Produção de embriões bovinos in vitro associada à maturação em sistema tridimensional de cultivo

Abstract

The in vitro production of embryos (PIVE) is the most used procedure when searching the productive increase of bovine herds. The technique consists of three consecutive steps, preceded by oocytes: in vitro maturation of oocytes (IVM), in vitro fertilization (IVF) and in vitro embryo culture (IVC). To overcome possible disadvantages of the two-dimensional (2D) culture system used in oocyte maturation, a three-dimensional (3D) culture system was developed that mimics the natural environment of cell development. The study was carried out at the Reproduction Biology Laboratory of the Federal University of Uberlândia and the objective of this study was to use the 3D system composed of nanoparticles and magnetic levitation, during the maturation of good and bad bovine oocytes, testing two concentrations of nanoparticles and comparing the rates of cleavage and blastocyst rates obtained in this system with those obtained in the 2D system. The bovine oocytes were obtained from ovaries from slaughterhouse and classified for quality in good and bad oocytes; matured in a three-dimensional culture system composed of magnetic nanoparticles composed of gold, iron oxide and poly-L-lysine, at concentrations of 50 μL / mL or 75 μL / mL, associated with magnetic levitation; fertilized and the probable embryos were cultured in vitro for 7 days. After 48 hours of IVF, the rate of cleavage was evaluated and, after in vitro culture of the embryos, the rate of blastocysts formed, both by percentage analysis. Using the Sigma Plot version 11 program, the chi-square test and the odds ratio test were applied. After evaluating the cleavage rates, the group of poor oocytes matured with the concentration of 75 μL / mL in the 3D system presented 1.6 times more chances of cleaving than poor oocytes matured in the 2D system; showing similar cleavage rates to groups of good oocytes matured in both the 2D and 3D systems at 50μL / mL. Regarding the blastocyst rates, the groups of bad oocytes and good oocytes matured at the concentration of 75 μL / mL in the 3D system had similar rates to that of the group of good oocytes matured in the 2D system. It was concluded that the 3D culture system, when used in the concentration of 75μL / mL of nanoparticles, allowed bad oocytes, generating production rates similar to those of the good oocyte groups matured in both culture systems.