The patch itself is a small square studded with a 10 by 10 array of conical microneedles, each roughly 800 micrometers tall with a base diameter of about 300 micrometers. What makes the device remarkable is not its size but its internal architecture. Every needle is built in two concentric layers, fabricated through a stepwise centrifugal casting process into a silicone mold. The outer shell is made of methacrylated hyaluronic acid, or HAMA, a hydrophilic polymer that is photocrosslinked under 425-nanometer light. The inner core, along with the backing layer of the patch, is made of chitosan, a naturally occurring cationic polysaccharide. Each compartment carries a different therapeutic payload: the shell holds MCC950, a selective small-molecule inhibitor of the NLRP3 inflammasome, while the core carries basic fibroblast growth factor, or bFGF, a potent driver of blood vessel formation.

The choice of NLRP3 as the early target reflects a growing consensus about what goes wrong after a heart attack. When cardiomyocytes die from oxygen starvation, they release danger-associated molecular patterns that activate the NLRP3 inflammasome, a multiprotein immune sensor found in cardiomyocytes, fibroblasts, and infiltrating immune cells. Once assembled, this complex triggers caspase-1, which matures the inflammatory cytokines interleukin-1 beta and interleukin-18, amplifying cell death, fibrosis, and adverse ventricular remodeling. MCC950 works by blocking the oligomerization of ASC, the adaptor protein that assembles the inflammasome, and previous animal studies have shown it can shrink infarct size and preserve cardiac function. But timing is everything: NLRP3 activation peaks in the acute window, so delayed or systemic dosing risks missing the therapeutic moment while exposing the rest of the body unnecessarily.

The release kinetics engineered into the patch address that problem directly. Under acidic conditions mimicking the ischemic microenvironment, the MCC950 surrogate released about 23 percent of its payload within 15 minutes and 79 percent within one hour, with near-complete release by three days. That burst profile aligns precisely with the acute inflammatory phase. The bFGF story is entirely different: confined within the chitosan core, whose protonated amino groups bind the growth factor electrostatically, only 34.5 percent had escaped by day one, 50.2 percent by day four, and roughly 94 percent over 15 days. This sustained trickle is exactly what bFGF needs, since protein therapeutics degrade rapidly and vanish from tissue without a protective carrier. The researchers also found that release was faster at pH 5.4 than at physiological pH 7.4, suggesting the acidic infarct environment itself may help accelerate early drug delivery.

Mechanically, the patch proved robust enough for cardiac work. Compression testing showed the core-shell design withstood a maximum force of 30 newtons before complete insertion, thanks largely to the stiffness contributed by the crosslinked HAMA network. When a fluorescently labeled patch was pressed onto freshly excised rat left ventricular tissue, confocal imaging detected tracer deposited to a depth of approximately 700 micrometers, confirming that the needles physically penetrate the superficial myocardium rather than merely resting on its surface. That penetration matters therapeutically: it shortens the diffusion distance drugs must travel, improves local retention, and avoids the leakage and uneven distribution that plague direct intramyocardial injection, while keeping systemic exposure far lower than oral or intravenous routes would allow.

In laboratory dishes, the dual-loaded patch showed both faces of its therapeutic personality. When H9C2 rat cardiomyoblast cells were deprived of oxygen and glucose for eight hours, a condition that mimics ischemia, apoptosis climbed to 23.11 percent. Treatment with the MCC950-loaded patch cut that figure to 6.91 percent, and the dual-loaded version lowered it further to 6.03 percent. Molecular analysis confirmed the mechanism: levels of NLRP3, caspase-1, IL-1 beta, and IL-18 all dropped sharply in the MCC950-containing groups, while bFGF alone had little anti-inflammatory effect. On the vascular side, the story reversed. Human umbilical vein endothelial cells exposed to bFGF-containing patches proliferated vigorously, reaching nearly 180 percent viability at 72 hours, closed scratch wounds at rates of 94 to 96 percent within 24 hours, and formed dense capillary-like networks on Matrigel. Crucially, co-delivery of MCC950 did not blunt bFGF activity, and vice versa.

The decisive test came in rats subjected to permanent ligation of the left anterior descending coronary artery, a standard model of severe myocardial infarction. Patches were applied directly to the epicardial surface immediately after ligation, and the animals were followed for four weeks. Seven days after treatment, infarct tissue from rats receiving the dual-loaded patch showed markedly suppressed expression of NLRP3, IL-1 beta, and IL-18, and their serum levels of both cytokines were significantly reduced compared with untreated infarcted animals. Immunostaining revealed that NLRP3 suppression deepened between day 7 and day 28, while TUNEL staining showed apoptotic cell death falling steadily in the dual-treated group, evidence of a sustained protective effect rather than a transient pharmacological blip.

The functional outcomes were striking. By day 28, rats treated with the dual-loaded patch had a left ventricular ejection fraction of 69.4 percent and fractional shortening of 39.8 percent, compared with just 34.5 percent and 17.0 percent in untreated infarcted controls. Single-agent patches helped, but consistently less. End-diastolic and end-systolic volumes, which balloon as the ventricle dilates and remodels, were best preserved in the dual-treated group. Histology told the same story: hematoxylin and eosin staining showed better-preserved tissue architecture, Masson’s trichrome staining revealed the smallest fibrotic area of any treatment group, and ventricular wall thinning was markedly alleviated. Markers of angiogenesis, CD31 and alpha-SMA, were most strongly expressed in the dual-loaded group at day 28, indicating both new vessel formation and vascular maturation, while Ki67 staining pointed to a persistently active reparative microenvironment.

The authors are candid about the limitations that stand between this patch and the clinic. The in vitro release studies were conducted in static buffer conditions that cannot fully reproduce the dynamic pH, enzymatic activity, and interstitial flow of a living infarct, and the H9C2 cell line, being immature cardiomyoblasts, may not faithfully represent adult human cardiac inflammatory responses. The 28-day rat study leaves open questions about long-term biodegradation of the HAMA and chitosan matrix, potential residue persistence, and systemic biosafety. Perhaps most practically, the patch was implanted through open-chest surgery, a procedure that would need to be adapted to minimally invasive thoracoscopic or catheter-based delivery for real patients. Manufacturing reproducibility, sterilization, storage stability, and regulatory consistency also remain to be addressed.

Even so, the conceptual advance is considerable. Most biomaterial platforms for cardiac repair release their cargoes simultaneously or with little temporal distinction, ignoring the fact that infarct healing is a staged biological program in which the priorities of week one are nearly opposite to those of week four. By encoding a therapeutic sequence directly into material architecture, a fast-hydrating shell paired with a slow-releasing core, the researchers have demonstrated that drug presentation can be synchronized with disease-stage biology rather than fighting against it. The same logic, the authors note, could extend beyond cardiology to any condition marked by a transition from acute inflammation to regenerative remodeling, from diabetic wounds to spinal cord injury. For the millions of heart attack survivors who face progressive heart failure despite reperfusion therapy, a tiny two-layer needle array that knows which drug to release, and when, offers a glimpse of what precision biomaterial therapy might look like.

Subject of Research: A core-shell microneedle patch for sequential anti-inflammatory and pro-angiogenic drug delivery to repair heart tissue after myocardial infarction

Article Title: A core-shell microneedle patch coordinates early anti-inflammatory modulation and sustained pro-angiogenic stimulation for cardiac repair after myocardial infarction

Article References: A core-shell microneedle patch coordinates early anti-inflammatory modulation and sustained pro-angiogenic stimulation for cardiac repair after myocardial infarction. (n.d.). https://doi.org/10.1016/j.mtbio.2026.103704

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103704

Keywords: myocardial infarction, microneedle patch, NLRP3 inflammasome, MCC950, bFGF, angiogenesis, cardiac repair, drug delivery, hyaluronic acid, chitosan, ventricular remodeling, biomaterials

The challenge the researchers set out to solve is one of geometry and biology combined. Most laboratory studies of Kawasaki disease rely on flat, two-dimensional sheets of endothelial cells, the thin lining that coats the inside of blood vessels. Such cultures are easy to grow and easy to analyze, but they bear little resemblance to the real thing. A coronary artery is a hollow, curved, multilayered tube in which endothelial cells interface with blood on one side and smooth muscle cells wrap the exterior, providing structural support. Animal models, particularly mice, have been used for decades, but the differences between mouse and human vascular and immune biology often limit how well findings translate to the clinic. The team, led by Xuting Zhang and colleagues at Wenzhou Medical University and collaborating institutions, hypothesized that recreating the true three-dimensional, bilayered architecture of a coronary artery would yield a far more faithful model of the disease.

Their manufacturing method of choice was microfluidic coaxial bioprinting, an elegant technique that exploits the same principle as a pipe within a pipe. The researchers assembled a device from glass capillaries and injection needles, aligning an inner capillary concentrically inside an outer one. Two fluids were pumped through this coaxial nozzle: an outer bioink containing 10 percent gelatin methacryloyl, or GelMA, blended with polyethylene glycol diacrylate, or PEGDA, and an inner sacrificial stream of 10 percent polyvinyl alcohol. When the co-flowing streams emerged from the capillary tip, ultraviolet light at 405 nanometers triggered photopolymerization of the outer hydrogel, locking in a continuous tube. The uncrosslinked PVA core was then simply washed away, leaving behind a hollow hydrogel microfiber with an open lumen running its entire length.

The precision achievable with this setup is remarkable. By adjusting the relative flow rates of the inner and outer fluids, the team could dial in the dimensions of the fibers at will. Holding the inner flow at 15 milliliters per hour and raising the outer flow from 15 to 35 milliliters per hour shifted the ratio of inner to outer diameter from about 65.5 percent down to 58.4 percent, while the outer diameter swelled from roughly 712 to 911 micrometers. Reversing the adjustment, by accelerating the inner stream while holding the outer one constant, enlarged both the overall caliber and the relative lumen. Throughput was equally impressive: a single milliliter of bioink yielded between roughly 4 and 6.5 meters of continuous hollow fiber, depending on the diameter chosen, underscoring the scalability of the approach.

Mechanical tuning came from the PEGDA content. Three formulations containing 2.5, 5, and 7.5 percent PEGDA in 10 percent GelMA produced hydrogels with Young’s moduli of approximately 73, 153, and 221 kilopascals respectively, and rheological testing confirmed the same trend in storage modulus. Swelling behavior plateaued within 24 hours, and the matrices retained more than 95 percent of their mass after a day in culture medium, yet dissolved completely within 24 hours when exposed to the enzyme collagenase, showing that degradation is enzymatically controllable rather than a product of passive hydrolysis. Importantly, the softest formulation, 10 percent GelMA with 2.5 percent PEGDA, proved best for early cell attachment, because PEGDA, while excellent for structural strength, tends to resist cell adhesion. That formulation was selected for all subsequent vascular constructs.

With the scaffold optimized, the researchers populated it with human cells in a deliberate sequence. First, human umbilical vein endothelial cells, or HUVECs, at a density of 10 million cells per milliliter were injected into the lumen and allowed 72 hours to engraft, forming a continuous endothelial monolayer with uniform circumferential alignment. Then human coronary artery smooth muscle cells, at 100 million cells per milliliter, were applied to the outer surface, where they colonized the exterior and formed a distinct smooth muscle layer. Confocal microscopy of the cytoskeleton and immunostaining confirmed the architecture: the endothelial marker CD31 lined the luminal surface, while alpha-smooth muscle actin was confined to the outer layer, faithfully reproducing the bilayered organization of a native coronary artery.

Crucially, the model was more than a structural mimic. When the team perfused fluorescent dextran molecules of 4 and 70 kilodaltons through the lumen, the endothelialized constructs allowed far less leakage into the surrounding hydrogel than acellular controls, demonstrating that the engineered endothelium functioned as a selective barrier to both small solutes and large plasma proteins, just as a real vessel does. As a positive control, exposure to the inflammatory molecule TNF-alpha for six hours triggered a cascade of endothelial activation: elevated lactate dehydrogenase release signaling membrane injury, increased oxidative stress, upregulation of the adhesion molecules ICAM-1, VCAM-1, and E-selectin, a surge of inflammatory cytokines and chemokines including IL-1beta, IL-6, IL-8, CX3CL1, CCL5, and MCP-1, and clear activation of the NF-kappaB signaling pathway, traced by the phosphorylation of I-kappaB-alpha and the p65 subunit.

The decisive test came when the constructs were bathed in serum drawn from children during the acute phase of Kawasaki disease, before intravenous immunoglobulin therapy, mixed at a 10 percent volume ratio into the culture medium, with serum from age-matched healthy children as the control. Within six hours, the patient serum drove the engineered arteries into a state that mirrored the disease: heightened endothelial injury and oxidative stress, intensified expression of all three adhesion molecules, a broad transcriptional inflammatory response, and robust NF-kappaB activation. The serum also triggered pyroptosis, a fiery form of programmed cell death, evidenced by upregulation of the inflammasome sensor NLRP3, the executioner protein gasdermin D, and caspase-1. This finding aligns with growing evidence that pyroptotic endothelial death contributes to the coronary artery lesions that make Kawasaki disease dangerous, and it suggests that NF-kappaB signaling and the NLRP3 inflammasome operate in a reinforcing loop rather than as separate, sequential events.

The platform then proved its worth as a drug-testing instrument. Pretreating the constructs with atorvastatin, the widely used statin, at a non-toxic concentration of 10 micromolar significantly blunted the inflammatory response to Kawasaki serum, suppressing adhesion molecule and cytokine expression and dampening NF-kappaB phosphorylation, consistent with the statin’s known anti-inflammatory, lipid-independent pleiotropic effects and with early clinical trials of atorvastatin in Kawasaki patients with coronary aneurysms. The selective NLRP3 inhibitor MCC950, also tested at 10 micromolar, likewise reduced ICAM-1 expression and inflammatory mediator transcripts, and it specifically shut down the pyroptotic machinery, lowering NLRP3, gasdermin D, caspase-1, and IL-1beta. Because intravenous immunoglobulin resistance remains a major clinical problem, the ability to distinguish these two mechanistically distinct protective strategies within a single human tissue model is exactly the kind of preclinical capability the field has lacked.

The authors are candid about the model’s current limits. The constructs were cultured under static conditions, without the fluid flow and shear stress that shape endothelial behavior in living arteries, and future versions will incorporate dynamic perfusion. The endothelial layer consists of HUVECs rather than coronary-specific endothelial cells, a pragmatic choice driven by the robust proliferation needed to form an intact barrier in a bioprinted scaffold. Even so, the achievement stands out. In a single platform, the team has combined tunable biofabrication, native-like multilayered architecture, functional barrier properties, patient-derived disease induction, and mechanistically resolved drug evaluation. For a disease that strikes young children, has no known cause, and can leave permanent cardiac damage, this bioprinted coronary artery equivalent offers a powerful new window into pathogenesis and a versatile testing ground for the therapies of tomorrow.

Subject of Research: Biomimetic 3D bioprinted coronary artery models for Kawasaki disease modeling and drug screening

Article Title: Engineering biomimetic coronary artery equivalents for Kawasaki disease modeling and drug screening

Article References: Zhang, X., Shao, C., Wang, Y., Liu, A., Rong, X., Jia, C., Yu, W., Zhang, H., Wu, R., Zhang, J., Zhang, L., Ye, F., & Chu, M. (2026). Engineering biomimetic coronary artery equivalents for Kawasaki disease modeling and drug screening. Materials Today Bio, 41, Article 103701. https://doi.org/10.1016/j.mtbio.2026.103701

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103701

Keywords: Kawasaki disease, coronary artery, bioprinting, microfluidics, GelMA, endothelial dysfunction, NF-kB, pyroptosis, NLRP3, atorvastatin, MCC950, drug screening