Low Serum Concentration in Ovine Embryo Culture Media

Background: Fetal bovine serum (FBS) is rich in nutrients, growth factors, hormones, and other essential compounds necessary for cell growth. However, its use has several disadvantages. Platelets in particular contain the majority of the potent mitogenic factors found in serum. Objectives: The present study aimed to evaluate the effect of platelet lysate (PL) on in vitro embryo production by replacing FBS, to determine if this modified Charles Rosenkrans medium (mCR2aa) can support ovine embryo development compared to the commercially available BO-IVC medium. Methods: In the first experiment, varying concentrations of FBS (0%, 2.5%, 5%, and 10%) and PL (0%, 2.5%, 5%, and 10%) were investigated in the mCR2aa culture medium. In the second experiment, the optimized mCR2aa medium was compared to the BO-IVC medium. Ovine oocytes were matured and fertilized in vitro using BO-IVM Bioscience medium and Brackett and Oliphant medium, respectively. Subsequently, the resulting zygotes were cultured in either mCR2aa medium supplemented with amino acids or BO-IVC medium, according to the experimental design, under a humidified atmosphere of 5% CO 2, 5% O 2, and 90% N 2at 38.5ºC. Results: The results indicated that using 5% PL in the mCR2aa culture medium reduced the serum percentage to 2.5%. Conclusions: It was not possible to completely eliminate serum from the mCR2aa medium solely by substituting it with PL. Further studies are needed to explore other serum properties such as chelating agents and antioxidant activities to fully optimize the mCR2aa medium without serum.