The techniques used by South Korean researchers to create the first cloned human embryos have been adapted by a University of Pittsburgh team to produce cloned monkey embryos.

Calvin Simerly of the Pittsburgh Development Center at Magee-Womens Research Institute reported today at the American Society for Cell Biology meeting in Washington, D.C., that three embryos developed to the stage at which embryonic stem cells could be recovered.

But 135 embryos that were transferred to 25 female monkeys failed to produce any pregnancies.

Gerald Schatten, the center's director, said the monkey experiments provide confirmation of the South Korean technique. Though no stable embryonic stem cell lines were produced from the three blastocysts, the work nevertheless suggests that therapeutic cloning to produce stem cells may well be possible in humans.

But Schatten said the failure to produce any pregnancies adds to the weight of evidence suggesting that reproductive cloning is difficult, if not impossible, in humans and other primates and that there is little prospect for producing a cloned human baby in the foreseeable future.

Though reproductive cloning is opposed by a wide array of scientists and non-scientists alike, scientists have been interested in producing cloned embryos as a means of obtaining embryonic stem cells for possible therapies. Stem cells obtained from a patient's clone presumably would be compatible with that patient's tissues and not subject to rejection by the patient's immune system.

More details in tomorrow's Pittsburgh Post-Gazette.