Scientific Abstract

Proposal No.  IBD-0114
Principal Investigator:  Ewa Carrier, M.D.
Applicant Organization:  University of California, San Diego (La Jolla, U.S.A.)
Project Title:  Repair of Crohn’s disease with stem cells
Period of Award:  September 1, 2004 – September 30, 2007

The primary objective of this work is to establish an animal model for stem cell therapy in Crohn’s disease.  Phase I studies demonstrated clinical improvement in patients with severe Crohn’s disease with autologous stem cells, but there is no understanding of the biological mechanisms underlying this repair.  This proposal will develop a murine model of stem cell repair in Crohn’s disease.

Our hypothesis is that stem cell ® stem cell niche interaction is necessary for differentiation and stem cell niche is needed to support incoming stem cells.  Therefore, the intestinal environment, with its crypts and “niches,” will support incoming embryonic and hematopoietic stem cells and allow them to engraft and differentiate.  In the setting of elevated pro-inflammatory cytokines and other triggering factors produced locally in the intestine, stem cells migrate to the site of injury and differentiate into intestinal epithelial cells to replace the injured, ulcerated epithelial and submucosal layers and to re-populate the intestine with immunologically balanced normally functioning lymphocytes.  Newly formed lymphocytes will cause TH ® Th2 shift, restoring immune balance in the intestine.  The embryonic stem (ES) cells are from transgenic mice expressing yellow fluorescent protein (EYFP-ES) and hematopoietic stem cells (HSC) are from the transgenic mice expressing cyan fluorescein protein (ECFP-HSC).  The spectra of these proteins are separate and non-overlapping and can easily be differentiated by fluorescent and confocal microscopy and FACs analyses.  The IL 10-/- knockout (KO) mouse has symptoms typical for human inflammatory bowel disease (IBD) and an immune imbalance that will provide additional stimulus for stem cells to differentiate.

The general hypothesis is that reconstitution of tissues in the intestine with naïve, pluripotent stem cells may represent an alternative therapeutic intervention for the treatment and prevention of IBD.  We have developed the following aims:

1)     to compare homing, migration and engraftment potential of ES-E and adult HSC in murine Crohn’s (CD IL10-/- KO) model;

2)     to establish differentiation potential of these cells in this model; and

3)     to study immune reconstitution and lymphocyte education/priming following stem cell injection.

We are proposing a two-step repair system:  1) intestinal epithelium repair by ES-E and 2) reconstitution of immune balance by HSC cells.  This work will develop a biological model for stem cell therapy in Crohn’s disease.