Sunday, 17 April 2011

Scientists Grow 'Embryonic Eye' in Test Tube From Stem Cells For The First Time

Regenerative medicine leapt forward as Japanese scientists were able to form the precursor of an eye from embryonic stem cells.
How a cluster of humble stem cells can transform into a complex organ, such as the startlingly sophisticated eye, has long been a mystery.
Now we’re a step closer to understanding this natural miracle of self-organisation care of a study by Japanese researchers that has shown how stem cells can develop into a embryonic eye. Writing in Nature, they have shown that..
a cluster of mouse embryonic stem cells placed in a special tissue culture medium will self-organise into a three-dimensional layered structure reminiscent of the optic cup, which is a two-walled pouch-like structure that develops into the inner and outer layers of the retina during embryogenesis.
The finding is not only revealing key insights into how the eye develops, but might form the basis of regenerative techniques for producing complex organs for transplant from stem cells.
What was particularly remarkable about the self-organisation on display is that the original culture in which the embryonic stem cells was placed was unstructured and the cells were not externally coaxed into any particular shape.
Yet they were able to differentiate and form into the complex structure that forms the precursor of the eye.
This suggests the unfolding of the optic cup is governed by intrinsic, sequential, self-organising 'program' that directs the construction of the complex organ from the bottom-up.
An embryonic stem cell-derived optic cup formed by self-organization in 3D culture. Green colour is fluorescence of GFP protein that was engineered to mark retinal tissue.

"What we’ve been able to do in this study is resolve a nearly century-old problem in embryology, by showing that retinal precursors have the inherent ability to give rise to the complex structure of the optic cup," said Dr Yoshiki Sasai, Group Director of the Laboratory for Neurogenesis and Organogenesis at Japan’s RIKEN Center for Developmental Biology in Kobe, and an author on the paper.
"It’s exciting to think that we are now well on the way to becoming able to generate not only differentiated cell types, but organised tissues from ES [embryonic stem] and iPS [induced pluripotent stem] cells, which may open new avenues toward applications in regenerative medicine."

According to Professor Bernie Tuch, Director of the NSW Stem Cell Network, the study raises hope for using stem cells to produce complex organs that might be usable for transplantation, one of the end goals of regenerative medicine.
"The message from this manuscript is that if appropriate stimuli are provided to embryonic stem cells in the laboratory, organ development can begin to be induced," he said.
"Whilst what was described relates to the eye, it is theoretically possible the same outcomes might be achieved with other organs using different stimuli."
The study is particularly promising when it comes to the prospect of using stem cells to treat degenerative eye diseases, said Professor Andrew Elefanty, from Monash University.
"The hope is that the culture systems that these scientists have developed will lead to discoveries that will eventually enable the growth of sheets of human retinal cells both for the study of eye diseases and eventually for the growth of new cells to treat patients with blindness. This last wish, however, is likely to still be some way off."
The paper was published in the print edition of Nature

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