Thermosensitive injectable polymer-based stem cell therapy for limb ischemia

 描述：严重肢体缺血（CLI）患者的特征是溃疡、疼痛和肢体丧失，相关死亡率高。对于不适合手术的CLI患者，干细胞治疗是增加灌注的一种有前途的替代方案。然而，最近的骨髓源性干细胞临床试验结果表明，由于两个主要障碍，缺乏持久的疗效：长期组织移植不良和效力低。 该资助通过平行开发1）热敏性可注射聚合物来解决这些障碍，这些聚合物能够改善缺血组织中干细胞的存活和增殖，2）有效生成MSC，这些MSC已经部分地向内皮谱系预致敏并表现出更高的效力。为了实现这些目标，产生了用内皮启动子（flk1）驱动的lacZ报告基因标记的小鼠MSC系，以进行多种血管分化方案的高通量测试。该筛选鉴定了层粘连蛋白I和胶原IV作为内皮细胞分化的有效分子诱导剂， 小鼠和人MSC。MSC的内皮预致敏显著改善了小鼠的缺血灌注。待测试的假设是，注射有在体温下胶凝的热敏聚合物的具有高修复效力的预致敏MSC将干细胞靶向缺血灶以促进其植入和治疗效力。该项目旨在了解参与MSC逐步内皮分化的分子因子和信号通路，并使用生物工程可注射聚合物产生组合疗法，以提供预处理的人MSC与基于肽的治疗剂，以改善后肢缺血小鼠模型的灌注。长期目标是开发一种非侵入性干细胞疗法，以增加CLI患者的肢体灌注。

 DESCRIPTION: Critical limb ischemia (CLI) in patients is characterized by ulceration, pain, and limb loss with associated high mortality. For CLI patients who are not suitable surgical candidates, stem cell therapy represents a promising alternative to increase perfusion. However, results from recent clinical trials with bone marrow-derived stem cells indicate a lack of lasting efficacy due to two major obstacles: poor long-term tissue engraftment and their low potency. This grant addresses these obstacles by parallel development of 1) thermosensitive injectable polymers that enable improved survival and proliferation of stem cells in ischemic tissue 2) efficient generation of MSCs which have been partially preprimed towards the endothelial lineage and exhibit higher potency. To accomplish these goals, a mouse MSC line genetically tagged with a lacZ reporter driven by an endothelial promoter (flk1) was generated to perform high-throughput testing of multiple vascular differentiation protocols. This screen identified laminin I and collagen IV as potent molecular inducers of endothelial differentiation of mouse and human MSCs. Endothelial prepriming of MSCs dramatically improved ischemic perfusion in mice. The hypothesis to be tested is that preprimed MSCs with high reparative potency injected with thermosensitive polymers which gel at body temperature will target stem cells to ischemic foci to promote their engraftment and therapeutic potency. The project seeks to understand the molecular factors and signaling pathways involved in stepwise endothelial differentiation of MSCs and to generate a combinatorial therapy using bioengineered injectable polymer to deliver the preprimed human MSCs with peptide-based therapeutics to improve perfusion in a mouse model of hindlimb ischemia. The long-term goal is to develop a non-invasive stem-cell therapy to augment limb perfusion in patients with CLI.