Mesenchymal Stem Cells Increase Alveolar Differentiation in Lung Progenitor Organoid Cultures

Kristen T Leeman,Joo-Hyeon Lee,Carla F Kim,Patrizia Pessina

doi:10.1038/s41598-019-42819-1

Abstract

Lung epithelial cell damage and dysfunctional repair play a role in the development of lung disease. Effective repair likely requires the normal functioning of alveolar stem/progenitor cells. For example, we have shown in a mouse model of bronchopulmonary dysplasia (BPD) that mesenchymal stem cells (MSC) protect against hyperoxic lung injury at least in part by increasing the number of Epcam+ Sca-1+ distal lung epithelial cells. These cells are capable of differentiating into both small airway (CCSP+) and alveolar (SPC+) epithelial cells in three-dimensional (3D) organoid cultures. To further understand the interactions between MSC and distal lung epithelial cells, we added MSC to lung progenitor 3D cultures. MSC stimulated Epcam+ Sca-1+ derived organoid formation, increased alveolar differentiation and decreased self-renewal. MSC-conditioned media was sufficient to promote alveolar organoid formation, demonstrating that soluble factors secreted by MSC are likely responsible for the response. This work provides strong evidence of a direct effect of MSC-secreted factors on lung progenitor cell differentiation.

Highlights

Repair in the distal lung is provided by a number of stem/progenitor populations, including Epcam+ Sca-1+ distal lung epithelial cells (a population enriched in lung progenitors formerly referred to as bronchioalveolar stem cells (BASCs)3), club (Clara) cells, AT2 cells, and alveolar progenitors
We have previously shown that in the mouse model of bronchopulmonary dysplasia (BPD), bone-marrow derived Mesenchymal stem cell (MSC) (BMSC) treatment led to an increased number of Sca-1+ cells in vivo and in vitro using traditional 2-dimensional cultures[14]
Sca-1− organoid formation was unaffected by stromal cell modulation between MSC and mouse endothelial cells (MEC); 3D cultures showed a nonsignificant difference in organoid forming efficiency with Sca-1−/MEC OFE 1.685 and Sca-1−/MSC OFE 1.76 (Fig. 1c)

Summary

Introduction

Repair in the distal lung is provided by a number of stem/progenitor populations, including Epcam+ Sca-1+ distal lung epithelial cells (a population enriched in lung progenitors formerly referred to as bronchioalveolar stem cells (BASCs)3), club (Clara) cells, AT2 cells, and alveolar progenitors. While the direct relationships between lung stem cell potential in culture and in vivo remain to be determined, these and related findings suggest that many different distal lung cell types have the capacity to respond to lung injury[1,14]. These data support the idea that lung injury repair in vivo is dependent on the specific type and location of injury, severity of damage, and the degree to which stroma that signal to epithelial cells are affected. This work uses a robust lung organoid system to show that critical signals secreted by the MSC trigger lung progenitor cells to differentiate and potentially play a critical role in enhancing repair of alveolar injury

Methods

Results

Conclusion