Current Techniques of Gene Editing in Pigs for Xenotransplantation.

Shortage of human organs for transplantation has created a demand for alternative solutions of which xenotransplantation is amongst the most promising one in the short term. However, the immune reaction following transplantation of a pig organ is greater than the one elicited during allotransplantation. Genetic engineering of the pig is required so that pig organs or tissues are made less immunogenic to humans by eliminating some antigens and by expressing human proteins that can reduce the damage by the host immune system. To generate founder animals with the desired mutations genetic engineering of somatic cells with multiplexed mutations combined with somatic cell nuclear transfer (SCNT) is the best solution with the technology available today. Safety concerns include potential zoonosis, primarily porcine endogenous retroviruses (PERVs). Ethical considerations might arise from the use animals involved in research. Genome editing techniques based CRISPR-Cas9, have greatly facilitated the modification of pig's genome to address coagulation and inflammation issues, to mention just a few, arising after the pig organ is transplanted into a human. However, further research is needed to ensure safety and efficacy of the genome edits introduced in the pig genome are compatible with the health and welfare of the pigs.