The presence of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) during meiosis improves porcine 'oocyte competence' as determined by early embryonic development after in-vitro fertilization

The present studies were designed to determine the effect of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) during meiosis or after in vitro fertilization on early embryonic development of porcine embryos. The presence of purified ovine TIMP-1 in culture medium after in vitro fertilization did not affect the incidence of embryo cleavage or development to the blastocyst stage at 48 h or 6 days after insemination, respectively. In contrast, when various concentrations (1.25, 2.50 and 5.00 μg/ml) of purified ovine TIMP-1 were added to the culture medium during the second half (24 h) of oocyte maturation, normal cleavage rates (64 ± 3% at 1.25 μg/ml, 57 ± 5% at 2.50 μg/ml and 56 ± 1% at 5.00 μg/ml) were higher (p<0.05) as compared to controls (43 ± 2%). In addition, the incidence of embryos that developed to the blastocyst stage was increased (p<0.05) when TIMP-1 was added (34 ± 3% at 1.25 Mg/ml, 32 ± 1% at 2.50 μg/ml and 28 ± 1% at 5.00 μg/ml) as compared to controls (22 ± 3%). There was no difference in the incidence (53 ± 1%) of oocytes fertilized normally. These results indicate that the presence of TIMP-1 during the second half of in vitro maturation enhanced the competence of porcine oocytes to develop to the 2- to 4-cell stages after in vitro fertilization, consequently increasing the incidence of blastocysts.