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Thursday, November 15, 2007

CLONING of PRIMATES


As all know they have already been cloned sheep (Dolly), mice and partially human beings (single embryonic clone created at the University of Newcastle/UK, that lasted a few days and did not produce any stem cell). For Josephine Quintavalle (Comment on Reproductive Ethics): "bring a clone to term is the only way to demonstrate that the cloned tissue is safe." I) So far, the cloning of primates and humans has been difficult (poor and inefficient reprogramming, poor embryonic development, are needed hundreds of eggs to produce early embryos). Some scientists believe that this is due to the fact that the cycle of cloned embryo, do not agree with the cycle of the subrogated mother. Novelty now is the recent cloning of primate fibroblasts, conducted in USA (Oregon National Primate Research Center/Oregon Stem Cell Center), employing the technique: Somatic Cell Nuclear Transfer (SCNT), in which the DNA of skin fibroblasts from a Rhesus macaca, adult, 10 years (called Semos) was inserted into a non fertilized egg, to which was previously extracted its own genetic material. To the reconstituted egg, was extracted (in early embryo stage), 2 stem cells lines (CRES-1, CRES-2), genetically identical to the donor (molecular analysis of nuclear and mitochondrial DNA of donor and clone, proved to be identical).

Finally multiple stem cell clones were differentiated into several types cells (heart and nerve cells) in vitro and in vivo, providing clues to the potential cure or alleviate symptoms of degenerative diseases (Diabetes, Parkinson's), while avoiding the rejection of the system inmnune. To generate these 2 lines of stem cells, were required 304 eggs, while for cloning Dolly, it took 277 eggs. II) Shoukhrat Mitalipov, head of the study, said that he have employed a machine emitting polarized light (Oosight Imaging System), to illuminate the structures and cellular DNA in real time, facilitating their removal. Past dyes Hoechst and ultraviolet light (according to Mitalipov), damaged the egg. Alison Murdoch and Mary Herbert (North of England Stem Cell Institute :NESCI), said that "this was the first convincing evidence that nuclear reprogramming is possible in primates." Previously, Gerald Schatten (2003), after studying 716 eggs monkeys, said that it was impossible to clone primate cells.

CLONACION de PRIMATES

Como es de conocimiento público, ya se han clonado ovejas (Dolly), ratones y parcialmente humanos (único clon embriónico creado en la Universidad de Newcastle/UK, duró pocos días y no produjo ninguna célula madre). Para Josephine Quintavalle (Comment on Reproductive Ethics): “traer un clon a término es el único modo de demostrar que el tejido clonado es seguro”. I) Hasta ahora la clonación de primates y humanos ha sido dificultosa (pobre e ineficiente reprogramación, pobre desarrollo embrionario, se necesitan centenas de huevos para generar embriones tempranos. Algunos cientificos opinan que ello se debe a que el ciclo del embrión clonado, no coincide con el ciclo de la madre que actúa como subrogada. La novedad ahora es la reciente clonación de fibroblastos de primate, realizada en USA (Oregon National Primate Research Center/Oregon Stem Cell Center), empleando la técnica : Somatic Cell Nuclear Transfer (SCNT), mediante la cual el DNA de fibroblastos de piel de un Rhesus macaca, adulto, de 10 años (llamado Semos), fué insertado en un huevo no fertilizado al que previamente se le había removido su propio material genético. Reconstituido el huevo, se extrajeron del embrión temprano, 2 lineas celulares de células madre (CRES-1, CRES-2), genéticamente idénticas a las del donador (análisis moleculares del DNA nuclear y mitocondrial de donador y clon, demostraron ser idénticos).

Finalmente los clones de células madre fueron diferenciadas a múltiples tipos celulares (células cardiacas y nerviosas), in vitro e in vivo, dando pié a la potencial cura o alivio de sintomas de enfermedades degenerativas (Diabetes, Parkinson), al mismo tiempo que se evita el rechazo del sistema inmnune. Para generar estas 2 lineas de células madre, fueron necesarios 304 huevos, mientras que para clonar a la oveja Dolly, fueron necesarios 277 huevos. II) Shoukhrat Mitalipov, jefe del estudio, refiere haber empleado una maquina emisora de luz polarizada (Oosight Imaging System), para iluminar las estructuras celulares y el DNA en tiempo real, facilitando su extracción. Los anteriores tintes de Hoechst y luz ultravioleta (según Mitalipov), dañaban al huevo. Alison Murdoch y Mary Herbert, del North-East England Stem Cell Institute (NESCI), dijeron que “era la primera evidencia convincente de que la reprogramación nuclear es posible en primates". Previamente, Gerald Schatten (2003), tras estudiar 716 huevos de monos, dijo que era imposible clonarlos.

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