High mobility group box 1 (HMGB1) enhances porcine parthenotes developing in vitro in the absence of BSA

High mobility group box 1 (HMGB1) is considered a component of chromatin and membranes with a role in a variety of biologically important processes. The aim of this study was to determine the effects of HMGB1 on the viability and development of porcine diploid parthenotes cultured in vitro. In vitro derived 4-cell parthenotes were cultured to blastocysts, with or without recombinant HMGB1, in the presence or absence of BSA. The addition of 1, 10, 100 or 1000 ng/mL HMGB1 into NCSU 23 medium containing 0.4% BSA did not enhance the development of 4-cell parthenotes to the blastocyst stage and did not change the total number of nuclei in the blastocysts. However, addition of 10 or 100 ng/mL HMGB1 into NCSU 23 medium in the absence of BSA increased (P < 0.05) both the development rate of parthenotes to the blastocyst stage and total cell numbers. When cultured in NCSU23 medium supplemented with 10 or 100 ng/mL HMGB1 and without BSA, apoptosis in parthenotes at the blastocyst stage was decreased (P < 0.05). Based on real time RT-PCR, the addition of HMGB1 to the culture medium in the absence of BSA decreased mRNA expression of pro-apoptotic genes Bak (P < 0.005) or Caspase3 (Casp3, P < 0.01), but not Bcl-xL (Bcl2l2). In conclusion, we inferred that recombinant HMGB1 in the culture medium in the absence of BSA prevented apoptosis of porcine parthenotes and enhanced porcine embryo viability.