Background Recombinant human erythropoietin (rHuEPO) induces endothelial ce
ll growth and angiogenesis in vitro. The mechanisms are unknown. Because an
increase in endothelial cell survival could play a role in this process, w
e examined the effect of rHuEPO on lipopolysaccharide (LPS)-induced apoptos
is in bovine pulmonary artery endothelial cells (BPAECs).
Methods. Four groups of cells were studied. The first group was preincubate
d in serum-free medium followed by treatment with LPS. The second group was
preincubated with rHuEPO followed by LPS. The third group was treated with
only rHuEPO. Control cells were cultured in the absence of rHuEPO and LPS.
Apoptosis was determined by Bow cytometric DNA analysis, propidium iodide
staining, cellular DNA fragmentation by ELISA, and gel electrophoresis.
Results. LPS-treated cells showed an increase in hypodiploid DNA (36.4 +/-
6.1%) compared with controls (9.8 +/- 3.3%, P< 0.001). Preincubation with r
HuEPO decreased this effect to 14.7 +/- 5.1% (P < 0.001). Apoptosis determi
ned by propidium iodide was observed in 33 +/- 8% of LPS-treated cells, but
in only 9 +/- 3% of cells preincubated with rHuEPO cells (P < 0.001). Simi
larly, DNA fragmentation was decreased in rHuEPO pretreated cells compared
with LPS alone (0.155 OD +/- 0.02 vs. 0.538 +/- 0.09 OD, P < 0.001). DNA br
eakdown was observed in only LPS-treated cells.
Conclusions. These results suggest that rHuEPO prevents LPS-induced apoptos
is in endothelial cells. This protective effect could be an important facto
r in the action of rHuEPO on vascular endothelium.