Blood, Vol. 95 No. 9 (May 1), 2000:
pp. 2967-2974
Selectively increased growth of fetal hemoglobin-expressing
adult erythroid progenitors after brief treatment of early
progenitors with transforming growth factor beta
Ralph M. Bohmer,
Thomas A. Campbell, and
Diana W. Bianchi
From the Division of Genetics, Department of Pediatrics, New England
Medical Center and Tufts University Medical School, Boston, MA, and
Wallac Inc, Akron, OH.
We have studied the effect of transforming growth factor beta
(TGF
) on erythropoiesis in cultures from adult peripheral blood, using flow cytometric enumeration of fetal hemoglobin (HbF)-containing cells. TGF caused a dramatic increase in the proportions of cells that accumulated HbF together with adult hemoglobin (HbA) (F+A+ cells). This highly significant (P < .0001) increase in
F+ cell proportion was achieved by TGF treatment during the first
4 days of culture and was sustained during further culture expansion in
the absence of TGF. The increase in F+ cell proportions did not
depend on the cytokine combination (EPO+SCF+IL3, EPO+SCF, EPO+IL3, SCF+IL3) used during the phase of TGF treatment.
Increased F+ cell proportions were paralleled by an increased
molecular ratio of HbF/ HbF+ HbA, measured by cation exchange
high-performance liquid chromatography (HPLC). In addition
to the effect on F+ cell proportions, TGF caused a dramatic
increase in overall cell division potential. By the time cultures
reached terminal growth arrest (12-14 days in controls and 18-26 days
after TGF), the overall numbers of F+ cells produced per initially
seeded clonogenic cell was approximately 10 times higher in the
TGF-treated cultures than in the controls. We propose to investigate
whether the TGF-induced increase in relative and absolute numbers of
nucleated F+ cells, as demonstrated in vitro, can be translated into
increased F+ erythrocytes in vivo, allowing therapeutic
application for some beta-hemoglobinopathies.
