Lung Physiology Jamie Havrilak, PhD Postdoctoral Research Associate Layden Lab October 26th, 2018
Nkx2.1- Lung epithelium Endomucin- Vasculature
Alveoli/Capillaries: Site of Gas Exchange in the Lung
Alveoli/Capillaries: Site of Gas Exchange in the Lung Artery CO 2 Air O 2 Capillary Vein
Alveoli/Capillaries: Site of Gas Exchange in the Lung Artery CO 2 Air O 2 Capillary Nkx2.1- epithelium Endomucin- blood vessels SMA-smooth muscle Vein
Alveolar Surface Area= 350-400 sq ft (100-150 m 2 ) Respired Air 11,000 liters/day
proximal Generation and organization of cell types distal http://www.eurostemcell.org/factsheet/lung-stem-cells-health-repair-and-disease
Epithelium -Ciliated cells -Goblet cells -Club cells -Alveolar type 1 and type 2 cells proximal distal Mesenchyme -Endothelial cells -Smooth muscle cells -fibroblasts -Pericytes http://depts.washington.edu/envh/lung.html
Distal Alveolus
Lung Diseases Respiratory Distress (RDS) Bronchopulmonary Dysplasia (BPD) Congenital Diaphragmatic Hernia (CDH) Asthma Pulmonary hypertension Lung Cancer Emphysema COPD Cystic fibrosis
Cystic Fibrosis
Common Lung Diseases Respiratory Distress (RDS) Chronic lung diseases of early infancy (BPD) Congenital Diaphragmatic Hernia (CDH) Asthma Pulmonary hypertension Lung Cancer Emphysema COPD Cystic fibrosis Why study lung development? If we understand how the lung develops, we can figure out how to repair it.
Stages of Human and Mouse Lung Development Alveolar Saccular Canalicular Pseudoglandular Embryonic Mouse (days): E9 E12 E16 E17 PN4 PN14 Human (weeks): 3w 7w 17w 26w 38w 18m Conception Branching morphogenesis begins Surfactant synthesis begins Birth Alveoli number increases Bud initiation Patterning is complete Formation of alveoli Lungs continue to develop after birth Havrilak and Shannon, 2015
Alveolar Saccular Canalicular Pseudoglandular Embryonic Mouse (days): E9 E12 E16 E17 PN4 PN14 Human (weeks): 3w 7w 17w 26w 38w 18m Conception Branching morphogenesis begins Surfactant synthesis begins Birth Alveoli number increases Bud initiation Patterning is complete Formation of alveoli Havrilak and Shannon, 2015 Premature Birth Respiratory Distress Disrupts Lung Development
Each of the germ layers gives rise to many different cell types Developmental Biology, 9e, Figure 1.7
Image from Zorn and Wells, 2009
The tracheal groove, arising from the foregut endoderm, branches to give rise to the conducting airways
Nkx2.1- Lung epithelium Early Stages of Lung Development I. Embryonic I. Embryonic E-cadherinendoderm Endomucin- Vasculature I. Embryonic II. Pseudoglandular II. Pseudoglandular II. Pseudoglandular Mesenchyme Havrilak and Shannon, Lung Development 2015 Image modified from the Pulmonary Biology Division website http://www.cincinnatichildrens.org/research/div/pulmonary-biology/faculty-research/whitsett-lab/projects.htm Epithelium
Lung Branching Morphogenesis Metzger et al, Nature 2008
Later Stages of Lung Development in the Mouse III. Canalicular IV. Saccular V. Alveolar V. Alveolar V. Alveolar
Lung Branching Morphogenesis Metzger et al, Nature 2008
Tissue interactions govern early lung morphogenesis Importance of Lung Mesenchyme Lung mesenchyme is essential for lung development Branching and differentiation of the epithelium depends on a close association with the lung mesenchyme. Mesenchyme Epithelium
Lung mesenchyme is necessary for lung epithelial branching Wessells, 1970
Lung Mesenchyme (M) Attracts Lung Epithelium (E) E M Mesenchymal inducers are diffusible
Lung epithelial development driven by mesenchymal signals How do we induce lung formation? Rankin and Zorn, 2015, J. Cell Biochem.
FGF signaling is an essential component of the regulatory networks between epithelium and mesenchyme in the developing lung Fgf10- is expressed in distal lung mesenchyme Signals to Fgf receptors in epithelium Deletion of FGF10 results in lung agenesis, as does deletion of its receptor FGFR2b. Image modified from Sekine, et al.,1999 Image modified from Cardoso and Kotton, 2008 Image modified from Min, et al.,1998 Genes and Dev
Interactions Between Multiple Signaling Pathways When? Where? How much? Gene regulatory network governing respiratory specification Rankin and Zorn, 2015, J. Cell Biochem.
Lung Morphogenesis and Differentiation 50 Cell Types Need to Orchestrate Proper: Regulation of Processes: Place Time Cell Types Cell Numbers Size Function Repair Commitment Specification Restriction Differentiation Proliferation Maturation Morphogenesis Patterning
Translational applications Currently no effective treatments Respiratory distress syndrome Chronic obstructive pulmonary disease Idiopathic pulmonary fibrosis Pathways that are activated during development may be activated during adult lung repair Model human disease (lung organoids) New or improved clinical therapies
Pluripotent stem cell (PSC)-derived organoids. Meritxell Huch, and Bon-Kyoung Koo Development 2015;142:3113-3125 2015. Published by The Company of Biologists Ltd
Induced pluripotent stem cell (ipsc) https://research.cchmc.org/stemcell/ipsc
Meritxell Huch, and Bon-Kyoung Koo Development 2015;142:3113-3125
Go through many different stages before it can become a lung cell Rankin and Zorn, 2015, J. Cell Biochem.
Interactions Between Multiple Signaling Pathways Gene regulatory network governing respiratory specification Rankin and Zorn, 2015, J. Cell Biochem.
How do we make a lung in a dish? Briana R Dye et al. elife Sciences 2015;4:e05098
Briana R Dye et al. elife Sciences 2015;4:e05098 Lung spheroids
Briana R Dye et al. elife Sciences 2015;4:e05098
3D Lung Organoids Chen, et al., 2017, Nature Cell Biology
Potential application of lung organoids in modeling human diseases Chen, et al., 2017, Nature Cell Biology
Thank you! email JAH715@lehigh.edu Questions?