Navigation auf uzh.ch

Suche

URPP Human Reproduction Reloaded | H2R

SP 4 CRISPR Technology in Human Reproduction - An interdisciplinary Approach

Scientific Research Questions

The range of reproductive options investigated by the URPP H2R includes the potential future scenarios that rely on CRISPR-based technologies. The opportunities and risks of human germline editing using the CRISPR technology are being discussed extensively worldwide. Genetic modification of the germline with CRISPR might represent a promising approach for curing monogenetic disorders (e.g. cystic fibrosis), and for reducing genetic risk factors associated with common chronic diseases in which multiple genes interact with environmental factors (e.g. obesity, coronary heart disease, diabetes, Alzheimer’s disease, and multiple cancers). However, the consequences of such modifications for future generations are still unclear; indications are ambiguous, and technical feasibility is challenging. Here, we intend to evaluate opportunities, risks, and limitations specific to the CRISPR technology for germline editing. We will address these specific questions:

  • Can we improve the precision, reliability, and safety of CRISPR to a point where we can consider its use in human embryos?
  • Do we understand enough about complex genetic diseases to be able to delay or suppress their onset?
  • Can modifying the human germline ever be ethically defensible?

This ambitious high-risk sub-project merges expertise from the fields of molecular biology, reproductive medicine, AI and machine learning, and genetics, and its findings will continue to be intensively discussed with colleagues from law, applied ethics and philosophy, theology, and sociology.

Several key questions are addressed in the second phase of SP 4:

  • Can we establish embryo genome-editing approaches in mammalian models that are safe and efficient enough to be considered for application in humans?
  • Can we efficiently correct genetic risk factors without generating mosaic embryos? Can we optimize the AI-assisted CRISPR design tools for genome editing in embryos and totipotent stem cells?
  • Can protein evolution combine with AI approaches to generate synthetic CRISPR tools with increased precision and efficiency?

Concurrent with this cutting-edge medical-technological research, we will conduct an interdisciplinary legal, ethical-philosophical, psychological, and social investigation whose findings will inform the evaluation of CRISPR. 

Goals

Our first goal is to assess the efficiency and precision of available CRISPR technologies and to develop improved variants. 
Our second goal is therefore to evaluate the technical feasibility of introducing multiple precise genetic changes in a single cell or zygote. 
Our third goal is to systematically introduce and study disease-associated allele variants in mouse models and ex vivo organoid models. Potential target diseases include cardiovascular diseases, obesity, and cancer. 

Research Agenda

In the first four years, we will mainly focus on testing the efficacy and safety of CRIPSR technologies, and in years 5 to 8 we will put an emphasis on the development of improved tools. Likewise, in the first four years, we will mainly try to understand why risk alleles are associated with certain genetic diseases, and in the years 5 to 8, we will attempt to develop CRISPR approaches that can correct mouse models carrying these risk alleles. Concurrent with this cutting-edge medical-technological research, we will conduct an interdisciplinary legal, ethical-
philosophical, psychological, and social investigation whose findings will inform the evaluation of CRISPR. 

Empirical Projects

Improving the molecular toolbox for imaging early embryo development using CRISPR-Cas9 (by Mikhael Poirier and Tommaso Cavazza)
The research project of Dr. Mikhael Poirier aims to evaluate the efficiency of genome editing in bovine embryos and develop new tools to image early embryo development. This project starts by optimizing the time of delivery of Cas9 to achieve better editing efficiency. Careful attention will be paid to how different times of delivery impact on side effects of Cas9 delivery into embryos, such as chromosome loss. In addition, using the optimized CRISPR-Cas9 protocol, this research works towards inserting reporter sequences in genes controlling cell differentiation and image their endogenous expression using high resolution quantitative live microscopy. In particular, this approach allows to determine the relationship between specific gene activity, embryonic cell differentiation, aneuploidy, and healthy and faulty embryonic development. This work has also the potential of developing an alternative strategy for transgenic mouse models for the investigation of gene function in early embryo development.

 

Mining and Engineering of Novel CRISPR-Cas Proteins (by Lea Bogensperger, Lilith Feer & Prof. Michael Krauthammer in collaboration with Prof. Gerald Schwank)
This project is conducted by Lilith Feer and Lea Bogensperger under the supervision of Prof. Michael Krauthammer and in collaboration with Prof. Gerald Schwank, aiming to design novel CRISPR-Cas proteins. Many CRISPR-Cas enzymes rely on the recognition of specific protospacer-adjacent motifs (PAMs) to target and edit genomic sites, which currently limits the range of potential target locations within the genome. To overcome this limitation, we are building an extensive database of CRISPR-Cas sequences along with their corresponding PAMs by mining bacterial and phage databases. Subsequently, we will leverage machine learning–based methods, such as protein language models, to design new CRISPR-Cas variants with greater flexibility in PAM recognition. Following in-silico evaluations, promising variants will undergo experimental validation in a wet laboratory setting.

 

The molecular mechanism of DNA damage response in bovine early embryo (by Ying Cai  and Prof. Tommaso Cavazza)
Ying`s PhD project, supervised by Prof. Cavazza, aims to adress the molecular mechanism of DNA damage response in the zygote, the 1-cell embryo. The zygote has the two parental genomes separated in two pronuclei and is susceptible to DNA damage, for instance, by DNA replication stress. In addition, genome editing of zygotes via CRISPR requires the creation of DNA breaks and their repair. Interestingly, DNA damage repair is inefficient in human and bovine zygotes, impairing their development and limiting the potential of genome editing. We still do not know how zygotes respond to DNA damage, if there are pronuclear specific differences, and if specific factors are limiting the DNA repair response. Ying will use the bovine embryo as the experimental model, combining cutting-edge living imaging technology, to address these questions about DNA damage response in zygotes and set the basis to improve CRISPR potential in this system.

 

Enlightening early embryogenesis: Impact of aneuploidy on embryo development (by Bernhard Magerl and Prof. Tommaso Cavazza)
The PhD project of Bernhard Magerl focuses on understanding the impact of aneuploidy on embryonic development. Early embryonic development refers to the critical period from fertilization to blastocyst formation. This process is notably inefficient, with approximately 50% of fertilized human oocytes failing to develop into a blastocyst. A significant factor contributing to this developmental failure is aneuploidy, defined as incorrect chromosome composition/number. Aneuploid cells can originate from errors in chromosome segregation during mitosis. These errors could occur at any stage of early embryonic development.

This project uses live fluorescence imaging to investigate aneuploidy during early embryonic development. In particular, the research will examine aneuploidy emergence patterns, cellular responses, and developmental impacts through detailed monitoring of chromosome and cell division dynamics. This study will reveal how embryos manage aneuploid cells and identify causes of embryonic failure, with implications for reproductive medicine, developmental biology, and clinical IVF treatments.

 

Transient in vivo prime editing for clinical applications (by Eleonora Ioannidi & Prof. Gerald Schwank)
Eleonora Ioannidi’s PhD research project “Transient in vivo prime editing for clinical applications” focuses on improving genome editing tools for their future use in gene therapy. Even though over the last few decades, genome editing technologies have been significantly improved, there are still challenges that need to be resolved prior their use for clinical applications such as their delivery and potential off targets. This project aims for making prime editing, a new technology that allows different modifications without causing double strand breaks, transient, while maintaining its precision and efficiency.

 

Advancing In Vivo Genome Editing through the Development of Next-Generation SpCas9 Nucleases (by Dr. Péter Kulcsár & Prof. Gerald Schwank)
The postdoctoral research project conducted by Dr. Péter Kulcsár, under the supervision of Prof. Gerald Schwank, focuses on the enhancement of Streptococcus pyogenes Cas9 (SpCas9) nucleases for future applications in somatic- and germline genome editing. The primary objective is to address the limitations of SpCas9, the most widely utilized Cas nuclease, by minimizing off-target editing and enhancing consistent indel pattern outcomes (i.e. single type of indel vs diverse indel patterns). While SpCas9 has been demonstrated to be highly efficient, it still poses challenges in terms of off-target cleavage, as it can inadvertently cleave not only at intended sites but also at off-target sites. Moreover, the outcomes of SpCas9-mediated editing exhibit significant diversity. These limitations restrict its broader application.

This project aims to develop more precise genome editing tools by generating novel variants of SpCas9 through the combination of rational design and directed protein evolution strategies. These efforts seek to enhance the specificity and accuracy of the nuclease, enabling its application in therapeutic contexts or germline editing.

 

Ethical Issues of Germline Genome Editing from a Reproductive Justice Perspective (by Agnes KandlbinderProf. Dr. Peter Schaber & Prof. Dr. Michael Coors)
Agnes Kandlbinder’s PhD research project “Ethical Issues of Germline Genome Editing from a Reproductive Justice Perspective” explores normative questions of Germline Genome Editing (GGE) at the intersection of applied ethics and societal debate. The cumulative dissertation critically examines both bioethical scholarship and activist discourses on GGE, particularly with regard to disability as a social justice issue. Thereby, the project aims to signpost how the public and academic discussion on research on GGE can be fruitfully brought forward in an inclusive way. Methodologically, Agnes combines tools of analytical applied ethics with a reproductive justice framework. The expected duration of the project is from February 2022 to February 2025.