Aarhus University Seal / Aarhus Universitets segl

Frogs and pigs help people

Cloned pigs with transferred genes from humans plus a soupçon of extract from frogs are some of the ingredients in Aarhus University's research into human diseases. New research may boost the efficiency of the technique.

[Translate to English:] Et stof fra frøer kan øge levedygtigheden af klonede grisefostre, som bruges i forskning i humansygdommme. Foto: Jacob Fog Bentzon

Miss Piggy and Kermit the Frog they are not - but almost. The fact is that a combination of pigs and frogs might benefit people. This will be revealed in research on human diseases at Aarhus University.


Danish pigs may with a small input from a small brown frog from Africa play an important role in Danish research for a number of human diseases ranging from atherosclerosis, cancer, psoriasis to Alzheimer's disease. Extract from frog eggs is used for a technique that also involves humans, pigs, genetic engineering and cloning. Aarhus University Research Foundation has just granted 0.5m DKK for a short-term project that aims to improve the part of the technique that involves the frogs.


But what do frogs and pigs have to do with human diseases? The answer is modern biotechnology. Attempts will be made to see if the pig may serve as a model for human diseases, while the frog might provide a substance that can improve the survival of cloned pig egg.


Pigs bred for disease experiments

This type of biotechnology involving the transfer of genes to pig cells which are then used for cloning. This is an area that scientists from Aarhus University are particularly skilled in.


- In the past five years some of the best results in cloning of pigs have been generated by us here at Aarhus University, says Professor Henrik Callesen.


- We hope the cloned pigs will be valuable as models for human diseases if the pigs can be used under controlled conditions for the examination of specific diseases instead of physicians having to examine these diseases in humans.


Before the pigs can be used as models for human diseases they first need to be produced. This requires a multi-step process to ensure the pigs also carry the genes for the disease the scientists are interested in. Initially copies of genes are transferred from humans to pig cells. These cells are then used for cloning. In this way a so-called transgenic egg has been made – in other words an egg that contains an additional gene from a different species. This egg will then develop in the uterus of a sow until the birth of the pigs. If the attempt is successful, these pigs may be transgenic for the disease in question. If that is the case, the transgenic pigs can then reproduce completely naturally, providing even more transgenic pigs for further studies.


Large variation

Along all the steps of this long process there will be large variations – even between the cloned pigs that have actually turned out to be not as identical as once believed. The process is furthermore not very effective. It is here that the frog will play its part. This is because the African frog Xenopus contains a substance that can be used to pre-treat the cells, thus improving their viability before they are used for cloning.


The trick is to extract the substance in the most efficient and productive manner. It is this process that the scientists will be developing in the new project. They will examine which properties of the frog egg extract can be used to identify the best extracts.


- We have already made some of the preparatory work and think we are very close to achieve the objective with this work, which will make cloning more efficient and uniform, says Henrik Callesen.


The project which starts on 1 January 2014 and lasts 10 months is supported by funds from the Aarhus University Research Foundation.


Further information: Professor Henrik Callesen, Department of Animal Science, email: henrik.callesen@agrsci.dk, telephone: +45 8715 7989, Mobile: +45 2080 3435