Efeito do meio condicionado por células tronco mesenquimais derivadas de tecido adiposo na maturação de oócitos bovinos e posterior desenvolvimento embrionário in vitro

Abstract

Stem cells are known for their property of self-renewal, differentiation into various cell lineages and immunomodulatory capabilities, in addition to express a large number of adhesion molecules, extracellular matrix proteins, cytokines and growth factor recptors, allowing interactions with other cells. They can be isolated from various tissues, but adult stem cells derived from adipose tissue stroma (MSC-d) have the advantage of being easely isolated, high yield and low morbidity. Based on this, the study hypothesis is to verify the effect of MSC-ad conditioned medium use in in vitro maturation on development rates of bovine embryos. To this end, bovine MSC ad were isolated then cultivated until the passage three (P3) in DMEM culture medium, supplemented with sodium bicarbonate, 10% fetal bovine serum (FBS), 50mL / mL gentamicin. When cultures reached 70% confluency, the medium was replaced with TCM199 supplemented with 0.2 mM pyruvate, 50 ul / ml gentamicin and 10% FBS (IVM medium). The MSC-ad were conditioned with medium TCM199 supplemented for a period of 0 (Control Group), 24 (COND-24 group), 48 (COND-48h group) and 72 hours (COND group-72h), wherein the end of each period, the supernatant medium was removed, filtered, aliquoted and frozen at -20 0 C. The medium was thawed only on MIV day, and supplemented with 0.5 uL of PMSG (concentration 7 IU / ml) and 0.5 uL of HCG. Slaughterhouse ovaries were punctured to obtain oophurus cumulus complexes (COCs) were matured for 24 hours in microdrops of conditioned mediums under mineral oil them incubated in an incubator at 5% CO 2 at 38.5 ° C. Nuclear maturation assessment was performed with 22 hours, then held 15 parthenogenetic activation of only oocytes that exhibited polar body concentration of at least 50 uM ionomycin for 5 minutes, inactivation with TCM199-Hepes 0.03g saturated with BSA, followed by incubation for 3 hours microdroplets 2mM 6-DMAP. After this period, the parthenogenesis were transferred as microdrops to a culture medium in vitro. development rates were evaluated in the second and seventh days after activation. The results were analyzed by ANOVA and Fisher's post-test adopting a significance level of 5%. For groups: Experimental CONTROL, COND-24, COND-48h and 72h-COND, we obtained the following results respectively: 83.7, 77.7, 81.4 and 76.1% of nuclear maturation; 87.5, 86.9, 74 and 80.3 and 23.8% cleavage, 27.5, 18 and 19.6% of blastocyst formation. There was no statistical difference between condinioned experimental groups (p<0.05). However, blastocyst rates were lower when compared with fresh IVM medium (42.1%) (p<0.05). This suggests that the efficiency was affected by the conditioning of the medium or freezing. Future studies should be conducted to assess the levels of growth factors, cytokines and chemokines secreted in IVM medium.