked in drug delivery design.

For years, researchers assumed that injured heart tissue, with its leaky and inflamed vasculature, would let nanoparticles slip through endothelial gaps directly to cardiomyocytes. Recent work has upended that assumption. Endothelial gaps account for only 3 to 25 percent of nanoparticle extravasation, and even in the peri-infarct zone, capillary permeability is largely restored after the ischemia-reperfusion period. In relatively intact regions of the heart, nanoparticle penetration depends mainly on endothelial cells swallowing particles and ferrying them across in a process called transcytosis. If that transport could be enhanced, the researchers reasoned, cardiac drug delivery would improve substantially.

The team’s insight came from the heart’s own metabolism. Because fatty acids supply most of the heart’s energy, cardiac microvascular endothelial cells express high levels of CD36, a transporter that ferries fatty acids across the capillary wall. The researchers hypothesized that decorating sEVs with KOdiA-PC, an oxidized phosphatidylcholine that binds CD36 with high affinity, would encourage endothelial cells to capture and transport the vesicles into the myocardium. They paired this with a second modification: the ischemic myocardium-targeting peptide IMT, which homes in on injured cardiomyocytes, attached via copper-free click chemistry.

The engineering worked. Flow cytometry showed that 93 percent of the modified vesicles carried both tags, and the particles retained their classic cup-shaped appearance with only a slight size increase to about 134 nanometers. In laboratory tests, KOdiA-PC-modified sEVs were taken up far more readily by mouse cardiac microvascular endothelial cells than by endothelial cells from the brain or umbilical vein, which express little CD36. Blocking CD36 with free KOdiA-PC reduced this uptake, confirming the receptor-mediated mechanism. Meanwhile, the IMT peptide boosted vesicle uptake by oxygen-glucose-deprived heart muscle cells in culture by roughly 2.6- to 3-fold compared with unmodified vesicles.

In living mice, the dual modification proved even more striking. In healthy animals, KOdiA-PC-modified vesicles accumulated in the heart at significantly higher levels than unmodified or IMT-only vesicles. In mice subjected to ischemia-reperfusion injury, the dual-tagged vesicles reached cardiac fluorescence signals about 2.3 times higher than either single modification achieved. Crucially, the targeting advantage persisted even when vesicles were administered two weeks after surgery, when endothelial gaps had closed, demonstrating that the CD36-mediated route works in intact myocardium as well as injured tissue. In mice genetically engineered to lack CD36 in both endothelial cells and cardiomyocytes, cardiac accumulation of KOdiA-PC-modified vesicles fell sharply, confirming that the receptor is indispensable for this delivery route.

With the delivery vehicle validated, the researchers loaded it with two complementary therapies. The first was edaravone, a clinically proven free radical scavenger that neutralizes the reactive oxygen species driving reperfusion injury. The second was small interfering RNA against PKA Cα, the major catalytic subunit of protein kinase A in cardiomyocytes. Persistent sympathetic activation after ischemic injury keeps PKA overactive, over-phosphorylating calcium-handling proteins and triggering calcium overload in heart cells. The team’s earlier work showed that cardiomyocyte-specific PKA inhibition can prevent this calcium overload, activate protective EPAC/ERK signaling, reduce apoptosis and improve cardiac function, outperforming the common beta-blocker metoprolol in animal studies.

The loading process achieved an encapsulation efficiency of 12.57 percent for edaravone and 91.66 percent for the siRNA. The vesicles also protected the genetic cargo: after two hours of exposure to RNase A, free siRNA was almost completely degraded, while roughly half of the vesicle-protected siRNA remained intact. In a transwell model simulating the capillary barrier, siRNA carried by KOdiA-PC-modified vesicles crossed layers of cardiac endothelial cells at rates about 4.7-fold higher than unmodified vesicles, and this advantage vanished when CD36 was blocked or knocked down, cementing the mechanism.

In mice with ischemia-reperfusion injury, the fully loaded dual-targeted vesicles, injected intravenously one day, one week and two weeks after surgery, cut the infarct area to 12.01 percent at 24 hours, compared with much larger damaged zones in controls. Over 21 days, heart function in untreated mice deteriorated to a left ventricular ejection fraction of 34.51 percent, while the dual-targeted group recovered significantly better, and fibrotic infarct size shrank to 5.91 percent of the left ventricle compared with 35.89 percent in untreated animals. In a permanent coronary ligation model, the system still delivered benefit: by day 42, treated mice reached ejection fractions near 45 to 48 percent versus about 24 percent in controls, with infarct sizes of 15.36 percent versus 28.92 percent.

Safety testing offered reassurance. Vesicle concentrations as high as 100 micrograms per milliliter did not impair heart cell viability in culture, in contrast to the commercial transfection reagent Lipofectamine 2000, which cut viability in half. In treated mice, kidney and liver function markers, organ weights and histology of major organs showed no adverse changes. The authors note that the strategy is modular: swapping the siRNA sequence or small molecule cargo could extend the platform to other cardiac diseases, and pairing the dual-targeting approach with vesicles from therapeutically active sources such as mesenchymal stem cells could further boost efficacy. For a field long stymied by the heart’s impermeable capillaries, hitching a ride on the organ’s own fatty acid ferry may prove a decisive advance.

Subject of Research: Dual-modified small extracellular vesicles for cardiac-targeted co-delivery of siPKA Cα RNA and edaravone against myocardial ischemia-reperfusion injury in mice

Article Title: Novel modifications of small extracellular vesicles to enhance cardiac-specific delivery of siPKA RNA and edaravone against ischemia-reperfusion cardiac injury

Article References: Pei, X., Li, R., Bai, Y., Yan, Q., Qi, X., Jiao, W., Wang, X., Yan, H., Yang, Q., Zhu, Y., He, H., & Chen, X. (2026). Novel modifications of small extracellular vesicles to enhance cardiac-specific delivery of siPKA RNA and edaravone against ischemia-reperfusion cardiac injury. Materials Today Bio, 41, Article 103760. https://doi.org/10.1016/j.mtbio.2026.103760

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103760

Keywords: small extracellular vesicles, myocardial ischemia-reperfusion injury, CD36, transendothelial transport, edaravone, siRNA delivery, PKA inhibition, cardiac targeting, nanomedicine, KOdiA-PC, heart disease, drug delivery