Up-regulated expression of CXCL12 in human spleens with extramedullary haematopoiesis

Extramedullary hematopoiesis: Elucidating the function of the hematopoietic stem cell niche (Review)

“…As the results of a previous study indicated, CXCL12 is expressed in the sinus endothelial cells of the EMH-positive spleen, which may function in the entrapment of circulating hematopoietic precursor cells, whereas the cluster of macrophage/differentiated hematopoietic cells is separated from the CXCL12-positive endothelial cells (19). Other types of cell, including macrophages, as well as nerve, adipose, and dendritic cells, may contribute to the maintenance and differentiation of hematopoietic cells in EMH-positive spleens.…”

“…1) (19). Furthermore, CXCL12 was demonstrated to be localized to the sinus endothelial cells of the red pulp in EMH-positive spleens; whereas, CXCL12 was expressed throughout the vascular endothelial cells of the white pulp in spleens of EMH-negative and -positive cases (19). EMH frequently occurs in the red pulp, and the data presented in the current review suggest that splenic sinus endothelial cells expressing CXCL12 may contribute to the attachment and recruitment of circulating hematopoietic precursor cells, forming bone marrow niche-like regions of EMH in the human spleen (19).…”

“…Several markers, including CD106, CD166, CD105, CD73 and CD44, are known to be useful in the isolation of MSCs from various organs, including bone marrow, placenta, adipose tissue, synovial membrane, endometrium and cartilage (53). The construction of niche-like regions during EMH may be attributed to the MSC-derived cells of EMH organs, although CXCL12-positive cells were only identified in the red pulp of EMH-positive sinus endothelial cells (19).…”

“…For example, it was demonstrated that stromal cells express CXCL12 and induce B-cell migration in the spleen (18). Recently, in a study by our group, whether CXCL12-positive cells were able to be identified and if they had a role in hematopoietic regions of the spleen during EMH was determined by investigating CXCL12 messenger (m)RNA expression levels and localization of CXCL12-positive cells in the spleen (19). A previous study suggested that hematopoiesis in bone marrow cannot be maintained by a vascular niche alone, as indicated by osteoblast deficient mice (20).…”

Splenic pooling and loss of VCAM-1 causes an engraftment defect in patients with myelofibrosis after allogeneic hematopoietic stem cell transplantation

“…34,35 On the other hand, Migliaccio et al demonstrated in gata-1 deficient MF mice and also MF patients a higher SDF-1 expression within the BM. 36 Moreover, we recently demonstrated that OPN, expressed by osteoblasts within the endosteal niche, also has chemotactic activity.…”