Lactoferrin inhibits platelet production from human megakaryocytes in vitro.

The mechanism of megakaryopoiesis, proplatelet formation (PPF) and platelet (PLT) production is not fully elucidated. Lactoferrin (LF) has been reported to have many biological functions including cell proliferation and differentiation, and the LF receptor is present on megakaryocytic cells. In the present study, we examined the effect of human LF (hLF) on PLT production from primary megakaryocytes (MKs).

CD41+/CD45+ cells without acetylcholinesterase activity are immature and a major megakaryocytic population in murine bone marrow.

Murine megakaryocytes (MKs) are defined by CD41/CD61 expression and acetylcholinesterase (AChE) activity; however, their stages of differentiation in bone marrow (BM) have not been fully elucidated. In murine lineage-negative (Lin(-))/CD45(+) BM cells, we found CD41(+) MKs without AChE activity (AChE(-)) except for CD41(++) MKs with AChE activity (AChE(+)), in which CD61 expression was similar to their CD41 level. Lin(-)/CD41(+)/CD45(+)/AChE(-) MKs could differentiate into AChE(+), with an accompanying increase in CD41/CD61 during in vitro culture.

Efficient gene expression in megakaryocytic cell line using nucleofection.

To clarify the mechanism of platelet production from megakaryocytes, expression of target proteins by gene transfection was examined using various gene delivery techniques. Transfection into hematopoietic cells, including megakaryocytes, by conventional gene delivery techniques such as electroporation and lipofection are known to be difficult. In this study, in addition to electroporation and lipofection, we tested other gene-transfer methods (nucleofection, transfection using inactivated virus envelope, and transferrin-linked cationic polymer) with the green fluorescent protein (GFP) gene into the human megakaryocytic cell line MEG-01.