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，并在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谱系细胞的分化潜力之外，它们对中胚层细胞（特别是造血谱系细胞）的分化潜力也为罕见血液疾病开辟了新的治疗时代。虽然iPSC向造血系统的成熟细胞分化已被证明是可行的，然而，迄今为止，具有长期再增殖潜力的真正造血干细胞的产生仍然难以捉摸。在这条线上，从多能干细胞来源产生功能成熟细胞可能代表细胞和基因治疗方法的新途径。在这里，单核细胞/巨噬细胞的产生可能是有吸引力的靶细胞，因为已知这些细胞是各种组织中的关键参与者。特别是肺泡巨噬细胞是非常重要的，因为这些细胞代表了肺中宿主防御的第一道防线，并且对于肺内稳态是重要的。GM-CSF受体基因（CSF 2 RA和CSF 2 RB）的突变导致肺泡巨噬细胞受损和危及生命的疾病肺泡蛋白沉积症（PAP）。PAP的特征是大量蛋白质在肺部积聚，导致进行性呼吸衰竭和对肺部感染的高度易感性。由于迄今为止没有治愈性治疗，因此非常需要新的治疗策略。为了研究新的治疗选择，我们评估了在小鼠和人源化PAP小鼠模型中造血干细胞衍生的巨噬细胞的向器官移植的可行性将iPSC向巨噬细胞的分化潜能与基因治疗领域和PAP的病理生理学相结合，通过遗传校正的、iPSC衍生的单核细胞/巨噬细胞的肺细胞移植（PCT），可能导致PAP的高度创新的治疗选择。在这里，将在两个高度相关的PAP-小鼠模型中研究遗传校正的iPSC衍生的巨噬细胞，以用于它们在亲器官移植中的创新用途。在临床转移情况下，这些iPSC细胞可以以患者特异性方式产生，遗传校正并分化为患者来源的造血细胞。如此产生的细胞不仅可以为PAP患者提供潜在的长期临床益处，而且还可以进一步消除对合适的HLA匹配供体的等待时间或进一步降低免疫排斥的风险。总之，这种方法不仅可以提高PAP患者的生活质量，而且还可以为使用成熟细胞（如巨噬细胞）而不是来自多能干细胞来源的干细胞的细胞治疗铺平道路。

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.