Stem cell gene therapy combination could help children battling a rare genetic disorder

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A child with Hunter Syndrome

Hunter syndrome is devastating. It’s caused by a single enzyme, IDS, that is either missing or malfunctioning. Without the enzyme the body is unable to break down complex sugar molecules and as those build up they cause permanent, progressive damage to the body and brain and, in some instances, result in severe mental disabilities. There is no cure and existing treatments are limited and expensive.

But now researchers at the University of Manchester in England have developed an approach that could help children – the vast majority of them boys – suffering from Hunter syndrome.

Working with a mouse model of the disease the researchers took some blood stem cells from the bone marrow and genetically re-engineered them to correct the mutation that caused the problem. They also added a “tag” to the IDS enzyme to help it more readily cross the blood brain barrier and deliver the therapy directly to the brain.

In a news release Brian Bigger, the lead researcher of the study published in EMBO Molecular Medicine, said the combination therapy helped correct bone, joint and brain disease in the mice.

“We expected the stem cell gene therapy approach to deliver IDS enzyme to the brain, as we have shown previously for another disease: Sanfilippo types A and B, but we were really surprised to discover how much better the tag made the therapy in the brain. It turns out that the tag didn’t only improve enzyme uptake across the blood brain barrier, but also improved uptake of the enzyme into cells and it appeared to be more stable in the bloodstream – all improvements on current technology.”

While the results are very encouraging it is important to remember the experiment was done in mice. So, the next step is to see if this might also work in people.

Joshua Davies has made a video highlighting the impact Hunter syndrome has on families: it’s called ‘Living Beyond Hope’

In a stem cell first, functioning human kidney structures grown in living animals

One of the ultimate quests in the stem cell field – growing organs to repair diseased or damaged ones – took a significant step forward this week. In a first, researchers at the University of Manchester, in the U.K., showed that human embryonic stem cell-derived kidney tissue forms into functional kidney structures, capable of filtering blood and producing urine, when implanted under the skin of mice.

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Cross-section of human stem cell-derived kidney tissue grown in mouse. When injected in blood, dextran (green) was taken up by the kidney structure, proving it’s functional. (Credit University of Manchester/ Stem Cell Reports)

When a person has end-stage kidney disease, their body can no longer filter out waste products and extra fluid from the blood which leads to serious health complications, even death. Blood filtration therapy, called dialysis, can substitute for a kidney but the average life expectancy is only about 10 years for patients receiving dialysis. Kidney transplants are another answer for treating kidney disease, but organ availability is in limited supply. About 2.2 million people die worldwide from a lack of access to these treatment options. So other therapeutic approaches to help end-stage kidney disease sufferers are sorely needed.

The current study, published in Stem Cell Reports, used human embryonic stem cells to grow kidney tissue in the lab. While the lab-grown tissues showed hallmarks of kidney structures, they were unable to fully develop into mature kidney structures in a culture dish. So the scientists tried implanting the human kidney tissue under the skin of mice and left it there for 12 weeks. The team showed that kidney structures, called glomeruli, which play a key role in filtering the blood, formed over that time and had become vascularized, or connected with the animal’s blood supply. The team further showed those structures were functional by injecting a fluorescently tagged substance called dextran. Tracing the fate of the dextran in the blood showed that it had been filtered and taken up by tubular structures in the kidney tissue which indicates urine production had begun.

Professor Sue Kimber, one of the leaders of the study, summed up the significance and current limitations of these results in a press release:

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Sue Kimber

“We have proved beyond any doubt these structures function as kidney cells by filtering blood and producing urine – though we can’t yet say what percentage of function exists. What is particularly exciting is that the structures are made of human cells which developed an excellent capillary blood supply, becoming linked to the vasculature of the mouse.

Though this structure was formed from several hundred glomeruli, and humans have about a million in their kidneys – this is clearly a major advance. It constitutes a proof of principle- but much work is yet to be done.”

To be sure, curing a person suffering from end-stage kidney disease with a stem cell-grown kidney is some ways off. But, on the nearer horizon, this advance will provide a means to study the human kidney in a living animal, a powerful tool for uncovering insights into kidney disease and new therapeutic approaches.

Meet the proteins that tell stem cells where to move and how

 

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Word cloud art work which shows all the proteins identified by the researchers

The environment you grow up in can have a huge influence on how you turn out. That applies to people, and to stem cells too. Now a new study has identified 60 proteins that can have a big impact on how cells react to the world around them, and how they communicate with each other.

Just as it is easier for us to move across firm ground than it is to slosh our way through a soggy, muddy field, it’s easier for stem cells to move smoothly and quickly over a solid surface than over a soft, giving surface. This is particularly true for tumor cells, which move much faster on a hard surface than any other kind.

It’s not just speed that is affected by the kind of surface you place stem cells on. For example certain stem cells placed on a hard surface will specialize and turn into bone, whereas if you place those same cells on a very soft surface they will turn into nerve cells.

The problem is we didn’t know much about why that was the case, we didn’t understand the mechanism at play that caused those cells to behave that way.

Now we do.

A team at the University of Manchester in England tackled this problem by researching integrins; these are receptors that are responsible for cell-to-cell communication, cell growth and function. Integrins are typically found at the surfaces and edges of cells and provide proteins with a convenient place to hang out when they interact with the world around them.

The researchers looked at 2400 examples of these integrin-protein clusters and, using mass spectrometry, narrowed their search down to 60 proteins that they identified as being essential in linking information from the integrins to the rest of the cellular world.

The work was published in Nature Cell Biology. In an accompanying news release Dr. Jon Humphries, one of the lead researchers, talked about the significance of the work:

“Understanding how cells sense their environment is an important step in understanding how, for example, cancer cells move or how stem cells take on different jobs.”

His colleague, Professor Martin Humphries, says understanding how cells sense where they are and how to behave gives us new insights into how we can use that knowledge to better control their movement:

“Our findings on how cells sense their environment have unlocked an important key to understanding how we can persuade cells to form different tissues and how we might stop cell movement in diseases such as cancer.”