Achievements and perspectives in cloned and transgenic cattle production by nuclear transfer: Influence of cell type, epigenetic status and new technology

Abstract

Genetically modified cattle production is motivated by many factors, including recombinant protein production for therapeutic purposes, disease models and animals presenting improved production traits. Nuclear transfer (NT), combined with efficient cultivation methods, genetic modification and donor cell selection is important for transgenic cattle production. Studies have found that adult cells (such as fibroblasts and cumulus cells, among others) used as nuclear donors achieved results similar to those of fetal cells, with the advantages of easier collection and a known genotype/phenotype. However, no consensus has been reached on the influence of cell type on transgene expression levels and post-reprogramming capacity after nuclear transfer, and these factors appear to be related to epigenetic factors. The development of new strategies, such as chromatin-modifying agents (CMAs), in vitro generation of induced pluripotent cells (iPS cells) and precise genome editing techniques are being explored and may influence nuclear reprogramming success for efficiently producing genetically modified bovine clones.