U. researchers advance cloning studies

One plus one equals eight?

It does according to a new study done by researchers at the Veterinary School of Medicine.

In the Oct. 1 edition of European Molecular Biology Organization Journal, Penn Vet School researchers reported that combining two cloned embryos at the precarious four-cell stage increased their survival rate from 1 to 8 percent.

This means that instead of one cloned mouse pup being born, a litter of four were produced, said K. John McLaughlin, professor of animal biology at the Vet School and one of the study's authors. Michele Boiani, Sigrid Eckardt, N. Adrian Leu and Hans Sch”ler, all of whom are affiliated with the University, co-wrote the paper.

One of cloning's main problems involves the proteins needed for embryonic development. The researchers noticed that cloned mouse embryos had half the normal number of cells for the blastocyst developmental stage, which normally follows the four-cell stage, the report noted.

They thought the blastocysts' lower cell count may have inhibited the expression of a protein called Oct4, which has been demonstrated to influence cloned embryos' viability. By combining two embryos at the four-cell stage, the viability of the cloned embryos improved.

"There are a couple of hypotheses" about why the vitality was improved, McLaughlin said, noting that his findings supported the idea that the additional cells compensate for damage found in any one cell's DNA.

"I think the results are very interesting," said Keith Latham, professor at the Fels Institute for Cancer Research at the Temple University School of Medicine. "The interesting aspect of the paper is that it shows how cells in aggregate embryos correct each other. It indicates a new understanding of cell-cell interactions in early embryos."

"The significance is not that clear yet," he added, noting that more research needs to be done to precisely determine why the aggregated embryos survive at a higher rate.

The study was funded through grants from the National Institutes of Health, the University of Pennsylvania Research Foundation, United States Department of Agriculture, Marion Dilley and David George Jones Funds and the state of Pennsylvania.

The paper is part of a four-year research program, McLaughlin said. Previous papers have been published, including one which identified an abnormal gene in clones.

Future research may involve "doing similar experiments with bovine embryos," McLaughlin said, adding that any such research in that area would be published over a year from now.

Please note All comments are eligible for publication in The Daily Pennsylvanian.