Mouse lung organoid responses to reduced, increased, and cyclic stretch

Area of Science:

• Biomedical Engineering
• Developmental Biology
• Pulmonary Medicine

Background:

• Lung development is significantly influenced by mechanical forces, particularly cyclic stretch.
• Pulmonary diseases often involve alterations in the lung's mechanical microenvironment, as seen in congenital diaphragmatic hernia (CDH).
• Existing cell culture and in vivo models have limitations in studying mechanotransduction in lung development.

Purpose of the Study:

• To develop novel mouse lung organoid (mLO) models for studying mechanotransduction.
• To investigate the effects of altered mechanical environments (increased, decreased, cyclic strain) on lung organoids.
• To elucidate the molecular mechanisms underlying mechanical force-induced changes in lung development.

Main Methods:

• Developed two mLO mechanotransductive models using postnatal day 5 (PND5) mouse lung CD326-positive cells and fibroblasts.
• Applied static (forskolin, disrupted) and cyclic biaxial strain to mLOs.
• Analyzed changes in mLO cross-sectional area, cell proliferation, gene expression (mRNA), and protein markers (αSMA, PDGFRα).

Main Results:

• Forskolin treatment increased mLO cross-sectional area and cell proliferation, while disruption decreased it.
• Cyclic strain significantly increased mRNAs of lung mesenchymal cell lineages compared to static or no stretch.
• Cyclic stretch upregulated TGF-β and integrin signaling, and increased αSMA-positive cells.

Conclusions:

• PND5 mLO models effectively simulate mechanical forces relevant to lung development.
• Static stretch enhances cell proliferation in developing lungs.
• Cyclic stretch is a key driver of mesenchymal gene expression changes critical for postnatal lung development.