Cloning is the process of making a genetically identical organism (inthis context a pig) through a nonsexual act. Cloning is an excellent method to mass produce pigs of the same genetic background.
Several species can be cloned by Somatic Cell Nuclear Transfer (SCNT) to enucleated metaphase II oocytes. Normally, the SCNT methods are complicated, involving two steps of micromanipulation. Recently, however, the technique has been simplified. A group of scientist lead by Professor Gabor Vajta at Aarhus University developed it for bovine SCNT without micromanipulation calling it Hand Made Cloning (HMC). Activation or “rebooting” of the reconstructed embryos is a crucial step in mammalian SCNT. The research group has introduced a combined electrical and chemical activation protocol and further improved the technique by combining partial Zona Pellucida digestion and oocyte cleaving with subsequent incubation.
In the present procedure, oocytes are taken from ovaries of normally slaughtered sows and matured in vitro. After partial zona pellucida digestion the oocytes are cleaved by hand under a simple dissection microscope and the halves without nucleus are collected for electrofusion with somatic cells.
With people working in parallel it is possible to produce very large numbers of reconstructed embryos per day. After incubation the quality of the blastocysts produced is analyzed and they are injected into the oviducts of foster sows under the auspices of an experienced veterinary surgeon.
The first cloned (non-transgenic) piglets were born in May 2006, and a second litter of 10 piglets were born on June 11th 2006. Since then the laboratory has been producing cloned pigs at a regular basis and refined the methods further.
Cloned pigs have the advantage of an identical genetic background which makes them ideal for clinical experiments where background variation must be minimized.