So What About Three-Person Embryos?


In 2013, Deiter Egli’s group at Harvard University successfully transferred chromosomes that were in the process of dividing and segregating (known as an incompletely assembled spindle-chromosome complex) from one human egg into another egg whose nucleus had been removed (Nature 493, 632–637 (31 January 2013) doi:10.1038/nature11800). They prevented the eggs from prematurely re-entering meiosis by cooling the chromosome/spindle complex to room temperature. This allowed normal polar body extrusion, efficient development to the blastocyst stage, and, eventually, the derivation of normal stem cells.

3-person-ivf

Egli’s technique allows the genome of one egg to initiate development in the cytoplasm of another egg. Why is this significant? Because within out cells is a bean-shaped vesicle called a mitochondrion. Mitochondria make the energy for our cells. To do this, mitochondria use a variety of proteins encoded on genes found in the nuclear genome. However, mitochondria also have their own genome that encodes some crucial mitochondrial proteins and RNAs. The human mitochondrial genome is a small, circular DNA molecule that encodes 37 different genes.

C:TypesetSBG36-32013-1302013-130.vp

Mutations in genes encoded by the mitochondrial genome tend to have rather catastrophic consequences for the fertility of women. When the egg undergoes fertilization, the vast majority of the mitochondria of the sperm are degraded and their mitochondrial DNA is eliminated (Katsumi Kasashima, Yasumitsu Nagao, and Hitoshi Endo. Reprod Med Biol. 2014; 13(1): 11–20). Research has shown that the father’s mitochondrial genome can make some very small contribution to the embryo, a phenomenon known as “paternal leakage,” but it is usually pretty small (Kuijper B1, Lane N, Pomiankowski A. J Evol Biol. 2015 Feb;28(2):468-80). Therefore, if the mother carries a deleterious mutation in her mitochondrial DNA, her eggs will usually not be able to progress through fertilization successfully and support the growth and development of the embryo. Consequently, the mother will be infertile.

This new technique by Egli, however, allows mothers who are infertile because of mutations in their mitochondria DNA, to have children who are genetically related to them. All that is needed are eggs from a healthy donor, and a laboratory that has the know-how and will to do this procedure. The mother’s eggs are harvested by standard IVF technologies, fertilized by the father’s spermatozoa, and after fertilization has ended, the chromosome-spindle complex is lifted from the young embryos and transferred into enucleated donor eggs that contain mitochondria with normal genomes. Development will then ensue without a hitch. Right?

Well not so fast. As it turns out, this procedure has been carried out in several different animal species, and the results are decidedly mixed (see Reinhardt and others, Science 2013;341:1345).

If we begin with insects, we can move new mitochondrial genomes into embryos by standard genetic techniques. If we do so in the fruit fly, Drosophila melanogaster, such mitochondrial transfer produces fly embryos that develop normally, but the animals show altered juvenile viability, adult male animals show accelerated aging and reduced fertility. Genetically, it is clear that transferring new mitochondria into an egg messes up the expression of nuclear genes. Identical experiments in the seed beetle causes altered development and metabolic rates, reduced fertility in males and reduced survival in females. Similar studies in copepods (Tigriopus californicus) causes reduced juvenile viability, and reduced mitochondrial function and energy production in adults.

If mice are subjected to these same experiments, the animals develop normally and survive to adulthood, but these adult mice show reduced growth and exercise ability and reduced learning ability in males.

The above-mentioned experiments used standard genetic breeding techniques to generate animal strains that had a mismatch between the nuclear and mitochondrial genome.  Such techniques are demonstrably non-invasive.  However, the technology applied in Egli’s laboratory were invasive, and included removing chromosome/spindle complexes and transferring them to donor eggs that had been enucleated. Therefore, the effects of these invasive procedures had to be tested as well. If such invasive procedures were tested in cultured mouse cells, the hybrid cells showed altered cellular respiration and growth. In short, their mitochondria worked poorly inside their new homes.

If Egli’s technique was used in non-human primates, macaques in particular, the animals developed to the juvenile stage and appeared normal.

On the strength (or weakness) of these experiments, some reproductive specialists in countries where such techniques can be performed without fear of prosecution have used mitochondrial transfer in human embryos. Again the results are quite mixed. Healthy children have been born by this procedure, but several others have not. Helen Pearson reported in Nature News on the 14th of October, 2005 about two Chinese babies that were made with mitochondrial transfer that died in utero at 24 and 29 weeks. Other outcomes include a miscarriage, an abortion of a fetus that had Turner Syndrome, at least two children with mixed mitochondria that studies linked with cognitive dysfunction and obesity, and a child born with a severe developmental disorder. I do not call these hopeful results.

Another experiment that gives me pause was published in the journal Cell Reports in June of 2014 by Joerg Patrick Burgstaller and others. This paper showed that even small amounts of diseased mitochondrial DNA in an embryo would spread throughout the organism. The amount of spread is wide and varied, but even small amounts of variant mitochondrial DNA did spread. This significance of this is stark for this debate. You see, Egli’s original paper in Nature showed that very small amounts of the original mitochondrial DNA are transferred to the donor egg. Granted it below 1% of the total mitochondrial DNA in the embryo, but it is still detectable. Burgstaller and others have shown that even with this small amount of mitochondrial DNA, it will still spread throughout the developing baby and given them a body with some cells that have most the diseased mitochondrial DNA, and others that have the normal mitochondrial DNA, and other cells that have a mixture of the two. Therefore, Egli’s technique is NOT a cure for conditions linked to mitochondrial DNA mutations. Let me repeat this for every one – Egli’s technique is NOT a cure for conditions linked to mitochondrial DNA mutations.

No vertebrates have yet been studied who have gone through mitochondrial replacement and survived to reproductive age. Given the decidedly mixed record of this technology in a variety of animal models and the paucity of data so far, this technology is clearly not ready for use in humans.

However, that has not stopped scientists and politicians in the United Kingdom from pushing this technology forward as a fertility treatment for infertile women who harbor mitochondrial DNA mutations.  Some in the scientific community warned about the potential dangers of this technology.  Their concerns were largely ignored and in many cases severely criticized.  Even worse, some thought that three-person embryos could grease the slippery slope in which this technology or similar ones like cloning would be applied as generalized treatments for infertility.  That concern was labeled ridiculous. No longer.

Science magazine reported that cloning magnate Shoukhrat Mitalipov has formed a partnership with disgraced fraudster Woo Suk Hwang.  The two are teaming up to form a joint commercial venture to use Mitalipov’s cloning techniques as a way to treat infertility and perhaps other diseases.  Mitalipov’s commercial venture Mitogenome Therapuetics and Hwang along with the company BoyaLife, which will reportedly put up more than $90 million into the effort.  Mitalipov has also generated news reports by asking FDA approval to use so-called 3-person IVF “mitochondrial transfer” technology, which shares some technical elements with cloning, to treat infertility. This surprised some in the UK, including members of Parliament who were hoodwinked into voting to approve the three-person embryo procedure by being told that this technology would only be used to treat mitochondrial diseases.

The slippery slope is real and unless citizens rise up and make noise, we are going to be dragged where angels fear to tread by over-zealous scientists who are willing to sacrifice young children for the sake of their own fame and success.  This technology is not ready for use in humans.  The approval of this technology in the UK is a very bad idea.  It will also spread to the use of cloning in general as a treatment for diseases, and we will then move to fetus farming.  May God give us the strength to say enough is enough.

The United States FDA’s Cellular, Tissue and Gene Therapies Advisory Committee will be holding a public hearing to “discuss considerations for the design of early-phase clinical trials of cellular and gene therapy products” including the three-parent IVF method. The public has until October 15 to send in written comments. If you are interested in making your views known, go here.

Cells Made From Embryonic Stem Cells Derived from Cloned Embryos Are Rejected by the Immune System


Researchers from Stanford University have shown that genetic differences in mitochondria found in cells made from pluripotent stem cells that were originally derived from cloned embryos can prompt rejection by the immune system of the host animal from which they were made, at least in mice.

According to a study in mice by researchers at the Stanford University School of Medicine and colleagues in Germany, England and at MIT, cells and tissues in mice made from cloned embryos are rejected by the body because of a previously unknown immune response to the cell’s mitochondria. These findings reveal a likely hurdle if such therapies are ever used in humans.

Regenerative therapies that utilize stem cells have the potential to repair organs, replace dead or dying tissues, and treat severe diseases.  Many stem cell scientists think that pluripotent stem cells, which can differentiate into any kind of cell in the body, show the most promise for regenerative medical applications in the clinic.  One method for deriving pluripotent stem cells that have the same genetic composition as that of the patients is called somatic cell nuclear transfer (SCNT) or cloning.  This method takes the nucleus of an adult cell and injects it into an egg cell from which the nucleus has been removed.

SCNT can potentially make pluripotent stem cells that can repair a patient’s body. “One attraction of SCNT has always been that the genetic identity of the new pluripotent cell would be the same as the patient’s, since the transplanted nucleus carries the patient’s DNA,” said cardiothoracic surgeon Sonja Schrepfer, MD, PhD, who was the co-senior author of the study, which was published online Nov. 20 in Cell Stem Cell.

“The hope has been that this would eliminate the problem of the patient’s immune system attacking the pluripotent cells as foreign tissue, which is a problem with most organs and tissues when they are transplanted from one patient to another,” added Schrepfer, a visiting scholar at Stanford’s Cardiovascular Institute, and Heisenberg Professor of the German Research Foundation at the University Heart Center in Hamburg, and at the German Center for Cardiovascular Research.

Several years ago, Stanford University professor of pathology and developmental biology, Irving Weissman, MD, chaired a National Academies panel on SCNT cells.  At this time, he raised the possibility that the immune system of a patient who received the cells derived from stem cells made from cloned embryos might still generate an immune response against proteins from the cells’ mitochondria.  Mitochondria are the energy factories for cells, and they have their own genetic system (a DNA chromosome, protein-making structures called ribosomes, and enzymes for expressing and replicating DNA).  This reaction could occur because cells created through SCNT contain mitochondria from the egg donor and not from the patient, and therefore could still appear as foreign tissue to the recipient’s immune system.

There were other indications that Weisman was probably correct.  An experiment that was published in 2002 by William Rideout in the laboratory of Rudolf Jaenisch at the Whitehead Institute for Biological Research in the journal Cell derived embryonic stem cells from cloned mouse embryos and then differentiated those embryonic stem cells into bone marrow-based blood making stem cells. These blood making stem cells were then used to reconstitute the bone marrow of a mouse that had a mutation that prevented their bone marrow from forming normal types of disease-fighting white blood cells. However, even though the recipient mouse was genetically identical to the embryonic stem cells that had been used to derived the blood-making stem cells, the immune systems of the recipient mouse still rejected the implanted cells after a time.  Weissman, however, was not able to directly test this claim himself at that time.  Weissman directs the Stanford Institute for Stem Cell Biology and Regenerative Medicine, and now, in collaboration with Schrepfer and her colleagues, he was able to test this hypothesis.

“There was a thought that because the mitochondria were on the inside of the cell, they would not be exposed to the host’s immune system,” Schrepfer said. “We found out that this was not the case.”

Schrepfer, who heads the Transplant and Stem Cell Immunobiology Laboratory in Hamburg, used cells that were created by transferring the nuclei of adult mouse cells into enucleated eggs cells from genetically different mice. When transplanted back into the nucleus donor strain, the cells were rejected although there were only two single nucleotide substitutions in the mitochondrial DNA of these SCNT-derived cells compared to that of the nucleus donor. “We were surprised to find that just two small differences in the mitochondrial DNA was enough to cause an immune reaction,” she said.

“We didn’t do the experiment in humans, but we assume the same sort of reaction could occur,” Schrepfer added.

Until recently, researchers were able to perform SCNT in many species, but not in humans.  However, scientists at the Oregon Health and Science University announced the successful derivation of human embryonic  stem cells from cloned, human embryos.  This reignited interest in eventually using SCNT for human therapies. Although many stem cell researchers are focused on a different method of creating pluripotent stem cells, called induced pluripotent stem cells, some believe that there are some applications for which SCNT-derived pluripotent cells are better suited.

The immunological reactions reported in the new paper will be a consideration if clinicians ever use SCNT-derived stem cells in human therapy, but Weissman thinks that such reactions should not prevent their use.  “This research informs us of the margin of safety that would be required if, in the distant future, we need to use SCNT to create pluripotent cells to produce the tissue stem cells to treat someone,” he said. “In that case, clinicians would likely be able to handle the immunological reaction using the immunosuppression methods that are currently available.”  I find such a statement somewhat cavalier given that the nature of the immunological rejection might be robust enough to endanger the patient regardless of the anti-rejection drugs that are used.

In the future, scientists might also lessen the immune reaction by using eggs from someone who is genetically similar to the recipient, such as a mother or sister, Schrepfer added.  Except that now you have added the dangers of egg retrieval to this treatment regimen, which not only greatly jacks up the price of this type of treatment, but now endangers another person just to treat this one patient.  Add to that the fact that you are making a cloned human embryo (a very young person) for the sole purpose of dismembering it, and now you have added a degree of barbarism to this treatment as well.

So if we some SCNT-based treatments for patients we have an added danger for the patient (immunological rejection), danger for the egg donor, the homicide of the young embryo, and a prohibitively expensive procedure that no insurance company in their right mind would fund. I say we abandon this mode of treatment for the morally-bankrupt option that it is and pursue more ethical ways of treating patients.

Embryonic Stem Cells From Cloned Embryos Vs Induced Pluripotent Stem Cells: Let the Debate Begin


In May of 2013, Shoukhrat Mitalipov and his coworkers from the Oregon Health and Science University, reported the derivation of human embryonic stem cells from cloned human embryos. Other stem cell scientists have confirmed that Mitalipov’s protocol works as well as he says it does.

Mitalipov and others have also examined the genetic integrity of embryonic stem cells made from cloned human embryos and induced pluripotent stem cells made from mature adult cells through genetic engineering and cell culture techniques. This paper was published in Nature in June 2014 and used genetically matched sets of human Embryonic Stem cells made from embryos donated from in vitro fertilization clinics, induced Pluripotent Stem cells and nuclear transfer ES cells (NT-ES cells) derived by somatic cell nuclear transfer (SCNT). All three of these sets of stem cells were subjected to genome-wide analyses. These analyses sowed that both NT-ES cells and iPS cells derived from the same somatic cells contained comparable numbers of genetic variations. However, DNA methylation, a form of DNA modification for regulatory purposes and gene expression profiles of NT-ES cells corresponded closely to those of IVF ES cells. However, the gene expression provide of iPS cells differed from these other two cell types and iPS cells also retained residual DNA methylation patterns typical of the parental somatic cells. From this study, Mitalipov stated that “human somatic cells can be faithfully reprogrammed to pluripotency by SCNT (that means cloning) and are therefore ideal for cell replacement therapies.”

Now a new study by Dieter Egli of the New York Stem Cell Foundation (NYSCF) in New York City, which included Mitalipov as a collaborator, has failed to demonstrate significant genetic differences between iPS cells and NT-ES cells. This is significant because Eglin has long been a rather vigorous proponent of cloning to make patient-specific stem cells. Egli gave an oral preview of his forthcoming paper on October 22nd, at the NYSCF annual conference. Egli told his audience, “This means that all of you who are working on iPS cells are probably working with cells that are actually very good. So I have good news for you,” he told them, eliciting murmurs and chuckles. “What this exactly means for the SCNT program, I don’t know yet.”

Egli and colleagues used skin cells from two people—a newborn and an adult—to create both stem cells from cloned embryos (using donor eggs) and iPS cells. Then they compared the genomes of these two types of cell lines with the genomes of the original skin cells in terms of genetic mutations, changes in gene expression, and differences in DNA methylation. Both methods resulted in about 10 mutations compared with the average genome of the mature source cells. These changes didn’t necessarily happen during reprogramming, however, Egli says, since many of these mutations were likely present in the original skin cells, and some could have arisen during the handling of cells before they were reprogrammed.

Both types of stem cells also carried a similar amount of methylation changes. Overall, the method didn’t seem to matter, Egli and his team concluded. Because he is a longtime proponent of SCNT, Egli says it would have been “more attractive” to reveal significant differences between the two kinds of stem cells. “This is simply not what we found.”

Now it would be premature to conclude that iPS cells are as good as NT-ES cells for regenerative purposes, but this certainly seems to throw a monkey wrench in the cloning bandwagon. Cloning would be quite complicated and expensive and also requires young, fertile women to donate their eggs. These egg donors must undergo potentially risky procedures to donate their eggs. Jennifer Lahl’s documentary Eggsploitation provides just a few of some of the horror stories that some women experienced donating their eggs. The long-term effects of this procedure is simply not known and asking young women to do this and potentially compromise their health or future fertility seems beyond the pale to me.

Alternatively, iPS technology keeps improving and may come to the clinic sooner than we think. Also, is a cloned embryo essentially different from one made through IVF or “the old-fashioned way.?” This whole things seems to me to involved the creation of very young human beings just so that we can dismember them and use them as spare parts. Such a practice is barbaric in the extreme.

For those who are interested, please see chapters 18 and 19 of my book The Stem Cell Epistles to read more about this important topic.

Mesenchymal Stem Cells Derived from Induced Pluripotent Stem Cells are Epigenetically Rejuvenated


Earlier this year, Miltalipov and his research group published a paper in Nature that compared the genetic integrity of embryonic stem cells made from embryos, to induced pluripotent stem cells and embryonic stem cells made from cloned embryos.  All three sets of stem cells seemed to have comparable numbers of mutations, but the induced pluripotent stem cells had “epigenetic changes” that were not found in either stem cell line from cloned or non-cloned embryos.

Genetic characteristics have to do with the sequence of the DNA molecules that make up the genome of an organism.  Epigenetic characteristics have nothing to do with the sequence of DNA, but instead are the result of small chemicals that are attached to the DNA molecule.  These small chemical tags affect gene expression patterns.  Every cell has a specific epigenetic signature.

During development, the cells that will form our eggs and sperm in our bodies, the “primordial germ cells,” begin their lives in the outer layer of the embryo.  During the third week of life, these primordial germ cells or PGCs move like amoebas and wander into the yolk sac wall and collect near the exit of a sac called the “allantois.”  The PGCs are outside the embryo at this time or extraembryonal.  Incidentally, yolk sac is a terrible name for this structure, since it does not produce yolk proteins.  Therefore other textbooks have renamed it the “primary umbilical vesicle,” which is a bit of a mouthful, but it probably better than “yolk sac.”

 

1 - Primordial germ cells 2 - Allantois 3 - Rectum 4 - Ectoderm 5 - Foregut 6 - Primordial Heart 7 - Secondary yolk sac 8 - Endoderm 9 - Mesoderm 10 - Amniotic cavity
1 – Primordial germ cells
2 – Allantois
3 – Rectum
4 – Ectoderm
5 – Foregut
6 – Primordial Heart
7 – Secondary yolk sac
8 – Endoderm
9 – Mesoderm
10 – Amniotic cavity

The embryo around this time undergoes a bending process as a result of its growth and the head bends toward the tail (known as the cranio-caudal curvature) and then the sides of the embryo fold downwards and eventually fuse (lateral folding).  This bending of the embryo allows the PGCs to wander back into the embryo again between the fourth and sixth week.  The PGCs move along the yolk sac wall to the vitelline and into the wall of the rectum.  After crossing the dorsal mesentery (which holds the developing intestines in place) they colonize the gonadal or genital ridge (which is the developing gonad). During their journey, and while in the gonadal ridge, the PGCs divide many times.

1 - Rectum 2 - Vitelline 3 - Allantois 4 - Nephrogenic cord (pink) 5 - Gonadal ridge (green) 6 - Primordial germ cells (red dots) 7 - Heart prominence
1 – Rectum
2 – Vitelline
3 – Allantois
4 – Nephrogenic cord (pink)
5 – Gonadal ridge (green)
6 – Primordial germ cells (red dots)
7 – Heart prominence

When the PGCs move into the developing gonad, the chemical tags on their DNA are completely removed (rather famous paper – Lee, et al., Development 129, 1807–1817 (2002).  This epigenetic erasure proceeds in order for the PGCs to develop into gametes and then received a gamete-specific set of epigenetic modifications.  These epigenetic modifications also extend to the proteins that package the DNA into chromosomes – proteins called histones.  Specific modifications of histone proteins and DNA lead to gamete-specific expression of genes.  Once fertilization occurs, and the embryological program is initiated, tissue-specific epigenetic modifications are conveyed onto the DNA and histones of particular cell populations.

This is a long-winded explanation, but because many cancer cells have abnormal epigenetic modifications, these epigenetic abnormalities in induced pluripotent stem cells (iPSCs) have been taken with some degree of seriousness.  Although, there is little evidence to date that links the cancer-causing capabilities of iPSCs with specific epigenetic modifications, although it certainly affects the ability of these cells to differentiate into various cell types.

A paper has just come from the laboratory of Wolfgang Wagner from the Aachen University Medical School, in Aachen, Germany that derived iPSCs from mesenchymal stem cells from human bone marrow, and then in a cool one-step procedure, differentiated these cells into mesenchymal stem cells (MSCs).  These  iPS-MSCs looked the same, and acted the same in cell culture as the parent MSCs, and had the same gene expression profiles as primary MSCs.  However, all age-related and tissue-specific epigenetic patterns had been erased by the reprogramming process.  This means that all the tissue-specific, senescence-associated, and age-related epigenetic patterns were erased during reprogramming.  Another feature of these iPS-MSCs is that they lacked but the ability to down-regulate the immune response, which is a major feature of MSCs.

Thus, this paper by the Wagner lab shows that MSCs derived from iPSCs are rejuvenated by the reprogramming process.  Also, the donor-specific epigenetic features are maintained, which was also discovered by Shao and others last year.  This suggests that epigenetic abnormalities are not an inherent property of the derivation of iPSCs, and that this feature is not an intractable characteristic of iPSCs derivation and may not prevent these cells from being successfully and safely used in the clinic.  However, this might be a cell type-specific phenomenon.  Also, the loss of the immune system regulatory capabilities of these iPS-MSCs is troubling and this requires further work.

iPS-MSCs

Chicken Induced Plurpotent Stem Cells Made With Minicircles


The safety of induced pluripotent stem cells (iPSCs) haws been debated in several studies and publications.  Original studies of the genetic differences between the cellular sources of iPSCs and the iPSCs derived from them tended to show a whole gaggle of new mutations that seemed to not appear in the original cells.  Therefore, several commentators warned about the “dark side of pluripotency.”. However, other studies that utilized higher-resolution techniques showers that many of these mutations that occurred in iPSCs did exist in the original cells before their reprogramming, but that these mutations occurred at low frequencies, but became amplified during the culturing of reprogrammed cells.

One feature that has received less attention in these discussions of the safety of iPSC derivation is that the method by which iPSCs are made has distinct consequences for the stem cells that are made.  Typically, methods that utilize gene vectors that do not integrate into the genomes of the host cells are inherently safer than those vectors that do integrate.  PiggyBac transposon vectors integrate, but self-excise soon after their integration, and, therefore, do not leave a trace or their previous integration.  Minicircles also do not integrate and tend to produce safer iPSCs.  For this reason, this present paper is of interest to us.

Franklin West and his colleagues at the University of Georgia have made chicken iPSCs using minicircles to reprogram adult cells.  West was interested in using iPSCs to make recombinant chickens, since chickens are a rather primary food source and major component of economic development in several countries.  Making transgenic or recombinant chickens by means of stem cell technology makes it possible to make animals with improved meat and egg production or disease resistance.

To this end, West and his group made chicken (c) iPSCs from skin fibroblast cells by means of a nonviral minicircle reprogramming method.  This resulted in ciPSCs that showed excellent stem cell appearance and expressed key stem cell marker genes (alkaline phosphatase, POU5F1, SOX2, NANOG, and SSEA-1).  These cells also showed very rapid growth in culture and expressed high levels of the enzyme telomerase, which is an enzyme that is vital for the maintenance of chromosomes.

When West and his research group transplanted late-passage ciPSCs into stage X chicken embryos, the cIPSCs successfully integrated into the growing embryo and contributed to tissues derived from all three primary germ layers (ectoderm, mesoderm, and endoderm).  These ciPSCs also contributed to the gonads, which means that the ciPSCs could make gametes that could contribute to the production of a new generation of chicken.

These ciPSCs provide an exciting new tool to create transgenic chickens and has broad and exciting implications for agricultural and transgenic animal fields at large.  However, it also demonstrates that iPSCs can be safely produced and used for agricultural purposes.  This means that if non-integration-based or non-viral-based techniques are used to make iPSCs it should be possible to make them safely for therapeutic purposes also.

Making Better Induced Pluripotent Stem Cells


On July 2nd of this year, a paper appeared in the journal Nature that performed complete genomic analyses of embryonic stem cells derived from embryos or cloned embryos, and induced pluripotent stem cells (iPSCs), which are made from reprogrammed adult cells.  They found that both embryonic stem cells made from cloned embryos and iPSCs derived from the same types of adult cells contained comparable numbers of newly introduced mutations.  However, when it came to the epigenetic modification of the genome (the small chemical tags attached to specific bases of DNA that gives the cell hints as to which genes to turn off), the epigenetic pattern of the embryonic stem cells made from cloned embryos more closely resembled that from embryonic stem cells.  The iPSCs still had some similarities with the adult cells from which they were derived whereas the embryonic stem cells made from cloned embryos were more completely reprogrammed.  From this the authors claimed that making embryonic stem cells by means of cloning is ideal for cell replacement therapies.

There is a big problem with this conclusion:  This was tried in animals and it did not work because of immunological rejection of the products from the stem cells.  For more information on this, see my book, The Stem Cell Epistles, chapter 18.

Despite this “bad news” for iPSCs, two recent papers have actually provided some good news for stem cells that can heal without destroying embryos.  The first paper comes from Timothy Nelson’s laboratory at the Mayo Clinic in Rochester, Minnesota.  Differentiation of iPSCs is, in some cases, rather efficient and the isolation procedures fail to effectively isolate the differentiated cells from potentially tumor-causing cells.  However, in other cases, the differentiation is inefficient and the isolation procedures are also rather poor, which leaves a large enough population of undifferentiated tumor-causing cells.

Nelson’ group has discovered that treating iPSCs and their derivatives with anti-cancer drugs like etoposide (a topoisomerase II inhibitor for those who are interested) increases engraftment efficiency and decreases the incidence of tumors.  My only problem with Nelson’s paper is that he and his colleagues used lentiviral vectors to make their iPSCs.  These vectors tend to produce iPSCs that are rather good at causing tumors.  I would have rather that he tried making iPSCs with other methods that do not leave permanent transgenes in the cells.  Nelson and his group transplanted their iPSC-derived cells into the hearts of mice where they could use high-resolution imaging to determine the number of cells that integrated into the heart and the presence of cell masses that were indicative of tumors.  None of the ectoposide-treated cell transplants caused tumors whereas 4 of the 5 transplants not treated with ectoposide caused tumors.  This paper appeared in Stem Cells and Development.

The second “good news” paper for iPSCs comes from Junji Takeda at the University of Osaka and Ken Igawa from the Tokyo Medical and Dental University, Japan.   In their paper from Stem Cells Translational Medicine, the Japanese groups collaborated to make iPSCs from skin based fibroblasts and then differentiate them into skin cells (keratinocytes).  However, they made the iPSCs in two different ways.  The first protocol utilized the piggyBac transposon system to make iPSCs.  The piggyBac system comes from moths, but it is highly active in mammalian cells.  It can deliver the genes to the cells, but the segment of DNA is then easily excised from the host cells without causing any mutations.  This system, therefore, will generate iPSCs that do not have any transgenes in them.  The second protocol used a system based on cytomegalovirus that leaves the transgenes in the cells but gradually inactivates their expression.

When these two types of iPSCs were compared, they seems to be essentially identical when grown in culture.  Thus in the pluripotent state, the cells were equivalent for the most part.  But once the iPSC lines were differentiated into skin cells, the transgene-free iPSCs formed skin cells that looked, behaved and had the same gene expression profile as normal human skin cells.  The transgene-containing iPSCs differentiated into skin cells, but they did not look quite like skin cells, did not have the same gene expression profile as normal human skin cells, and did not behave like normal human skin cells.

The moral of this story is that not all iPSC lines are created equally and the way you derive them is as important as the cell type from which they were derived.  Also, even incomplete differentiation does not need to be an obstacle for iPSCs, since the cancer-causing cells can be removed by means of specific drugs.  Finally, not all that glitters is gold.  Cloned embryos may give you stem cells that look more like embryonic stem cells, but so what.  These might still suffer from many of the same set backs.  Add to that the ethical problems with getting women to give up their eggs for research and cures (see Jennifer Lahl’s movie Eggsploitation for more disturbing information about that), and you have a losing combination.

Scientists Make Cloned Stem Cells from Adult Cells


For the first time, stem cell scientists have derived stem cells from cloned human embryos that were made from adult cells.  This brings them closer to developing patient-specific lines of cells that can be used to treat a whole host of human maladies, but at a cost.  This research was described in the April 17th online edition of the journal Cell Stem Cell.

In May of last year, Shoukhrat Mitalipov from the Oregon Health and Science University, reported the derivation of human embryonic stem cells from cloned human embryos.  However, these cloned were made using cells that came from infants.  Miltalipov worked out a new protocol for cloning human embryos by using nonhuman primate embryos, in particular those from a Rhesus monkey.

In this study, the donor cells came from two men, a 35-year-old and a 75-year-old.  By using the protocol developed by Mitalipov and his group, Robert Lanza, Young Gie Chung, and Dong Ryul Lee and their colleagues made personalized embryonic stem cells from these two men.

Stem cell biologist Paul Knoepfler, an associate professor at the University of California at Davis who runs the widely read Stem Cell Blog, called the new research “exciting, important, and technically convincing.”  He continued: “In theory you could use those stem cells to produce almost any kind of cell and give it back to a person as a therapy.”

In their paper, Young Gie Chung from the Research Institute for Stem Cell Research for CHA Health Systems in Los Angeles, Robert Lanza from Advanced Cell Technology in Marlborough, Mass., and their co-authors pointed out the potential promise of this technology for new regenerative therapies.  However, their work is also an important discovery for human cloning, since it shows that age-associated changes are not necessarily an impediment to SCNT-based nuclear reprogramming of human cells.

Even though it was the intent of Chung and others to gestate these cloned embryos to form cloned children, this work could be the first step toward creating a baby with the same genetic makeup as a donor.  Thus, this technology presents a so-called “dual-use dilemma.”

Marcy Darnovsky, executive director of the Berkeley, Calif.-based Center for Genetics and Society, explained that many technologies developed for good can be used in ways that the inventor may not have intended and may not like.

“This and every technical advance in cloning human tissue raises the possibility that somebody will use it to clone a human being, and that is a prospect everyone is against,” Darnovsky said.

This paper represents a collaboration between members of academic laboratories and industry.  Funding for this work came from a private medical foundation and South Korea’s Ministry of Science.

Technically, the somatic-cell nuclear transfer protocols used in paper are still somewhat inefficient.  Chung’s team had to attempt 39 times to produce only two blastocyst-stage embryos.  Their first attempts were complete failures, but when they modified the Mitalipov protocol and activated the cloned embryos 2 hours after fusion rather than 30 minutes after fusion, the embryos grew successfully.

“We have reaffirmed that it is possible to generate patient-specific stem cells using [this] technology,” Chung said.

Shoukhrat Mitalipov, director of the Center for Embryonic Cell and Gene Therapy at Oregon Health & Science University, who developed the method that Chung’s group built upon, said that this work involves eggs that have not been fertilized.

“There will always be opposition to embryonic research, but the potential benefits are huge,” Mitalipov said.

Yes, there will be opposition to destructive research on embryos because they are the youngest among us.  No they do not have the right to vote, drive a car, or buy a hunting license, but they have the right to not be harmed.  To deny them that right because they cannot presently exercise particular capacities assumes that the embryo undergoes essential changes as it develops.  But human embryos develop into the kinds of entities they become because of their intrinsic human nature that drives them to do so.  Yes development is a progressive program that causes the embryo to acquire new structures and capabilities that it previously did not have, but what kind of entity can develop into a human adult that is not itself human?  It takes a human embryo to make a human fetus, which makes a human new-born baby, which makes a human toddler, and do on.  This continuum or development and change occurs throughout or lives and this continuum begins at the end of fertilization.

Cloned embryos begin this continuum at the completion of somatic cell nuclear transfer (SCNT).  SCNT works as a stand-in for fertilization, but the result is still the same – a human embryo.  It also should have the right not to be harmed, but instead she is being produced solely for the purpose of being dismembered.  Is this the way we should treat the smallest and most defenseless among us? surely not.  All this talk about, “well we did not form a fully human being” is a crock.  Yes you did.  You formed a fully formed human embryo.  We were all human embryos at one time and these embryos developed into you and me.  We were inarticulate and incapable at the time, but we gained those capacities over time.  Again, how can something that gives rise to a human child not be human?  The embryo is a human being, but it is a very young human being.  Youth should not disqualify it from being able to live.

Seventeen years ago, when Ian Wilmut from the Roslin Institute in Edinburgh, Scotland announced news about the birth of the first sheep cloned from somatic cells named Dolly, several legislators called for a ban on human cloning.  Several countries took measures to limit or outlaw such work, but in the United States.  The cloning issue was obfuscated by dividing it into “reproductive cloning” for the purposes of making cloned children, and “therapeutic cloning” for the development of new therapies.  Unfortunately, this dichotomy is slightly disingenuous since the techniques for both of these procedures are exactly the same except that reproductive cloning uses a surrogate mother to gestate the cloned embryo and bring her to term.  Both of these procedures produce human embryos, but one uses them to make a baby and the other destroys them before they can do so.

President George W. Bush tried to split the difference by restricting federal funding for stem cell research that harms to a human embryo.  This led to talk of Bush’s “embryonic stem cell ban,” which was inaccurate and was used unfairly used to paint Bush as an idiot.  However, some 15 states have laws addressing human cloning, and about half of them ban both reproductive and therapeutic cloning.

Embryonic stem cell research has typically used embryos that are left over from the fertility industry.  However, some religious groups such as the U.S. Conference of Catholic Bishops and others as well  objected to this, since it destroys a very young human being.

However, about seven years ago, Shinya Yamanaka and his colleagues discovered a way to make induced pluripotent stem cells from mature adult cells.  Genetic engineering techniques could convert ordinary cells into pluripotent stem cells without the need for human eggs.  While this technique did not present the same ethical issues, some induced pluripotent stem cells lines contain significant genetic abnormalities and there is still debate over how safe these cells are for clinical use.

The research conducted by Mitalipov and Chung provides a second way of producing pluripotent cells through laboratory techniques that is, in my view, far less ethical and will almost certainly also have unintended consequences as well.