Inhibitors of heme oxygenase reduce invasion of human primary cytotrophoblast cells in vitro.

Having previously demonstrated that heme oxygenase (HO) is expressed on invasive trophoblast within the human placental bed, we have now further hypothesised that HO may play a role in trophoblast invasion. To begin to test this hypothesis we have used a well characterised in vitro model of trophoblast invasion to determine whether antibodies raised against HO-1 and HO-2, or selective inhibition of HO with the HO inhibitor zinc protoporhyrin-9 (Zn PP-9), would affect the invasive ability of trophoblast cells. Cytotrophoblast cells were purified from term human placenta then cultured on Matrigel-coated chambers in the presence or absence of HO antibodies or Zn PP-9. The HO-1 antibody had no effect on invasion whereas the presence of the HO-2 antibody significantly inhibition invasion (p<0.05). The presence of Zn PP-9 resulted in a significant reduction in invasion (p<0.05) whereas the vehicle alone had no effect. Taken together these results suggest, that at least in vitro, HO-2 may be important in controlling trophoblast invasion.