CULTURE OF SYNCYTIOTROPHOBLAST FOR THE STUDY OF HUMAN PLACENTAL-TRANSFER .1. ISOLATION AND PURIFICATION OF CYTOTROPHOBLAST

Criteria for a successful model for the study of trans-syncytiotrophob last transfer include isolating substantially pure trophoblast cells f rom placental villous tissue, and obtaining from them phenotypical vil lous syncytial syncytiotrophoblast during culture. For studies involvi ng the basal membrane, including overall transfer, basal uptake and ou tput, and controls acting at the basal membrane, a two-sided model is required with a separate compartment of culture medium in contact with the basal cell surface. All current methods of isolating cytotrophobl ast, the precursor of syncytiotrophoblast, derive from the original ti ssue trypsinization method of Thiede (1960), which produces cultures o f villous cytotrophoblast cells contaminated with other placental cell types. Lessons learned from successful and unsuccessful development o f the model over 35 years are outlined, and recently established metho ds for purifying the isolated mixed cells discussed. These include sed imentation and centrifugation methods, immunological and receptor bind ing methods, and more selective release of trophoblast cells from tiss ue. Immune now cytometric cell sorting methods are potentially capable of isolating subpopulations of various phenotypical trophoblast types . We conclude that satisfactory methods are now available for isolatin g and purifyng cytotrophoblast from early or late gestation human plac enta. (C) 1997 W. B. Saunders Company Ltd.