Platelets Can Replicate in the Blood Steam Despite the Absense of Nuclei

Among the many ideas that were drummed into my head during my early training years was that platelets could not reproduce in the blood stream. This stands to reason in that they are anucleate, having budded off from the cytoplasm of megakaryocytes in the marrow. It now turns out that this idea may not be correct (see: Understanding Of Blood Cell Development Challenged By Discovery That Platelets Can Reproduce In Circulation ). Below is an excerpt from an article from the web:

University of Utah researchers led an international team of scientists that is the first to report on the previously undescribed ability of platelets to reproduce themselves in the circulation....Platelets develop from precursor cells found in the bone marrow, a process that is called thrombopoiesis. During the final stages of thrombopoiesis, platelets are shed from the cytoplasm of their precursors and then enter the bloodstream. Because they lack nuclei, circulating platelets are often referred to as "cytoplasts." Because DNA resides in the nucleus, platelets were previously considered incapable of reproducing themselves. However, according to this new study....,[researchers found that ] platelets increase in number by generating beaded extensions that resemble a pearl necklace. Development of these extensions, which contain two or more new platelets, does not require a nucleus. [They also] found that the newly formed platelets are structurally and functionally indistinguishable from normal platelets and are similar in size, shape, and metabolic activity. Importantly, the group also demonstrated that platelets produce progeny in human whole blood cultures.....[The group also] found that platelets used for transfusion are also capable of generating new platelets, even after they are stored in bags for five days. This suggests that platelet numbers may be expanded after they are removed from the body, a finding that could have a significant impact on transfusion medicine.

If these research observations are correct, numerous new ideas will need to be explored. At a very basic research level, a key question is how platelets can reproduce without a nucleus. From an applied and therapeutic level, new options present themselves for thrombocytopenic patients. Currently, they are either transfused with banked platelet-rich products or treated with drugs to stimulate the bone marrow to produce more. If we can better understand the mechanism that causes circulating platelets to reproduce, this might result in a new approach to treatment. Also note the statement above: platelets produce progeny in human whole blood cultures. Researchers have tried for decades to grow red and white blood cells in-vitro (see: Blood Pharming: An Experimental Technology to Produce Red Cells in the Battlefield ). Perhaps it may be possible to apply some of these techniques to platelets alone.