Babesia divergens was cultivated in RPMI 1640
(25 mM HEPES) supplemented with 10% human serum (RPMI-10%
HS) with a high percentage of parasitized erythrocytes (PPE)
([ges ]40%). Standardization of in vitro tests,
purification of
exoantigens, biochemical studies and the safety of the culture handler
motivated the development of a serum-free defined
medium. Removal of serum greatly reduced the PPE but, after a period of
adaptation, the culture was continuous and the
parasite was able to develop a 3% routine PPE. Addition of vitamins or
reduced
glutathione in basal medium (RPMI)
did not improve the PPE. The supplementation of basal medium with lipidic
carrier (Albumax I or bovine serum
albumin–Cohn's fraction V) promoted the growth of B.
divergens with high PPE (>30%) close to those obtained in
RPMI–10% HS. Neither protein nor lipid fractions alone were able
to
restore the growth of B. divergens. Nevertheless,
the whole lipid fraction from serum or Albumax I added to delipidated albumin
partially restored the growth (7% PPE),
indicating that the presentation of specific lipids by a carrier is
crucial for the parasite. All the data indicate that Albumax
I can replace human serum offering the advantages of safety, standardization
for chemosensitivity tests, and exoantigen purification.
Characterization of cultured rat oligodendrocytes proliferating in a serum-free, chemically defined medium.
