Gene expression of human littoral cells and splenic vascular endothelial cells from the spleens of normal individuals and patients with myelofibrosis

The vascular lining cells in the human spleens include littoral cells (LCs) and other splenic vascular endothelial cells (SVECs). LCs that comprise about 30 percent of the splenic red pulp are specialzed endothelial cells distinct from SVECs. They line the splenic sinusoids and function as the filters and scavengers for senescent or altered red blood cells. Patients with advanced forms of myelofibrosis (MF) often develope extramedullary hematopoiesis in the spleen.Vascular lining cells within MF spleens are thought to serve as a supportive microenvironment for MF hematopoietic cells. In this study we isolated MF and normal LCs and SVECs from human spleens using immunostaining and flow cytometric sorting and used microarrays to analyze the underling mechanism of LCs' unique functions that distinguish them from SVECs, and the properties of MF LCs and SVECs and their contributions to the microenvironment of MF spleens. Normal human spleens were obtained from National Disease Research Interchange (NDRI) from healthy donors who required splenectomy for a traumatic injury. MF spleens were obtained from patients with advanced forms of MF who have marked splenomegaly and were undergoing therapeutic splenectomy. All patients signed an informed consent. CD34- CD8a+ CD31+ CD3- CD45- LCs and CD34+ CD8a- CD31+ CD3- CD45 SVECs were isolated from the normal and MF spleens and their gene expression profiles were compared.