ABSTRACT
It is first important to review normal platelet development and regulation in a
healthy system. The hematopoietic stem cell gives rise to the early commonmyeloid
progenitor, which then leads to the development of a commonmegakaryocyte (MK)
erythroid progenitor (MEP). The transcription factor GATA-1 plays an important
role in the differentiation of theMEP. TheMEP can then either lead to the early and
late erythroid progenitors (burst-forming unit erythroid (BFU-E)) and CFU-E or to
the MK progenitors (BFU-MK or CFU-MK). As MKs mature, they increase their
cytoplasmic mass and undergo endoreduplication and the cytoplasm eventually
forms proplatelets. Platelets then either bud off the tip of the proplatelets or are
released from a pool when the cytoplasm fragments; around 2000 to 5000 platelets
from each cell. This process is controlled by various cytokines working in concert
together. In a normal state 1011 platelets are produced daily, with platelets lasting
about eight to nine days in the circulation (1).
