Transfer-molded wrappable microneedle meshes for perivascular drug delivery
After surgical procedures such as coronary/peripheral bypass grafting or endarterectomy for the treatment of organ ischemia derived from atherosclerosis, intimal hyperplasia (IH) which leads to restenosis or occlusion at the site of graft anastomosis frequently occurs. In order to inhibit IH caused by abnormal growth of smooth muscle cells (SMCs) in tunica media, various perivascular drug delivery devices are reported for delivery of anti-proliferation drugs into vascular tissue. However, there still remain conflicting requirements such as local and unidirectional delivery vs device porosity, and conformal tight device installation vs pulsatile expansion and constriction of blood vessels. In this study, a biodegradable microneedle (MN) array is developed on a flexible woven surgical mesh using a transfer molding method. Mechanical properties of ‘wrappable’ MN meshes are investigated and compared to the properties of blood vessels. Ex vivo and in vivo animal studies demonstrate enhanced drug delivery efficiency, efficacy for IH reduction, and safety of MN mesh. In particular, MN mesh showed significantly reduced neointiamal formation (11.1%) compared to other competitive groups (23.7 and 22.2%) after 4-week in vivo animal study. Additionally, wrappable MN meshes effectively suppressed side effects such as IH due to mechanical constriction, loss of toxic drug to the surroundings, and cell death that were frequently observed with other previous perivascular drug delivery devices.