A two-step liquid culture--a novel culture procedure for studying erythroid cell development.

The red blood cell (RBC) has a major contribution to biological research. For example, the basic knowledge on the structure and function of the plasma membrane and the structure, function and genetics of proteins came from studies of RBC and hemoglobin (Hb). The reasons why the RBC has become such a useful experimental tool is due to several facts: (a) peripheral blood (PB) is readily available; (b) pure populations of RBC can be easily isolated from other blood cells; (c) RBC can be maintained in vitro for weeks under simple conditions (physiological salt solution at 4 degrees C) and finally, (d) the mature RBC is a rather simplified cell that lost many cellular structures and functions as a result of its extreme specialization. When studying the developmental aspects of erythroid cell differentiation and maturation, one faces a more complicated situation. Like other hemopoietic cells, the origin of RBC is in precursors in the bone marrow (BM). However, unlike PB, BM is not readily available and it consists of a mixture of cells of various types and stages of differentiation, which makes the purification of a particular cell population quite difficult.