Preclinical Study of Lung Spheroid Cell Therapy in Rodent Models of Pulmonary Fibrosis.

CORES, JHON. Preclinical Study of Lung Spheroid Cell Therapy in Rodent Models of Pulmonary Fibrosis. (Under the direction of Dr. Ke Cheng and Dr. Matthew Fisher). Idiopathic pulmonary fibrosis (IPF) is the most commonly diagnosed interstitial lung disease (ILD) in the United States. It is a chronic, progressive lung disorder with the histopathology of usual interstitial pneumonia. Onset is suspected to be the result of recurring lung epithelial injury, which generates chronic wound-healing malfunctions. Fibroblasts are activated and recruited into the interstitial space and differentiate into apoptotic-resistant myofibroblast phenotypes that deposit extracellular matrix unremittingly. Its prognosis is poor, with a median survival of 2-3 years after diagnosis. Commonly associated symptoms include breathlessness, unproductive dyspnea, and eventual respiratory failure. There is no cure for IPF, and treatment is largely limited to palliative care. In 2014, two IPF-specific anti-fibrotic pharmaceutical agents entered the market: nintedanib and pirfenidone. While the drugs have been shown to stop the progression of fibrosis, they do not reverse the condition or extend patient life. The lack of viable therapeutic options has combined with a heightened interest in the use of biologics as possible therapeutic agents, resulting in the emergence of stem cell therapy as a promising contender for IPF treatment. The lungs are relatively easy to target via intravenous injection. Once in the pulmonary architecture, the cells are thought to release beneficial factors via paracrine mechanisms. However, most of the stem cell studies targeting IPF in animal models have been conducted using mesenchymal cells. Instead, the cell therapy paradigm presented in this dissertation makes use of a collection of endogenous lung stem cells and supporting cell lines, together called Lung Spheroid Cells (LSCs). LSCs differ from other cell therapy products in three main ways: 1) The cells grow in 3D suspension; 2) The cells are endogenous and autologous; 3) The cells are not phenotypically isolated. The data presented in this dissertation demonstrates the safety and efficacy of LSC intravenous injections in various rodent models of bleomycin-induced lung fibrosis. The experimental studies discussed herein were designed and performed in accordance with FDA guidelines with the aim of meeting the requirements for submitting an investigational new drug (IND) application which may allow LSCs to be tested in human patients. Initially, a proof of concept model demonstrated a rapid and robust method of generating therapeutic LSCs from non-fibrotic adult human lung tissues to treat severe combined immunodeficiency (SCID) mice with bleomycin-induced pulmonary fibrosis. The intravenous injection of human LSCs inhibited apoptosis, fibrosis, and infiltration while promoting angiogenesis. Ultimately, LSCs from healthy lung tissues were shown to be viable therapeutic cells. Subsequently, rat LSCs were applied in an allogeneic therapy. The goal was to assess the safety and efficacy of healthy Wistar Kyoto rat LSCs in attenuating the progression of bleomycininduced pulmonary fibrosis in Wistar Kyoto (WKY) and Brown Norway (BN) rats. The study demonstrated a reduction in fibrotic thickening, matrix deposition, and apoptosis, and an increase in angiogenesis, as well as the protection of Type I and Type II pneumocytes. Lastly, a definitive safety and efficacy study was conducted using Wistar Kyoto and Nude rats that achieved the following goals: 1) An LSC injection schedule that is considered therapeutic, rather than preventative. Injections were administered after the onset of fibrosis, rather than during the inflammatory stage of the bleomycin model; 2) The expansion and injection of LSCs derived from IPF patient biopsies; 3) A dose escalation study in order to discern the minimum effective dose that imparts therapeutic benefits; 4) A definitive safety evaluation, including an assessment of tumorigenicity of the LSCs after injection, liver function assays, and adverse events assessments. Ultimately, IPF-derived LSCs proved to be an effective cell therapy with the potential for clinical applications.