功能性多肽上调HIF-1α促进神经干细胞修复脑梗死的MRI分子影像学研究

Neural stem cells (NSCs) transplantation is a promising new treatment model for cerebral infarction. However, the detrimental microenvironment in the infarct area makes it difficult for transplanted NSCs surviving for a long time, which severely limits the therapeutic effect. How to improve the viability rate of transplanted NSCs is an urgent problem need to be solved. Upregulating the HIF-1α of transplanted stem cells to promote microenvironment angiogenesis is an effective solution. Based on the successful synthesis of a kind of biocompatible positive charge nano micelles in our early study, this project is intended to prepared a novel multifunctional nanocarrier loading polypeptide with proline residues and superparamagnetic iron oxide nanoparticles (SPIONs). Upon this multifunctional nanocarrier, SPIONs will label NSCs paramagnetically, and functional polypeptide will be directionally transported into NSCs to competitively combinate with intracellular hif-1α hydroxylase and enhance the stability of hif-1α, consequently up regulate HIF-1 target gene of NSCs and promote angiogenesis. We will investigate the polypeptide transfection efficiency, the labeling effect and the biological of the multifunctional nanocarrier in vitro and in vivo, to clarify the effect of functional polypeptide on the upregulation of hif-1α in NCSs and the effect of promoting angiogenesis. We aim to establish a visible stem cell tracking and functional regulation technique to improve the viability of stem cells by microenvironment modulation, for promoting the therapeutic effect and the clinical transformation of stem cell therapy.

神经干细胞移植是脑梗死极有前景的新治疗模式，然而梗死区异常微环境导致干细胞移植后难以长期存活，严重限制了其治疗效果。如何提高干细胞移植后的存活率是亟待解决的问题。诱导移植干细胞上调HIF-1α促进微环境血管生成是解决此问题的有效方法。本项目拟在前期制备的生物相容性正电荷纳米胶束基础上，制备负载具有脯氨酸残基的肽段及超顺磁性氧化铁纳米粒子的多功能纳米载体，进行神经干细胞标记同时，定向输送功能性多肽竞争性结合细胞内HIF-1α羟化酶提高HIF-1α稳定性，上调神经干细胞HIF-1促进微环境血管生成，在细胞和动物整体水平考察多功能纳米载体输送多肽的效率、示踪效果及生物安全性，明确功能多肽上调神经干细胞HIF-1α的效果及其促进血管生成的作用，建立可视化引导干细胞示踪及功能调控技术，通过微环境调制提高干细胞存活能力，提升干细胞治疗效果，推动干细胞治疗的临床转化。

神经干细胞（neural stem cells，NSCs）移植是脑梗死极有前景的新治疗策略，但NSCs移植到梗死组织后，其向神经元定向分化的比率低，且NSCs存活率低，这严重影响了其治疗效果，限制了NSCs移植的临床转化。近年来发现NSCs移植后的存活、分化、迁移与神经血管微环境，即神经血管单元的重构密切相关。神经血管单元理论的提出，促进了基于微环境提高NSCs治疗效果新策略的探索。缺氧诱导因子（hypoxia inducible factor，HIF）是乏氧条件下促血管生成信号通路的主要调控分子，是调控血管微环境的关键信号分子。针对NSCs移植后向神经元分化比率、存活率低的问题，本课题从神经血管单元角度出发，采用负载SPIO及功能性多肽的mPEG-TEPA-CA5纳米胶束，将功能性多肽高效、安全地输送至NSCs的同时，实现了NSCs的磁性标记；通过功能性多肽模拟HIF-1α结构的功能性多肽，在体内、体外上调HIF-1α相关通路表达，提高NSCs移植后的存活及损伤响应能力：实验组较对照组检测到更多的nestin+GFP+细胞（78.65±1.92% vs. 43.39±5.03%）及更多CXCR4+GFP+细胞（68.24±5.24% vs. 44.60±0.72%）。并且在移植后第1、2周有效的缩小了脑梗死体积；同时SPIO标记实现了移植后NSCs的活体、动态MR示踪。本研究为功能性多肽调控干细胞，提高干细胞脑梗死治疗效果奠定了基础。项目资助发表SCI论文三篇，待发表SCI论文2篇，培养了1名硕士研究生并已取得硕士学位。项目投入经费21万元，累计支出18.6019万元，各项支出与预算基本相符，结余2.3981万元，经费使用符合规范。

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