The proliferation in suspension of the progenitors of the blast cells in
acute myeloblastic leukemia
N Nara and EA McCulloch
A minority of blast cells in acute myeloblastic leukemia (AML) form
colonies in culture in methylcellulose when stimulated by media conditioned
by normal leukocytes in the presence of phytohemagglutinin (PHA-LCM). Blast
colonies can be replated successfully, either as pooled cells or
suspensions from single colonies. However, the plating efficiency declines
with repeated passages, and more than four subcultures have not been
achieved. In this study, blast populations were cultured in suspension,
with fetal calf serum, alpha-minimal essential medium and PHA-LCM. In cells
from 17 of 18 patients, exponential growth of clonogenic blast cells was
maintained for six to seven days without reculturing. Colonies obtained
from progenitors taken from liquid culture and replated in methylcellulose
were replated to obtain the secondary plating efficiency (PE2). In 14
cases, this value was maintained or increased. In three instances, PE2 fell
following culture in methylcellulose. When cells in suspension were
recultured, exponential growth continued. In nine instances, exponential
growth was maintained for from seven to 70 days. During this time, PE2 was
maintained. Results from experiments using velocity sedimentation
separation and analysis of single colonies were consistent with the view
that the increase in clonogenic cells in suspension was a manifestation of
their self-renewal capacity. The observations also support a model of blast
progenitor growth that contains the postulate that these are capable not
only of self-renewal but also of determination-like events leading to loss
of proliferative capacity.
Volume 65,
Issue 6,
pp. 1484-1493,
06/01/1985
Copyright © 1985 by The American Society of Hematology
