Meeting Abstract
In the extensive history of bone marrow studies, understanding the mechanisms of hematopoietic stem cell activation and mobilization of immune cells into the bloodstream has been of critical interest to physicians and scientists. Important implications exist for this field of research for cellular transplantation protocols for hematological diseases, as well as for diseases related to vascular disorders. However, scientists have generally favored investigations of the endosteal (i.e., bone) niche in comparison to its vascular counterpart. Over the past decade, there has been a gradual shift in perspective, with the scientific community beginning to acknowledge the autonomous importance of both endosteal and vascular microenvironments. Elasmobranchs (sharks, skates and rays) are cartilaginous fishes and therefore lack the endosteal niche present in mammalian bone marrow. These animals possess hematopoietic tissues (the Leydig and epigonal organs) uniquely composed of only a vascular niche, where hematopoietic stem and progenitor cells are maintained and produced, respectively. Inhibiting the connection between the chemokine ligand, CXCL12, and its receptor, CXCR4, has been shown to be critical for stem cell activation and mobilization of immune cells. In this study, tissues were collected from little skates (Leucoraja erinacea) treated with either elasmobranch ringers solution or AMD3100, a CXCR4 antagonist used to mobilize cells in human transplant donors. The efficacy of AMD3100 was assessed via serological, histological and immunohistochemical staining methods and significant mobilization of leukocytes was discovered. These data clarify the source of mobilized leukocytes in elasmobranchs and provide proof of principle that these animal models are useful for studies of hematopoiesis and angiogenesis.
