Related Experiment Videos
Effects of pyruvate and glucose on the development of human preimplantation embryos in vitro
J Conaghan1, A H Handyside, R M Winston
1Institute of Obstetrics and Gynaecology, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Insights
Pyruvate is essential for human embryo development, supporting blastocyst formation. Glucose cannot replace pyruvate, and optimal development requires specific pyruvate concentrations, highlighting its critical role in early embryogenesis.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Embryology
Background:
- Human preimplantation embryos develop in vitro for over six days.
- The roles of key nutrients like pyruvate and glucose in early embryonic development are not fully understood.
- Embryonic nutrient requirements evolve during preimplantation stages.
Purpose of the Study:
- To investigate the impact of varying pyruvate and glucose concentrations on human preimplantation embryo development.
- To determine the necessity of pyruvate for blastocyst formation and metabolic activity.
- To assess glucose's ability to support development in the absence of pyruvate.
Main Methods:
- Culturing surplus human preimplantation embryos from the two-to-four-cell stage to blastocyst.
- Utilizing culture media with different concentrations of pyruvate and glucose.
- Exposing embryos to specific nutrient conditions between the one-cell and two-to-four-cell stages.
Main Results:
- Pyruvate alone supported blastocyst development in 59% of embryos.
- Pyruvate-free medium led to developmental arrest in 84% of embryos, with reduced metabolic activity in survivors.
- Embryos could not utilize glucose to compensate for pyruvate deficiency; optimal development occurred at 0.47 mmol/L pyruvate.
- Absence of glucose enhanced development to the eight-cell stage and resulted in blastocysts with significantly more cells.
Conclusions:
- Pyruvate is a critical nutrient for human blastocyst development.
- Glucose cannot substitute for pyruvate during early human embryogenesis.
- Optimal pyruvate concentration is essential for maximizing embryo development and blastocyst cell number.
Abstract:
Although human embryos will develop in vitro for six days or more, little is known about the effects of the primary nutrients, pyruvate and glucose, on development. Because the nutrient requirements of embryos change throughout preimplantation development, the effects of altering substrate concentrations in the culture medium were examined, using 'surplus' human preimplantation embryos cultured from the two-four-cell stage to the blastocyst stage in medium containing various concentrations of pyruvate and glucose. Between the one-cell stage and the two-four-cell stage all of the embryos were exposed to 0.47 mmol pyruvate l-1 and 5.5 mmol glucose l-1. Pyruvate as sole substrate in the medium could support blastocyst development to an extent of 59% (10 of 17). Conversely, culture of embryos in pyruvate-free medium resulted in the developmental arrest of 84% (21 of 25) of embryos, and for the 16% (4 of 25) that did reach the blastocyst stage there was a significant decrease in metabolic activity on day 4-5, during the morula to blastocyst stage transition. Embryos could not use glucose to compensate for the lack of pyruvate in the medium. Pyruvate uptake was related to exogenous concentration and optimal development occurred at the highest concentration tested, 0.47 mmol l-1. Embryo development to the eight-cell stage was slightly enhanced 82% (14 of 17) versus 60% (24 of 40) when no glucose was added to the medium, and the resulting blastocysts had significantly more cells (99.1 +/- 13.5 versus 58.4 +/- 8.2; P < 0.02) than did embryos grown in the presence of 1 mmol glucose l-1.(ABSTRACT TRUNCATED AT 250 WORDS)