The blood cells are generated in a complex process by which hematopoietic stem cells proliferate and differentiate, resulting in the different types of mature blood cells (erythrocytes, platelets, lymphocytes, monocytes and granulocytes). This process is known as Hematopoiesis, which occurs in the bone marrow, where the cells, the products generated by them and the structural proteins, form a complex tridimensional network where takes place the regulation of the generation and development of the different types of blood cells. Any alteration or fault in this complex process can lead to the appearance of different diseases, some of which have consequences as serious as death. For this reason, the study of the functioning of hematopoiesis is …ver más…

The blood cells are divided into two groups: myeloid and lymphoid. The first include the granulocytes (neutrophils, basophils and eosinophils), monocytes, erythrocytes and thrombocytes, whereas the second, include B lymphocytes, T lymphocytes and NK cells. Myeloid cells are produced through a process known as myelopoiesis while the lymphoid cells, result from lymphopoiesis.

The maturation in each of the hematopoietic lineage is defined by two fundamental processes: the permanent loss of self-renewal potential and the acquisition of a specific identity. These processes are controlled by genetic programs where the genes that maintain the ability of auto-renewal are turned off, while genes that regulate the differentiation are turn on. Thus, the hematopoietic progenitors are differentiate into precursor cells, through a series of events where, alternating groups of genes in association with various growth factors determine the cellular destiny in which each mature cell has an identity and a final function.

To protect the individual of cell exhaustion, the HSC must generate all blood cell lines required during its existence, for it is very useful their multipotentiality and capacity for self-renewal. However, it has also been seen that HSC use the clonal succession mechanism, consisting in the differentiation in a few clones of HSC and the generation of mature blood cells when it´s required, such as in infectious processes in