Selected factors influencing angiogenesis and hematopoietic niche

Angiogenesis is the vital, multistage process in which new blood vessels are created by sprouting from pre-existing vessels. It takes part in carcinogenesis and contributes to progression, metastases, and dissemination of neoplastic disease. In the bone marrow, angiogenesis influences the hematopoietic stem cells (HSC) proliferation, differentiation, and maintenance of normal hematopoiesis under both physiological and stress conditions. The bone marrow niche contains different types of cells, including macrophages, osteoblasts, mesenchymal stem cells, endothelial progenitors, and endothelial cells. All of these interact and form a unique microenvironment necessary for the appropriate function, and preservation of HSC in the quiescent state, and take a major part in the process of mobilization to peripheral blood and homing after transplantation. Cytokines active in the hematopoietic niche as well as miRNAs regulating hemato- poiesis, and angiogenesis have a significant influence on processes occurring in the bone marrow. The aim of this review was to present selected proteins, and molecules associated with angiogenesis as well as bone marrow niche processes: VEGF, ANGPT1, ANGPT2, MMP-9, SDF-1, miRNA-15a, miRNA-16, miRNA-126, miRNA-146a, and miRNA-223.