New Method for Generating Human Stem Cells is Remarkably Efficient

Progress toward producing cells safe to use as disease treatments
Friday, 01 October 2010

The ability to efficiently generate patient-specific stem cells from differentiated cells and then reliably direct them to form specialized cells (like neurons or muscle) has tremendous therapeutic potential for replacing diseased or damaged tissues. However, despite some successes, there have been significant limitations associated with existing methods used to generate human induced pluripotent stem cells (iPSCs).

Now, a study published by Cell Press on September 30th in the journal Cell Stem Cell presents a novel strategy for creating iPSCs that exhibits some significant advantages when compared with current iPSC technologies. The new method does not require risky genetic modification and holds great promise for making the reprogramming process more therapeutically relevant.


At the same time they appear to have

found a way to produce and program

iPS cells in an experimental and medically

useful way, Derrick Rossi’s (above) group

reports it has also found a method that is

far more efficient than previous methods

for producing iPS cells. Credit: Photograph

by Justin Ide/Harvard Staff Photographer.

"Clinical application of iPSCs is currently hampered by low efficiency of iPSC generation and protocols that permanently alter the genome to effect cellular reprogramming," explains senior study author, Dr. Derrick J. Rossi from Harvard Medical School.

"Perhaps even more importantly, safe and effective means of directing the fate of patient-specific iPS cells towards clinically useful cell types are lacking."

In the current study, Dr. Rossi and colleagues did not take the standard approach to permanently alter the genome to achieve expression of protein factors known to reprogram adult cells into iPSCs. Instead, they developed synthetic modified messenger RNA molecules (which they termed "modified RNAs") that encoded the appropriate proteins but did not integrate into the cell's DNA.

Repeated administration of the modified RNAs resulted in robust expression of the reprogramming proteins in mature skin cells that were then converted to iPSCs with startling efficiency.

"We weren't really expecting the modified RNAs to work so effectively, but the reprogramming efficiencies we observed with our approach were very high," says Dr. Rossi.

Importantly, the modified RNA method was also used to successfully to control the fate of the iPSCs.

"Creation of iPSCs is the critical first step towards patient-specific therapies, but to truly realize the promise of iPS cell technology for regenerative medicine or disease modelling, we must harness the potential of iPS cells to generate clinically useful cell types," notes Dr. Rossi.

RNA-induced iPSCs with an RNA associated with muscle cell development caused the cells to differentiate into muscle cells — again simply, efficiently and without the immediate risk of inducing genetic mutations.

These findings demonstrate that the novel RNA-induced iPSC technology offers significant advantages over existing methodologies.

"Our technology represents a safe, efficient strategy for somatic cell reprogramming and directing cell fate that has wide ranging applicability for basic research, disease modelling and regenerative medicine," concludes Dr. Rossi.

"We believe that our approach has the potential to become a major and perhaps even central enabling technology for cell-based therapies."

Source: Cell Press
Contact: Cathleen Genova

Reference:
Highly Efficient Reprogramming to Pluripotency and Directed Differentiation of Human Cells with Synthetic Modified mRNA
Luigi Warren, Philip D. Manos, Tim Ahfeldt, Yuin-Han Loh, Hu Li, Frank Lau, Wataru Ebina, Pankaj K. Mandal, Zachary D. Smith, Alexander Meissner, George Q. Daley, Andrew S. Brack, James J. Collins, Chad Cowan, Thorsten M. Schlaeger, and Derrick J. Rossi
Cell Stem Cell, 30 September 2010, 10.1016/j.stem.2010.08.012

See also:
mRNA Offers A Safer Way to Reprogram Cells
CellNEWS - Saturday, 24 July 2010
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ZenMaster

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For more on stem cells and cloning, go to CellNEWS at
http://cellnews-blog.blogspot.com/

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The Lost Correspondence of Francis Crick

New twists in double helix discovery story are uncovered. Two Watson School professors find unread correspondence of Francis Crick
Thursday, 30 September 2010

The story of the double helix's discovery has a few new twists. Two professors at the Watson School of Biological Sciences at Cold Spring Harbor Laboratory (CSHL) have uncovered a new primary source – a never-before-read stack of letters to and from Francis Crick, and other historical materials dating from the years 1950-76.

The letters both confirm and extend current knowledge of the circumstances surrounding the epoch-making discovery of DNA's elegant double-helical structure, for which Crick, James D. Watson (now CSHL's chancellor emeritus) and Maurice Wilkins were awarded the 1962 Nobel Prize in Medicine and Physiology. Unlike the structure itself, which amazed even its discoverers in its simplicity, the story of the discovery has revealed a complex tangle of people, ambitions and institutional politics behind the process of scientific investigation.

"It's primarily the insights these new letters provide about the personalities of the discoverers that people will find most fascinating," says Alex Gann, Ph.D., who along with Jan Witkowski, Ph.D., uncovered the new Crick materials and co-authored a paper on them that appears in the journal Nature Sept. 30.

Following the publication of landmark works including Watson's confessional ‘The Double Helix’ in 1968 and Horace Freeland Judson's ‘The Eighth Day of Creation’ 11 years later, most historians have been content to believe that the archives had been fully explored and would not reveal much more about the double helix story. But 34 of the newfound letters are between Crick and Wilkins and draw attention to what Gann and Witkowski have described as Wilkins' "tortured soul" during the critical period 1951-53, when Watson and Crick were alternately put on, taken off and then restored to an effort to discover DNA's structure.

"We are really between forces which may grind all of us into little pieces," Wilkins wrote to Crick in one letter.

As Witkowski explains, "Maurice Wilkins on the one hand wanted to be open – he believed science should be open and was all in favour of cooperation, the exchange of ideas and data; but on the other hand, he was also mindful of his own career: he knew he had to get results and publish papers."

As the upstarts Watson and Crick, then unknowns, jockeyed for permission at Cambridge to explore the DNA structure problem, Wilkins, at King's College, was already well engaged in experimentation that would prove vital in determination of the solution. Wilkins' boss at King's, John Randall, hired Rosalind Franklin and had, unknown to Wilkins, assured her that she was in "sole charge" of the DNA work at King's. This led to conflicts between Franklin and Wilkins, who assumed he and Franklin would be partners.

This was but the beginning of a series of now historic misunderstandings. Between the lines of the newly discovered Crick letters with Wilkins, one grasps, on Wilkins' end, the anguish, and on Crick's, what at times comes across as the self-assurance and jocularity of the player possessing superior position.

This is but a fraction of the newly found letters, which were uncovered unexpectedly in the midst of an archival collection of materials donated to Cold Spring Harbor by Sydney Brenner, the distinguished molecular biologist and Nobel laureate, who worked alongside Crick following discovery of the double helix. The two shared an office at Cambridge from 1956 to 1977. Coincidentally, the CSHL Press has just released a new biography of Brenner by Errol Friedberg.

Among the new letters, there are some 30 between Crick and George Gamow, dating to 1953-64. Other of his correspondents included Leo Szilard, C. P. Snow, and J. Robert Oppenheimer, among many others. The most important of the new letters, cited in the Gann-Witkowski paper, are now in the process of being digitized at the CSHL Archives to facilitate public access.

Mila Pollock, Executive Director of the CSHL Library and Archives, says it is her hope that digitization will proceed so that the Crick correspondence in its entirety will be accessible to all via the Internet. The greater part of the collection resides at the Wellcome Library.

Source: Cold Spring Harbor Laboratory
Contact: Peter Tarr

Reference:
The Lost Correspondence of Francis Crick
Alexander Gann and Jan A. Witkowski
Nature 467, 519-524 (30 September 2010), doi:10.1038/467519a
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ZenMaster

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For more on stem cells and cloning, go to CellNEWS at
http://cellnews-blog.blogspot.com/

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Glowing Stem Cells May Help Repair Damaged Hearts

Glowing Stem Cells May Help Repair Damaged Hearts
Tuesday, 28 September 2010

Stem cells that glow like fireflies could someday help doctors heal damaged hearts without cutting into patients' chests.

In his University of Central Florida lab, Steven Ebert, an associate professor in UCF's College of Medicine, engineered stem cells with the same enzyme that makes fireflies glow. The "firefly" stem cells glow brighter and brighter as they develop into healthy heart muscle, allowing doctors to track whether and where the stem cells are working.

Researchers are keenly interested in stem cells because they typically morph into the organs where they are transplanted. But why and how fast they do it is still a mystery. Now Ebert's cells give researchers the ability to see the cells in action with the use of a special camera lens that picks up the glow under a microscope.

"The question that we answered was, 'How do you follow these cells in the lab and find out where they're going?'" said Ebert.

If doctors can figure out exactly how the cells repair and regenerate cardiac tissue, stem cell therapies could offer hope to more than 17.6 million Americans who suffer from coronary disease. The glow of the enzyme also means therapies would no longer require cutting into patients' chest cavities to monitor the healing.

Now that scientists can track the stem cells, Ebert said he hopes to use them in disease models to determine how they heal a damaged heart and what conditions are most suitable for the stems cells to thrive.

Source: University of Central Florida
Contact: Zenaida Gonzalez Kotala

Reference:
Generation of Novel Reporter Stem Cells and Their Application for Molecular Imaging of Cardiac-Differentiated Stem Cells In Vivo
Ramana K. Kammili, David G. Taylor, Jixiang Xia, Kingsley Osuala, Kellie Thompson, Donald R. Menick, Steven N. Ebert
Stem Cells and Development. September 2010, 19(9): 1437-1448, doi:10.1089/scd.2009.0308
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ZenMaster

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For more on stem cells and cloning, go to CellNEWS at
http://cellnews-blog.blogspot.com/

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