RECODE: Defining Environmental Design Criteria for Directed Differentiation of Type 1 from Type 2 Lung Alveolar Epithelial Cells

Injury to the lungs can have devastating consequences, as exemplified by the recent COVID19 pandemic. However, the cellular and molecular mechanisms by which the lung repairs itself remain poorly understood. The objective of this RECODE project is to utilize novel and sophisticated bioengineering approaches to better define cell and molecular pathways underlying lung development and repair.

The project focuses on cells involved in the major function of the lung: gas exchange which provides oxygen to the body. This information will inform the development of new tunable biomaterials to guide lung cell development. The research efforts of this RECODE project are integrated with educational and outreach objectives to promote active learning in biomedical engineering and biologic sciences undergraduates, to develop outreach programs to encourage and inspire local high school science, engineering, and mathematical sciences students by hosting educational workshops poster sessions, and to promote biomedical engineering research and education towards the general public at each of the participating sites in Vermont, Colorado, and Iowa.

There remains a critical need for better understanding of fundamental cellular and molecular mechanisms of lung development and repair, particularly with respect to the alveolar epithelium, a fundamental component of gas exchange. Current in vitro model systems, including organoid cultures, have provided important information but fail to fully reproduce native tissue structure or relevant environmental influences such as extracellular matrix (ECM) composition or stiffness.

The central vision of this RECODE project is to devise and validate a robust system for delineating the mechanisms by which ECM composition and stiffness regulate differentiation of alveolar type 2 epithelial cells (AT2s) to alveolar type 1 epithelial cells (AT1s). Utilizing AT2s derived from human induced pluripotent stem cells (iAT2s), sophisticated tissue engineering approaches incorporating hydrogels derived from alveolar-enriched regions (aECM) of decellularized human lungs will be developed to evaluate effects of physiologically relevant ECM composition and stiffness on AT2 to AT1 directed differentiation.

In silico modeling will be deployed in parallel to direct the empiric studies and to develop a holistic differentiation control framework. These approaches will be assessed in specific directed objectives: 1) To determine the specific ECM components regulating primary vs iAT2 stemness and driving AT1 differentiation; 2) To investigate the impact of dynamically tunable microenvironmental stiffness on primary vs iAT2 stemness and AT1 differentiation; and 3) To leverage agent-based and statistical modeling to predict combinatorial effects of composition and stiffness on primary vs iAT2 to AT1 differentiation.

These unique and innovative approaches involve a multidisciplinary and multi-institutional combination of materials science, lung regenerative medicine, lung stem cell biology, and in silico modeling. Further, the paradigms and approaches generated will have broader impact and applicability to understanding cell-ECM interactions in enabling cell differentiation in a wider range of organ systems.

This RECODE project is jointly funded by the Engineering Biology and Health Cluster in the Division of Chemical, Bioengineering, Environmental, and Transport Systems, the Established Program to Stimulate Competitive Research (EPSCoR), and the Physiological Mechanisms and Biomechanics Program and Animal Developmental Mechanisms Program in the Division of Integrative Organismal Systems.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.