Plasmodium falciparum in vitro culture: improvements using umbilical cord serum and medium modifications.

Umbilical cord serum is a cheap, readily available source of human serum which promotes in vitro P. falciparum growth as well or even better than adult serum, and gives more consistent results. By increasing to 35 mM the HEPES concentration in RPMI medium, the time elapsed between two medium changes can be extended to 48 hours (or even to 72 hours if optimum multiplication rates are not required). An initial parasitemia of 0.2% with medium changes on day 2 and 3, generally results in 6 to 12% parasitemia on day 4 (30 to 60 X/96 hours).