Stem cell research—why is it regarded as a threat?

An investigation of the economic and ethical arguments made against research with human embryonic stem cells

. 2001 Mar 15; 2(3): 165–168. 

Science & Society

Viewpoint

Author information Copyright and License information Disclaimer

The British House of Lords voted on January 22, 2001 to ease restrictions on the use of human embryonic stem cells. Researchers in the UK are now allowed to use early stage human embryos for therapeutic purposes, mainly to retrieve stem cells. This decision comes amidst a heated debate regarding the medical and economic potential of stem cell research as against its ethical pitfalls. The scientific, legal, ethical and philosophical arguments have been discussed extensively (Mieth, 2000; Colman and Burley, 2001). In this report I therefore propose to take it as established that stem cell technology has great promise for the treatment of a variety of diseases and, indeed, that stem cell therapy may hold exciting prospects for medical advances in the first decades of the 21^st century.

What I wish to discuss is why the prospect of stem cell therapy has been greeted, in quite widespread circles, not as an innovation to be welcomed but as a threat to be resisted. In part, this is the characteristic reaction of Luddites, who regard all technological innovation as threatening and look back nostalgically to a fictitious, golden, pre-industrial past. There are, however, also serious arguments that have been made against stem cell research; and it is these that I would like to discuss.

Stem cell technologies would be very expensive and available only to rich countries and to rich people

It is indisputable that most novel medical technologies are expensive. However, they usually get cheaper as the scale on which they are used increases. A good example is bone marrow transplantation, which initially was extremely expensive. A few decades later, bone marrow transplantation has become a routine procedure that is cheap enough to be used for the treatment of numerous diseases. The same will certainly happen with other therapeutics—be it β-interferon to treat multiple sclerosis, protease inhibitors to block HIV or monoclonal antibodies to target cancer cells. These agents are very expensive now because the cost of their development, testing and production has to be met, but they will rapidly become cheaper as more patients are treated, as the manufacturing process becomes more efficient and as patents expire.

There is, however, a further argument against this particular threat. One of the major financial problems of health care since World War II has been that major advances in clinical research resulted in ways of controlling diseases rather than curing them. The elderly and many chronically ill people in the First World now live a life of high quality. But this depends on the long-term administration of drugs to treat a number of conditions including high blood pressure, diabetes, rheumatoid arthritis and asthma. Consequently, the cost of health care in these countries has dramatically increased over the last few decades. Even for diseases such as Parkinson’s disease that cannot be adequately controlled, continuous therapy is given over many years to relieve symptoms. Stem cell therapy may indeed lead to cures for many ailments. It may become possible to cure Parkinson’s disease with grafts of brain cells. It is also likely that diabetes will be curable using stem cell treatment. It may also be possible to achieve at least something approaching a cure for cardiovascular diseases by replacing damaged endothelial cells in the blood vessels or the cardiomyocytes in the heart itself. If these promises hold true, stem cell therapy might result in a reduction in the overall cost of healthcare as a number of currently incurable diseases are cured.

Stem cell research would deviate efforts from other health strategies

It is difficult to tell in advance what type of research will give rise to what type of benefit. The fundamental research from which stem cell technology originated came from studies in developmental biology whose utility could not have been foreseen. Furthermore, current research into the mechanisms of cellular reprogramming and into the growth requirements of different cell lineages will not only advance scientific knowledge, but is also likely to become of widespread value in clinical medicine.

These two preceding arguments are essentially economic. The following are predominantly ethical and should therefore be given greater weight. But before considering them, it is worth remembering Onora O’Neill’s eloquent warning against declamatory or polemical ethics at the Millennium Festival of Medicine. Ethics is a subject grounded in philosophy and religion. Ethics cannot be determined by polling people and asking them what they think is right or wrong and simply accepting the view of the majority. It does require support from logically and philosophically coherent arguments.

Interference with the genome involves ‘playing God’

This argument reflects the view that divine creation is perfect and that it is inappropriate to alter it in any way. Such a point of view is particularly difficult to sustain in Western Europe where every acre of land bears the marks of more than 2000 years of human activity, and where no primordial wilderness remains. Ever since Homo sapiens gave up being a hunter and gatherer and took to herding animals and agriculture, he has modified the environment. All major food plants and domestic animals have been extensively modified over millennia. It is therefore impossible to sustain the idea that genetic interventions for food plants, animals and the therapy of human diseases are a categorical break from what has gone on throughout evolution.

The proposition that any attempt to interfere with the ‘perfect divine creation’ is morally wrong is also not widely held by theologians. The following quotation is from Professor Iain Torrance, Professor of Divinity in Aberdeen (personal communication), on the subject of co-creation:

‘Creation, understood in the light of the trajectory of the incarnation, is not a simple act. It is an enabling: a process in which a created realm is brought to its own reality and enabled to be itself. I suggest that this may give us a charter for some acts in which we do co-operate with God, though it would be rash ever to claim confidently that any specific act were such. I believe we are invited to share in this activity of enabling, which brings the created world closer to perfection. We never know what perfection is or when we have arrived there. Art is a kind of creation of beauty and may in some sense act as an analogy.

I believe we have an authority to intervene, so as to heal and restore, but not to manipulate and destroy.’

Unfortunately, the idea of a perfect creation was adopted by the early evolutionary biologists who, understandably, were greatly impressed by the elegance of evolutionary adaptation. They therefore tended to replace a perfect divine creation with a perfect evolutionary adaptation. But when scientists began to study the molecular mechanisms of evolution, it turned out that there are only a limited number of strategies available to achieve adaptation. The evolution of many molecular systems demonstrates that adaptation is by no means a perfect process but very much a matter of ‘muddling through’. It is perfectly clear, for example, that no competent engineer would design a creature walking on two legs as badly adapted to the upright posture as is Man. If Man were really made physically in the image of God, it would be bad news for an immortal God.

There has been a desire among political figures as widely separated as Karl Marx and Adolf Hitler to incorporate ‘scientific Darwinism’ into their particular political theories. They have generally failed to understand the nature of the evolutionary process, particularly in believing that natural selection produces an overall, optimal phenotype. To give a current example, if the HIV pandemic continues unabated it will provide a very strong selective pressure in favour of those few people who lack the receptors—CD4 and CCR5—to which the virus attaches. One can imagine that, in due course, their progeny could become dominant in large parts of the world. However, there is no reason whatsoever to believe that these survivors would necessarily be particularly intelligent, beautiful, moral or have other survival characteristics. Furthermore, mutation of the receptor genes may impair their immune system’s ability to deal with other diseases. Survival of the fittest—an unfortunate phrase in any case—simply describes those who are fittest to survive under those selective pressures that exist at any one time.

The idea of ‘playing God’ also carries with it the proposition that there is knowledge that may be too dangerous for mankind to know. This is an entirely pernicious proposition, which finds few defenders in modern democratic societies. On the other hand, there is a general agreement that there are things which should not be done—in science as in other areas of life. In the context of stem cell research, this may be summed up by Kant’s injunction that ‘humanity is to be treated as an end in itself’. The intention of stem cell research is to produce treatments for human diseases. It is difficult not to regard this as a worthy end, and more difficult to see that there could be any moral objection to curing the sick, as demanded by the Hippocratic oath.

Somatic cell nuclear transfer is immoral as it involves creating embryos only to destroy them

The essential problem here is to decide at what stage of development a human embryo acquires the interests—and the rights to protect these interests—that characterize a human being, i.e. when does an embryo become part of humanity? This is a problem that has occupied a great deal of theological and philosophical attention and the arguments have been extensively discussed (Dunstan, 1990; Dunstan and Seller, 1988).

One principal condition is regarded as sufficient to confer interests and the right to defend them—sentience. In this context, sentience is neither the ability to think—which is in any case very difficult to define—nor is it the ability to feel pain. Sentience is defined as the ability to form any links with the outside world. Until an organism has a rudimentary central nervous system and some sense receptors—be it for pain, touch, smell, taste, sight or sound—it cannot form any contact with the outside world and therefore is not sentient. It therefore does not seem possible to attribute sentience to a pre-implantation embryo, or indeed even to an implanted embryo until it has developed some form of nervous system and sense organs. Along the same line, we now universally accept that a human being is dead when no contact with the outside world can be demonstrated by central nervous function. Certainly, death is regarded as having occurred well before every individual cell of the body has died.

The medieval church took the view that an embryo acquired a soul, or it became animatus, at the same time that it became formatus, i.e. when it acquired recognisable human form. This doctrine was derived from Aristotle who curiously believed males to become formatus at 40 days, whereas females were not so until 80 days of gestation. The medieval church held that the abortion of an embryo that was neither formatus nor animatus was only a fineable offence; and it was only after an embryo had become animatus that abortion became a mortal sin. At the core of the refusal of the Roman Catholic Church to countenance embryo research is a doctrine by Pope Pius IX, who declared in 1869 that an embryo acquires full human status at fertilization. This may have been partly in response to an increased frequency of abortion but it is likely also to have been influenced by a desire to bring Christian doctrine into line with 19^thcentury embryology.

But women lose large numbers of pre-implantation embryos throughout their reproductive life. These embryos are not mourned, they are not given burial and no one says prayers for them. The intra-uterine coil, widely used as a method of contraception—though not permitted by the Roman Catholic church—is designed to prevent implantation of embryos and, again, is not regarded as being morally reprehensible.

Further difficulties for the view that full human status is acquired at fertilization arise from advances in reproductive biology. Somatic cell nuclear transfer does not involve fertilization and thus turns the Pius IX doctrine ad absurdum, since it makes it possible to see in any somatic cell whose nucleus can be introduced into an oocyte, the potential for giving rise to a complete human being. When reprogramming of cells becomes better understood, it may be possible to convert somatic cells into embryos without the need for an oocyte. If, ultimately, any somatic cell has the potential of being grown into a complete embryo and, subsequently, into a human being, it would logically mean that we should ascribe a moral status to every cell in the body—a concept that is clearly ridiculous.

The view that an embryo does not acquire the status of a human being until it is obviously of human form with a central nervous system and organs (as is the view of the Protestant church), or even until it is delivered (which is the view of the Jewish religion), is more defensible on philosophical grounds than is stating that human status is acquired at fertilization. Of course, any decision relating to the particular point in development at which an embryo acquires full human status must be partially arbitrary. There are other cases where there is blurring at the interface of two categories or where distinctions are made slightly arbitrarily. This is the case in distinguishing between plants and animals; in distinguishing between male and female; and in distinguishing between the living and dead at the end of life. But the fact that making distinctions can sometimes be difficult is not an argument for making fundamentalist distinctions or making no distinction at all.

Allowing stem cell research is the thin end of a wedge leading to neo-eugenics, ‘designer’ children, and discrimination against the less-than-perfect

Francis Cornford wrote in the Microcosmographica Academica: ‘The Principle of the Wedge is that you should not act justly now for fear of raising expectations that you may act still more justly in the future—expectations which you are afraid you will not have the courage to satisfy. A little reflection will make it evident that the Wedge argument implies the admission that the persons who use it cannot prove that the action is not just. If they could, that would be the sole and sufficient reason for not doing it, and this argument would be superfluous.’ (Cornford, 1908). It is inherent in what Cornford writes that the fear that one may not behave justly on a future occasion is hardly a reason for not behaving justly on the present occasion.

In addition to this philosophical argument, one should consider that there are also cogent biological reasons for opposing reproductive cloning using cell nuclear transfer. This is a form of vegetative reproduction, a technique used only by plants and a few lower animals. The late William Hamilton pointed out (Hamilton et al., 1990) that primitive animals which have the opportunity of adopting vegetative reproduction have uniformly failed to do so. He argues that it is the challenge of parasitism that makes the use of sexual reproduction, with its re-assortment of genes at each generation, advantageous in evolutionary terms.

In fact, the use of reproductive cloning can be defended only for farm animals, where this technique may be the best for producing, for example, cows that are resistant to BSE or sheep resistant to scrapie. Reproductive cloning should not be applied to Man and its widespread use might be evolutionarily harmful. We are also not sure yet whether somatic cells used for generating embryos carry mutations that have the potential to harm later generations. However, this is not a problem when using stem cells for therapeutic purposes.

The Universal Declaration on the Human Genome (http://www.unesco.org/ibc/uk/genome/projet/), which UNESCO hopes will be incorporated into national laws, specifically prohibits the use of genetic manipulation to ‘improve’ humans. Vigilance will certainly always be needed to prevent the misuse of this technology, but it is unlikely that the use of stem cells carries any particularly devastating dangers.

Eventually, an ‘immortal’ population could evolve and that would create its own moral problems

This proposal derives from John Harris who is sufficiently impressed by the promises of stem cell therapy to believe that we may have to face a population that can live two or even more centuries (Harris, 2000). Success on that sort of scale seems a long way off—but it would be an accolade to medicine to have that set of problems to face!

I wish to close with another quotation from the Microcosmographica Academica: ‘There is only one reason for doing something; the rest are arguments for doing nothing.’ The Luddites can always produce a variety of more or less plausible arguments for resisting technological innovation. But without innovation we would not have moved on from the Stone Age to the Computer Age in only ∼100 generations. The present arguments for doing nothing are no more potent than all preceding ones.

References

• Colman A. and Burley, J.C. (2001) A legal and ethical tightrope. EMBO Reports, 2, 2–5. [PMC free article] [PubMed]
• Cornford F.M. (1908) Microcosmographica Academica. Bowes & Bowes, Cambridge, UK.
• Dunstan G.R. (1990) The Human Embryo: Aristotle and the Arabic and European Traditions. University of Exeter Press, Exeter, UK.
• Dunstan G.R. and Seller, M.J. (1988) The Status of the Human Embryo: Perspectives from Moral Tradition. King Edward’s Hospital Fund for London & Oxford University Press, Oxford, UK.
• Hamilton W.D., Axelrod, R. and Tanese, R. (1990) Sexual reproduction as an adaptation to resist parasites. Proc. Natl Acad. Sci. USA, 87, 3566–3573. [PMC free article] [PubMed]
• Harris J. (2000) Essays on science and society: intimations of immortality. Science, 288, 5. [PubMed]
• Mieth D. (2000) Going to the roots of the stem cell debate. EMBO Reports, 1, 4–6. [PMC free article] [PubMed]

via https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1083849/

Scientists create human esophagus in stem cell first

Ana SandoiuFriday 21 September 2018

The esophagus runs from the throat into the stomach.

The esophagus is the muscular tube that moves the food and liquids we ingest from our throats all the way to our stomachs.

This organ is made of different types of tissue, including muscle, connective tissue, and mucous membrane.

Scientists at the Cincinnati Children's Center for Stem Cell and Organoid Medicine (CuSTOM) in Ohio have artificially grown these tissues in the laboratory using pluripotent stem cells, or stem cells that can take any form and create any tissue in the body.

The team — which was led by Jim Wells, Ph.D., the chief scientific officer at CuSTOM — grew fully formed human esophagi in the laboratory and detailed its findings in a paper published in the journal Cell Stem Cell. 

To their knowledge, this is the first time that such a feat has been achieved using only pluripotent stem cells.

Laboratory-grown esophagus organoids might help treat a range of conditions, such as esophageal cancer and gastroesophageal reflux disease (GERD).

They may also help treat more rare congenital diseases, such as esophageal atresia (a condition in which the upper esophagus does not connect with the lower esophagus) and esophageal achalasia (wherein the esophagus does not contract and so cannot pass food).

According to recent estimates, GERD — also known as acid reflux — affects around 20 percent of the United States population. In 2018, over 17,000 people in the U.S. will develop esophageal cancer.

As Wells and team explain in their paper, having a fully functional model of the human esophagus — in the form of a laboratory-grown organoid — contributes to a better understanding of these diseases.

The findings may also lead to better treatments using regenerative medicine.

Key protein helps scientists grow esophagus

As they were trying to form the organoids, Wells and team focused on a protein called Sox2 and the gene that encodes it. Previous research had shown that disruption in this protein leads to a range of esophageal conditions.

The scientists cultured human tissue cells, as well as cells from the tissues of mice and frogs, to examine more closely the role of Sox2 in the embryonic development of the esophagus.

The team revealed that Sox2 drives the formation of esophageal cells by inhibiting another genetic pathway that would "tell" stem cells to form into respiratory cells instead.

They also wanted to study the effects of Sox2 deprivation in these key developmental stages. The experiment revealed that the loss of Sox2 resulted in a form of esophageal atresia in the mice.

Finally, they were able to create esophagus organoids that were 300–800 micrometers long at 2 months. The scientists then tested the composition of the laboratory-grown tissues and compared it with that of human esophageal tissue obtained from biopsies.

Wells and team report that the two types of tissue had a very similar composition. Wells comments on the clinical significance of the organoids, saying:

"In addition to being a new model to study birth defects like esophageal atresia, the organoids can be used to study diseases like eosinophilic esophagitis and Barrett's metaplasia, or to bioengineer genetically matched esophageal tissue for individual patients."

"Disorders of the esophagus and trachea are prevalent enough in people that organoid models of human esophagus could be greatly beneficial."

Jim Wells, Ph.D.

via https://www.medicalnewstoday.com/articles/323118.php

New research uncovers some of the 'magical' properties of royal jelly.

In the complex hierarchy of the beehive, the queen bee is the sacred matriarch who keeps the colony alive and organized.

The queen bee lays the eggs from which the larvae will hatch. These larvae later become either the new workers, which are the female bees who do all the work around the hive, or the drones, the male bees whose job it is to mate with the queen.

When a queen bee dies, the colony has to ensure that a new one takes her place.

To produce a new queen bee, worker bees select the most suitable larvae and feed them royal jelly. This will allow one of them to develop into the healthy, strong, and extremely fertile adult female who then becomes the new queen bee.

Royal jelly comprises water, proteins, and sugars, but how exactly it stimulates some larvae to grow into queens rather than worker bees has remained unclear.

Still, due to its seemingly "magical" properties, many people hail this substance as a miraculous ingredient that can boost health and help maintain youth.

In a new study from the Stanford University School of Medicine in California, a team of researchers has decided to investigate how and why royal jelly might be beneficial. They have looked at its effect on one of the most promising targets of clinical research, namely mammalian stem cells. These undifferentiated cells are capable of turning into any specialized cells, serving any function.

"In folklore, royal jelly is kind of like a super-medicine, particularly in Asia and Europe, but the DNA sequence of royalactin, the active component in the jelly, is unique to honeybees. Now, we've identified a structurally similar mammalian protein that can maintain stem cell pluripotency," explains senior author Dr. Kevin Wang.

The researchers tell the story of their current findings in the journal Nature Communications.

The 'magic' ingredient of royal jelly

"I've always been interested in the control of cell size, and the honeybee is a fantastic model to study this," says Dr. Wang. "These larvae all start out the same on day zero, but end up with dramatic and lasting differences in size. How does this happen?"

In this study, Dr. Wang and his team honed in on a protein called royalactin that is present in royal jelly. They believed that this protein may be, in great measure, responsible for stimulating the impressive cell growth in the larvae that the worker bees select to become queen bees.

In order to study its effects, the researchers decided to apply royalactin to embryonic stem cells, or undifferentiated cells, that they had collected from mice.

"For royal jelly to have an effect on queen development, it has to work on early progenitor cells in the bee larvae," Dr. Wang notes. "So we decided to see what effect it had, if any, on embryonic stem cells," he adds.

Embryonic stem cells are the perfect candidate in clinical research as they have the potential to turn into any specialized cell, playing any role. This potential is called "pluripotency."

Replacing aging, damaged specialized cells with fresh ones that have grown from stem cells has, in theory, the potential to help address any number of diseases. As a result, it is important for researchers to have access to healthy, "youthful" stem cells that they can keep in the labs in their undifferentiated forms until they need to use them.

A protein named 'Regina'

However, Dr. Wang explains, stem cells soon differentiate under lab conditions and become unusable. To keep their pluripotency intact, researchers have had to devise complex inhibitors.

When they added royalactin to embryonic stem cells, the investigators found that it maintained their pluripotency for longer — specifically, for 20 generations — without the need to administer the usual inhibitors.

"This was unexpected. Normally, these embryonic stem cells are grown in the presence of an inhibitor called leukemia inhibitor factor that stops them from differentiating inappropriately in culture, but we found that royalactin blocked differentiation even in the absence of [leukemia inhibitor factor]," Dr. Wang notes.

Still, the researchers did not understand this response. They felt that the mammalian stem cells should not have responded so well to royalactin since mammals do not produce that protein.

They then wondered if they could find a mammalian-produced protein that might match the shape of royalactin rather than its sequence and that may also serve the purpose of sustaining cell "stemness."

Sure enough, they identified a mammalian protein called NHLRC3, which, they thought, may have a structure close to that of royalactin and might serve a similar purpose. NHLRC3, explains Dr. Wang, occurs in all early animal embryos, including those of humans.

When the researchers applied this protein to mouse embryonic stem cells, they found that, like royalactin, it helped maintain their pluripotency. For this reason, the team decided to rename this protein "Regina," which means "queen" in Latin.

"It's fascinating. Our experiments imply Regina is an important molecule governing pluripotency and the production of progenitor cells that give rise to the tissues of the embryo. We've connected something mythical to something real."

Dr. Kevin Wang

In the future, the researchers plan to find out whether Regina can boost wound healing and cell regeneration. They also want to look into more ways of keeping stem cells "youthful" in the laboratory.

Stem cells are undifferentiated cells that can turn into specific cells, as the body needs them.

Scientists and doctors are interested in stem cells as they help to explain how some functions of the body work, and how they sometimes go wrong.

Stem cells also show promise for treating some diseases that currently have no cure.

Sources of stem cells

Stem cells originate from two main sources: adult body tissues and embryos. Scientists are also working on ways to develop stem cells from other cells, using genetic "reprogramming" techniques.

Adult stem cells

Stem cells can turn into any type of cell before they become differentiated.

A person's body contains stem cells throughout their life. The body can use these stem cells whenever it needs them.

Also called tissue-specific or somatic stem cells, adult stem cells exist throughout the body from the time an embryo develops.

The cells are in a non-specific state, but they are more specialized than embryonic stem cells. They remain in this state until the body needs them for a specific purpose, say, as skin or muscle cells.

Day-to-day living means the body is constantly renewing its tissues. In some parts of the body, such as the gut and bone marrow, stem cells regularly divide to produce new body tissues for maintenance and repair.

Stem cells are present inside different types of tissue. Scientists have found stem cells in tissues, including:

• the brain
• bone marrow
• blood and blood vessels
• skeletal muscles
• skin
• the liver

However, stem cells can be difficult to find. They can stay non-dividing and non-specific for years until the body summons them to repair or grow new tissue.

Adult stem cells can divide or self-renew indefinitely. This means they can generate various cell types from the originating organ or even regenerate the original organ, entirely.

This division and regeneration are how a skin wound heals, or how an organ such as the liver, for example, can repair itself after damage.

In the past, scientists believed adult stem cells could only differentiate based on their tissue of origin. However, some evidence now suggests that they can differentiate to become other cell types, as well.

Embryonic stem cells

From the very earliest stage of pregnancy, after the sperm fertilizes the egg, an embryo forms.

Around 3–5 days after a sperm fertilizes an egg, the embryo takes the form of a blastocyst or ball of cells.

The blastocyst contains stem cells and will later implant in the womb. Embryonic stem cells come from a blastocyst that is 4–5 days old.

When scientists take stem cells from embryos, these are usually extra embryos that result from in vitro fertilization (IVF).

In IVF clinics, the doctors fertilize several eggs in a test tube, to ensure that at least one survives. They will then implant a limited number of eggs to start a pregnancy.

When a sperm fertilizes an egg, these cells combine to form a single cell called a zygote.

This single-celled zygote then starts to divide, forming 2, 4, 8, 16 cells, and so on. Now it is an embryo.

Soon, and before the embryo implants in the uterus, this mass of around 150–200 cells is the blastocyst. The blastocyst consists of two parts:

• an outer cell mass that becomes part of the placenta
• an inner cell mass that will develop into the human body

The inner cell mass is where embryonic stem cells are found. Scientists call these totipotent cells. The term totipotent refer to the fact that they have total potential to develop into any cell in the body.

With the right stimulation, the cells can become blood cells, skin cells, and all the other cell types that a body needs.

In early pregnancy, the blastocyst stage continues for about 5 days before the embryo implants in the uterus, or womb. At this stage, stem cells begin to differentiate.

Embryonic stem cells can differentiate into more cell types than adult stem cells.

Mesenchymal stem cells (MSCs)

MSCs come from the connective tissue or stroma that surrounds the body's organs and other tissues.

Scientists have used MSCs to create new body tissues, such as bone, cartilage, and fat cells. They may one day play a role in solving a wide range of health problems.

Induced pluripotent stem cells (iPS)

Scientists create these in a lab, using skin cells and other tissue-specific cells. These cells behave in a similar way to embryonic stem cells, so they could be useful for developing a range of therapies.

However, more research and development is necessary.

To grow stem cells, scientists first extract samples from adult tissue or an embryo. They then place these cells in a controlled culture where they will divide and reproduce but not specialize further.

Stem cells that are dividing and reproducing in a controlled culture are called a stem-cell line.

Researchers manage and share stem-cell lines for different purposes. They can stimulate the stem cells to specialize in a particular way. This process is known as directed differentiation.

Until now, it has been easier to grow large numbers of embryonic stem cells than adult stem cells. However, scientists are making progress with both cell types.

Types of stem cells

Researchers categorize stem cells, according to their potential to differentiate into other types of cells.

Embryonic stem cells are the most potent, as their job is to become every type of cell in the body.

The full classification includes:

Totipotent: These stem cells can differentiate into all possible cell types. The first few cells that appear as the zygote starts to divide are totipotent.

Pluripotent: These cells can turn into almost any cell. Cells from the early embryo are pluripotent.

Multipotent: These cells can differentiate into a closely related family of cells. Adult hematopoietic stem cells, for example, can become red and white blood cells or platelets.

Oligopotent: These can differentiate into a few different cell types. Adult lymphoid or myeloid stem cells can do this.

Unipotent: These can only produce cells of one kind, which is their own type. However, they are still stem cells because they can renew themselves. Examples include adult muscle stem cells.

Embryonic stem cells are considered pluripotent instead of totipotent because they cannot become part of the extra-embryonic membranes or the placenta.

Uses

Transplants with stem cells are already helping people with diseases such as lymphoma.

Stem cells themselves do not serve any single purpose but are important for several reasons.

First, with the right stimulation, many stem cells can take on the role of any type of cell, and they can regenerate damaged tissue, under the right conditions.

This potential could save lives or repair wounds and tissue damage in people after an illness or injury. Scientists see many possible uses for stem cells.

Tissue regeneration

Tissue regeneration is probably the most important use of stem cells.

Until now, a person who needed a new kidney, for example, had to wait for a donor and then undergo a transplant.

There is a shortage of donor organs but, by instructing stem cells to differentiate in a certain way, scientists could use them to grow a specific tissue type or organ.

As an example, doctors have already used stem cells from just beneath the skin's surface to make new skin tissue. They can then repair a severe burn or another injury by grafting this tissue onto the damaged skin, and new skin will grow back.

Cardiovascular disease treatment

In 2013, a team of researchers from Massachusetts General Hospital reported in PNAS Early Editionthat they had created blood vessels in laboratory mice, using human stem cells.

Within 2 weeks of implanting the stem cells, networks of blood-perfused vessels had formed. The quality of these new blood vessels was as good as the nearby natural ones.

The authors hoped that this type of technique could eventually help to treat people with cardiovascular and vascular diseases.

Brain disease treatment

Doctors may one day be able to use replacement cells and tissues to treat brain diseases, such as Parkinson's and Alzheimer's.

In Parkinson's, for example, damage to brain cells leads to uncontrolled muscle movements. Scientists could use stem cells to replenish the damaged brain tissue. This could bring back the specialized brain cells that stop the uncontrolled muscle movements.

Researchers have already tried differentiating embryonic stem cells into these types of cells, so treatments are promising.

Cell deficiency therapy

Scientists hope one day to be able to develop healthy heart cells in a laboratory that they can transplant into people with heart disease.

These new cells could repair heart damage by repopulating the heart with healthy tissue.

Similarly, people with type I diabetes could receive pancreatic cells to replace the insulin-producing cells that their own immune systems have lost or destroyed.

The only current therapy is a pancreatic transplant, and very few pancreases are available for transplant.

Blood disease treatments

Doctors now routinely use adult hematopoietic stem cells to treat diseases, such as leukemia, sickle cell anemia, and other immunodeficiency problems.

Hematopoietic stem cells occur in blood and bone marrow and can produce all blood cell types, including red blood cells that carry oxygen and white blood cells that fight disease.

Donating or harvesting stem cells

People can donate stem cells to help a loved one, or possibly for their own use in the future.

Donations can come from the following sources:

Bone marrow: These cells are taken under a general anesthetic, usually from the hip or pelvic bone. Technicians then isolate the stem cells from the bone marrow for storage or donation.

Peripheral stem cells: A person receives several injections that cause their bone marrow to release stem cells into the blood. Next, blood is removed from the body, a machine separates out the stem cells, and doctors return the blood to the body.

Umbilical cord blood: Stem cells can be harvested from the umbilical cord after delivery, with no harm to the baby. Some people donate the cord blood, and others store it.

This harvesting of stem cells can be expensive, but the advantages for future needs include:

• the stem cells are easily accessible
• less chance of transplanted tissue being rejected if it comes from the recipient's own body

What is cord blood banking?Find out more about cord blood banks and how they work.READ NOW

Research and scientific discovery

Through stem-cell research, scientists hope to discover cures for diseases that are currently incurable.

Stem cells are useful not only as potential therapies but also for research purposes.

For example, scientists have found that switching a particular gene on or off can cause it to differentiate. Knowing this is helping them to investigate which genes and mutations cause which effects.

Armed with this knowledge, they may be able to discover what causes a wide range of illnesses and conditions, some of which do not yet have a cure.

Abnormal cell division and differentiation are responsible for conditions that include cancer and congenital disabilities that stem from birth. Knowing what causes the cells to divide in the wrong way could lead to a cure.

Stem cells can also help in the development of new drugs. Instead of testing drugs on human volunteers, scientists can assess how a drug affects normal, healthy tissue by testing it on tissue grown from stem cells.

---

From https://www.medicalnewstoday.com/articles/323343.php

A "superbug" gene

that was first detected in India — and allows bacteria to evade "last resort" antibiotics — has now been found thousands of miles away, in a remote region of the Arctic, according to a new study.

The findings underscore just how far and wide antibiotic resistance geneshave spread, now reaching some of the most far-flung areas of the planet.

"Encroachment into areas like the Arctic reinforces how rapid and far-reaching the spread of antibiotic resistance has become," senior study author David Graham, a professor of ecosystems engineering at Newcastle University in the United Kingdom, said in a statement. The findings confirm that solutions to antibiotic resistance "must be viewed in global rather than just local terms." [6 Superbugs to Watch Out For]

Not "local" to the Arctic

Antibiotic resistance has existed for much longer than humans have been around. Indeed, bacteria naturally produce substances to defend themselves against other bacteria or microorganisms. (For example, penicillin comes from a type of mold, or fungus.)

But through overuse of antibiotic drugs, humans have accelerated the rate of bacterial evolution, and in turn, the development of antibiotic resistance in these organisms, leading to "a new world of resistant strains that never existed before," Graham said.

One such strain, carrying a gene called blaNDM-1, was discovered in India in 2008. This gene gave bacteria resistant to a class of antibiotics known as Carbapenems, which doctors generally use as a last resort to treat bacterial infections. Since its discovery, the blaNDM-1 gene has been detected in more than 100 countries.

But the researchers were still surprised when it showed up in the Arctic. "A clinically important [antibiotic resistance gene] originating from South Asia is clearly not 'local' to the Arctic," Graham said.

No longer 'pristine'

By traveling to the Arctic, the researchers were actually hoping to get a picture of the types of antibiotic resistance genes that existed before the era of antibiotics. But they found that a slew of modern antibiotic resistance genes were already there.

In the study, the researchers analyzed DNA extracted from soil cores in Spitsbergen, a Norwegian island in the Arctic Ocean. They found a total of 131 antibiotic resistance genes, many of which did not appear to be of local origin.

These genes likely spread through the fecal matter of birds, other wildlife, and human visitors to the area, the researchers said.

But the researchers were still able to find what they were looking for: isolated polar areas where levels of antibiotic resistance genes were so low "they might provide nature's baseline of antimicrobial resistance," Graham said.

Appropriate use of antibiotics in medicine and agriculture is crucial to reducing antibiotic resistance, Clare McCann, lead author of the paper and a research associate at Newcastle University, said in the statement. But she added that it's also critical to understand exactly how antibiotic resistance spreads around the world, including through routes such as water and soil.

The study was published Jan. 27 in the journal Environment International.

• 27 Devastating Infectious Diseases
• 10 Things You Need to Know about Arctic Sea Ice
• Tiny & Nasty: Images of Things That Make Us Sick

Originally published on Live Science.

Electronic cigarettes are often thought of as "healthier" than conventional cigarettes, but the jury's still out on their potential health risks. Now, a new study has found a link between e-cigarette use and an increased risk of stroke and heart attacks.

The study analyzed information from about 400,000 Americans who took part in a national health survey in 2016. Of these, about 66,800 reported that they regularly used e-cigarettes.

Compared with non-e-cigarette users, regular users had about a 70 percent higher risk of stroke, a 60 percent higher risk of heart attack or angina (chest pain) and a 40 percent higher risk of coronary heart disease.

About 79 percent of e-cigarette users also reported using conventional cigarettes, compared with just 37 percent of non-e-cigarette users. [4 Myths About E-Cigarettes]

But the findings linking e-cigarettes with an increased risk of stroke, heart attack and coronary heart disease held even after the researchers took into account whether people were also conventional cigarette smokers, said study lead author Dr. Paul Ndunda, an assistant professor at the University of Kansas School of Medicine.

What's more, when the researchers analyzed a subset of participants who reported smoking fewer than 100 conventional cigarettes in their lives (meaning they were not regular users of cigarettes), they found that e-cigarette users were still 29 percent more likely to report having a stroke, 25 percent more likely to report having a heart attack and 18 percent more likely to report having coronary heart disease, Ndunda told Live Science.

The findings will be presented next week at American Stroke Association's International Stroke Conference 2019 in Honolulu, but has not been published in a peer-reviewed journal.

The new finding is "quite concerning," said Dr. Larry Goldstein, co-director of the Kentucky Neuroscience Institute at the University of Kentucky, who was not involved with the study. "This is the first real data that we're seeing associating e-cigarette use with hard cardiovascular events" like heart attacks and strokes, Goldstein said in a video interview with the American Stroke Association, which is a division of the American Heart Association (AHA). However, Goldstein noted that the study had limitations. For example, the researchers weren't able to take into account some factors that are known to increase people's risk of stroke and heart disease, such as high blood pressure, alcohol use and an unhealthy diet.

In addition, because the study only examined people's responses at one point in time, it is not able to tease out cause and effect — that is, it cannot prove that e-cigarette use was the cause of people's cardiovascular problems, or whether people who use e-cigarettes have other characteristics that increased their risk.

Still, Goldstein said that these early findings need to be taken seriously, especially given the relatively large percentage of young people who use e-cigarettes. In 2016, about 11 percent of U.S. high school students reported using e-cigarettes in the last 30 days.

Unlike conventional cigarettes, which heat and burn tobacco, e-cigarettes heat up and vaporize a liquid, which usually contains nicotine and other flavorings.

The AHA cautions against the use of e-cigarettes, saying that they may pose health risks that scientists do not yet fully understand. And since e-cigarettes usually contain nicotine, they may get people addicted to the substance, according to the AHA.

Some previous studies have also suggested that the flavorings in e-cigarettes themselves may be harmful. A study published last year in the journal Arteriosclerosis, Thrombosis and Vascular Biology found that e-cigarette chemical flavorings had harmful effects on blood vessel cells in a lab dish.

• Kick the Habit: 10 Scientific Quit-Smoking Tips
• 8 Tips for Parents of Teens with Depression
• 9 New Ways to Keep Your Heart Healthy

Originally published on Live Science.