SYNTHETIC SERUM SUBSTITUTE (SSS) - A GLOBULIN-ENRICHED PROTEIN-SUPPLEMENT FOR HUMAN EMBRYO CULTURE

Objective: The purpose of the present study was to evaluate whether an IVF protein supplement prepared from human serum albumin (HSA) and hu man globulins would retain performance characteristics equivalent to t hose reported for the commercial plasma expanders, Plasmatein (Alpha T herapeutics, Los Angeles, California) and Plasmanate (Cutter Biologica l, Miles Inc., Elkhart, Indiana). Methods: Pronuclear-stage human embr yos were randomly divided and cultured in human tubal fluid medium (HT F) supplemented with either HSA (5 mg/mL) or Plasmatein (10%, v/v; 5 m g/ml) as a means of indirectly assessing the effect alpha- and beta-gl obulins have on embryonic development. Those results coupled with the known composition characteristics of Plasmatein were used as the start ing basis to formulate test lots of synthetic serum substitute (SSS). Results: Significantly (P < 0.05) more of the human embryos cultured i n Plasmatein supplemented medium reached the four-cell or greater stag e by 40 hr postinsemination than a comparable group cultured in HSA al one. Lot 1 of SSS, formulated, with HSA (84% of total protein) and hum an globulins (16% of total protein) and on aqueous lipoprotein fractio n derived from human plasma (Excyte IV; Miles Diagnostics, Kankakee, I llinois), produced accelerated early embryonic growth relative to cont rol murine embryos grown in the presence of Plasmatein, however, the p ercentage of the embryos reaching the hatched blastocyst stage was dec reased (45 vs 100%). Human embryos from seven patients, randomized to HTF medium supplemented With Plasmatein or lot 1 of SSS, showed equiva lent growth at 36-40 hr postinsemination, A microprecipitate developed in media supplemented with lot I after several days of culture. The E xcyte IV concentration was reduced and, ultimately, eliminated from th e subsequent and final prototype lots of SSS. Murine embryos grown in the presence of lipoprotein free SSS showed significantly accelerated (P < 0.01) growth at 17 hr postthaw compared to Plasmatein and all emb ryos progressed to hatching by 41 hr. Human embryos, randomized to eit her Plasmatein or lot 3 of SSS, showed significantly accelerated growt h (P < 0.01) when scored at 38 hr following insemination. Conclusion: Synthetic serum substitute provides a convient, standardized means of adding protein to media used in assisted reproductive technology (ART) procedures.