A pharmacological approach to drive lung repair

The lungs have a remarkable ability to repair themselves after they become damaged by environmental insults like pollution or from respiratory infections like Influenza. However, some individuals are not able to adequately repair their lungs and this can result in diseases where repair is abnormal. Such diseases include emphysema and Idiopathic pulmonary fibrosis (IPF), as well as common infections like Influenza from which a significant number of people die.
This proposal aims to strengthen the capacity that the lungs already have to repair themselves by administering a potential pro-repair protein called Wnt5a. This protein has been shown to stimulate lung stem cells after injury occurs and it is these stem cells that are needed to drive the lung repair process. However we don't yet understand exactly how the Wnt5a protein carries out this key role and this is what we will determine. We will use time-lapse imaging to video the response of lung cells to Wnt5a treatment and track exactly how this protein stimulates repair. As part of this proposal we will also encase Wnt5a protein in tiny particles of gel and formulate a Wnt5a-gel treatment that can be administered to the lungs to stimulate repair. Encasing Wnt5a in a degradable gel will enable sustained and targeted administration of this treatment. We will test the efficiency of Wnt5a-gel to stimulate lung repair by spraying it onto slices of human lung tissue that have been injured. These experiments will enable us to determine whether Wnt5a could be a viable pro-repair treatment for the lungs.

The lung alveoli are capable of intrinsic repair, driven at least in part by alveolar epithelial progenitor populations (AEP) which increase following injury. Although the adult lungs are capable of repair, the extent to which this occurs differs between individuals and is abnormal in many lung diseases. Importantly, we still have little knowledge about the cell biology and dynamics of alveolar repair and how the AEP cells contribute. Advances in understanding alveolar repair have been hampered by the lack of suitable models. Our group has developed methods to conduct time-lapse imaging of live lung repair in precision-cut tissue slices (PCLS) from mouse and human (the Acid-injury and repair, AIR model). PCLS are a highly versatile ex-vivo model of the lung in which all resident cell types are present in the same ratios and with the same cell-cell and cell-matrix interactions as in vivo. Using the AIR model we will test our hypothesis that the growth factor Wnt5a could be used as a pharmacological pro-repair treatment.

AIM1 We will conduct 12 hr time-lapse imaging experiments of AEP in spatially injured PCLS (AIR model). We will label the AEP in live mouse PCLS with the progenitor marker TM4SF1 and track them to determine their origin, and role in repair at 12, 24, 48hr and 4,7,10 and 20 days after injury. For culture beyond 48hr, PCLS will be encased in Polyethylene glycol (PEG) hydrogel to extend their viability using an established technique.

AIM2 We will examine how Wnt5a treatment of PCLS affects AEP and whether this can stimulate functional repair of lung tissue using the AIR model and imaging techniques outlined in AIM 1.

AIM3 We will investigate whether Wnt5a encapsulated in alginate hydrogel could be used to drive repair of human lung tissue. We will optimise the hydrogel formulation by tracking gel stiffness and Wnt5a release dynamics. Wnt5a-hydrogel will then be added to human PCLS and we will track the magnitude of repair following acid injury.