McGregor, Christopher GA;
Byrne, Guerard W;
Fan, Zhiqiang;
Davies, Christopher J;
Polejaeva, Irina A;
(2023)
Genetically engineered sheep: A new paradigm for future preclinical testing of biological heart valves.
Journal of Thoracic and Cardiovascular Surgery
, 166
(4)
e142-e152.
10.1016/j.jtcvs.2023.02.007.
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Abstract
BACKGROUND: Heart valve implantation in juvenile sheep to demonstrate biocompatibility and physiologic performance is the accepted model for regulatory approval of new biological heart valves (BHVs). However, this standard model does not detect the immunologic incompatibility between the major xenogeneic antigen, galactose-α-1,3-galactose (Gal), which is present in all current commercial BHVs, and patients who universally produce anti-Gal antibody. This clinical discordance leads to induced anti-Gal antibody in BHV recipients, promoting tissue calcification and premature structural valve degeneration, especially in young patients. The objective of the present study was to develop genetically engineered sheep that, like humans, produce anti-Gal antibody and mirror current clinical immune discordance. METHODS: Guide RNA for CRISPR Cas9 nuclease was transfected into sheep fetal fibroblasts, creating a biallelic frame shift mutation in exon 4 of the ovine α-galactosyltransferase gene (GGTA1). Somatic cell nuclear transfer was performed, and cloned embryos were transferred to synchronized recipients. Cloned offspring were analyzed for expression of Gal antigen and spontaneous production of anti-Gal antibody. RESULTS: Two of 4 surviving sheep survived long-term. One of the 2 was devoid of the Gal antigen (GalKO) and expressed cytotoxic anti-Gal antibody by age 2 to 3 months, which increased to clinically relevant levels by 6 months. CONCLUSIONS: GalKO sheep represent a new, clinically relevant advanced standard for preclinical testing of BHVs (surgical or transcatheter) by accounting for the first time for human immune responses to residual Gal antigen that persists after current BHV tissue processing. This will identify the consequences of immune disparity preclinically and avoid unexpected past clinical sequelae.
| Type: | Article |
|---|---|
| Title: | Genetically engineered sheep: A new paradigm for future preclinical testing of biological heart valves |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.jtcvs.2023.02.007 |
| Publisher version: | https://doi.org/10.1016/j.jtcvs.2023.02.007 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Biological heart valve, immune injury, sheep, structural valve degeneration |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Cardiovascular Science UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Cardiovascular Science > Pre-clinical and Fundamental Science |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10170514 |
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