Wednesday, June 25, 2008

TISSUE TRANSPLANT WITHOUT REJECTION


Not far away is the day that Weismann, Driesch and Roux (1800), developed the first theoretical proposals aimed at clarifying the transformation of an embryo in another adult (differentiation). Shortly thereafter (1928), Hans Spemann used eggs salamadra to show that the nucleus containing the DNA, could instruct the growth and development of an organism. In 1952, Robert Briggs and Thomas King transferred the nucleus of an egg to an embryo of a frog generating tadpoles, noting that the method did not work if the nucleus of a cell come from an adult, although John Gurdon achieved it later in frogs. In 1984, James McGrath and Davor Solter developed methods for nuclear transfer in most laboratory animals. But it was not until the birth of the sheep Dolly in 1997, when the idea of nuclear transfer (nucleus of a somatic cell, transferred to an egg previously devoid of its nucleus), using genomes of mammals adults was carried out successfully, showing that differentiation was not an irreversible process.

In recent years Shinya Yamanaka (Kyoto University/Japan), showed that it was possible to "reprogram" adult human cells into an embryonic stage, infecting cells with skin retrovirus carrying 4 genes with transcription factors, opening new avenues of knowledge in this area. A series of studies of this type have been reported recently in the Annual meeting of the International Society for Stem Cell Research (ISSCR), in Philadelphia/USA, placing regenerative medicine of damaged tissue, very close to us. The event was attended by John Gurdon (Wellcome Trust/Cancer Research UK) and Rudolf Jaenisch, (Biomedical Research Cambridge,MA USA), a pioneer of trasgénic mice. The transfer modified nuclear techniques may be applied to resuscitate endangered or extint species, creating animals with desirable characteristics to produce human proteins in the milk vaccine and generating specific embryonic stem cell lines to prevent rejection of transplanted tissues. While there is a possibility that genomes and or cells can be recreated through genetic engineering (without using eggs), was already discussed the possibility that pancreatic cells (normally secreting digestive enzymes), be converted directly into beta cells producing insulin or that epithelial cells of eye fundus, be induced to become a new kind of versatile stem cells.

TRANSPLANTE DE TEJIDOS, SIN RECHAZO.


No está lejos el dia que Weismann, Roux and Driesch (1800), desarrollaron las primeras propuestas teóricas tendientes a esclarecer la transformación de un embrión en otro individuo adulto (diferenciación). Poco después (1928), Hans Spemann empleó huevos de salamadra para demostrar que el núcleo que contiene al DNA, podia instruir el crecimiento y desarrollo de un organismo. En 1952, Robert Briggs and Thomas King transfirieron el núcleo de un embrión al óvulo de una rana generando renacuajos, notando que el método no funcionaba si el nucleo procedia de una celula adulta, aunque John Gurdon si lograra hacerlo más tarde en ranas. In 1984, James McGrath and Davor Solter desarrollaron métodos para la transferencia nuclear en la mayoria de animales de laboratorio. Pero no fué hasta el nacimiento de la oveja Dolly en 1997, en que la idea de transferencia nuclear (núcleo de una celula somatica, transferida a un óvulo con núcleo previamente enucleado), empleando genomas de mamiferos adultos fué llevada a cabo exitosamente, demostrándose que la diferenciación no era un proceso irreversible.


En los últimos años Shinya Yamanaka (Kyoto/Japan University), demostró que era posible "reprogramar" células adultas humanas hacia un estado embrionario, infectando células de piel con retrovirus que portaban 4 genes con factores de transcripción, aperturando nuevas avenidas de conocimiento en esta área. Una serie de estudios de este tipo han sido reportados recientemente en el Aannual meeting of the International Society for Stem Cell Research (ISSCR), en Philadelphia/USA, colocando la medicina regenerativa de tejidos dañados, muy cerca de nosotros. El certamen contó con la presencia de John Gurdon (Wellcome Trust/Cancer Research UK) y Rudolf Jaenisch, (Biomedical Research Cambridge, MA USA), pionero en ratones trasgénicos. Las técnicas de transferencia nculear modificadas, podrán ser aplicadas a resucitar especies en extincion, generar animales con caracteristicas deseables para producir proteinas humanas en la leche vacuna y generar lineas celulares especificas de celulas madre embrionarias que eviten el rechazo de tejidos transplantados. En tanto existe la posibilidad de que los genomas y/o las células sean recreadas mediante ingeneria genética (sin empleo de óvulos), se habla yá de la posibilidad de que células pancreáticas (normalmente secretoras de enzimas digestivas), sean convertidas directamente en células beta productoras de insulina o, que células epiteliales del fondo de ojo, sean inducidas a convertirse en un nuevo tipo versátil de células madre.

2 comments:

Anonymous said...

[url=http://akreoplastoes.net/][img]http://akreoplastoes.net/img-add/euro2.jpg[/img][/url]
[b]educational software com, [url=http://akreoplastoes.net/]microsoft office professional 2003 product key[/url]
[url=http://akreoplastoes.net/][/url] discount children's software software stores london
oem software wiki [url=http://akreoplastoes.net/]stop photoshop cs4 calling adobe[/url] pos software reseller
[url=http://rastimores.net/]buy cheap software reviews[/url] make windows xp look like vista
[url=http://rastimores.net/]music software to buy[/url] buy photoshop cd
office 2003 activation bypass [url=http://rastimores.net/]buy cheap softwares[/url][/b]

Anonymous said...

[url=http://sapresodas.net/][img]http://sapresodas.net/img-add/euro2.jpg[/img][/url]
[b]message store software, [url=http://vioperdosas.net/]autodesk autocad[/url]
[url=http://sapresodas.net/]adobe photo shop software[/url] microsoft office military discount filemaker pro 10 upgrade
mcafee free download for windows xp [url=http://sapresodas.net/]List Software[/url] adobe photoshop cs3 serial number
[url=http://vioperdosas.net/]buy software student[/url] 32-bit Retail Price
[url=http://vioperdosas.net/]adobe macromedia software llc[/url] photoshop to buy for
academic software online [url=http://sapresodas.net/]software oems[/url][/b]