In Vitro Production of Multigene Transgenic Blastocysts via Sperm-Mediated Gene Transfer Allows Rapid Screening of Constructs to Be Used in Xenotransplantation Experiments

Multigene transgenic pigs would be of benefit for large animal models and in particular for xenotransplantation, where extensive genetic manipulation of donor pigs is required to make them suitable for organ grafting to humans. We have previously produced multitransgenic pigs via sperm-mediated gene transfer (SMGT) using integrative constructs expressing 3 different reporter genes. The aim of the present work was to evaluate the efficacy and safety of using 3 integrative constructs carrying 3 different human genes involved in the modulation of inflammatory responses. We developed an in vitro fertilization system to demonstrate that SMGT can be used to efficiently produce multigene transgenic embryos through a 1-step genetic modification using multiple integrative constructs each carrying a different human gene involved in the modulation of inflammatory processes (hHO1, hCD39, and hCD73). The results suggest that this system allowed an effective preliminary test of transgenesis optimization, greatly reducing the number of animals used in the experiments and fulfilling important ethical issues. We performed 5 in vitro fertilization experiments using sperm cells preincubated with all 3 integrative constructs. A total of 1,498 oocytes were fertilized to obtain 775 embryos, among which 340 further developed into blastocysts. We did not observe any toxicity related to the transgenesis procedure that affected normal embryo development. We observed 68.5% transgenesis efficiency. Blastocysts were 48% single, 31% double, and 21% triple transgenic.