Xie, Jingwei

Abstract Porous nanofibrous microspheres (PNMs) present a versatile and minimally invasive strategy for tissue regeneration, combining biomimetic morphology, tunable structure, and injectability. While self‐assembly and co‐axial electrospray are explored for PNM fabrication, these methods are limited in compositional versatility and production scalability. Here, a 3D‐printed microfluidic platform is presented that enables large‐scale fabrication of PNMs with precise control over size, pore architecture, and morphology. PNMs can be functionalized with bioactive molecules through UV crosslinking, enhancing their regenerative potential by promoting osteogenesis in human bone marrow stromal cells (hBMSCs), angiogenesis in human umbilical vein endothelial cells (HUVECs), and exerting anti‐inflammatory effects on macrophages. Subcutaneous implantation in rats demonstrates that PNMs support cell infiltration, minimize fibrosis, and facilitate tissue integration, achieving complete cell penetration and tissue incorporation within 14 days. These findings establish PNMs as versatile, scalable, and customizable platforms, ideal for applications as injectable drugs or cell carriers, as well as powders, offering promising solutions for wound healing and tissue regeneration.

BACKGROUND: Apelin is an endogenous prepropeptide that regulates cardiac homeostasis and various physiological processes. Intravenous injection has been shown to improve cardiac contractility in patients with heart failure. However, its short half-life prevents studying its impact on left ventricular remodeling in the long term. Here, we aim to study whether microparticle-mediated slow release of apelin improves heart function and left ventricular remodeling in mice with myocardial infarction (MI). METHODS: A cardiac patch was fabricated by embedding apelin-containing microparticles in a fibrin gel scaffold. MI was induced via permanent ligation of the left anterior descending coronary artery in adult C57BL/6J mice followed by epicardial patch placement immediately after (acute MI) or 28 days (chronic MI) post-MI. Four groups were included in this study, namely sham, MI, MI plus empty microparticle-embedded patch treatment, and MI plus apelin-containing microparticle-embedded patch treatment. Cardiac function was assessed by transthoracic echocardiography. Cardiomyocyte morphology, apoptosis, and cardiac fibrosis were evaluated by histology. Cardioprotective pathways were determined by RNA sequencing, quantitative polymerase chain reaction, and Western blot. RESULTS: The level of endogenous apelin was largely reduced in the first 7 days after MI induction and it was normalized by day 28. Apelin-13 encapsulated in poly(lactic-co-glycolic acid) microparticles displayed a sustained release pattern for up to 28 days. Treatment with apelin-containing microparticle-embedded patch inhibited cardiac hypertrophy and reduced scar size in both acute and chronic MI models, which is associated with improved cardiac function. Data from cellular and molecular analyses showed that apelin inhibits the activation and proliferation of cardiac fibroblasts by preventing transforming growth factor-β–mediated activation of Smad2/3 (supporessor of mothers against decapentaplegic 2/3) and downstream profibrotic gene expression. CONCLUSIONS: Poly(lactic-co-glycolic acid) microparticles prolonged the apelin release time in the mouse hearts. Epicardial delivery of the apelin-containing microparticle-embedded patch protects mice from both acute and chronic MI-induced cardiac dysfunction, inhibits cardiac fibrosis, and improves left ventricular remodeling.