The first horse obtained by cloning was born at Avantea and it is the first mammal in the world born from the same donor animal cells used in nuclear transfer.
The result of the experiment was obtained by the research group of prof. Cesare Galli, at the Laboratory of Reproductive Technologies (now Avantea) in Cremona. All Avantea team took part to the research: Irina Lagutina, Gabriella Crotti, Silvia Colleoni, Paola Turini, Nunzia Ponderato, Roberto Duchi and Giovanna Lazzari. The first cloned horse is a female, born on 28 May 2003. Prometea, of normal weight, of 36 kilograms. Mother and daughter are absolutely identical, as also confirmed by DNA tests. Both are Haflinger completely brown with a white stripe on the snout.
The technique
The researchers of Galli's group followed an innovative technique, in which the pellucid zone surrounding the oocyte was removed to facilitate the merger of the egg with the nucleus from the somatic cell. Moreover, it was desired along a path that respected the animal health. The oocytes used in the experiment were in fact taken from slaughtered animals, and once performed nuclear transfer has been made to develop to the stage of a hundred cells (blastocyst). The embryos obtained were then transferred into the uterus with a non-invasive technique for trans-cervical route. A very different way instead was followed in the United States for the first clone of a mule, Idaho Gem. To get that result, reported last May in the journal Science, fetal cells were used instead of mature cells, the nucleus of which had been placed in oocytes transferred to the uterus immediately, without waiting for the embryo to be formed.
The experiment
To get the first clone of a horse two cell lines from skin cells of an adult purebred Arabian stallion and of an Haflinger (a native breed from Trentino Alto Adige) mare were used. 513 nuclear transfers were carried out in as many eggs from cell line obtained from the skin of the purebred Arabian. From these, eight embryos were formed (transferred to 4 recipients) from which they had 2 unsuccessful pregnancies. With the second cell line, derived from the Haflinger mare, 328 nuclear transfers were carried out, from which 14 were obtained. Among these, 9 were transferred into the uterus into 5 recipients and were obtained 2 pregnancies, one of which was successful.
The mare that gave birth to her clone
It happened by chance that the horse that gave birth to its clone was also the donor of the adult cell used in nuclear transfer. Practically the filly who gave birth came from a cell of its skin. "It 's a very interesting result and we got it by chance - said Galli - but now it opens new perspectives in the study of immunity in pregnancy." The result we obtained, the researcher continued, "calls into question the theories on the maintenance of pregnancy, according to which it was necessary that the fetus would be recognized as foreign.
Clones and thoroughbred
Horse clonining also opens up the possibility of obtaining clones of thoroughbred champions that are now often castrated because otherwise difficult to manage. The technique developed in Italy is easier than other techniques so far used, such as that used in the United States for mule cloning. To obtain a copy of champion horses now becomes possible, but it can not be guarantee that the clone of a champion horse can give the same performance as the original. The clone may instead be used for reproductive purposes, since it could be the only option that can allow these animals to preserve the breed for reproductive purposes.