Genetically corrected induced pluripotent stem cells-derived tissue-macrophages as an innovative therapy approach of hereditary Pulmonary Alveolar proteinosis (PAP)

由于其无限的自我更新以及分化潜力，诱导多能干细胞成为再生医学非常理想的细胞类型，2012年获得诺贝尔医学或生理学奖。除了它们对内胚层或外胚层细胞的分化潜能外，它们还对中胚层细胞--特别是造血系细胞--的分化潜能开启了罕见血液病治疗的新纪元。尽管IPSC向造血系统的成熟细胞分化已被证明是可行的，但到目前为止，仍难以产生具有长期再繁殖潜力的真正的造血干细胞。在这方面，从多能干细胞来源产生功能成熟细胞可能代表着细胞和基因治疗方法的一条新途径。在这里，单核/巨噬细胞的产生可能是一个有吸引力的靶细胞，因为这些细胞被认为是各种组织中的关键角色。尤其是肺泡巨噬细胞非常重要，因为这些细胞代表着肺部的第一道宿主防线，对肺内环境的稳定非常重要。GM-CSF受体基因(CSF2RA和CSF2RB)的突变会导致肺泡巨噬细胞受损，并导致危及生命的肺泡蛋白沉积症(PAP)。PAP的特点是大量蛋白质在肺内积聚，导致进行性呼吸衰竭和肺部感染的高度易感性。由于到目前为止还没有治愈的方法，新的治疗策略是非常可取的。为了探索新的治疗方案，我们评估了在小鼠和人源化的PAP小鼠模型中进行造血干细胞来源的巨噬细胞器官变性移植的可行性。将IPSC向巨噬细胞的分化潜能与PAP的基因治疗和病理生理学领域相结合，可能会导致通过基因纠正的IPSC来源的单核/巨噬细胞的肺细胞移植(PCT)来治疗PAP的高度创新的选择。在这里，基因修正的IPSC来源的巨噬细胞将在两个高度相关的PAP小鼠模型中进行研究，以用于器官移植的创新应用。在临床移植方案中，这些IPSC细胞可以以患者特有的方式生成，经过基因纠正并分化为患者来源的造血细胞。这样产生的细胞不仅可以为PAP患者带来潜在的长期临床益处，而且还将进一步消除合适的HLA匹配供者的等待时间或进一步降低免疫排斥的风险。总而言之，这种方法不仅将提高PAP患者的生活质量，还将为使用成熟细胞(如巨噬细胞)而不是来自多能干细胞来源的干细胞进行细胞治疗铺平道路。

Due to their unlimited self-renewal- as well as differentiation potential, induced pluripotent stem cells became a highly desirable cell type for regenerative medicine, recognized by the nobel-prize for medicine or physiology in 2012. Besides their differentiation potential towards cells of the endo- or ectodermal lineage, also their differentiation potential towards cells of the mesoderm- in particular hematopoietic lineage opens a new therapeutic era for rare-hematological disorders. Although differentiation of iPSC towards mature cells of the hematopoietic system has been proven to be feasible, however, generation of bona fide hematopoietic stem cells with long term repopulating potential remains elusive as of now. In this line, generation of functional mature cells from pluripotent stem cells sources may represent a novel way for cell and gene therapy approaches. Here, the generation of monocyte/macrophages might be an attractive target cell, as these cells are known to be key players in various tissues. Especially alveolar macrophages are of great importance as these cells represent the first line of host-defense in the lungs and are important for lung homeostasis. Mutations in the GM-CSF receptor genes (CSF2RA and CSF2RB) lead to impaired alveolar macrophages and to the life-threatening disease pulmonary alveolar proteinosis (PAP). PAP is characterized by massive protein accumulation in the lungs leading to progressive respiratory failure and a high susceptibility for pulmonary infections. As no curative treatment is available to-date, new therapeutic strategies are highly desirable. In order to investigate novel therapeutic options, we have evaluated the feasibility of organotropic transplantation of hematopoietic stem cell derived macrophages in a murine as well as in a humanized PAP mouse model (manuscript attached).Combining the differentiation potential of iPSC towards macrophages with the field of gene therapy and the pathophysiology of PAP, may lead to a highly innovative treatment option for PAP by a pulmonary-cell-transplant (PCT) of genetically corrected, iPSC derived monocyte/macrophages. Here, genetically corrected iPSC derived macrophages will be investigated in two highly relevant PAP-mouse models for their innovative use in organotropic transplantation. In a clinical transfer scenario, these iPSC cells could be generated in a patient specific manner, genetically corrected and differentiated towards hematopoietic cells of patient origin. The so generated cells would not only allow for a potential long-lasting clinical benefit for the PAP patients, but would further abrogate the waiting time for suitable HLA-matched donors or further decrease the risk of immune rejection. Taken together, this approach would not only increase the quality of life of PAP patients, but would also pave the way for cell-therapeutics using mature cells, such as macrophages, rather than stem cells derived from pluripotent stem cell sources.