#94 : Study to Improve Clinical Results of Male Infertility Treatment ROSI (Round Spermatid Injection) with Correcting Genetic Expression by Histone Deacetylase Inhibitor

Abstract

Background and Aims: While the histone deacetylase inhibitor Scriptaid has been reported to be effective to improve ROSI results, there are also reports that offspring born after its use are stunted. In order to examine the conflicting results of basic research, experiments were conducted using mice, and the results are reported herein. Method: B6D2F1 mice were used, with Scriptaid liquid at 250nM in 10% SPS-HTF and 5mM strontium chloride, and Gx-TL (Vitrolife) was used as the embryo culture medium. Comparisons were made among three groups: (1) immersion of round spermatid cells in Scriptaid solution for 10 minutes before ROSI, (2) immersion of oocytes in Scriptaid solution for 16-18 hours after ROSI, and (3) conventional method without using Scriptaid. Results: No abnormalities were observed in the newborn offspring from all three groups, and their growth curves were normal at 10 weeks of age. There were no signs of stunting, which had been a concern. No abnormalities were found in the offspring born to the first generation. Conclusion: In basic animal experiments using the histone deacetylase inhibitor Scriptaid, normal results were obtained. The Ministry of Health, Labour and Welfare requires submission of an application for basic experiments using human gametes for ROSI. The problem is the judgment that the histone deacetylase inhibitor directly affects nucleic acids, but the histones targeted by the inhibitor are nucleosomes, not nucleic acids. Furthermore, the inhibitor does not target gene expression specific to the histones, and therefore does not constitute genome editing by definition. After obtaining approval for basic experiments, we aim to conduct basic experiments using human gametes and accumulate data on the risks and safety of this method.