Isolation of mouse megakaryocytes. I. Separation of two fractions enriched in different maturational stages.

Megakaryocytes (MK) were isolated from mouse bone marrow by centrifugation on discontinuous gradients of isotonic albumin or Percoll and characterized by acetylcholinesterase (AChE) staining. The apparent density distributions of MK varied greatly depending upon the nature of the gradient medium and the composition of the cell suspension buffer while the density range of the other bone marrow cells remained largely unchanged. The present findings also indicate that the unusual morphological and functional characteristics of MK may underlie the observed shift in their density profile. Thrombocytopoietic stimulatory factor (TSF) was administered to mice 18 h before killing to elevate the normally low numbers of earlier MK in the bone marrow and to improve the yield of immature MK during the subsequent isolation procedure. Cells belonging to earlier stages in maturation were separated from the more mature ones on discontinuous Percoll density gradients, providing a basis for further investigation of MK development.