Enrichment of early fetal-liver hemopoietic stem cells of the rat using monoclonal antibodies against the transferrin receptor, Thy-1, and MRC-OX82

Mitigation of Multi-Organ Radiation Injury with ACE2 Agonist Diminazene Aceturate

The renin-angiotensin system (RAS) is known to regulate the pathogenesis of radiation-induced injury as inhibitors of the RAS enzyme angiotensin converting enzyme (ACE) have established function as mitigators of multi-organ radiation injury. To further elucidate the role of RAS signaling during both the acute and delayed syndromes of radiation exposure, we have evaluated whether pharmacologic modulation of alternate RAS enzyme angiotensin converting enzyme 2 (ACE2) reduces the pathogenesis of multi-organ radiation-induced injuries. Here, we demonstrate pharmacologic ACE2 activation with the small molecule ACE2 agonist diminazene aceturate (DIZE) improves survival in rat models of both hematologic acute radiation syndrome (H-ARS) and multi-organ delayed effects of acute radiation exposure (DEARE). In the H-ARS model, DIZE treatment increased 30-day survival by 30% compared to vehicle control rats after a LD50/30 total-body irradiation (TBI) dose of 7.75 Gy. In the mitigation of DEARE, ACE2 agonism with DIZE increased median survival by 30 days, reduced breathing rate, and reduced blood urea nitrogen (BUN) levels compared to control rats after partial-body irradiation (PBI) of 13.5 Gy. DIZE treatment was observed to have systemic effects which may explain the multi-organ benefits observed including mobilization of hematopoietic progenitors to the circulation and a reduction in plasma TGF-beta levels. These data suggest the ACE2 enzyme plays a critical role in the RAS-mediated pathogenesis of radiation injury and may be a potential therapeutic target for the development of medical countermeasures for acute radiation exposure.

Measurement of macrophage growth and differentiation

This unit provides protocols for measuring the abundance and growth of macrophage precursors in agar cultures and the proliferation of isolated mature macrophages in vitro, by either direct cell counting or by DNA measurement. Methods for the immunohistochemical identification of macrophages and the determination of their proliferative status in vivo by immunofluorescence are also included. It also describes methods for characterization of macrophage differentiation through the immunofluorescence analysis of cell-surface expression of CSF-1 receptor.

Isolation and characterization of hepatic stem cells, or "oval cells," from rat livers

The pace of research on the potential therapeutic uses of liver stem cells or "oval cells" has accelerated significantly in recent years. Concurrent advancements in techniques for the isolation and characterization of these cells have helped fuel this research. Several models now exist for the induction of oval cell proliferation in rodents. Protocols for the isolation and culture of these cells have evolved to the point that they may be set up in any laboratory equipped for cell culture. The advent of magnetic cell sorting has eliminated reliance on expensive flow cytometric sorting equipment to generate highly enriched populations of oval cells. Our laboratory has had much success in using the oval cell surface marker Thy-1 in combination with magnetic sorting to produce material suitable for testing the influence of a myriad of chemical signaling molecules on the oval cell phenotype. This chapter will describe our basic strategy for oval cell induction and isolation. Additionally, two in vitro procedures are described which the reader may find useful in the early stages of developing an oval cell research project.

Esophageal stem cells--a review of their identification and characterization

The incidence of adenocarcinoma of the esophagus has increased faster than any other internal malignancy over the last 40 years. Despite this, surprisingly little is known about the basic biology of this tissue, particularly with regards to the organization of cell proliferation within the epithelium. This is a matter of crucial importance for our understanding of the pathogenesis of esophageal cancer. Nevertheless, significant advances have recently been made in the identification and functional characterization of both murine and human esophageal stem cells and their progeny in recent years. This places investigators in an exciting position to gain further insights into the processes of tissue renewal and repair on the one hand and the development of dysplasia and malignancy on the other.

Development of rat CD45+ 13-day-old fetal liver cells in SCID mouse fetal thymic organ cultures

A phenotypic analysis of the lympho-hemopoietic cells which occur in the liver of 13-day-old fetal rats was achieved by flow cytometry in an attempt to further characterize the rat lymphoid progenitor cells. A small fraction of rat 13-day-old fetal liver (r13FL) cells, which weakly expressed the leukocyte common antigen CD45, constituted a homogeneous Thy-1(hi), CD71(-), CD44(+), MHC class I+, CD43(+) cell subpopulation negative for CD45RC, CD3, TCRalphabeta, TCRgammadelta, CD2, CD5, CD4, CD8, CD25, CD28, NKR-P1a and sIg. On the contrary, the CD45(-) cells were a heterogeneous cell subset which expressed Thy-1, CD71 and CD44 at distinct levels. After MACS separation, the CD45(+) r13FL cells, but not the CD45(-) cell subset, in vitro repopulated 14-day-old SCID mouse fetal thymic lobes providing rat T cells, both TCRalphabeta and TCRgammadelta, NK cells, and thymic dendritic cells but not B lymphocytes. Interestingly, NKR-P1a(lo) TCRalphabeta+ or TCRgammadelta+ cells developed in the xenogeneic cultures, and a rare CD4(+)CD8(+) double-positive subpopulation among the TCRgammadelta-expressing cells accumulated in the oldest cultures. These results are discussed from the double perspective of the nature of the precursor cells which colonize the fetal thymus and the relevance of the xenogeneic SCID mouse fetal thymic microenvironment for supporting rat lymphopoiesis.