Transplantation of layer-by-layer assembled neural stem cells tethered with vascular endothelial growth factor reservoir promotes neurogenesis and angiogenesis after ischemic stroke in mice

Transplantation of neural stem cells (NSCs) is a promising therapeutic strategy for ischemic stroke. However, most of engrafted NSCs hardly survive for a long time, and the majority of transplanted NSCs differentiate into astrocytes around infarct core due to harsh microenvironment after ischemic stroke. Therefore, exploring ap-proaches to foster the regenerative ability of transplanted NSCs in hostile niche is a feasible strategy to reha-bilitate lesions. Here, a feasible method for grafted NSCs modified by layer-by-layer (LbL) assembly (LbL-NSCs) using gelatin and hyaluronic acid (HA) was developed. The results indicated the LbL-NSCs were biocompatible, and held the ability of promoting NSCs differentiation into neurons. Subsequently, vascular endothelial growth factor (VEGF) was laden into gelatin to generate LbL-NSCs tethered with VEGF reservoir [LbL (VEGF)-NSCs], and the VEGF releasing from LbL (VEGF)-NSCs was sustained under pH 7.4 in vitro. Afterward, the results demon-strated transplantation of LbL (VEGF)-NSCs facilitated implanted NSCs survival and differentiation into neurons in distal middle cerebral artery occlusion (dMCAO) mice. Additionally, engraftment of LbL (VEGF)-NSCs rein-forced neurogenesis, angiogenesis, survival of host neurons, and blood brain barrier (BBB) repair, thereafter enhancing functional recovery through reducing the volume of infarct core in dMCAO mice. This investigation provides an appropriate approach for modifying NSCs by LbL assembly using gelatin loaded with VEGF and HA to expedite the rehabilitative ability of engrafted NSCs following ischemic stroke.