In vitro embryo production in animal breeding: Enhancing oocyte quality from peri-pubertal donors to promote biosecure and sustainable food production
Lead Research Organisation:
University of Kent
Department Name: Sch of Biosciences
Abstract
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Technical Summary
With increasing global population and per capita meat/milk consumption, in vitro produced (IVP), genomically evaluated (SNP chip) cattle and pig embryos can accelerate worldwide livestock genetic improvement and facilitate dissemination of genetics with minimal environmental, biosecurity and welfare problems. Further significant benefits will arise when oocytes are donated from younger, peri-pubertal donors, however, developmental competency of such oocytes is poor due to deficiencies in mitochondrial number/metabolism and related increased chromosomal abnormality. Through a fundamental study of biochemical and chromosomal events that occur during oocyte maturation this LINK proposal will address the hypothesis that peri-pubertal IVP can be improved with appropriate modifications to (i) in vitro maturation (IVM), (ii) ovarian stimulation, and (iii) diet that enhance mitochondrial number/function and minimise chromosome abnormalities. We further hypothesise that such modifications, in combination with judicious selection of embryos with normal chromosomal and mitochondrial number (preimplantation genetic diagnosis, PGD), will lead to improvements in live-birth rates in both species following embryo transfer. To test these hypotheses we will implement a series of experiments that will lead to a step-change in the nature of chemically-defined IVM media/protocols that promote mitochondrial biogenesis/metabolism during regulated meiotic progression. Improvements will be defined by measures of energy metabolism, oxidative stress, mitochondrial number, aneuploidy (by "Karyomapping") and embryo morphokinetics. Cattle studies will also integrate mild ('coasted') ovarian stimulation regimes and novel dietary strategies that advance puberty onset and enhance yields of developmentally competent oocytes. The proposal outcomes for each species will be the best strategies to emerge from these experiments combined with PGD of transferable embryos to improve live-birth rates.
Planned Impact
Need for LINK: The successful development of in vitro produced embryo transfer (IVP-ET) using peri-pubertal livestock donors necessitates fundamental research into deficiencies in oocyte maturation. These deficiencies represent a barrier to the use of embryo-based reproductive technologies in pig and cattle breeding, thereby limiting the rate of genetic improvement that can be achieved. Our industry partners are global leaders in IVP of livestock embryos and have been instrumental in driving technological innovations within the sector. Their technical expertise and access to animal resources represents an essential contribution to this project that facilitates the required scale of activity and industry-relevant endpoints for successful delivery of the scientific objectives. Uniquely, they provide technical expertise in live-animal egg recovery (cattle) and large-scale ETs (cattle and pigs) necessary to measure the ultimate endpoint of our scientific hypotheses - that the transfer of genomically evaluated embryos from peri-pubertal donors leads to live-birth rates comparable to natural conception in sexually mature animals.
Breeding companies: Our industry partners are among the largest global livestock breeding companies operating within the UK with a 28% (pigs) and 35% (cattle) share of the domestic market. They will implement emerging technical improvements, ultimately enhancing industrial processes by: (i) significantly reducing the time-interval to genetic selection; and (ii) facilitating international transport of genetically superior stock in a high animal-welfare, low-cost and bio-secure manner. The assurance of enhanced live-birth rates following embryo transfer is central to the success of this project and the companies' business models. IVP-ET will generate a new global market for livestock embryos and place the UK livestock breeding industry at the forefront of technical innovation in this field. In the pig sector we anticipate the UK market share of our partners will increase from 28 to 40% over 5 years post-project. For cattle the current global semen market exceeds US$1.5 bn annually, with nearly 200 m doses/year sold at an average price of US$10. The potential for IVP-ET to infiltrate this market is significant - if 1% of the semen market was replaced by IVP-ET that would equate to 2 m embryo transfers per annum (5-fold greater than the current 400 K global IVP-ET estimate).
Livestock breeders and producers: We expect that industry-wide use of developmentally competent, genomically and cytogenetically evaluated embryos from peri-pubertal donors will increase the rate of slaughter stock value inflation. This is projected to be >50% increase in the net value of genetic improvement per slaughter pig (from £1.50 to £2.30/pig/annum). This benefit will arise because of the advances in genetic improvement, moving from male selection based on artificial insemination (AI) to female selection based on IVP-ET from peri-pubertal donors. The latter facilitates greater female 'selection intensity' (i.e. oocyte collections require fewer, more elite females for breeding) whilst reducing the age of donors when selection decisions are made (by around 12-15 months in cattle). We estimate that for 1.9 million UK dairy cows with a replacement rate of 30%, the Profitable Life Index (PLI) could be increased by £20/heifer/annum or £11.3 million.
Human assisted reproduction (ART): Aneuploidy is the leading cause of ART failure in humans (accounting for >50% embryo loss). Current systems for in vitro maturation (IVM) of human oocytes are suboptimal and the technique is not widely practiced. IVM can be of great benefit to women undergoing fertility preservation and is used when ovarian stimulation has been contraindicated. Thus, there is considerable interest in developing chemically-defined IVM systems and aneuploidy screening for use in human ART. New information from the current project will inform on improvements to both.
Breeding companies: Our industry partners are among the largest global livestock breeding companies operating within the UK with a 28% (pigs) and 35% (cattle) share of the domestic market. They will implement emerging technical improvements, ultimately enhancing industrial processes by: (i) significantly reducing the time-interval to genetic selection; and (ii) facilitating international transport of genetically superior stock in a high animal-welfare, low-cost and bio-secure manner. The assurance of enhanced live-birth rates following embryo transfer is central to the success of this project and the companies' business models. IVP-ET will generate a new global market for livestock embryos and place the UK livestock breeding industry at the forefront of technical innovation in this field. In the pig sector we anticipate the UK market share of our partners will increase from 28 to 40% over 5 years post-project. For cattle the current global semen market exceeds US$1.5 bn annually, with nearly 200 m doses/year sold at an average price of US$10. The potential for IVP-ET to infiltrate this market is significant - if 1% of the semen market was replaced by IVP-ET that would equate to 2 m embryo transfers per annum (5-fold greater than the current 400 K global IVP-ET estimate).
Livestock breeders and producers: We expect that industry-wide use of developmentally competent, genomically and cytogenetically evaluated embryos from peri-pubertal donors will increase the rate of slaughter stock value inflation. This is projected to be >50% increase in the net value of genetic improvement per slaughter pig (from £1.50 to £2.30/pig/annum). This benefit will arise because of the advances in genetic improvement, moving from male selection based on artificial insemination (AI) to female selection based on IVP-ET from peri-pubertal donors. The latter facilitates greater female 'selection intensity' (i.e. oocyte collections require fewer, more elite females for breeding) whilst reducing the age of donors when selection decisions are made (by around 12-15 months in cattle). We estimate that for 1.9 million UK dairy cows with a replacement rate of 30%, the Profitable Life Index (PLI) could be increased by £20/heifer/annum or £11.3 million.
Human assisted reproduction (ART): Aneuploidy is the leading cause of ART failure in humans (accounting for >50% embryo loss). Current systems for in vitro maturation (IVM) of human oocytes are suboptimal and the technique is not widely practiced. IVM can be of great benefit to women undergoing fertility preservation and is used when ovarian stimulation has been contraindicated. Thus, there is considerable interest in developing chemically-defined IVM systems and aneuploidy screening for use in human ART. New information from the current project will inform on improvements to both.
Organisations
People |
ORCID iD |
| Darren Griffin (Principal Investigator) |
Publications
Coticchio G
(2021)
Plasticity of the human preimplantation embryo: developmental dogmas, variations on themes and self-correction.
in Human reproduction update
Jennings RL
(2020)
A new Approach for Accurate Detection of Chromosome Rearrangements That Affect Fertility in Cattle.
in Animals : an open access journal from MDPI
Silvestri G
(2020)
Identification of optimal assisted aspiration conditions of oocytes for use in porcine in vitro maturation: A re-evaluation of the relationship between the cumulus oocyte complex and oocyte quality
in Veterinary Medicine and Science
Silvestri G
(2022)
Effects of single or serial embryo splitting on the development and morphokinetics of in vitro produced bovine embryos
in The European Zoological Journal
Turner KJ
(2019)
Karyomapping for simultaneous genomic evaluation and aneuploidy screening of preimplantation bovine embryos: The first live-born calves.
in Theriogenology
| Description | Cattle embryo development is now well established and we are genetically screening Pig blastulation rate is up to 35% significant association between implantation rate and aneuploidy levels as per narrative below Single Nucleotide Polymorphism (SNP) data obtained at the embryonic stage is used in cattle breeding to calculate the genetic value of an animal before a pregnancy is established, leading to improved selective breeding. However, the cost of the procedure can be high due to the number of recipients not getting pregnant after receiving a SNP typed embryo. Aneuploidies are the most common cause of embryo development arrest, so it might be beneficial to screen out aneuploid embryos by employing preimplantation genetic testing for aneuploidy (PGT-A). Here, we applied a novel PGT-A algorithm, which employs the same SNP information used to calculate genetic merit, to obtain ploidy diagnoses. We performed a retrospective analysis in n=1129 bovine embryos of transferable quality produced by the company Boviteq (Saint-Hyacinthe, Canada). Embryo morphology (good or excellent) affected pregnancy rates, which were 59.9% for excellent embryos and 44.9% for good embryos (general linear model, P=.035). Nevertheless, live birth rates were not improved by morphology-based selection (40.1% vs 39.1%, P=.88). In contrast, pregnancy rates were significantly higher in euploid rather than aneuploid embryos (60,9% vs 16,1%, P=1.3E-10) as were live birth rates (50.9% vs 12.5%, P=4.7E-8). The proportion of aneuploid embryos in this sample was 13.8% (156/1129); 25.3% (41/162) of chromosomal abnormalities had paternal origin and 74.7% (121/162) maternal origin. The incidence of monosomy appeared higher than that of trisomy, however the difference was not significant (58% vs 42%, chi-square, P=.1241). Our results indicate that embryos classified as euploid by PGT-A have better developmental competence and their selection for transfer could reduce for breeders the economic losses associated with pregnancy loss. At present, a bigger database is being analysed to elucidate the effects of specific chromosomal abnormalities. Cattle Objective 1 - IVM Trophectoderm biopsies accurately represent the ploidy status of the overall embryo Incidence of aneuploidy declines in developmentally more advanced embryos High degree of variability in the incidence of aneuploidy between donors Metabolic regulation of mitochondrial function linked to lipid metabolism during IVM and oocyte quality Objective 2 - Ovarian Stimulation In vitro oocyte maturation rather than ovarian stimulation contributes to aneuploidy Considerable between donor variability in ovarian response to stimulation - particularly in peri-pubertal donors Progesterone support during ovarian stimulation key to enhancing oocyte quality and embryo development Objective 3 - Nutrition/metabolism Removal of complex proteins during IVM emphasises the importance of donor nutrition in determining oocyte quality Donor lipid metabolism and/or lipid metabolism during IVM key to future success with defined IVM media Objective 4 - Screening for pregnancy outcomes Aneuploidy screening by SNP typing and Karyomapping established to cattle embryos SNP-array analyses facilitate simultaneous genomic evaluation and aneuploidy screening Maternal meiotic errors are the prevalent cause of aneuploidy PGT-A significantly improves ET outcomes by improving pregnancies per embryo transferred Pigs Objective 1 Developed a serum-free IVM system to mature porcine oocytes from both peri and pre pubertal gilts Working with pre-pubertal animals resulted in higher experimental variability Donor selection might be a tool to overcome this Mitochondrial activity enhancers did not provide a significant advantage While additional growth factors appear unnecessary, oxidative stress control might bring further improvements Objective 4 Aneuploidy screening by SNP typing and Karyomapping now possible in pig embryos Aneuploidy incidence appears very high in IVP generated embryos OCT overcomes traditional barriers to animal embryo imaging and allows for multidimensional reconstruction of the samples in study |
| Exploitation Route | We hope these will eventually be commercialised and we are in advanced discussions to this effect |
| Sectors | Agriculture, Food and Drink |
| URL | https://www.griffin-lab.com/commerical |
| Description | Some public talks, some live births. In cattle, IVF and PGT (using single nucleotide polymorphism information) is usually performed in high volumes from genetically elite parents. In this context, transfer of embryos detected to have a lower genetic merit (e.g. low milk yield, poor disease resistance) reduces the financial return achieved by the breeding programme. Underlying research in the Griffin lab, initiated in 2015, sought to apply Karyomapping for PGT-A for the first time to improve cattle IVF success rates. Application of this technology published in 2019 led to the first live born calves [4] and, to date, a highly significant (6%) increase in pregnancy rates (unpublished results). Karyomapping is now being applied, experimentally, in the pig IVF lab set up by Griffin in 2012 (unpublished results). Commercial Impact of Karyomapping on IVF service providers in clinical and agricultural settings Karyomapping was first patented by BlueGnome in 2010 (Alan Handyside named as inventor) and BlueGnome acquired by Illumina in 2013. In 2019, Vitrolife acquired the rights to market and distribute Karyomapping services as one of their portfolio of products [a] to diagnostic laboratories such as Cooper [b] and Igenomix [c]. Karyomapping has had significant positive impact on a number of companies offering IVF services. In a medical context this includes Cooper Genomics who calculate that the >10,000 clinical cases they have processed to date account for 65-75% of all Karyomapping tests thus far performed world-wide [b]. A conservative estimate therefore is that the total number of Karyomapping cases performed has exceeded 15,000 at the time of writing. Igenomix, have, more recently, adopted Karyomapping as a Flagship Product in their UK and Italian operations and have applied the technology to approximately 2000 embryos (300+ clinical cases) to date [c]. The companies confirm that this has increased profitability [a,b,c], enhanced he company profile, become an important marketing tool [a,b,c], and has contributed to job creation [a]. In preliminary studies, Karyomapping has been applied to 2000 cattle embryos, demonstrating conclusively a tenfold improvement in pregnancy rates in normal vs. aneuploid embryos. Commercial impact [d,e] includes company investment in the university, increased profitability, establishment of a new company, Activf-ET [d] and increased company profile. |
| First Year Of Impact | 2019 |
| Sector | Agriculture, Food and Drink |
| Impact Types | Economic |
| Description | Making of a TV documentary entitled "Generation Genome" |
| Form Of Engagement Activity | A broadcast e.g. TV/radio/film/podcast (other than news/press) |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Schools |
| Results and Impact | Production of Generation Genome - a six episode BFI supported science series started filming and saw us travel to many parts of the country filming exciting content with young people and lead presenters Prof Darren Griffin and Ogo Anokwuru. Included our work on this grant Generation Genome is KMTV Creative Productions latest special project, and it is very special indeed. Co Funded by the British Film Institute, The University of Kent, and KMTV, this documentary series is a testament to scientific research. The KMTV creative team are travelling the UK talking to children and their support networks about genetics.Teachers, research scientists and practitioners from all over the UK have spoken to us about the many ways genes are important to us. We delve into how genetic disorders affect us in the present, how ancient DNA is being used to understand our past, or how the latest innovations will shape our future, we have explored it all. DNA is important to every living cell on the planet and therefore it creeps into many areas of our lives. So far, we have spoken to individuals living with challenging and life changing genetic disorders like cystic fibrosis and sickle cell disease. With the current advancements in genetic medicine, it is so important that it directly improves the lives of those living with painful and difficult disorders. We've spoken to coaches about training their athletes and how important their DNA is to how they perform. We attended the colourful and inspiring Pride Manchester 2021 with an incredible young girl in the queer community. We explored to what extent does science understand our sexual orientation to be genetic, and what do people in the LGBTQ+ community think? We had the pleasure of visiting an Imam of the Muslim community in Bradford who spoke to us about his thoughts about genetic medicine and medical ethics. We were able to share in the enthusiasm and talent of some young fossil hunters and Britain's youngest falconers who are using our knowledge of ancient DNA to inform how we conserve our wildlife today. In September, a massive and ambitious endeavour to take our set and crew back around the UK to meet with schools and talk about genetics began. With the help of experts and those affected by these conversations making up our panel, we started filming our "GG Group Chats". This is where children get to actually watch the documentary for the first time and ask all their burning questions to the panel. It has been inspiring to say the least, to hear the questions and opinions of young people in the country, to see how interested they are in the world of genetics. It is clear that this documentary will contribute to the collection of valuable genetic research and resources that will be handed down to our young people. The best part is that the information is coming straight from field experts, teachers, patients and children themselves. |
| Year(s) Of Engagement Activity | 2021,2022,2023 |
| URL | https://blogs.kent.ac.uk/kmtv/2021/10/11/what-is-generation-genome/# |