Category Archives: Stem Cells

Scientists said Tuesday they had used stem cells to grow human heart tissue that contracted spontaneously in a petri dish -- marking progress in the quest to manufacture transplant organs.

A team from the University of Pittsburgh, Pennsylvania, used induced pluripotent stem (iPS) cells generated from human skin cells to create precursor heart cells called MCPs. iPS cells are mature human cells "reprogrammed" into a versatile, primitive state from which they can be prompted to develop into any kind of cell of the body.

The primitive heart cells created in this way were attached to a mouse heart "scaffold" from which the researchers had removed all mouse heart cells, they wrote in the journal Nature Communications. The scaffold is a network of non-living tissue composed of proteins and carbohydrates to which cells adhere and grow on.

Placed on the 3D scaffold, the precursor cells grew and developed into heart muscle, and after 20 days of blood supply the reconstructed mouse organ "began contracting again at the rate of 40 to 50 beats per minute," said a University of Pittsburgh statement.

"It is still far from making a whole human heart," added senior researcher Lei Yang.

Ways have to be found to make the heart contract strongly enough to pump blood effectively and to rebuild the heart's electrical conduction system.

"However, we provide a novel resource of cells -- iPS cell-derived MCPs -- for future heart tissue engineering," Yang told AFP by email. "We hope our study would be used in the future to replace a piece of tissue damaged by a heart attack, or perhaps an entire organ, in patients with heart disease."

According to the World Health Organisation, an estimated 17 million people die of cardiovascular ailments every year, most of them from heart disease. Due to a shortage of donor organs, "end-stage heart failure is irreversible," said the study. More than half of patients with heart disease do not benefit from drugs.

"Heart tissue engineering holds a great promise... based on the reconstruction of patient-specific cardiac muscle," the researchers wrote.

Last month, scientists in Japan said they had grown functional human liver tissue from stem cells in a similar process. Creating lab-grown tissue to replenish organs damaged by accident or disease is a Holy Grail for the pioneering field of stem cell research.

More:
Stem Cells Grow Beating Heart

Aug. 12, 2013 CHD5 has previously been proposed as a tumour suppressor, acting as a brake that prevents healthy cells from developing into cancer cells. But the part played by the protein in healthy tissue, and whether this role is important for its ability to counter tumour growth, has remained largely uncharted. Working with colleagues at Trinity College in Dublin and BRIC in Copenhagen, researchers at Karolinska Institutet have revealed its function in normal nervous system development and as a tumour suppressor.

The recently published study shows that when stem cells approach the final phase of their specialisation as neurons, CHD5 begins to be expressed at high levels. CHD5 can reshape the chromatin, in which DNA is packed around proteins, and in so doing either facilitate or obstruct the expression of genes. Ulrika Nyman, postdoc researcher in Dr Johan Holmberg's research group and one of the main authors of the current study, explains that on switching off CHD5 in the stem cells of mice embryos during the period in which the brain develops and the majority of neurons are formed, they found was that without CHD5, a stem cell is unable to silence the expression of a number of stem cell genes and genes that are actually to be expressed in muscle, blood or intestinal cells. They also observed an inability in the stem cell to switch on the expression of genes necessary for it to mature into a neuron, leaving it trapped in a stage between stem cell and neuron.

The gene that codes for CHD5 is found on part of chromosome 1 (1p36), which is often lost in tumour cells in a number of cancers, particularly neuroblastoma, a disease that strikes almost only children and which is thought to arise during the development of the peripheral nervous system. Neuroblastoma lacking this section of chromosome and thus also CHD5 are often more aggressive and more rapidly fatal. Treatment with retinoic acid can make immature nerve cells and some neuroblastoma cells mature into specialised nerve cells, but when the researchers prevented neuroblastoma cells from upregulating CHD5, the tumours no longer responded to retinoic acid treatment.

"In the absence of CHD5, neural tumour cells cannot mature into harmless neurons, but continue to divide, making the tumour more malignant and much harder to treat," says Dr Holmberg at the Department of Cell and Molecular Biology. "We now hope to be able to restore the ability to upregulate CHD5 in aggressive tumour cells and make them mature into harmless nerve cells."

Share this story on Facebook, Twitter, and Google:

Other social bookmarking and sharing tools:

Story Source:

The above story is based on materials provided by Karolinska Institutet, via EurekAlert!, a service of AAAS.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Originally posted here:
Tumor suppressor is needed for stem cells to mature into neurons

MINNEAPOLIS -

Statistics from the Department of Health and Human Services reveal that an average of 18 people die while waiting for organ transplants each day. About 2,500 hearts are available, with a waiting list of about 100,000 patients in need.

"I couldn't walk, or breathe, or eat," said Allan Isaacs, a congestive heart failure patient.

That was life with congestive heart failure for Isaacs, 71, but after a left ventricular assist device was implanted into his chest, Allan's life got moving again.

Allan said he now does "15 minutes on the elliptical and about 30 minutes on the treadmill."

The LVAD helps pump oxygen rich blood throughout the body, but Isaacs' recovery may also have to do with the fact that his treatment may have included injections of his own bone marrow stem cells.

Isaacs is taking part in a leading edge blind study at the University of Minnesota Medical Center.

We isolate the stem cells and when they go for surgery we inject those cells on the heart wall, said Dr. Ganesh Raveendran, director of the cardiac catheterization laboratory at the University of Minnesota Medical Center.

One-third of the patients receive a placebo, the rest get 10 injections of stem cells into their hearts. Muscle tissue is then analyzed to "see whether these cells have made any meaningful change, whether the cells have transformed into cardiac muscle," Raveendran explained.

In many cases an LVAD is a bridge to transplant, but researchers and Isaacs hope this stem cell therapy could eliminate that need.

Go here to see the original:
Health Beat: Heart stem cells, LVAD may avoid transplants

U.S. scientists removed the heart from the mouse and stripped it of its cells before treating the heart with human stem cells and made it beat again The breakthrough could lead to the development of transplant organs for patients thanks to stem cells produced from simple skin biopsies University of Pittsburgh researchers used induced pluripotent stem cells - adult stem cells that act like embryonic ones

By Sarah Griffiths

PUBLISHED: 10:27 EST, 13 August 2013 | UPDATED: 11:03 EST, 13 August 2013

U.S. scientists have 'grown' a beating mouse heart from human stem cells, leading many to hope that human organs could one day be created.

The heart - which had been removed from the mouse and stripped of its cells - was treated with human stem cells and started to beat again.

The breakthrough could lead to the development of transplant organs for patients thanks to stem cells produced from simple skin biopsies.

Scientists have 'grown' a beating mouse heart from human stem cells, leading many to hope that human organs could one day be regrown. This image shows a closely packed layer of cells in the cardiac muscles

These specialised cells - induced pluripotent stem cells or iPS cells - are adult stem cells which act like embryonic ones, gaining the ability to become any cell in the human body. But embryos do not have to be destroyed to create a supply.

In principle iPS cells could be used to treat a wide range of disorders, from diabetes to Parkinson's.

Rather than managing the symptoms of the disease, the cells would be used to regenerate the affected parts of the body.

Excerpt from:
Mouse heart made from HUMAN stem cells grown by scientists

Q. Can you tell us what stem cells are? Can they really be the panacea we are looking for?

- reilly_od@yahoo.com

A. As we all know, humans arise from just a single cell, the fertilized ovum, which is the result of the union of the father's sperm cell and the mother's egg cell. Soon after it has formed, the fertilized ovum multiplies many times over to produce cells called stem cells.

The stem cells that are produced during the first few days of embryonic development are totipotential; they are very versatile cells that can transform to any specialized cell and have unlimited capability to divide and produce exact copies of themselves. But soon after they have been produced, these cells begin to specialize or differentiate, which means they commit themselves to producing only certain cell types, something they need to do to form the various tissues and organs.

As the fetus matures in the womb, its stem cells become more and more specialized such that at birth, their capabilities have markedly reduced. They can no longer produce new organs, but they can still replace those cells in the tissues and organs that die due to physiologic reasons or injury. Stems cells gradually decrease in number and potential as the individual grows older that is why with age, wounds take longer to heal, infections become more difficult to fend-off, etc. But stem cells persist throughout life. They reside in those organs whose existing functional cells they have the capability to replace.

The number and capability of stem cells vary depending on where they are located. In those organs where the lifespan of the functional cells is rather short, they are quite numerous and versatile. For example, the bone marrow has enough stem cells to continuously produce all types of blood cells. Likewise, the gastrointestinal tract and the skin have enough stem cells that can replace cells that are normally shed off or die because of injury.

But in those organs where the functional cells are long-lived such as the brain and muscles, very few stem cells persist to adulthood. Thus, often, nerve cells and muscle cells (such as those in the heart) that are lost are replaced not by functional cells, but by cells that form scar tissue.

Stem cells can be harvested, cultured in the laboratory to increase their number and then introduced to patients to replace damaged, injured or dead cells in, conceivably, any tissue or organ. Are stem cells, therefore, the panacea and fountain of youth that humanity has been seeking for since time immemorial?

Stem cell therapies that are presently being legally performed involve harvesting bone marrow stem cells from the patient to be treated. Bone marrow stem cells can replace bone marrow cells.

Thus, stem cell therapy has proven success in patients with dysfunctional bone marrow, multiple myeloma, leukemias (cancers of the blood) and a few other conditions.

Read more here:
A primer on Stem Cells

Washington, Aug 13 : A new research has revealed that healthy brain cells, once damaged by radiation designed to kill brain tumours, can be regenerated.

Alfredo Quiones-Hinojosa, M.D., a professor of neurosurgery at the Johns Hopkins University School of Medicine, who conducted the study in mice, found that neural stem cells, the body's source of new brain cells, are resistant to radiation, and can be roused from a hibernation-like state to reproduce and generate new cells able to migrate, replace injured cells and potentially restore lost function.

The findings, Quiones-Hinojosa adds, may have implications not only for brain cancer patients, but also for people with progressive neurological diseases such as multiple sclerosis (MS) and Parkinson's disease (PD), in which cognitive functions worsen as the brain suffers permanent damage over time.

The researchers examined the impact of radiation on mouse neural stem cells by testing the rodents' responses to a subsequent brain injury.

In the weeks after radiation, the researchers injected the mice with lysolecithin, a substance that caused brain damage by inducing a demyelinating brain lesion, much like that present in MS.

They found that neural stem cells within the irradiated sub-ventricular zone of the brain generated new cells, which rushed to the damaged site to rescue newly injured cells. A month later, the new cells had incorporated into the demyelinated area where new myelin, the protein insulation that protects nerves, was being produced.

The study is published in the journal Stem Cells.

Link:
Brain stem cells can be regenerated following anti-cancer treatment

T cells, colored blue here, move in to attack.

In addition to fighting off invaders that arrive from outside the body, the immune system is also able to identify cells that have gone bad inside the body. Even though cancer cells look a lot like normal ones, immune cells can often tell the differenceenough that people who receive long-term treatments of immunosuppressive drugs have a higher incidence of cancer.

But the immune system clearly has its limits, or cancer wouldn't be a problem.Cancer cells evolve ways to avoid detection or use the immune system's own signals to tamp down its activity.A number of researchers have been looking for ways to reestablish the immune system's superiority, boosting it in a way that it once again clears out cancer cells. One option for doing so has been to simply boost the cells that already recognize a tumor by isolating them and growing them in large numbers in culture.

This doesn't consistently work, however, as it can be hard to identify and isolate tumor-specific immune cells. A team of researchers has figured out a way of taking stem cells, converting them into immune cells, and directing them to attack one type of cancer.

When most people think of immune function, they tend to think of the cells that make antibodies, called B cells. The antibodies they make stick to invading cells and viruses, keeping the invaders from infecting cells and helping to attract immune cells to destroy them. But there's a second branch of the immune system that targets human cells after they become infected. The T cells recognize strange or unfamiliar proteins on the surface of human cells. When they spot them, the T cells attack and kill the infected cell while boosting the rest of the immune response.

Cancer cells can also have odd-looking proteins on their surface. These proteins can be recognized by T cells, which will then attempt to kill the cancer cell. In many cases, these anti-cancer T cells are present in the bodies of cancer patients; they're just not active in large enough numbers to keep the cancer in check. Some researchers have reasoned that getting more of these cells into the body could give the immune system an edge, so they set about isolating them, growing large numbers outside the body and then putting them back into the bloodstream.

For some cancers, initial trials of this technique suggested it could have promise. But it's not always easy to identify and isolate the immune cells that are targeting a cancer, nor is it necessarily easy to grow large numbers of them in culture.

The alternative is to use stem cells, which do grow extremely well in culture and can be available in large numbers. The problem is that stem cells don't start out recognizing anything in particular. In the body, both T and B cells mature through an elaborate process that gets rid of any cells that recognize normal, healthy human proteins and selects for those that actually have a reasonable chance of recognizing an invader. It's simply not possible to put stem cells through a similar process in a culture dish.

The new paper involves a clever solution to most of these problems. The authors started with existing T cells, which would have alreadygone through the selection process that prevents them from attacking normal cells. They then used the techniques that have been developed to induce them to adopt a stem cell fate to grow them up into large numbers.

Most of the results, however, would recognize something other than the cancer involved. So the authors engineered a hybrid receptor, with one part that recognizes a common leukemia protein and another part that plugs in to the normal T cell receptor system. They inserted these into their stem cells, converting all of them into cells that could recognize leukemia. They then converted the stem cells into T cells.

Read the original here:
Stem cells turned into cancer-killing immune cells