Analysis of cell niches in primary, secondary and reactive bone marrow diseases and their clinical interfaces

Abstract

The bone marrow is the organ responsible for the hematopoiesis, a phenomenon that is related to the differentiation of hemopoietic stem cell (HSC) into erythrocytes, granulocytes, monocytes, lymphocytes and platelets. It is constituted by the hematopoietic tissue, fatty tissue, protein matrix and sinusoidal. It is contained inside the spongy bones, in contact with the cortical and trabecular bone tissue. In 1978, Ray Schofield conceptualized a niche as a specific location, inside the bone morrow, where the HSC originates, it rest and proliferates. Currently, it is known that the niche is more than a morphological simple compartment, but a functional and dynamic site that remodels and influences the function of the HSC and yours pathogens, exercising a definitive role on the normal and neoplasic HSC. The bone marrow niches are called: endosteal or osteoblastic, vascular and perivascular, perineural and protein matrix. Studies demonstrate that niches and their cellular and protein components influence and determine the maintenance of active and quiescent HSC, being determinant in the maintenance, progression and relapse of deseases of bone marrow. The objective of this project is to study, in neoplasic and reactional contexts the number and distributions of HSC in differents niches, comparing with normal samples. The niches will be evaluated by means of immunohistochemical study using the markers CD34, Factor VIII, CD 44, CD 31 and CD117. The results will be associated with the set of morphological criteria and reticulinic framework, besides being also associated to extracellular matrix proteins fibronectin and galectin. These observations should contribute to explain the bone marrow failure in these diseases, correlating with early relapses and prognostic. (AU)