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

Extramedullary hematopoiesis (EMH) occurs under various circumstances, including during embryonic/developmental periods, pathological status secondary to insufficient bone marrow function or ineffective hematopoiesis, in hematological disorders, for example malignancies, as well as stromal disorders of the bone. EMH is characterized by hematopoietic cell accumulations in multiple body locations. Common EMH locations observed in clinical and pathological practice include the spleen, liver, lymph nodes and para‑vertebral regions.

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

Aims: To determine the expression of CXCL12 in human spleens with extramedullary haematopoiesis (EMH) for clarifying the association of splenic haematopoietic stem cells (HSCs) with CXCL12, which has been demonstrated to be a marker of bone marrow niches.

Methods: We examined the expression of mRNA for CXCL12 by quantitative reverse transcription polymerase chain reaction (RT-PCR) and localised the CXCL12 protein by immunohistochemical staining in EMH negative and positive spleen samples from autopsy cases.

Results: Expression of CXCL12 was significantly higher in samples from EMH positive cases than those from EMH negative cases.