Characterization of Human Lung Epithelial Stem/Progenitor Cells

Abstract

Understanding the regeneration of the human lung epithelium following injury is essential to the development of new therapies for lung diseases such as COPD (Chronic
Obstructive Pulmonary Disease) and IPF (Idiopathic Pulmonary Fibrosis). However, the
current knowledge of the stem/progenitor cell hierarchy of the human lung epithelium is
lacking. Based on known surface markers for basal cells, a type of epithelial progenitor
cell, we have used flow cytometry to construct a list of surface marker candidates for a
more thorough characterization of basal cell subpopulations in human lung tissue samples. We show a comparison between surface marker expressions in healthy lung and IPF tissue that illustrates differences in cell type composition caused by the disease. In line, we also observed a higher frequency of basal cells in more fibrotic IPF tissue compared to less fibrotic tissue. These results indicate that we are able to identify subpopulations of basal cells that may be involved in the pathogenesis of IPF. Finally, to evaluate progenitor properties of human lung epithelial cell populations, we have established a differentiation culture system, ALI (Air Liquid Interface).

Popular Abstract

Unlocking the secrets of human lung regeneration

Stem cell-based therapies are currently being used to treat leukemia, and are under development for Parkinson’s disease and diabetes. It is highly feasible that diseases of the lung can be similarly treated. This project investigated lung stem cells in order to elucidate the regenerative function of the human lung, with the ultimate goal being to cure lung diseases that, unfortunately, are on the rise.
The frequency and costs of treatment of lung diseases such as Chronic Obstructive Pulmonary Disease (COPD) are high. The disease is caused by factors such as smoking and air pollution, and is, according to the World Health Organization, expected to continue to increase, to the point of becoming the third leading cause of death in 2030. Currently, the only effective treatment is lung transplantation, which is only available to a small number of patients due to the lack of compatible donors. The need for an alternative treatment for COPD, and other lung diseases such as Idiopathic Pulmonary Fibrosis (IPF), is therefore apparent. This treatment could consist of cell therapy, whereby a supply of healthy lung stem cells would be transplanted into the diseased lung in order to multiply and differentiate into healthy lung tissue, thus inducing self-repair of the diseased lung.

The development of new cells, tissues and organs in the human body is made possible by stem cells. These are cells that can divide, and thus multiply themselves, as well as differentiate, which means that they can develop into specific cell types according to which type of stem cell they are and what is needed in the body.

During the last decades, more and more stem cell hierarchies have been defined, and for many organs and parts of the body, such as the blood regeneration system, the complete process from embryonic stem cells to adult tissue has been described in detail. In contrast, the situation in the lung remains unclear. It is known that the airway lining of the human lung, called the epithelium, can regenerate following injury, but not the mechanisms by which it happens. In addition, an obstacle in the study of lung epithelial cells is the lack of known surface markers that could distinguish between different cell types. Knowledge of the cellular structure of the human lung epithelium and which cells have stem properties will contribute to an understanding of the natural regeneration of the healthy lung, as well as the cause of different lung diseases.

The purpose of our project is to attempt to further identify and characterize stem cells in the epithelium of the human lung, as well as to find new cell surface markers, by studying tissue samples from both healthy and diseased patients. So far, we have tested and compared healthy lung tissue with samples from a patient with IPF, both fibrotic and less fibrotic tissue, by Flow Cytometry. We have constructed a list of cell surface markers that we found were expressed on stem cells in the lung tissue, and in our future research these markers will be used to more closely determine which markers that designate which cell types.

Another success in our research was the cultivation of epithelial cells in a specially designed assay called Air Liquid Interface (ALI) culture. Microscopy of the cultivated samples showed a fully formed epithelial layer similar to the ones observed in freshly isolated lung tissue samples, meaning that this assay can be used to test different lung cell types

The chosen cell surface marker candidates, together with the optimized ALI culture assay, will help us to continue the project and hopefully lead to a complete characterization of the lung epithelium, bringing us closer to developing effective treatments for diseases of the lung.

• author: Wijk, Sofia
• supervisor: Mattias Magnusson
• organization: Pure and Applied Biochemistry
• course: KBK820 20151
• year: 2015
• type: H2 - Master's Degree (Two Years)
• subject: Medicine and Health Sciences; Biology and Life Sciences
• keywords: Stem cells, Air-Liquid Interface, Human, tillämpad biokemi, applied biochemistry, COPD, FLow Cytometry, IPF, Lung
• language: English
• id: 7369681
• date added to LUP: 2015-09-16 07:57:13
• date last changed: 2015-09-16 07:57:13