Sperm pretreatment with heparin and l-glutathione, sex-sorting, and double cryopreservation to improve intracytoplasmic sperm injection in bovine

In bovine, intracytoplasmic sperm injection (ICSI) remains inefficient partially due to low levels of sperm decondensation. The aim of this study was to determine whether the injection of normal size sperm pretreated with heparin (Hep) and l-glutathione (GSH), the use of sex-sorted sperm, the double round of sperm freezing/thawing (re frozen), or the combination of these approaches can improve sperm decondensation and embryo development after ICSI in cattle. Cleavage and blastocyst rates were evaluated on days 2 and 7 post ICSI. Quality of ICSI blastocysts was analyzed by the relative expression of four genes by qPCR and the DNA fragmentation index by TUNEL assay. For all assays, semen samples were co-incubated with pCX-EGFP 50 ng/μl before ICSI. GFP expression, which can be detected by fluorescence microscopy, was used as a tool to estimate the success of sperm decondensation after ICSI. The use of normal size sperm pretreated with 80 μM Hep-15 mM GSH for 20 h (Hep-GSH) increased cleavage, blastocyst and EGFP + blastocysts rates (60.8, 19.4 and 61.9%) compared to control ICSI (35, 4.9 and 20%) (p