Bioengineering a chimeric human lung

在美国，近2500万人患有终末期肺病， 每年约有140，000名患者死于慢性阻塞性肺疾病，是第三大 常见死因肺移植-这些患者唯一确定的治疗方法，仍然是 由于供体器官严重短缺，在某种程度上，五个供体肺中只有一个是 用于移植。恢复被拒绝/边缘质量供体肺的能力将从根本上改变 成千上万等待肺移植的患者的预后。我们建议使用捐赠人 选择性去除靶向损伤肺上皮 同时保留周围细胞、基质、基底膜和肺血管。 然后，裸露的上皮区域将被来源于人表皮细胞的上皮祖细胞重新增殖。 iPSCs，以生物工程改造符合移植标准的功能性嵌合人肺。我们 假设急性损伤的人肺的功能性再生可以在体外实现 通过靶向替换肺受损区域的肺上皮，同时保留完整的肺， 基质和脉管系统，在设计用于模拟产前肺发育的条件下。为了验证这一 假设，我们提出了三个具体目标。目的1是获得肺细胞（假定的远端尖端 祖细胞，pDTP），并表征其身份、表型和成熟水平。 目的二是探讨急性肺损伤的肺组织再生 使用两种模型，使用iPSC衍生的肺细胞对上皮细胞进行细胞培养：（i）体外培养的肺切片，和（ii） 离体血管灌注和空气通气支持的整个人肺。目标3：从功能上 通过长期交叉循环支持（长达7天）和支气管/肺泡 输注pDTP，进行实时功能评估和成像。这三个目标将得到实现。 以综合方式，每一个目标通知其他两个目标。这项提案的最终目的是 是通过结合四种主要的方法来实现移植排斥的供体肺的功能恢复， 创新成分：（1）衍生有效无限数量的上皮肺祖细胞 （2）选择性去除肺上皮（大多数肺损伤的部位） 同时维持天然肺脉管系统（能够实现连续的血液灌注）， （3）延长离体肺支持的持续时间，从数小时到数天， 为灌注和通气的肺提供代谢清除和全身因子，和（4） 在离体肺恢复期间实施实时治疗诊断（诊断+治疗）成像。

Nearly 25 million people suffer from end-stage lung disease in the United States with a staggering ~140,000 patients dying each year from chronic obstructive pulmonary disease alone, the third most common cause of death. Lung transplantation - the only definitive treatment for these patients, remains hampered by the severe shortage of donor organs, to the extent that only one out of five donor lungs is used for transplant. The ability to recover rejected/marginal quality donor lungs would radically change the prognosis for thousands of patients awaiting lung transplantation. We propose to use donor human lungs rejected because of acute injury, and selectively remove the lung epithelium in targeted injured regions while preserving the surrounding cells, matrix, basement membranes and lung vasculature. Denuded epithelial regions will then be repopulated by epithelial progenitors derived from human iPSCs, to bioengineer a functional chimeric human lung that meets transplantation criteria. Our hypothesis is that the functional regeneration of acutely injured human lungs ex vivo can be achieved by targeted replacement of lung epithelium in damaged regions of the lung, while preserving intact lung matrix and vasculature, under conditions designed to emulate prenatal lung development. To test this hypothesis, we propose three specific aims. Aim 1 is to derive pulmonary cells (putative distal tip progenitors, pDTPs) from iPS cells and to characterize their identity, phenotype and level of maturity. Aim 2 is to investigate regeneration of acutely injured human lungs by replacing the injured lung epithelium with iPSC-derived pulmonary cells, using two models: (i) lung slices cultured in vitro, and (ii) whole human lungs supported with vascular perfusion and air ventilation ex vivo. Aim 3 is to functionally recover the lungs ex vivo, by long-term cross-circulation support (up to 7 days) and bronchial/alveolar infusion of pDTPs, with real-time functional assessment and imaging. These three aims will be pursued in an integrated fashion, with each aim informing the other two aims. The ultimate goal of this proposal is to achieve functional recovery of donor lungs rejected for transplantation by combining four major innovative components: (1) Derivation of effectively unlimited numbers of epithelial lung progenitors (pDTPs) from human iPSCs, (2) Selective removal of lung epithelium (the site of most lung damage) while maintaining native lung vasculature (enabling continuous blood perfusion) followed by delivery of pDTPs to the denuded epithelium, (3) Extended duration of ex vivo lung support, from hours to days, by  providing metabolic clearance and systemic factors to the perfused and ventilated lung, and (4) Implementation of real-time theranostic (diagnostic + therapeutic) imaging during ex vivo lung recovery.