The Ethics of Human Embryo Editing via CRISPR-Cas9 Technology: A Systematic Review of Ethical Arguments, Reasons, and Concerns.

The possibility of editing the genomes of human embryos has generated significant discussion and interest as a matter of science and ethics. While it holds significant promise to prevent or treat disease, research on and potential clinical applications of human embryo editing also raise ethical, regulatory, and safety concerns. This systematic review included 223 publications to identify the ethical arguments, reasons, and concerns that have been offered for and against the editing of human embryos using CRISPR-Cas9 technology. We identified six major themes: risk/harm; potential benefit; oversight; informed consent; justice, equity, and other social considerations; and eugenics. We explore these themes and provide an overview and analysis of the critical points in the current literature.

Nanoparticle-mediated genome editing in single-cell embryos via peptide nucleic acids.

Through preimplantation genetic diagnosis, genetic diseases can be detected during the early stages of embryogenesis, but effective treatments for many of these disorders are lacking. Gene editing could allow for correction of the underlying mutation during embryogenesis to prevent disease pathogenesis or even provide a cure. Here, we demonstrate that administration of peptide nucleic acids and single-stranded donor DNA oligonucleotides encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanoparticles to single-cell embryos allows for editing of an eGFP-beta globin fusion transgene. Blastocysts from treated embryos exhibit high levels of editing (~94%), normal physiological development, normal morphology, and no detected off-target genomic effects. Treated embryos reimplanted to surrogate moms show normal growth without gross developmental abnormalities and with no identified off-target effects. Mice from reimplanted embryos consistently show editing, characterized by mosaicism across multiple organs with some organ biopsies showing up to 100% editing. This proof-of-concept work demonstrates for the first time the use of peptide nucleic acid (PNA)/DNA nanoparticles as a means to achieve embryonic gene editing.

CRISPR/Cas9-editing of KISS1 to generate pigs with hypogonadotropic hypogonadism as a castration free trait.

Introduction: Most male pigs are surgically castrated to avoid puberty-derived boar taint and aggressiveness. However, this surgical intervention represents a welfare concern in swine production. Disrupting porcine KISS1 is hypothesized to delay or abolish puberty by inducing variable hypogonadotropism and thus preventing the need for castration. Methods: To test this hypothesis, we generated the first KISS1-edited large animal using CRISPR/Cas9-ribonucleoproteins and single-stranded donor oligonucleotides. The targeted region preceded the sequence encoding a conserved core motif of kisspeptin. Genome editors were intracytoplasmically injected into 684 swine zygotes and transferred to 19 hormonally synchronized surrogate sows. In nine litters, 49 American Yorkshire and 20 Duroc liveborn piglets were naturally farrowed. Results: Thirty-five of these pigs bore KISS1-disruptive alleles ranging in frequency from 5% to 97% and did not phenotypically differ from their wild-type counterparts. In contrast, four KISS1-edited pigs (two boars and two gilts) with disruptive allele frequencies of 96% and 100% demonstrated full hypogonadotropism, infantile reproductive tracts, and failed to reach sexual maturity. Change in body weight during development was unaffected by editing KISS1. Founder pigs partially carrying KISS1-disruptive alleles were bred resulting in a total of 53 KISS1 +/+, 60 KISS1 +/-, and 34 KISS1 -/- F1 liveborn piglets, confirming germline transmission. Discussion: Results demonstrate that a high proportion of KISS1 alleles in pigs must be disrupted before variation in gonadotropin secretion is observed, suggesting that even a small amount of kisspeptin ligand is sufficient to confer proper sexual development and puberty in pigs. Follow-on studies will evaluate fertility restoration in KISS1 KO breeding stock to fully realize the potential of KISS1 gene edits to eliminate the need for surgical castration.

Ethics Big and Small, Thinking Fast and Slow.

In the Hastings Center Report's July-August 2022 issue, articles by Jessica Amalraj and Kavita Shah Arora and by Inmaculada de Melo-Martín take up very different concerns under the broad topic of reproductive ethics and public policy. Amalraj and Arora call for public deliberation and consensus building to revise a Medicaid sterilization policy, and de Melo-Martín argues that social resources should not be used to support reproductive embryo editing but should instead be put toward pre- and postnatal interventions that, compared to embryonic genome editing, can help far more people have children who are healthy and genetically related to them. The third article, by Bryan Sisk and James M. DuBois, offers a framework to guide clinicians in their everyday communication with patients and their family members. Elsewhere in the issue are arguments about the responsibilities health care organizations have to address large societal problems affecting well-being.