Hello,

We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not an Insider? Subscribe now for unlimited access to online articles.

Rewriting Life

Growing Retinas

Embryonic stem cells growing in a dish ­spontaneously form ­retina-like structures.

Source: “Self-organizing optic-cup morphogenesis in three-dimensional culture”
Mototsugu Eiraku, Yoshiki Sasai, et al.
Nature 472: 51-56

The eyes have it: A soup of chemicals and undifferentiated embryonic stem cells (gray) growing in a dish spontaneously generates two cup-shaped structures (green), which resemble the embryonic retina.

Results: Mouse embryonic stem cells growing in a dish can spontaneously assemble into three-­dimensional structures reminiscent of the early embryonic retina.

This story is part of our July/August 2011 Issue
See the rest of the issue
Subscribe

Why it matters: Most efforts to grow organlike structures from stem cells involve some kind of scaffolding, often coated with specific signaling molecules, to encourage growth of the proper cell types and tissue architecture. But these findings show that at least some aspects of organ development are pre­programmed into the cells, suggesting that it may be possible to grow some tissue structures much more simply. Such retinal tissue might eventually be able to replace human tissue damaged by degenerative eye diseases.

Methods: Researchers began with about 3,000 mouse embryonic stem cells mixed with a cocktail of chemicals involved in retinal development. Over a two-week period, clusters of stem cells began to grow into balloonlike sacs, which then grew inward. These dual-layer structures resembled the optic cup, an early developmental precursor to the retina.

Next Steps: The group is now working on transplanting these structures into blind mice, in the hope of restoring vision. They are also trying to replicate the research using human cells and hope to have a human version of the system within two years.

Evolving Faster

A new way of directing protein evolution could speed drug development

Source: “A system for the continuous directed evolution of biomolecules”
David R. Liu et al.
Nature 472: 499-503

Results: Scientists used a new approach to create an enzyme designed to bind to a specific target. The process, which involved 200 rounds of protein evolution that would have taken years with conventional methods, was completed in just a week.

Why it matters: Directed evolution—sequentially introducing mutations into a protein to generate a molecule that performs a desired function—can create antibodies and other proteins that fight diseases, including cancer. But current methods are often too slow and labor-intensive to be broadly useful in drug development.

Methods: Researchers engineered M13, a rapidly replicating bacteriophage that infects E. coli, to carry a gene for the protein they wanted to modify. They then grew the viruses inside E. coli cells in an environment designed to boost the number of mistakes made when the viral DNA was copied, generating a library of slightly different proteins. The researchers linked the desired function, such as the ability to bind to the target, to a substance the viruses needed for survival, so only those viruses with the best versions of the protein progressed to subsequent rounds of evolution. Evolution took place at a rate of up to 40 rounds per day, 100 times the rate achieved with other methods.

Next Steps: The team plans to use the system to produce therapeutic proteins and to study seminal questions in evolution, such as whether replicating the same evolutionary conditions will generate different outcomes—and what factors determine these outcomes if so.

Tech Obsessive?
Become an Insider to get the story behind the story — and before anyone else.

Subscribe today
More from Rewriting Life

Reprogramming our bodies to make us healthier.

Want more award-winning journalism? Subscribe and become an Insider.
  • Insider Plus {! insider.prices.plus !}* Best Value

    {! insider.display.menuOptionsLabel !}

    Everything included in Insider Basic, plus the digital magazine, extensive archive, ad-free web experience, and discounts to partner offerings and MIT Technology Review events.

    See details+

    Print + Digital Magazine (6 bi-monthly issues)

    Unlimited online access including all articles, multimedia, and more

    The Download newsletter with top tech stories delivered daily to your inbox

    Technology Review PDF magazine archive, including articles, images, and covers dating back to 1899

    10% Discount to MIT Technology Review events and MIT Press

    Ad-free website experience

  • Insider Basic {! insider.prices.basic !}*

    {! insider.display.menuOptionsLabel !}

    Six issues of our award winning print magazine, unlimited online access plus The Download with the top tech stories delivered daily to your inbox.

    See details+

    Print Magazine (6 bi-monthly issues)

    Unlimited online access including all articles, multimedia, and more

    The Download newsletter with top tech stories delivered daily to your inbox

  • Insider Online Only {! insider.prices.online !}*

    {! insider.display.menuOptionsLabel !}

    Unlimited online access including articles and video, plus The Download with the top tech stories delivered daily to your inbox.

    See details+

    Unlimited online access including all articles, multimedia, and more

    The Download newsletter with top tech stories delivered daily to your inbox

/3
You've read of three free articles this month. for unlimited online access. You've read of three free articles this month. for unlimited online access. This is your last free article this month. for unlimited online access. You've read all your free articles this month. for unlimited online access. You've read of three free articles this month. for more, or for unlimited online access. for two more free articles, or for unlimited online access.