The new study, led by Su-Chun Zhang, compared five embryonic stem cell lines with twelve induced stem cell lines. They found that the induced pluripotent stem cells (iPS) converted to neuron cells do not match all the differentiations made by embryonic stem cells. The study also showed that iPS cells created without using genes, which in theory should have resulted in ‘cleaner’ differentiation, did no better than gene induced cells. As Dr. Zhang explains…

It was predicted that the absence of exotic genetic factors would result in cells essentially identical to embryonic stem cells. “It is totally surprising that doesn’t happen at all,” says Zhang. “It tells us the techniques for generating induced pluripotent stem cells are still not optimal. There is room for improvement.”

Despite their unpredictability, Zhang notes that induced stem cells can still be used to make pure populations of specific types of cells, making them useful for some applications such as testing potential new drugs for efficacy and toxicity. He also noted that the limitations identified by his group are technical issues likely to be resolved relatively quickly.

“It appears to be a technical issue,” he says. “Technical things can usually be overcome.”

The key, he explains, is determining what things are at play that make the induced cells different.

[Source: EurekAlert]

It is unclear whether not knowing ‘what things are at play’ – possibly some fundamental information is missing – constitutes a technical issue.

Of course, turning fat cells into stem cells is not simple. In the case of this research, it resulted from a fortunate combination of skills and knowledge.

The finding brings together disparate areas of Stanford research. Kay’s laboratory invented the minicircles several years ago in a quest to develop suitable gene therapy techniques. At the same time, Longaker was discovering the unusual prevalence and developmental flexibility of stem cells from human fat. Meanwhile, Wu was searching for ways to create patient-specific cell lines to study some of the common, yet devastating, heart problems he was seeing in the clinic.
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“This is a great example of collaboration,” said Longaker. “This discovery represents research from four different departments: pediatrics, surgery, cardiology and radiology. We were all doing our own things, and it wasn’t until we focused on cross-applications of our research that we realized the potential.”

“About three years ago Mark gave a talk and I asked him if we could use minicircles for cardiac gene therapy,” said Wu. “And then it clicked for me, that we should also be able to use them for non-viral reprogramming of adult cells.”

[Source: EurekAlert]

Kay’s ‘minicircles’ are DNA elements arranged in microscopic rings. These can be injected into the body of a cell to look and work somewhat like the cell’s own plasmids (circular DNA molecules found outside of the cell nucleus). The minicircles then direct the cell’s RNA to produce DNA, RNA, or other proteins for therapeutic effect. This is a proven technique that has a great virtue in not using viruses to reprogram DNA/RNA (viruses being difficult to safely filter and control). However, the technique had not been used before to reprogram adult cells into stem cells.

The minicircles were applied to fat cells because Wu’s and Longaker’s research had shown this type of adult cell to have a good DNA configuration for reprogramming and was relatively easy to isolate.

The final experiments with minicircles and fat cells, done in vitro (in a Petri dish), showed that stem cells were created at the rate of about 0.005% of cells – a low rate compared to other techniques, but given the plenitude of fat cells, not a problem for production. The stem cells produced appear to have no differences from pluripotent cells from other sources.

As time will tell, if this method for producing stem cells is viable and scalable (can be done in large quantities), then it is indeed a major step toward making stem cells available for many kinds of diagnostic and therapeutic applications.

Unfortunately, with all the noise the quietly important may go unnoticed. When I see this headline: Researchers directly turn mouse skin cells into neurons, skipping iPS stage; it’s likely to go floating past my consciousness without even dragging its feet. There are so many stories these days involving creation of this or that stem cell, or of turning this or that stem cell into some other type of cell. All of them promise to make creation of stem cells easier, or the use of stem cells to replace/repair this or that body cell. Each announcement represents one of a thousand steps, a few of which will certainly lead to important medical procedures, but for now just a lot of ‘attaboys!’ for the scientists toiling on their research agenda.

I bet you’ve already forgotten the ‘Researchers directly turn mouse skin cells into neurons, skipping iPS stage.’ It could be you’re unfamiliar with the abbreviation iPS. It stands for induced Pluripotent Stem cell. Pluripotent stem cells can turn into almost any kind of cell. They’re not as flexible that way as embryonic or totipotent stem cells, but close. When a researcher ‘induces’ a pluripotent stem cell, it means they take a typical ‘adult cell’ – one that has already undergone differentiation to become a specific type of cell, say a skin cell – and one way or another forces it to become a stem cell of the pluripotent variety. Stem cell research is full of attempts to create cells from anything other than embryonic stem cells, largely because of the controversy and ethical uncertainty of using cells from human embryos. The typical approach is: Take a mouse cell, a skin (epithelial) cell, and induce it to become a pluripotent cell. Then take the iPS cell and turn it into another kind of cell, for example, a neuron. This seems logical, since differentiating a pluripotent (or embryonic) stem cell is what these cells are meant to do.

This two phase method, with many steps, is time consuming. What if you could go directly from an adult cell, the skin cell, and turn it into a neuron, without going through the iPS phase? Obviously it would be quicker, but most researchers would say, ‘It doesn’t work that way.’ Ah, but it can.

To make this ‘unprecedented’ transformation, it’s necessary to get down and molecular to alter a few genes. But which genes? This is where the researchers at Stanford University (California, USA) started to earn their grant money. They began with a candidate list of 19 genes in mice, all involved with epigenetic reprogramming or neural development. They altered these genes in a virus (lentivirus) and injected the virus into the skin cells of mice. In just over a month some cells developed properties associated with neurons. Further testing narrowed the genes down to just three, and when these were altered and injected, about 20% of the skin cells from the tail of mice became functional neurons.

This was astonishing in (at least) two respects: The rate of cell differentiation success, 20%, is phenomenally high. Typically only 1-2% of adult cells can be induced to become pluripotent. Second, the speed was also extraordinary, just a week as compared to many weeks for the iPS procedure. Faster, better, cheaper – take all three. As one of the researchers put it:

“We actively and directly induced one cell type to become a completely different cell type,” said Marius Wernig, MD, assistant professor of pathology and a member of Stanford’s Institute for Stem Cell Biology and Regenerative Medicine. “These are fully functional neurons. They can do all the principal things that neurons in the brain do.” That includes making connections with and signaling to other nerve cells — critical functions if the cells are eventually to be used as therapy for Parkinson’s disease or other disorders.
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“We were very surprised by both the timing and the efficiency,” said Wernig. “This is much more straightforward than going through iPS cells, and it’s likely to be a very viable alternative.” Quickly making neurons from a specific patient may allow researchers to study particular disease processes such as Parkinson’s in a laboratory dish, or one day to even manufacture cells for therapy.

The research suggests that the pluripotent stage, rather than being a required touchstone for identity-shifting cells, may simply be another possible cellular state. Wernig speculates that finding the right combination of cell-fate-specific genes may trigger a domino effect in the recipient cell, wiping away restrictive DNA modifications and imprinting a new developmental fate on the genomic landscape.

“It may be hard to prove,” said Wernig, “but I no longer think that the induction of iPS cells is a reversal of development. It’s probably more of a direct conversion like what we’re seeing here, from one cell type to another that just happens to be more embryonic-like. This tips our ideas about epigenetic regulation upside down.”

[Source: EurekAlert]

That last line, “…tips our ideas about epigenetic regulation upside down” is the kicker, potentially the initial words of a call to ‘revolution.’ He’s saying, modestly, that stem cell scientists may have it all wrong. In the domain of cell differentiation, any cell can go any which way, it all depends on the genetics, the genetics depend on their expression (epigenetic regulation), and could be added, expression is keyed to both the DNA and the environment.

How serious are the Stanford researchers about their findings? They’ve applied for a patent on the technique.

Here’s a recent announcement that pushes into important territory.

A team led by scientists from The Scripps Research Institute has developed a method that dramatically improves the efficiency of creating stem cells from human adult tissue, without the use of embryonic cells. The research makes great strides in addressing a major practical challenge in the development of stem-cell-based medicine.
The findings were published in an advance, online issue of the journal Nature Methods on October 18, 2009.
The new technique, which uses three small drug-like chemicals, is 200 times more efficient and twice as fast as conventional methods for transforming adult human cells into stem cells (in this case called “induced pluripotent stem cells” or “iPS cells”).

“Both in terms of speed and efficiency, we achieved major improvements over conventional conditions,” said Scripps Research Associate Professor Sheng Ding, Ph.D., who led the study. “This is the first example in human cells of how reprogramming speed can be accelerated. I believe that the field will quickly adopt this method, accelerating iPS cell research significantly.”

In May of 2009, the Scripps team offered a solution to the problem of inducing stem cells by inserting two genes (c-Myc and Oct4) with known carcinogenic potential. They demonstrated a technique using pure – safe – proteins to induce cell conversion. Then the team turned to the problem of making quantities of stem cells more rapidly.

Attempting to increase the efficiency of the process even further, the team decided to enlist another natural pathway, the cell survival pathway. After screening a library of compounds targeting this pathway, the team focused on a novel compound called Thiazovivin.

The researchers found that a technique using Thiazovivin in combination with the two previously selected chemicals, SB43142 and PD0325901, beat the efficiency of the classic method by 200 times.

In addition, while the classic method required four weeks to complete, the new method took two weeks.

In addition to its virtues of speed and efficiency, Ding emphasizes that the safety profile of the new method is highly promising. Not only is the method based on natural biological processes, he said, but also the type of molecules used have all been tested in humans.

[Source: EurekAlert]

A team of Harvard Stem Cell Institute (HSCI) researchers has made a major advance toward producing induced pluripotent stem cells, or iPS cells, that are safe enough to use in treating diseases in patients.

The chemical the team used is a small molecule that members named RepSox in honor of another Boston team. It replaces Sox2 and cMyc, two of the four genes currently being used to reprogram adult skin cells into an embryonic-like state. Because cMyc is a tumor promoter and iPS cells created using it could never be used to treat patients, researchers have been looking for ways to turn back the cellular clock without the use of genes.

“This discovery is exciting because it demonstrates the feasibility of using chemicals to make safer patient-specific stem cells for transplantation medicine,” said Justin K. Ichida, a postdoctoral fellow in Eggan’s lab and the first author on the study. “One of the most important things we learned is that with respect to molecular pathways there may be several ways to convert one type of cell into another. By using a nonbiased chemical screening approach, we uncovered a previously unknown way to make stem cells. The big challenge over the next decade will be to figure out how to make the right cells for disease treatment. This approach will be important for achieving that goal.”

[Source: Stem Cell Digest]

Umbilical cord blood cells can successfully be reprogrammed to function like embryonic stem cells, setting the basis for the creation of a comprehensive bank of tissue-matched, cord blood-derived induced pluripotent stem (iPS) cells for off-the-shelf applications, report researchers at the Salk Institute for Biological Studies and the Center for Regenerative Medicine in Barcelona, Spain.

“Cord blood stem cells could serve as a safe, “ready-to-use” source for the generation of iPS cells, since they are easily accessible, immunologically immature and quick to return to an embryonic stem cell-like state,” says Juan-Carlos Izpisúa Belmonte, Ph.D., a professor in the Salk’s Gene Expression Laboratory, who led the study published in the October issue of the journal Cell Stem Cell.

[Reference: AAAS: Medicine]

Spurred, in part, by the controversy over embryonic stem cells, scientific teams all over the world have turned to many different sources (body tissues like muscle, bone, and now umbilical blood) for the production of both pluripotent and totipotent cells. Umbilical blood is a particularly useful source because the cells are immature, that is, closer to the original embryonic stem cells, than cells derived from adult cells. Umbilical cells also are less prone to immunological contamination. In short, this promises to be a readily available, relatively easy to process, and uncontroversial source.