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Conventional patterns of human intestinal proliferation in a severe-combined immunodeficient xenograft model
A N Shmakov1, A L Morey, D J Ferguson
1Department of Cellular Physiology, Babraham Institute, Cambridge, UK.
Insights
This study shows a human intestinal xenograft model accurately mimics pediatric gut cell division. The model reveals specific patterns of human cell proliferation in the gut crypts, making it useful for therapeutic research.
Area of Science:
- Gastroenterology
- Cell Biology
- Immunology
Background:
- Human intestinal proliferation patterns are complex.
- Understanding these patterns is crucial for developing targeted therapies.
- Murine xenograft models offer a potential avenue for studying human intestinal biology.
Purpose of the Study:
- To characterize human intestinal cell proliferation in an immunodeficient murine xenograft model.
- To validate the model's ability to mimic normal pediatric gut cell division.
- To assess the utility of this model for studying responses to various therapeutic interventions.
Main Methods:
- Utilized a double-label technique combining MIB-1 immunohistochemistry and [3H]thymidine autoradiography.
- Employed MIB-1 monoclonal antibody to specifically label human proliferating cells.
- Confirmed cell origin using ultrastructural in situ hybridization with human- and mouse-specific DNA probes.
Main Results:
- Demonstrated a close mimicry of normal pediatric gut cell division.
- Found high correlation between MIB-1 and [3H]thymidine labeling, with exceptions in regenerating epithelium.
- Identified highest proliferation rates in crypt epithelium (15.7%-26.7% cycling cells), with S-phase comprising half the cell cycle.
- Observed tissue-specific distribution of proliferating epithelial cells within xenograft crypts.
Conclusions:
- The immunodeficient murine xenograft model accurately replicates human intestinal proliferation patterns.
- The model exhibits functional pluripotent epithelial stem cells and typical cellular dynamics.
- This model is a valuable tool for investigating human intestinal crypt responses to therapies like chemotherapy, radiotherapy, and gene therapy.
Abstract:
The present work describes the pattern of human intestinal proliferation in an immunodeficient murine xenograft model, which we have shown to closely mimic cell division in normal paediatric gut. Cellular proliferation was measured using a double-label technique combining MIB-1 immunohistochemistry and [3H]thymidine autoradiography, to critically compare values for the tissue growth fraction (G1, G2, S- and M-phase cells) and DNA synthesizing (S-phase) cells in xenograft epithelium, lamina propria, muscularis externa and intraepithelial lymphocytes. The MIB-1 monoclonal antibody (which recognises the cell-cycle dependent nuclear antigen Ki-67) specifically labelled proliferating human cells within the xenografts and did not cross-react with dividing murine cells. This was confirmed using ultrastructural in situ hybridisation with human- and mouse-specific DNA probes to identify the genetic origin of proliferating cells. In general, we found a good tissue correlation between MIB-1 and [3H]thymidine labelling, the only exception being an apparent dysregulation of Ki-67 antigen expression in regenerating xenograft epithelium. In developed xenograft intestine, the highest levels of proliferation were consistently recorded within the crypt epithelium, where 15.7%-26.7% of cells were actively cycling and S-phase occupied approximately half of the cell cycle. The frequency distribution of proliferating epithelial cells within small and large intestinal xenograft crypts was clearly tissue-specific, showing typical patterns of cell division. Therefore, the presence of functional pluripotent epithelial stem cells and conventional spatio-temporal patterns in cellular proliferation, migration, de-cycling, lineage commitment and cytodifferentiation now makes this an attractive experimental model with which to study human intestinal crypt responses to various types of tissue manipulation, e.g. cytotoxic, radiotherapeutic, dietary, endocrine and gene-targeting therapy.