Dnmt1 is required for proximal-distal patterning of the lung endoderm and for restraining alveolar type 2 cell fate

AbstractEpithelial cell organoids have increased opportunities to probe questions on tissue development and disease in vitro and for therapeutic cell transplantation. Despite their potential, current protocols to grow these organoids almost exclusively depend on culture within three-dimensional (3D) Matrigel, which limits defined culture conditions, introduces animal components, and results in heterogenous organoids (i.e., shape, size, composition). Here, we describe a method that relies on polymeric hydrogel substrates for the generation and expansion of lung alveolar organoids (alveolospheres). Using synthetic hydrogels with defined chemical and physical properties, human induced pluripotent stem cell (iPSC)-derived alveolar type 2 cells (iAT2s) self-assemble into alveolospheres and propagate in Matrigel-free conditions. By engineering pre-defined microcavities within these hydrogels, the heterogeneity of alveolosphere size and structure was reduced when compared to 3D culture while maintaining alveolar type 2 cell fate of human iAT2 and primary mouse tissue-derived progenitor cells. This hydrogel system is a facile and accessible culture system for the culture of primary and iPSC-derived lung progenitors and the method could be expanded to the culture of other epithelial progenitor and stem cell aggregates.

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Acquisition of alveolar fate and differentiation competence by human fetal lung epithelial progenitor cells

10.1101/2021.06.30.450501 ◽

2021 ◽

Author(s):

Kyungtae Lim ◽

Walfred Tang ◽

Dawei Sun ◽

Peng He ◽

Sarah Teichmann ◽

...

Keyword(s):

Cell Fate ◽

Molecular Mechanisms ◽

Human Lung ◽

Fetal Lung ◽

Alveolar Type ◽

Alveolar Development ◽

Wnt Inhibitor ◽

Key Aspects ◽

Epithelial Progenitor Cells

Variation in lung alveolar development is strongly linked to disease susceptibility. However, the cellular and molecular mechanisms underlying alveolar development are difficult to study in humans. Using primary human fetal lungs we have characterized a tip progenitor cell population with alveolar fate potential. These data allowed us to benchmark a self-organising organoid system which captures key aspects of lung lineage commitment and can be efficiently differentiated to alveolar type 2 cell fate. Our data show that Wnt and FGF signalling, and the downstream transcription factors NKX2.1 and TFAP2C, promote human alveolar or airway fate respectively. Moreover, we have functionally validated cell-cell interactions in human lung alveolar patterning. We show that Wnt signalling from differentiating fibroblasts promotes alveolar type 2 cell identity, whereas myofibroblasts secrete the Wnt inhibitor, NOTUM, providing spatial patterning. Our organoid system recapitulates key aspects of human lung development allowing mechanistic experiments to determine the underpinning molecular regulation.

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Loss of Nrf2 promotes alveolar type 2 cell loss in irradiated, fibrotic lung

Free Radical Biology and Medicine ◽

10.1016/j.freeradbiomed.2017.08.026 ◽

2017 ◽

Vol 112 ◽

pp. 578-586 ◽

Cited By ~ 7

Author(s):

Geri Traver ◽

Stacey Mont ◽

David Gius ◽

William E. Lawson ◽

George X. Ding ◽

...

Keyword(s):

Cell Loss ◽

Alveolar Type

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Hypercapnia limits β-catenin mediated alveolar type 2 cell progenitor function by altering Wnt production from adjacent fibroblasts

10.1101/2022.01.12.475264 ◽

2022 ◽

Author(s):

Laura A Dada ◽

Lynn C Welch ◽

Natalia D Magnani ◽

Ziyou Ren ◽

Patricia L Brazee ◽

...

Keyword(s):

Alveolar Type ◽

Mechanically Ventilated ◽

Persistent Symptoms ◽

Low Tidal Volume ◽

Lung Repair ◽

Ventilator Induced Lung Injury ◽

Lung Flooding ◽

Volume Ventilation

Persistent symptoms and radiographic abnormalities suggestive of failed lung repair are among the most common symptoms in patients with COVID-19 after hospital discharge. In mechanically ventilated patients with ARDS secondary to SARS-CoV-2 pneumonia, low tidal volume ventilation to reduce ventilator-induced lung injury necessarily elevate blood CO2 levels, often leading to hypercapnia. The role of hypercapnia on lung repair after injury is not completely understood. Here, we show that hypercapnia limits β-catenin signaling in alveolar type 2 (AT2) cells, leading to reduced proliferative capacity. Hypercapnia alters expression of major Wnts in PDGFRα-fibroblasts from those maintaining AT2 progenitor activity and towards those that antagonize β-catenin signaling and limit progenitor function. Activation of β-catenin signaling in AT2 cells, rescues the effects of hypercapnia on proliferation. Inhibition of AT2 proliferation in hypercapnic patients may contribute to impaired lung repair after injury, preventing sealing of the epithelial barrier, increasing lung flooding, ventilator dependency and mortality.

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