An anisotropic cardiac patch with barbed microneedles for enhanced tissue anchorage and myocardial repair

Microneedle patches can penetrate the myocardium to facilitate integration with cardiac tissue, offering a promising approach for myocardial infarction (MI) repair. However, their clinical translation has been hindered by insufficient fixation stability during cardiac contractions and mismatch with myocardial anisotropy. To address these challenges, a bioinspired three-dimensional cardiac patch integrating barbed microneedles and an anisotropic lightweight mesh was designed. The microneedle with outward-expanding barbs (OEBMN) demonstrated 10.8-fold stronger tissue anchorage than the barbless microneedle, while achieving a 6-fold reduction in the force ratio (insertion force/pulling-out force), indicating an enhanced anchoring performance. The OEBMN enabled sutureless patch transplantation onto the epicardium, ensuring more uniform stress distribution than suture-fixation systems where stress concentrations typically occur at knotting sites. The knitted mesh exhibited sufficient strength to provide long-term mechanical compensation to the infarcted myocardium, whereas the honeycomb-like structure satisfied the native myocardial anisotropy. Furthermore, the cardiac patch promoted comprehensive mechanical integration with the infarcted heart through OEBMNs, enabling multi-directional support from the inner myocardium to the epicardium. The rat MI model experiments revealed that the patch not only improved cardiac function and electrophysiological characteristics but also increased ventricular wall thickness, reduced fibrosis, and promoted angiogenesis. Transcriptome sequencing revealed that the potential mechanisms by which the patch promotes myocardial repair mainly include inhibiting apoptosis- and fibrosis-related pathways. Overall, this study proposes a sutureless fixation strategy for cardiac patches and highlights the latent potential of providing anisotropic mechanical support for MI repair. STATEMENT OF SIGNIFICANCE: Microneedle patches offer a promising platform for myocardial repair by directly penetrating cardiac tissue and enabling mechanical integration with the tissue. However, their application is hindered by limited fixation stability and structural mismatch with anisotropic myocardium. Herein, a cardiac patch combining an anisotropic lightweight mesh with microneedles featuring outward-expanding barbs was constructed. This design allows stable anchoring, sutureless implantation with reduced insertion force, uniform stress transmission, and anisotropic mechanical support to inhibit ventricular dilation. In vivo results showed that the patch significantly enhanced cardiac contractile function, reduced ventricular fibrosis, and increased ventricular wall thickness. This unique design demonstrates substantial potential for sutureless fixation scenarios and the repair of infarcted myocardium.