3/24/2023 0 Comments Mediunic novels![]() ![]() Similarities between KSOM and most of the commercially available “single step” media are particularly striking 11. ![]() The extensive influence of KSOM and G1/2 on the composition of clinical embryo culture media is evident, with most commercial media closely resembling, if not replicating, published formulations of these two media 10, 11, 12, 13. 6, 7, use two media to mimic known differences in the concentrations of nutrients present in the oviductal and uterine environments 8, 9. Conversely, sequential culture systems, notably the G1/2 series (Tables 1 and 2) developed by Gardner et al. Utilization of this and other similar media is based on the theory that providing the embryo with all of the nutrients it may require throughout preimplantation development allows the embryo to ‘choose’ which nutrients it uses and when. and the formulation of potassium simplex optimized medium (KSOM Table 1) 4, 5. Use of a single culture medium from the one cell to blastocyst stage is largely based on the work of Biggers et al. Currently, there are two prevailing theories regarding the composition of culture media to support blastocyst development. With the shift in human IVF towards blastocyst transfer and the associated increase in the time embryos spend in vitro, the need for media capable of supporting the development of high quality blastocysts has become essential 2, 3. These statistics clearly demonstrate a need for improved embryo culture media that produce high quality embryos capable of implantation, maintenance of pregnancy, and development into healthy offspring. According to the National ART Summary 1, the percentage of in vitro produced human embryos capable of implantation is less than 42%, even in women age 35 or younger. In the United States, implantation and live birth rates in clinical ART cycles remain low. This novel approach to culture medium formulation could help define the optimal nutrient requirements of embryos in culture and provide a means of shifting metabolic activity towards the utilization of specific metabolic pathways that may be beneficial for embryo viability. Similarly, embryos produced in the RN medium with elevated (50% control) concentrations of pyruvate and lactate in the first step medium and EAA and Glu in the second step medium were competent to implant and develop into fetuses at a similar rate as embryos produced in the control medium. In addition, blastocysts produced in RN + PL contained more ICM cells and ATP than blastocysts cultured in our control (100% nutrient) medium however, metabolic activity was altered. ![]() Addition of pyruvate and L-lactate (+PL) to RN at 50% of standard concentrations restored blastocyst development, hatching, and cell number. Concentrations of carbohydrates, amino acids, and vitamins could be reduced by 50% with no detrimental effects, but blastocyst development was impaired at 25% of standard nutrient provision (reduced nutrient medium RN). Our objective was to determine the impact of reduced nutrient concentrations in culture medium on mouse embryo development, metabolism, and quality as a possible platform for next generation medium formulation. Previous results from our laboratory demonstrated that uptake of nutrients by the embryo is significantly less than what is supplied in traditional culture media. Further refinement of culture media is needed to improve the quality of embryos generated in vitro. ![]()
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