Mature Liver Cells Seem to be Better Than Stem Cells for Liver Therapy

Japanese research team has compared the ability of liver progenitor cells (liver stem cells) and mature liver cells to effectively repopulate a damaged liver. They have concluded that mature liver cells (hepatocytes) are better than stem cells for liver repopulation.

Workers in the laboratory of Toshihiro Mitaka of the Cancer Research Institute of the Sapporo Medical University School of Medicine, Sapporo, Japan used a rat model to test these hypotheses. They injured the livers of these rats with surgery and chemicals and then used transplanted cells to repopulate these livers. Up to two weeks after transplantation, the growth rate of the stem cells was significantly higher than that of the mature liver cells, but after two weeks the majority of the stem cells died before they could confer any significant benefit on the liver. The mature cells, however, grew slower, but survived much better.

Toshihiro Mitaka made this comment: “Cell-based therapies as an alternative to liver transplantation to treat liver disease have shown promise. However, the repopulation efficiency of hepatic progenitor/stem cells and mature hepatocytes (liver cells) had not been comprehensively assessed and questions concerning the efficiency of each needed to be resolved.”

Mitaka’s team noticed that the shortage of liver cell sources and the difficulties of preserving the available liver cell sources by freezing (cryopreservation) have limited the available material, and therefore, the clinical applications of cell-based therapies for liver disease. Liver stem cells (liver progenitor cells) have been considered to be the best option to treat liver disease, since they can be expanded in culture and preserved by freezing for long periods of time.

However, once the liver progenitor cells were transplanted into the damaged livers of rats, the stem cells failed to survive terribly well. After two months, the vast majority of the transplanted stem cells had disappeared. In contrast, the mature liver cells gradually repopulated the rat livers and the even continued growing and repopulating the damaged livers for one year after transplantation.

Transplanted liver cells did not make uniform cells. Mitaka noted that “the small hepatocytes repopulated significantly less well than the larger ones. We also found that serial transplantations did not enhance nor diminish the repopulation capacity of the cells to any significant degree.”

In this paper, Mitaka and his colleagues argue that because the stem cells died much earlier than the mature hepatocytes, the stem cells were eliminated from the host livers and this reduced their potential regenerative capacity. They conclude in the paper that further “experiments are required to clarify the mechanism by which this might occur.”

My take on this is that damaged livers probably contain a respectable amount of inflammation. Therefore, they are probably a rather hostile environment for any transplanted cells. We have seen in previous posts that stem cells have a mechanism to resist stressful conditions, but also, that this pathway for resisting stress must be activated in the stem cells before they are capable of resisting stress. Therefore, I would suggest that the next experiment Mitaka and his co-workers should do, is to either precondition his stem cells with oxygen and glucose deprivation or pre-treat them with insulin-like growth factor-1 (IGF-1). Both of these treatments have been shown to activate the stress resistant pathway in stem cells transplanted into the heart. Therefore, if this pathway could be induced in liver progenitor cells, then perhaps the stem cells can be stress-adapted and tolerate the stressful conditions in the damaged livers.

Stem Cell Dormancy Enables Them to Remain Viable Days After Death

A collaboration of several researchers from French Institutions has demonstrated that humans and mouse stem cells have the ability to become dormant when their environment becomes hostile, including several days after the death of the organism. This ability to significantly reduce metabolic activity enables them to preserve their potential for cellular division, even a long time after death. Once isolated from the cadaver, the stem cells retain their healing abilities. This discovery could be the beginning of new therapeutic avenues for treating numerous diseases.

Skeletal muscle stem cells have the ability to survive for seventeen days in humans and sixteen days in mice, after death. This discovery was made by researchers from the Institut Pasteur, the Université de Versailles Saint-Quentin-en-Yvelines, the Paris Public Hospital Network (AP-HP), and the CNRS under the direction of Professor Fabrice Chrétien, in collaboration with a team led by Professor Shahragim Tajbakhsh. These laboratories showed that once the stem cells from the cadavers were grown in culture, they retained their capacity to differentiate into perfectly functioning muscle cells.

Once they made this surprising discovery, the next step was to determine precisely how these cells survive such adverse conditions. As it turns out, the stem cells enter a deeper state of sleep (quiescence), and this drastically lowers their metabolism. This so-called “dormant” state results from stripping the functional structures of the cell to their bare minimum. For example, these cells have fewer mitochondria (cellular power plants using oxygen to produce energy in cells) and diminished stores of energy.

Fabrice Chrétien explained it this way: “We can compare this to pathological conditions where cells are severely deficient in resources, before regaining a normal cell cycle for regenerating damaged tissues and organs. When muscle is in the acute phase of a lesion, the distribution of oxygen is highly disrupted. We have even observed that muscle stem cells in anoxia (totally deprived of oxygen) at 4°C have a better survival rate than those regularly exposed to ambient levels of oxygen.”

Chrétien’s team wondered if other cell types showed similar capacities. Once again, the results were surprising. Stem cells from bone marrow where blood remained viable for four days after death in mice. More importantly, they retained their ability to reconstitute tissue after a bone marrow transplant.

This discovery could form the basis of a new source, and more importantly new methods of conservation, for those stem cells used to treat different conditions. For example, leukemia treatments require a bone marrow transplant to restore those blood and immune cells that were destroyed by chemotherapy and radiation. By harvesting stem cells from the bone marrow of consenting donors after death, doctors could address to some extent, the shortage of tissues and cells. Although highly promising, this approach in the realm of cellular therapy still requires more testing and validation before it can be used in clinical applications. However, it paves the way to investigate the viability of stem cells from all tissues and organs post-mortem.

Reprogramming Heart Fibroblasts into Heart Muscle Cells Goes to Human Trials

Last month, this blog reported on the conversion of heart-based fibroblasts into heart muscle cells after a heart attack in living, laboratory animals by means of gene therapy. Another researcher has utilized a different strategy to achieve the same result. This work has also provided the means for biotechnology companies to begin clinical trials using this very strategy.

Scar formation (fibrosis), prevents the regeneration of heart muscle and creates a scar that does not contract. The loss of contractile function leads to heart failure and death. Therapeutic goals for these conditions include limiting scar formation.

To that end, Eric C. Olson and his colleagues from UT Southwestern were able to introduce four genes (GATA4, HAND2, MEFC2, and TBX5) into heart-based fibroblasts and convert them into beating heart muscle cells. To do this, Olson and his army of graduate students, technicians, and postdoctoral research fellows made genetically engineered viruses that encoded the four genes (collective known as GHMT).  When the GHMT-viruses were injected into mouse hearts after a heart attack, the four genes reprogrammed the fibroblasts into heart muscle cells in tissue culture and inside living animals.  Furthermore, when GHMT is introduced into fibroblasts after a heart attack, the fibroblasts do not make scar tissue, but heart muscle.

Olson and his team also used techniques that allowed them to trace cells and their descendents.  These techniques showed that the heart muscle that formed after the heart attack were the result of cells that had been infected by the engineered viruses (that is, they contained viral DNA).  Thus the new heart muscle came about because the virally-infected fibroblasts turned into heart muscle that began to beat.  Also, heart imaging also showed that infection of the heart with GHMT viruses greatly boosted heart function after a heart attack in comparison to control heart that were infected by the viruses that did not contain GHMT.

Can such a technology make it way to clinical trials?  Fortunately, Eric Olson is not only chairman of the Molecular Biology department as UT Southwestern, but he is also co-founder of a medical technology company known as LoneStar Heart Inc.  Olson’s company hopes to extend his findings in laboratory animals and eventually gain approval to begin human clinical trials.  Olson noted, “These studies establish proof-of-concept for in vivo cellular reprogramming as a new approach for heart repair. However, much work remains to be done to determine if this strategy might eventually be effective in humans. We are working hard toward that goal.”

LoneStar Heart is capitalizing on previous work by Olson and others in his laboratory that have established that the delivery of the four previously mentioned genes increases heart regeneration in laboratory animals and in cultured human heart cells.  LoneStar Heart is currently trying to complete the animal studies required before the Food and Drug Administration will consider permitting a human clinical trial

Lonestar Heart, however, has other products that might play a role in treating the hearts of patients whose hearts have started to enlarge. Heart enlargement results when the heart is overworked and it reacts to this overwork by enlarging. The enlargement stretches the heart and makes the walls of the heart thinner. The result is that the heart does not beat in a coordinated fashion, and patients with enlarged hearts are at risk for irregular heart beats or sudden cardiac death.

To address enlargement of the heart, LoneStar Heart has made a product called Algisyl-LVR that is a biopolymer that stiffens when it is injected into the heart. Injection of Algisyl-LVR into the walls of a heart that has enlarged thickens the heart wall without interfering with heart function. The artificial thickening of the heart walls decreases the stress on the heart and helps reverse heart enlargement. Algisyl-LVR is presently being tested in Europe in clinical trials under the product name AUGMENT-HF.  These remarkable products will hopefully be on the market before long.

British Medical Association (Again) Urges Doctors To Abdicate Their Professional Duty

Wesley Smith blogs on the British Medical Journal article that argues that British physicians should end their opposition to physician-assisted suicide. Instead, the Journal argues, this is a question for society and doctors should be neutral about it.

Smith rightly notes that this is preposterous, since doctors are a part of society and have a sworn duty to the well-being of their patients. Shame on the British Medical Association for pulling a stunt like this and shame on the Journal of being complicit in the promotion of doctor-based murder.

Read Smith’s post here.

Transplantation Of Lung Stem Cells Improves Emphysema

In an animal model of emphysema, transplantations of their own lung-derived mesenchymal stem cells (MSCs) increased blood flow, oxygen transport and the synthesis of extracellular matrix. This approach could offer a potential alternative to conventional stem cell-based therapies for the treatment of emphysema.

Emphysema results from destruction of the tiny little sacs in the lung called alveoli. The alveoli surfaces are densely-packed with a network of delicate blood vessels. These blood vessels are the site of oxygen exchange. When a patient contracts emphysema, the walls of the alveoli break down and the tiny air sacs are transformed into a giant air sac. This provides far less surface area for the exchange of oxygen, and the patient has shortness of breath and difficulty catching their breath.

Edward P. Ingenito of Brigham and Women’s Hospital, who was part of this study, gave this perspective: “Mesenchymal stem cells are considered for transplantation because they are readily available, highly proliferative and display multi-lineage potential. Although MSCs have been isolated from various adult tissues, including fat, liver and lung tissues, cells derived from bone marrow (BM) have therapeutic utility and may be useful in treating advanced lung diseases, such as emphysema.”

According to the authors, previous transplantation studies that used bone marrow-derived MSCs and delivered them via an intravenous method have shown that such a treatment only marginally improves the condition of the lung. Also, therapeutic responses in those studies were limited to animal models of inflammatory lung diseases, such as asthma and acute lung injury. For this study, however, researchers isolated highly proliferative mesenchymal cells from adult lung tissue, and delivered them by means of an endoscopic delivery system that included the MSCs and a scaffold composed of natural extracellular matrix components.

According to Ingenito, “LMSCs display efficient retention in the lung when delivered endobronchially and have regenerative capacity through expression of basement membrane proteins and growth factors,”

Despite the use of autologous cells, only a fraction of the LMSCs delivered to the lungs alveolar compartment appeared to engraft. The lost likely reason for the low engraftment rates is due to the rates of cell death. Just as in the heart after a heart attack, diseased lungs represent a hostile environment, and this stressed the cells, which induced programmed cell death. The inability of the stressed cells to attach to their proper niches prevented them from surviving in the lung.

Even though the rates of engraftment were quite low, the findings of this study did suggest that LMSCs could contribute to lung remodeling and functional improvement 28 days after transplantation in 13 female sheep.  “Although the data is from a small number of animals, results show that autologous LMSC therapy using endoscopic delivery and a biocompatible scaffold to promote engraftment is associated with tissue remodeling and increased perfusion, without scarring or inflammation,” Ingenito said. “However, questions concerning mechanism of action and pattern of physiological response remain topics for future investigation.”
For the abstract of this study, see here.

University of Wisconsin Scientists Find a New, Better Way to Turn Stem Cells into Heart Muscle Cells

Stem cell researchers and cardiologists from the University of Wisconsin-Madison have designed a new and improved protocol to turn embryonic and induced pluripotent stem cells into heart muscle cells.

The study leader, Sean Palecek, who is also professor of chemical and biological engineering at the University of Wisconsin-Madison, and his colleagues Timothy Kamp, professor of cardiology at UW School of Medicine and Public Health, and Xiaojun Lian, a UW graduate student, have developed a technique for efficient and abundant production of heart muscle cells. This technique will provide scientists a better and more abundant source of material for drug studies and a better model system to study diseases and heart pathologies.

Heart muscle cells (also known as cardiomyocytes) are essential cells that compose the beating heart. However, it is rather difficult to make large quantities of them. Typically, cultured heart muscle cells only survive or a short period time, which greatly complicates using them for any experiments or drug tests. Now, however, these UW researchers have devised an inexpensive method for developing an abundance of heart muscle cells in the laboratory.

Cardiologist Timothy Kamp explained: “Many forms of heart disease are due to the loss or death of functioning cardiomyocytes, so strategies to replace heart cells in the diseased heart continue to be of interest. For example, in a large heart attack up to 1 billion cardiomyocytes die. The heart has a limited ability to repair itself, so being able to supply large numbers of potentially patient-matched cardiomyocytes could help.”

Why is their method so much more efficient? The UW research team discovered that by changing a signaling pathway called Wnt pathway, they could guide the stem cells to differentiate into heart muscle cells. All they had to do was turn the Wnt pathway on and off at different times by using two small molecules.

The Wnt signaling pathway is an extremely common signaling pathway that exists in virtually all multicellular organisms and is used multiple times during development.  Wnt signaling begins with the secretion of a small protein can a Wnt protein.  Wnt proteins are produced by cells to send signals to nearby cells.  When the cells receiving the signal are bound by the Wnt protein, a series of events are set into motion inside the cell.  The receptor that binds the Wnt protein consists of a protein that is a member of the Frizzled gene family.  Frizzled receptors bind the Wnt protein in combination with another protein called LRP.  The binding of Wnt, LRP and Frizzled brings an internal protein called Disheveled to the membrane.  Once Disheveled come to the membrane, it becomes activated.  How this activation occurs in still unclear, but Disheveled inhibits GSK-3 (glycogen synthase kinase-3).  GSK-3 normally attaches phosphate groups to a protein called beta-catenin.  This phosphate group attachment marks beta-catenin for destruction, but once GSK-3 is inhibited by activated Disheveled, beta-catenin is no longer destroyed and when the levels of beta-catenin build up in the cytoplasm, it goes to the nucleus where it combines with another protein called TCF and regulates gene expression.  Once again we see that a signal transduction pathway begins at the cell surface and results in changes in gene expression.

“Our protocol is more efficient and robust,” said Palecek. “We have been able to reliably generate greater than 80 percent cardiomyocytes in the final population while other methods produce about 30 percent cardiomyocytes with high batch-to-batch variability.”

Palacek continued: “The biggest advantage of our method is that it uses small molecule chemicals to regulate biological signals. It is completely defined, and therefore more reproducible. And the small molecules are much less expensive than protein growth factors.”

Kamp noted that the “fact that turning on and off one master signaling pathway in the cells can orchestrate the complex developmental dance completely is a remarkable finding as there are many other signaling pathways and molecules involved.”

This protocol has the capacity to revolutionized the use of heart muscle cells for drug testing.  Also, because the Wnt signaling pathway is required during heart development, this protocol also has the ability to clarify the exact role of this pathway during heart differentiation.  Finally, if stem cells are eventually used for therapeutic purposes, this protocol or one like it will certainly be employed to convert stem cells into heart muscle cells.

Infanticide Advocate Peter Singer is Awarded Australis’s Highest Civic Award

Princeton University’s Professor of Ethics Peter Singer has been appointment as a Companion of the Order of Australia (he is a native Australian). I will not mince words on this one. This is a new low for the government of Australia. Here are some of the things Singer has advocated:

He is best known for ethically endorsing infanticide. According to Singer, people are not human persons unless they can do certain things. This is called functionalism, and it leads people to regard certain human beings as being in a class of “human non-persons.” For example, Singer does not think humans reach “full moral status” until after the age of two. He supports non-voluntary euthanasia of human “non-persons” fo0r any reason. Not liking the color of their eyes, they cry too much. they pooped on your carpet, they threw up on your nice clothes, they are a girl and not a boy. Mind you, this is the same chap who gets all choked up about the use of animals in research because is multiples animal suffering. Instead of appealing to the more noble aspects of human nature, where we exercise those properties that make us truly human (compassion, defending the weak and defenseless), Singer would have us eat our young the way brute beasts do. Furthermore, he would commend us for it. We used to demarcate between barbaric societies and civilizations that did such things. Now we have become the barbarians, but according to Singer, that’s just fine.

In keeping with this disgusting, misanthropic philosophy, Singer supports using cognitively disabled human beings in medical experiments instead of animals. The laboratory animals, you see, have a higher “quality of life” according to Singer. How does he know that? Well they can do more. They can walk, groom themselves, feed themselves, and defecate without anyone’s help. The mentally disabled person it still essentially a person, but Singer doesn’t let that get in the way. People who cannot do are not people any more. They might even be trapped inside a body that no longer works, but Singer does not let that get in the way either. As far as he is concerned, person is as person does. He forgets that must BE something to eventually DO something. He has gotten the cart before the horse and we have abortion on demand, euthanasia in Holland and Brazil as the result of it.

Singer has also defended bestiality. These are, according the Singer, “mutually satisfying activities” between humans and animals should not be opposed. Now, pray tell, how does Singer know that the animal is enjoying it? Is he also Dr. Doolittle and can talk to the animals? This is disgusting. We used to think such people were sick in the head (not to mention to horrific sexually transmitted diseases you can get from such activities), but Singer thinks they are just alright.

Singer started the “Great Ape Project.” This project would establish a “community of equals” among humans, gorillas, bonobos, chimpanzees, and orangutans. The day one of those creatures asks me for admission to such a project, I will think about it, but for now, they are too busy killing each other in the wild and spreading their feces all over each other to care about it.

Singer has also questioned whether “the continuance of our species is justifiable.” Do we need any more evidence of his own self-loathing?

Finally, Singer believes “speciesism” — viewing humans as having greater value than animals — is akin to racism. Oh, just between you and me, racism is a HUMAN concept. Bringing animals into it is a category mistake of the first degree. Humans are exceptional among the creatures of the earth. We and we alone are the stewards of the earth and its resources. The animals don’t give a rip about such things and it is not even on their cognitive radar. Human exceptionalism is the basis of human law, human rights, and everything from property values, antislavery movements, anti-genocide activities and so on. Without human exceptionalism, we become no better than the animals.

Singer’s philosophy is perverted. It takes what is profane, disgusting and devilish, and calls it morally upright. It is the result of misanthropy and self-loathing and he wants use to hate ourselves as much as he hates himself. His philosophy produces a society that is unworkable and objectionable in every way. He should not be rewarded, but derided.