Thermosensitive injectable polymer-based stem cell therapy for limb ischemia

 描述：严重肢体缺血 (CLI) 患者的特点是溃疡、疼痛和肢体丧失，并伴有高死亡率。对于不适合手术的 CLI 患者，干细胞疗法是增加灌注的一种有前途的替代方案。然而，最近的骨髓干细胞临床试验结果表明，由于两个主要障碍，骨髓干细胞缺乏持久功效：长期组织移植能力差和效力低。 该资助通过并行开发 1) 热敏可注射聚合物来解决这些障碍，该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 已部分预引发内皮谱系并表现出更高的效力。为了实现这些目标，我们生成了带有内皮启动子 (flk1) 驱动的 lacZ 报告基因的小鼠 MSC 系，以对多种血管分化方案进行高通量测试。该筛选鉴定出层粘连蛋白 I 和胶原 IV 是内皮细胞分化的有效分子诱导剂。 小鼠和人类 MSC。间充质干细胞的内皮预启动显着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引发MSC将把干细胞靶向缺血病灶，以促进它们的植入和治疗效力。该项目旨在了解间充质干细胞逐步内皮分化所涉及的分子因素和信号通路，并使用生物工程可注射聚合物产生一种组合疗法，通过基于肽的治疗剂输送预引发的人类间充质干细胞，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来增强 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.