The discovAIR project: a roadmap towards the Human Lung Cell Atlas

The Human Cell Atlas (HCA) consortium aims to establish an atlas of all organs in the healthy human body at single-cell resolution to increase our understanding of basic biological processes that govern development, physiology and anatomy, and to accelerate diagnosis and treatment of disease. The Lung Biological Network of the HCA aims to generate the Human Lung Cell Atlas as a reference for the cellular repertoire, molecular cell states and phenotypes, and cell–cell interactions that characterise normal lung homeostasis in healthy lung tissue. Such a reference atlas of the healthy human lung will facilitate mapping the changes in the cellular landscape in disease. The discovAIR project is one of six pilot actions for the HCA funded by the European Commission in the context of the H2020 framework programme. discovAIR aims to establish the first draft of an integrated Human Lung Cell Atlas, combining single-cell transcriptional and epigenetic profiling with spatially resolving techniques on matched tissue samples, as well as including a number of chronic and infectious diseases of the lung. The integrated Human Lung Cell Atlas will be available as a resource for the wider respiratory community, including basic and translational scientists, clinical medicine, and the private sector, as well as for patients with lung disease and the interested lay public. We anticipate that the Human Lung Cell Atlas will be the founding stone for a more detailed understanding of the pathogenesis of lung diseases, guiding the design of novel diagnostics and preventive or curative interventions.

The discovAIR project contributes to the Human Cell Atlas Lung Biological Network by establishing a first draft of the Human Lung Cell Atlas, advancing our insight into the cellular complexity and spatial organisation of the lung in health and diseasehttps://bit.ly/3zX4cad

Fresh Noncultured Endothelial Progenitor Cells Improve Neonatal Lung Hyperoxia-Induced Alveolar Injury

Treatment of preterm human infants with high oxygen can result in disrupted lung alveolar and vascular development. Local or systemic administration of endothelial progenitor cells (EPCs) is reported to remedy such disruption in animal models. In this study, the effects of both fresh (enriched for KDR) and cultured bone marrow (BM)-derived cell populations with EPC characteristics were examined following hyperoxia in neonatal mouse lungs. Intraperitoneal injection of fresh EPCs into five-day-old mice treated with 90% oxygen resulted in full recovery of hyperoxia-induced alveolar disruption by 56 days of age. Partial recovery in septal number following hyperoxia was observed following injection of short-term cultured EPCs, yet aberrant tissue growths appeared following injection of long-term cultured cells. Fresh and long-term cultured cells had no impact on blood vessel development. Short-term cultured cells increased blood vessel number in normoxic and hyperoxic mice by 28 days but had no impact on day 56. Injection of fresh EPCs into normoxic mice significantly reduced alveolarization compared with phosphate buffered saline-injected normoxic controls. These results indicate that fresh BM EPCs have a higher and safer corrective profile in a hyperoxia-induced lung injury model compared with cultured BM EPCs but may be detrimental to the normoxic lung. The appearance of aberrant tissue growths and other side effects following injection of cultured EPCs warrants further investigation. Stem Cells Translational Medicine 2017;6:2094-2105.

Transient vascular and long-term alveolar deficits following a hyperoxic injury to neonatal mouse lung

Background

The lungs of very preterm human babies display deficits in alveolarization and vascularization as a result of the clinical use of high oxygen treatment (leading to hyperoxia) required to decrease the risk of mortality. Detailed analyses of the persistence of the respiratory deficits following this treatment and means to restore a normal state have not been investigated in full detail. In this study, high oxygen administration to neonatal mouse lungs was established as a proxy to hyperoxia in human preterm infant lungs, to better characterize the associated deficits and thus provide a means to assist in the development of treatments in the future.

Methods

Ninety percent oxygen was administered to newborn mice for four consecutive days. The effects of this treatment upon alveolarization and vascularization were investigated by morphometric, histochemical, immunohistochemical and protein analyses at day five (D5), D28 and D56 postpartum.

Results

Relative to control untreated lungs, septation of hyperoxic lungs was significantly reduced and airspaces were significantly enlarged at all stages examined. Furthermore, compared to controls, the number of secondary septa per tissue area was significantly reduced at D5, significantly increased at D28 and then the same as controls at D56. Analysis of vascularization parameters indicated a reduction in mature blood vessel number and the amount of Pecam1 at D5. Both of these parameters returned to control levels by D28.

Conclusions

This study suggests that administration of high oxygen to underdeveloped lungs has a transient reductive effect on secondary septal number and pulmonary vascularization and a significant long-term reduction in alveolarization persisting into adulthood. This model can be used for future research of premature lung disease therapies in humans, addressing these short term septal and vascular and long term alveolar deficits, specifically relating to injury by hyperoxia.