Reconstruction of Human Respiratory Platform for in Vitro Drug Development

Recapitulating the complex cellular and functional environment of a lung in vitro would provide critical advantages over conventional pulmonary toxicity and assessment models. However, the human lung is a complex organ system that contains numerous cells types and performs multiple mechanical/physiological functions. To capture multiple critical features of the human lung system in vitro, we have undertaken a stepwise approach to engineer a complex microfluidic platform. Our objective was twofold - develop a platform with two key lung components bronchiole and alveolar compartments, and simulate the unique structural complexity of the lung.  To reconstitute the complex lung physiology and the microenvironment that maintains cell differentiation, we fabricated our human lung organ platform by integrating both bronchiolar and alveolar lung compartments. We stacking laser patterned substrates integrated with silicone based adhesive transfer tapes. The bronchiolar component contains a porous polyester membrane to create the air liquid interface required for the growth of bronchiole tissue. Artificial human bronchiole tissue was reconstructed by culturing human bronchial epithelial cells (HBTECs) on the membrane. Human alveoli environment was mimicked by growing human alveolar epithelial cells (A549) on inflatable polydimethylsiloxane (PDMS) membranes. HBTECs can be seeded on porous membrane and differentiated with air liquid interface after 2 weeks. A549 cells were viable before and after with cyclic stretching (25% of surface area changed) of the PDMS membrane for 2 days. The bronchiolar and alveolar cells can be cultured and differentiated in bronchiolar and alveolar tissues culture system. These systems mimic complex lung organ physiology suitable for systemic absorption, distribution, metabolism, excretion, and toxicology (ADMET) studies and the recapitulation of human pulmonary diseases. Validation of the lung construct was performed using the well-established drug amiodarone.