Somatic cell nuclear transfer in pigs: recent achievements and future possibilities

Abstract

During the past 6 years, considerable advancement has been achieved in experimental embryology of pigs. This process was mainly generated by the rapidly increasing need for transgenic pigs for biomedical research purposes, both for future xenotransplantation to replace damaged human organs or tissues, and for creating authentic animal models for human diseases to study aetiology, pathogenesis and possible therapy. Theoretically, among various possibilities, an established somatic cell nuclear transfer system with genetically engineered donor cells seems to be an efficient and reliable approach to achieve this goal. However, as the result of unfortunate coincidence of known and unknown factors, porcine embryology had been a handicapped branch of reproductive research in domestic animals and a very intensive and focused research was required to eliminate or minimise this handicap. This review summarises recent achievements both in the background technologies (maturation, activation, embryo culture) and the actual performance of the nuclear replacement. Recent simplified methods for in vivo development after embryo transfer are also discussed. Finally, several fields of potential application for human medical purposes are discussed. The authors conclude that although in this early phase of research no direct evidence can be provided about the practical use of transgenic pigs produced by somatic cell nuclear transfer as organ donors or disease models, the future chances even in medium term are good, and at least proportional with the efforts and sums that are invested into this research area worldwide.

High developmental potential in vitro and in vivo of cattle embryos cloned without micromanipulators

“…Concerns about removing zona from embryos include the possibility of viral infection of them (however the risk is the same for conventional cloning, due to the rupture of the zona), the potential failures in DNA methylation in these embryos, as shown for mouse zona free embryos [18] and the impossibility for group culture of embryos due to aggregation of adjacent embryos; however this problem has been overcame by the use of WOW culture [3]. In the last years this method has been successfully used for production of bovine [2,[19][20][21], horse [22][23], mouse [24] and pig [25] offspring. Finally, and probable one of the most important features of HMC is its simplicity, speed of work and low cost when compared to traditional cloning using micromanipulators.…”

Application of Genetically Modified and Cloned Pigs in Translational Research

“…Dev. 55: [225][226][227][228][229][230] 2009) t present, pigs are not only considered important livestock but are also essential large-animal models in various types of biomedical research [1][2][3][4][5][6]. Furthermore, due to recent technological advances in genetic modification and somatic cell cloning, the range of applications for porcine models has increased markedly [7][8][9][10][11][12][13][14].…”

Factors Determining the Efficiency of Porcine Somatic Cell Nuclear Transfer: Data Analysis with Over 200,000 Reconstructed Embryos

“…Introduction P roduction of transgenic domestic pigs for biomedical purposes offers unique possibilities for biomedical research and applications (Lind et al, 2007;Vajta et al, 2007). Due to similarities in organ size, physiology, metabolism, and genetics, the pig can be an alternative source of organs for xenotransplantation and a feasible model for studying various human diseases and pharmaceutical effects.…”