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和分化潜力，诱导多能干细胞成为再生医学非常理想的细胞类型，并于2012年获得诺贝尔医学奖或生理学奖。除了向内胚层或外胚层细胞分化的潜力外，它们对中胚层细胞特别是造血细胞的分化潜力也为罕见血液疾病的治疗开辟了一个新的时代。虽然iPSC向造血系统成熟细胞的分化已被证明是可行的，但是，到目前为止，具有长期再生潜力的真正的造血干细胞的产生仍然是难以捉摸的。在这方面，从多能干细胞来源产生功能成熟细胞可能代表了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一个有吸引力的靶细胞，因为这些细胞已知在各种组织中起关键作用。特别是肺泡巨噬细胞非常重要，因为这些细胞代表了肺部宿主防御的第一道防线，对肺内稳态很重要。GM-CSF受体基因（CSF2RA和CSF2RB）的突变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部积聚，导致进行性呼吸衰竭，对肺部感染易感性高。由于目前尚无有效的治疗方法，新的治疗策略是非常可取的。为了研究新的治疗方案，我们评估了造血干细胞来源的巨噬细胞在小鼠和人源化PAP小鼠模型中移植的可行性（手稿附）。将iPSC向巨噬细胞分化的潜力与基因治疗领域和PAP的病理生理学相结合，可能会通过基因校正的iPSC衍生单核细胞/巨噬细胞的肺细胞移植（PCT），为PAP提供一种高度创新的治疗选择。在这里，基因校正的iPSC衍生巨噬细胞将在两种高度相关的pap小鼠模型中进行研究，以探索其在嗜器官移植中的创新应用。在临床移植场景中，这些iPSC细胞可以以患者特异性的方式生成，经过基因校正并向患者造血细胞分化。这种生成的细胞不仅可以为PAP患者带来潜在的长期临床益处，而且还可以进一步缩短等待合适的hla匹配供体的时间，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.