Mesenchymal Stem Cell Transplantation Improves Heart Remodeling After a Heart Attack


Stem cell scientists from the University of Maryland, Baltimore have used bone marrow mesenchymal stem cells (MSCs) to treat sheep that had suffered a heart attack. They found that the injected stem cells prevented the heart from deteriorating.

This work was a collaboration between the laboratories of Mark Pittenger, ZhonGjun Wu and Bartley Griffith from the Department of Surgery and the Artificial Organ Laboratory.

After a heart attack, the region of the heart that was deprived of oxygen undergoes cell death and is replaced by a heart scar. However, the region next to the dead cells also undergo problematic changes. The cells in these regions adjacent to dead region must contract more forcibly in order to compensate for the noncontracting dead region. These cells enlarge, but some undergo cell death due to inadequate blood supply. There are other changes that can occur, such as abnormalities in Calcium ion handling and poor contractability.

Thus, the problems that result from a heart attack can spread throughout the heart and cause heart failure. In this experiment, the U of Maryland scientists injected MSCs into the sheep hearts four hours after a heart attack to determine if the stem cells could prevent the region adjacent to the dead heart cells from deteriorating.

In this experiment, bone marrow MSCs were isolated from sheep bone marrow and put through a battery of tests to ensure that they could differentiate into bone, cartilage, and fat. Once the researchers were satisfied that the MSCs were proper MSCs, they induced heart attacks in the sheep, and then injected ~200 million MSCs into the area right next to the region of the heart that died.

After 12 weeks, tissue biopsies from these sheep hearts were taken and examined. Also, the sheep hearts were measured for their heart function and structure.

The sheep that did not receive any MSC injections continued to deteriorate and showed signs of stress. The cells adjacent to the dead region expressed a cadre of genes associated with increased cell stress. Furthermore, there was increased cell death and evidence of scarring in the region adjacent to the death region. There was also evidence of Calcium ion-handling problems in the adjacent tissue and increased cell death.

On the other hand, the hearts of the sheep that had received injections of MSCs into the area adjacent to the dead region showed a reduced expression of those genes associated with increased cell stress. Also, these hearts contracted better than those that had not received stem cell injections. There was also less cell death, less scarring, and no evidence of Calcium ion-handling problems.

Changes that occur in the heart after a heart attack are collectively referred to as “remodeling.” Remodeling begins regionally, in those areas near the dead heart cells, but these deleterious changes spread to the rest of the heart, resulting in heart failure. The injections of MSCs into the area next to the dead region clearly prevented remodeling from occurring.

This pre-clinical study is a remarkable study for another reason: the MSCs used in this study were allogeneic. Allogeneic is a fancy way of saying that they did not come from the same animal that suffered the heart attack, but from some other healthy animal. Therefore, the delivery of a donor’s MSCs into the heart of a heart attack patient could potentially prevent heart remodeling.

The main problem with this experiment is that the MSCs were injected directly into the heart muscle. In humans, such a procedure requires special equipment and carries potential risks that include perforation of the heart wall, rupture of the heart wall, or further damaging the heart muscle. Therefore, if such a technology could be adapted to a more practical delivery system in humans, then certainly human clinical trials should be forthcoming.

See Yunshan Zhao, et al., “Mesenchymal stem cell transplantation improves regional cardiac remodeling following ovine infarction.” Stem Cells Translational Medicine 2012;1:685-95.

Merry Christmas to All My Readers!!


Luke 2:1-20:

In those days Caesar Augustus issued a decree that a census should be taken of the entire Roman world. (This was the first census that took place while[a] Quirinius was governor of Syria.) And everyone went to their own town to register.

So Joseph also went up from the town of Nazareth in Galilee to Judea, to Bethlehem the town of David, because he belonged to the house and line of David. He went there to register with Mary, who was pledged to be married to him and was expecting a child. While they were there, the time came for the baby to be born, and she gave birth to her firstborn, a son. She wrapped him in cloths and placed him in a manger, because there was no guest room available for them.

And there were shepherds living out in the fields nearby, keeping watch over their flocks at night. An angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were terrified. But the angel said to them, “Do not be afraid. I bring you good news that will cause great joy for all the people. Today in the town of David a Savior has been born to you; he is the Messiah, the Lord. This will be a sign to you: You will find a baby wrapped in cloths and lying in a manger.”

Suddenly a great company of the heavenly host appeared with the angel, praising God and saying,

“Glory to God in the highest heaven,
and on earth peace to those on whom his favor rests.”
When the angels had left them and gone into heaven, the shepherds said to one another, “Let’s go to Bethlehem and see this thing that has happened, which the Lord has told us about.”

So they hurried off and found Mary and Joseph, and the baby, who was lying in the manger. When they had seen him, they spread the word concerning what had been told them about this child, and all who heard it were amazed at what the shepherds said to them. But Mary treasured up all these things and pondered them in her heart. The shepherds returned, glorifying and praising God for all the things they had heard and seen, which were just as they had been told

A very Merry Christmas to all.  God Bless You – All of You!!!

Bioprinted Amniotic Fluid-Derived Stem Cells Accelerate The Healing of Large Skin Wounds


Bioprinting is a contrived term that describes the deposition of cells on surfaces by means of inkjet printer technology. Because the inkjet squirts small quantities of ink in a precisely specified shape and pattern, inkjets can be adapted to the application of cells on living surfaces or on scaffolds fashioned in the form of living organs or tissues.

Shay Soker at the Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina, has published a remarkable study that uses inkjet technology to deposit stem cells over large skin wounds. His study shows that bioprinting is a potentially very efficient way to deliver stem cells to wounds.

There are on estimate a half a million burns treated in the US each year. Extensive burns and so-called full thickness skin wounds are usually very traumatic for patients. The mortality rates of burns are about 5% and cost ~2 billion per year. Present strategies for treating burns tend to produce extensive scarring and relatively poor cosmetic outcomes.

Tissue engineering approached have the potential to provide more effective treatments for such injuries. Graft products such as Dermagraft and TransCyte from Advanced BioHealing and Apligraft from Organogenesis are cellularized graft products composed or a polymer scaffold that is seeded with cells. Unfortunately, these are expensive to make. Cell spraying and bioprinting, which deposits cells encased in hydrogel spheres all around the wound are a cheaper and potentially more attractive approach to wound therapy.

Soker’s team used stem cells from amniotic fluid and mesenchymal stem cells for this experiments. These stem cells were grown in culture, mixed in fibrin-collagen hydrogels, and bioprinted to surgically-produced wounds on the backs of hairless (nude) mice. The wounds all closed at approximately the same rate over a two-week period for those wounds treated with amniotic-fluid stem cells or mesenchymal stem cells. Wound closing was slow for those treated with only hydrogels.

Amniotic Fluid Stem Cells
Amniotic Fluid Stem Cells

After the wounds closed, biopsies of the wounds showed that the wounds that had been treated with amniotic fluid stem cells were filled with small blood vessels. Wounds bioprinted with mesenchymal stem cells did not have quite as many blood vessels as those seen in mice treated with amniotic stem cells, and those treated only with hydrogels had hardly any. However, when the biopsies were examined in detail to find the stem cells, they were not to be found. Therefore, the stem cells were not incorporated into the wounds, but induced healing through molecules that they secreted.

Not satisfied with this, Soker and his colleagues examined the gene expression patterns of the amniotic fluid stem cells and compared them to the gene expression patterns of mesenchymal stem cells. As expected, the amniotic fluid stem cells had oodles and oodles of growth factors. Fibroblast growth factors, Insulin-like growth factors, Vascular endothelial growth factor, Hepatic growth factor, and several others were made by amniotic fluid stem cells. Mesenchymal stem cells made their fair share of growth factors, but not nearly as many ans their amniotic fluid counterparts.

From these experiments, Soker concluded that even though bioprinting is a new technology, is can deliver cells effectively to surface wounds. Also, the stem cells do not directly contribute to the healing of the wound, but induce other cells to migrate into the wound and heal it. The delivery of bioprinted cells in hydrogels has the potential to rebuild a tissue from the ground up.

See Aleksander Skardai, et al., “Bioprinted Amniotic-Fluid-Derived Stem Cells Accelerate Healing of Large Skin Wounds,” Stem Cells Translational Medicine 2012;1:792-802.

John Gurdon Embraces Human Cloning


Wesley Smith has reported that Nobel Laureate John Gurdon, who shared the Nobel Prize in Medicine this year with Japanese induced pluripotent stem cell discoverer Shinya Yamanaka, has come out in favor of human cloning.

From the story in the Daily Mail:
‘I take the view that anything you can do to relieve suffering or improve human health will usually be widely accepted by the public – that is to say if cloning actually turned out to be solving some problems and was useful to people, I think it would be accepted,’ he said. During his public lectures – which include speeches at Oxford and Cambridge Universities – he often asks his audience if they would be in favour of allowing parents of deceased children, who are no longer fertile, to create another using the mother’s eggs and skin cells from the first child, assuming the technique was safe and effective.

‘The average vote on that is 60 per cent in favour,’ he said. ‘The reasons for “no” are usually that the new child would feel they were some sort of a replacement for something and not valid in their own right. ‘But if the mother and father, if relevant, want to follow that route, why should you or I stop them?’

 

Smith then quotes from his magnificent book “Consumers Guide to a Brave New World,” which all my readers to RUN out to buy and read over and over again:

Scientists would have to clone thousands of embryos and grow them to the blastocyst stage [one week] to ensure that part of the process leading up to transfer into a uterus could be “safe,” monitoring and analyzing each embryo, destroying each one in the process. Next, cloned embryos would have to be transferred into the uteruses of women volunteers [or implanted in an artificial womb]. The initial purpose would be analysis of development, not bringing the pregnancy to a live birth. Each of these clonal pregnancies would be terminated at various points of development, each fetus destroyed for scientific analysis. The surrogate mothers would also have to be closely monitored and tested, not only during the pregnancies but also for a substantial length of time after the abortions.

Finally, if these experiments demonstrated that it was probably safe to proceed, a few clonal pregnancies would be allowed to go to full term. Yet even then, the born cloned babies would have to be constantly monitored to determine whether any health problems develop. Each would have to be followed (and undergo a battery of tests both physical and psychological) for their entire lives, since there is no way to predict if problems [associated with gene expression] might arise later in childhood, adolescence, adulthood, or even into the senior years.

 

Smith, in my view, is spot on. Therapeutic cloning will not stop at using cloned blastocysts to make patient-specific embryonic stem cell lines. The reason for this is that even though cells made from differentiated embryonic stem cells can have therapeutic value, such cells can also be rejected by the immune system of the host animal. A much more fail-safe way to do this experiment is to gestate the embryos to the fetal stage and use the fetal tissues.

Once we go down the road of cloning and destroying embryos just to make embryonic stem cell lines from them, what’s to keep us from aborting fetuses just to get their cells? This slippery slope is real and speaks volumes, none of it good, about a society that sacrifices its youngest and more vulnerable members to serve the needs of others. It cheapens human life to the nth degree and at its lowest point, it simple murder.

Gurdon, however, speaks of reproductive cloning to replace children lost through tragedy. While I can appreciate the sentiment, sentiment is an extremely poor reason basis for ethics. Folks, biology is not destiny. Cloning experiments in animals have shown us that even cloned embryos made from material taken from the same mother, that are genetically identical are neither identical to their mothers nor are they identical to each other. Random events that occur during development and the way each individual responds to their environment shapes them in a unique manner. The cloned sheep Dolly was completely unlike her cloned siblings in personality, behavior, or overall appearance. The same can be said for CC (for “Carbon Copy”), the first cloned cat, which looked unlike her mother and had a very different personality.

Yet these cloned children are asked from the second they are born to replace another child who is unlike them. The cloned child is a human person and while the right for each person to be authentically who there are in an inherent right of all human beings, this very right is denied these cloned kids – they are born for the very reason that they can be someone else. This is a violation of everything it means to be human, and it is the very reason no good thing can come from human cloning.

Gurdon is a brilliant scientist, but as we have seen before, great scientists sometimes make terrible ethicists.

A Patient-Friendly Way to Make Stem Cells


Scientists at Cambridge University in the laboratory Amer Ahmed Rana have used blood samples to isolate cells from which patient-specific stem cells were made. Because blood samples are far more routine than tissue or organ biopsies, they can provide a much more patient-friendly way to secure material for the production of patient-specific stem cells.

Induced pluripotent stem cells (iPSCs) are made from adult cells by genetic engineering techniques that introduce four specific genes into them. The adult cells then de-differentiate to a more developmentally primitive state and if these cells survive and are successfully cultured, they will form an iPSC line.

Rana and his co-workers cultured blood drawn from several heart patients to isolate a blood cells known as a “late outgrowth endothelial progenitor cell” or L-EPC. Endothelial cells are those cells that compose blood vessels, and endothelial progenitor cells or EPCs are the stem cell population that make endothelial cells. EPCs are found in bone marrow, but some are also found in the peripheral circulation.

There are two main types of EPCs: early-outgrowth and late-outgrowth EPCs. Early-outgrowth EPCs are among the first cells to form spindle-shaped clusters of cells only a few days after being placed in culture. Early-outgrowth EPCs secrete high levels of blood vessel-inducing molecules, but they have only a limited ability to proliferate. They also are able to ingest bacteria, like other white blood cells. Late outgrowth EPCs are much rarer and they grow very well in culture, but are unable to ingest bacteria. They also can form capillaries and repair damaged blood vessels when injected into laboratory animals. There is a debate as to whether or not these cells come from the bone marrow or are dislodged from blood vessels.

Rana and his colleagues have designed a protocol for converting L-EPCs into iPSCs that can then be differentiated into heart, or blood vessel cells rather easily. This practical and rather efficient method does not require tissue biopsies, which are painful and impractical in very young or very old patients, and only requires the cells available from a single, routine blood sample.

Also, because blood samples can be efficiently and safely frozen, the cells from the blood sample can be locked in time for later use, when the patient needs regenerative treatments. The ease of this procedure should, Rana hopes, push it further toward human clinical trials in the near future.

Growth Factors to Heal the Heart


When the heart suffers a heart attack, local areas of the heart experience cell death as a result of blockage in a coronary vessel. The cell death is followed by local inflammation which causes further cell death and produces a heart scar. This produces a situation in which a portion of the heart does not contract and also does not conduct impulses to beat. Can this dead heart tissue live again?

Several experiments have used stem cells to refurbish the dead heart tissue, and a variety of different stem cells can clearly produce new heart cells that help the heart beat better. Can growth factors that stimulate cell growth and division do a similar job?

Just injecting growth factors into the bloodstream will not do because the growth factors will not spend any appreciable time in or around the heart cells. Is there another way to do it? Yes. The answer is hydrogels.

Hydrogels are semi-solid materials that can be made and in which the growth factors can be embedded. The hydrogels are gradually degraded while they release growth factors into the heart tissue. The slow but stead release of various growth factors can induce the heart to heal itself.

Works from the laboratory of Michael E. Davis at Georgia Institute of Technology and Emory University School of Medicine in Atlanta, Georgia have published a paper in PLoS ONE describing this very strategy. Using rats that had suffered heart attacks, Davis and his group applied a polyethylene glycol-based hydrogel laced with two growth factors, hepatic growth factor (HGF) and vascular endothelial growth factor (VEGF) to the hearts of these animals.

There were no immediate effects to the application of these hydrogels as determined by electrocardiograms. However, with the passage of time, some remarkable changes to the hearts of these rats were observed. Three weeks after the application of hydrogels to rat hearts, animals treated hydrogel material only, injected with growth factors only showed no significant improvement over those rats that were not injected with anything. But those rats whose hearts had been injected with hydrogels laced with VEGF showed a 50% increase in blood vessel density and those injected with hydrogel imbued with HGF and VEGF showed a 100% increase in blood vessel density. These same rats also showed a huge reduction in the size of the heart scar (41.5 % vs 13.9% fibrosis), and also showed significant increased in heart function after three weeks.

Why did these growth factors work so well? Several experiments conducted by Davis’ group showed that the stem cell population in the heart, the cardiac progenitor cells or CPCs, were pitched into overdrive by the growth factors, In short, in the presence of these two growth factors, the cells went nuts. They went to area where the hydrogel had been applied and made new heart muscle cells and blood vessels.

Therefore, these two growth factors can be applied to the heart to elicit healing within the heart after a heart attack. The hydrogels keep the growth factors there and release them slowly so tat they can perform their healing magic.

Hopefully this experiment will lead to preclinical studies in larger animals (pigs and sheep), and then, hopefully, clinical trials in human patients.  See Salimath AS, et al., PLoS ONE 2012 7(11) e50980.

Mesenchymal Stem Cells Found Around Blood Vessels in the Liver


Mesenchymal stem cells (MSCs) are found throughout the body and it is possible that every organ in our body has a MSC population. MSCs have the ability to differentiate into three main tissues: bone, fat and cartilage. However, the efficiency of this differentiation differs from one MSC population to another. Also, some MSCs can form smooth muscle for blood vessels and there is even evidence that MSCs can form blood vessels under certain conditions (for example, see Wingate K, Bonani W, Tan Y, Bryant SJ, Tan W. Acta Biomater. 2012 8(4):1440-9. doi: 10.1016/j.actbio.2011.12.032).

One of the places MSCs are usually found is around blood vessels. MSCs like to hang out on the outside of blood vessels in some tissues, and for this reason, MSCs are sometimes called “perivascular” stem cells.

One organ that has a stem cell population is the liver, but there is disagreement as to where they reside. Now a new publication has established that cells that hang out near blood vessels in liver are the MSC population in liver.

Eva Schmelzer from the McGowan Institute for Regenerative Medicine at the University of Pittsburgh has published a fine paper in the journal Stem Cells and Development detailing, with the help of her trusty laboratory colleagues, the characterization of liver MSCs.

Briefly, Schmelzer and her colleagues obtained fetal and adult lover tissue from tissue suppliers and minced them up, digested them with the appropriate enzymes, pushed them through cell strainers and then destroyed all the contaminating red blood cells. The remaining cells were grown in a cell culture medium. The stem cells would outgrow all the other cells, which would make their isolation and purification easy.

To purify the cells, Schmelzer’s co-workers used a technique called “flow cytometry.” When they had purified the liver MSCs, they set about characterizing them.

The liver MSCs grew quite well in culture and also grew quickly. They also expressed lots of surface proteins normally found on MSCs, confirming that they are MSCs. When gene expression experiments examined what genes these MSCs expressed, they expressed some smooth muscle genes and a several other genes enriched in cells near blood vessels. When Schmelzer examined cross sections of liver to determine where these cells are located, she found them curled up next to blood vessels.

In culture, the liver MSCs did not make very good cartilage or fat. However, they did make very good smooth muscle and bone. The efficiency of MSC differentiation tends to depend on where they were isolated. The rule of thumb is that MSCs most easily differentiate into those tissues that are closest to their own tissue of origin. Therefore, we would expect bone marrow MSCs to make better bone and cartilage than fat-based MSCs, and we would expect fat-based MSCs to make better fat than bone or liver-based MSCs. The ability of liver MSCs to be so good and making bone might be a little surprising, but when we consider that bone marrow stem cells begin their lives in the liver before they migrate to the bone marrow, perhaps this finding makes more sense.

In short, the adult and fetal liver contain a MSC population that is found on the outside of the blood vessels and these cells have an excellent capacity to make bone and smooth muscle for blood vessels. Thus liver biopsies might provide do more than provide material for diagnostic purposes – they might secure cells for regenerative purposes.