Meeting Abstract

36.9  Thursday, Jan. 5  Novel insights into stem cell activity and angiogenesis from an elasmobranch, Leucoraja erinacea MCLEOD, L; CACCIATORE, C; LUPICA, N; LUTTON, BV*; Endicott College; Endicott College; Endicott College; Endicott College blutton@endicott.edu

In this study we introduce a unique model system that may provide novel insight into the complex bone marrow niche of mammals. Understanding the mechanisms of interaction between cells and molecules therein is crucial for developing a) strategies to mobilize hematopoietic stem and progenitor cells (HSPC) for cellular transplantation and b) anti-angiogenic factors for cancer therapeutics. The elasmobranch model offers a novel perspective because these species do not possess bone and therefore lack the endosteal component of the mammalian bone marrow niche. Thus, the epigonal and Leydig organs of Leucoraja erinacea supply HSPC to the body, and previous studies have demonstrated an increase in angiogenesis and proliferation of epigonal cells during the reproductive period. In this study we have assessed the expression of the chemokine receptor 4 (CXCR4) gene, known to play a major role in angiogenesis and the regulation of HSPC homing/mobilization in mammalian bone marrow via linkage to the chemokine ligand 12 (CXCL12). We have shown that CXCR4 is constitutively expressed in the Leydig organ and is upregulated in the epigonal organ during reproductive activity, supporting the hypothesis that reproductive factors are involved in regulation of angiogenesis and stem cell mobilization. We have also begun to characterize the relationship between HSPC and the vascular niche of L. erinacea in vivo, using the BrdU label retention method, which we anticipate will provide important insight into the vascular niche of mammals.