RETRACTED: Evidence of a pluripotent human embryonic stem cell line derived from a cloned blastocyst

Investigation of the potential teratogenic effects of fructose on the embryo using the rat whole embryo culture model

Excessive consumption of fructose-sweetened foods and beverages is a growing concern worldwide. Studies have demonstrated that fructose consumption before and during pregnancy can result in adverse outcomes such as decreased decidualization, increased fetal losses, and low birth weight. The study investigated the teratogenic effects of fructose on rat embryos during organogenesis using whole embryo culture. Within the scope of the study, 4 groups were formed as control, low, medium, and high-dose fructose (HDF) with 10 embryos in each group. The 9.5-day-old rat embryos were cultured with different concentrations of fructose (1, 5 and 10 mM) for 48 h and the possible effects of fructose were examined using morphological scoring, histochemistry, immunofluorescence, and TUNEL methods. According to the analyses, protein synthesis and proliferation were decreased, vascular formation was suppressed, and apoptosis was increased in embryos exposed to fructose, especially at concentrations of 5 mM and above. According to the morphological scoring results, it was determined that heart, hind limb, and somite development were retarded in all experimental groups compared to the control group, developmental retardation increased in direct proportion to fructose concentration, and also significant malformations were observed in all parameters examined in the HDF group. In addition, analysis of yolk sac diameter, head length, crown rump length and somite numbers showed that these parameters were significantly decreased in all experimental groups. End of the study, it was concluded that fructose at concentrations of 1 mM and above may induce embryonic development retardation and other anomalies by decreasing protein synthesis and cell proliferation, suppressing vascular formation, and increasing apoptosis in embryonic tissues.

Small Molecular Approaches for Cellular Reprogramming and Tissue Engineering: Functions as Mediators of the Cell Signaling Pathway

Utilizing induced pluripotent stem cells (iPSCs) in drug screening and cell replacement therapy has emerged as a method with revolutionary applications. With the advent of patient-specific iPSCs and the subsequent development of cells that exhibit disease phenotypes, the focus of medication research will now shift toward the pathology of human diseases. Regular iPSCs can also be utilized to generate cells that assess the negative impacts of medications. These cells provide a much more precise and cost-efficient approach compared to many animal models. In this review, we explore the utilization of small-molecule drugs to enhance the growth of iPSCs and gain insights into the process of reprogramming. We mainly focus on the functions of small molecules in modulating different signaling pathways, thereby modulating cell fate. Understanding the way small molecule drugs interact with iPSC technology has the potential to significantly enhance the understanding of physiological pathways in stem cells and practical applications of iPSC-based therapy and screening systems, revolutionizing the treatment of diseases.

Pluripotent Stem Cell-Based Cell Therapy-Promise and Challenges

Human pluripotent stem cells such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) provide unprecedented opportunities for cell therapies against intractable diseases and injuries. Both ESCs and iPSCs are already being used in clinical trials. However, we continue to encounter practical issues that limit their use, including their inherent properties of tumorigenicity, immunogenicity, and heterogeneity. Here, I review two decades of research aimed at overcoming these three difficulties.

Intrinsic and extrinsic pathways of apoptosis: Role in cancer development and prognosis

Apoptosis, also named programmed cell death, is a fundament process required for morphogenetic homeostasis during early development and in pathophysiological conditions. It is come into existence in 1972 by work of Kerr, Wyllie and Currie and later on investigated during the research on development of the C. elegans. Trigger by several stimuli, apoptosis is necessary during the embryonic development and aging as homeostatic mechanism to control the cell population and also play a key role as defense mechanism against the immune responses and elimination of damaged cells. Cancer, a genetic disease, is a growing burden on the health and economy of both developing and developed countries. Every year there is tremendously increasing in the number of new cancer cases and mortality rate. Although, there is a significant improvement have been made in biotechnological and bioinformatic fields however, the therapeutic advantages and cancer etiology is still under explored. Several studies determined the deregulation of different apoptotic components during the cancer development and progression. Apoptosis relies on activation of distinct signaling pathways that are often deregulated in cancer. Thus, exploring the single or more than one apoptotic component underlying their expression in carcinogenesis could help to track the disease progression. Current book chapter will provide the several evidences supporting the use of different apoptotic components as prognosis and prediction markers in various human cancer types.

Advancements in Cancer Stem Cell Isolation and Characterization

Occurrence of stem cells (CSCs) in cancer is well established in last two decades. These rare cells share several properties including presence of common surface markers, stem cell markers, chemo- and radio- resistance and are highly metastatic in nature; thus, considered as valuable prognostic and therapeutic targets in cancer. However, the studies related to CSCs pave number of issues due to rare cell population and difficulties in their isolation ascribed to common stem cell marker. Various techniques including flow cytometry, laser micro-dissection, fluorescent nanodiamonds and microfluidics are used for the isolation of these rare cells. In this review, we have included the advance strategies adopted for the isolation of CSCs using above mentioned techniques. Furthermore, CSCs are primarily found in the core of the solid tumors and their microenvironment plays an important role in maintenance, self-renewal, division and tumor development. Therefore, in vivo tracking and model development become obligatory for functional studies of CSCs. Fluorescence and bioluminescence tagging has been widely used for transplantation assay and lineage tracking experiments to improve our understanding towards CSCs behaviour in their niche. Techniques such as Magnetic resonance imaging (MRI) and Positron emission tomography (PET) have proved useful for tracking of endogenous CSCs which could be helpful in their identification in clinical settings.

Human Embryonic Stem Cell Research, Abortion, and Publication Bias in the New England Journal of Medicine

Publication bias in medical journals depends on outside influences and the particular ideological bent of the editorial board. The New England Journal of Medicine (NEJM) is a premier medical scientific publication having among the highest impact rankings of any research journal. The Vioxx question and industry ties it highlighted have led to legitimate questions of whether significant conflicts of interest have arisen within NEJM that compromise the free exchange of scientific information and ideas. Over the past two decades, several socially charged areas have been treated with considerable bias in the editorial policy of NEJM, including the issues of human embryonic stem cell research and abortion. From 2000 to 2017, NEJM published over twenty pieces favorable toward human embryonic stem cell research and over fifty pieces favorable to abortion, with virtually no publication of contrary opinion. An aggressive editorial defense of Planned Parenthood Federation most recently seems particularly striking. A secular journal which is meant to represent the entire spectrum of physician opinion in controversial issues has a practical, if not also an ethical, responsibility to provide an unbiased forum for intelligible discussion for evaluation of the merits of particular issues. To do otherwise is publication bias that suppresses legitimate contrary viewpoints having merit and validity.

NONTECHNICAL SUMMARY

Publication bias in medical journals is detrimental to the free exchange of ideas regarding controversial issues. From 2000 to 2017, a premier publication, the New England Journal of Medicine (NEJM), has shown considerable bias in only publishing articles and editorials highly favorable toward human embryonic stem cell research and abortion, without permitting valid discussion and publication of contrary opinion. The recent strong editorial defense by NEJM of Planned Parenthood Federation in their sale of aborted fetal body parts seems particularly striking and disproportionate. Publication bias suppresses legitimate contrary viewpoints with merit and validity, suppressing fair debate in controversial issues.

Hubris and Sciences

There has been an increasing awareness of the importance of leadership and decision making, including scientists and academics, over recent times. By whom and how decisions are made can have serious implications across all levels of society. Several people have been successful in their life and have been inflicted by excessive pride and self-confidence. There are times when the manifestations of such behaviours demonstrate noticeable signs of narcissism and on extreme cases, hubris. Hubris is an old concept originated from the Greek mythology.  The risk of hubris affects politicians, leaders in business, scientists, academia, the military, entertainers, athletes and doctors (among many others). Power, especially absolute and unchecked power, is intoxicating and is manifested behaviourally in a variety of ways, ranging from amplified cognitive functions to lack of inhibition, poor judgment, extreme narcissism, deviant behaviour, and even cruelty. Hubristic behaviour of overconfidence, extreme pride together with an unwillingness to disregard advice makes powerful people in leadership positions to over-reach themselves with negative consequences for themselves and others. As the dangerous consequences of hubristic behaviours become more apparent and well described it is imperative that individuals, organisations and governments act to prevent such phenomena. Responsible leaders, including acclaimed scientists should exercise greater humility to the complexity and inherent uncertainty of their activities and strive to seek out and challenge hubristic behaviours.

Effects of Embryo Aggregation and PXD101 on the In Vitro Development of Mouse Somatic Cell Nuclear Transfer Embryos

To improve the cloning efficiency of somatic cell nuclear transfer (SCNT) and to establish nuclear transfer embryonic stem cells (NT-ESCs) reliably, it is necessary to produce high-quality blastocysts derived from mice SCNT embryos. Therefore, the present study aims to investigate an optimal method for mouse SCNT embryo production and NT-ESCs derivation by comparing the effects of two methods: the treatment of histone deacetylase inhibitor PXD101 after SCNT, embryo aggregation and their combination treatment. The results suggest that embryo aggregation at four-cell stage and 50 nM PXD101 treated for 10 hours during and after activation could improve both mouse SCNT embryos' development (PXD101: 40.0% vs. 18.5%; p < 0.05; aggregation: 40.2% vs. 18.5%; p < 0.05) and also enhance the isolation rate of NT-ESCs (PXD101: 38.2% vs. 12.5%; p < 0.05; aggregation: 39.0% vs. 12.5%; p < 0.05). The combination of their treatments had a higher development rate (43.6%) and significantly higher NT-ESCs isolation rate (54.7%), therefore, we concluded that the combination of these two methods (50 nM PXD101 treated for 10 hours after SCNT and then aggregated at four-cell stage) is considered as the optimal way for the in vitro development of SCNT embryo and subsequent NT-ESCs isolation in mice, providing a new approach for the practical improvement of mouse cloning techniques and opening new opportunities to improve cloning efficiencies in other species.

End-Stage Organ Failure: Will Regenerative Medicine Keep its Promise?

End-stage organ failure is a major cause of death worldwide that can occur in patients of all ages and transplantation is the current standard of care for chronic end-stage disease of many organs. Despite the success of organ transplantation, it is becoming clear that there will never be enough organs made available through donation to meet the increasing demand. The past decade's rapid advancement in stem cell biology and tissue engineering generated an explosive outburst of reports that gave rise to regenerative medicine, a new field that promises to “fix” damaged organs through regeneration provided by transplanted cells, stimulation of endogenous repair mechanisms, or implantation of bioengineered tissue. Whether, and if so when, regenerative medicine will keep its promise is uncertain. As we continue to strive to find new effective solutions, alternative approaches based on the development of targeted, preventive interventions aimed at maintaining normal organ function, instead of repairing organ damage, should also be pursued.

Mathematical models of cell phenotype regulation and reprogramming: Make cancer cells sensitive again!

A cell's phenotype is the observable actualization of complex interactions between its genome, epigenome, and local environment. While traditional views in cancer have held that cellular and tumor phenotypes are largely functions of genomic instability, increasing attention has recently been given to epigenetic and microenvironmental influences. Such non-genetic factors allow cancer cells to experience intrinsic diversity and plasticity, and at the tumor level can result in phenotypic heterogeneity and treatment evasion. In 2006, Takahashi and Yamanaka exploited the epigenome's plasticity by "reprogramming" differentiated cells into a pluripotent state by inducing expression of a cocktail of four transcription factors. Recent advances in cancer biology have shown not only that cellular reprogramming is possible for malignant cells, but it may provide a foundation for future therapies. Nevertheless, cell reprogramming experiments are frequently plagued by low efficiency, activation of aberrant transcriptional programs, instability, and often rely on expertise gathered from systems which may not translate directly to cancer. Here, we review a theoretical framework tracing back to Waddington's epigenetic landscape which may be used to derive quantitative and qualitative understanding of cellular reprogramming. Implications for tumor heterogeneity, evolution and adaptation are discussed in the context of designing new treatments to re-sensitize recalcitrant tumors. This article is part of a Special Issue entitled: Evolutionary principles - heterogeneity in cancer?, edited by Dr. Robert A. Gatenby.

Ethical aspects of nuclear and mitochondrial DNA transfer

Somatic cell nuclear transfer (SCNT) (cloning), as a reproductive or therapeutic method, and mitochondrial DNA transfer, as a method to prevent the transmission of mitochondrial diseases, are analyzed in this paper from a bioethics perspective. The licit purpose of being able to treat certain diseases, as in the case of SCNT, cannot justify, in any case, resorting to illicit means such as the manipulation, selection, and elimination of human embryos in the blastocyst phase, by using cell lines obtained from them. Crossing this line paves the way (as utilitarian ethics advocates) to assuming any cost in scientific experimentation so long as satisfactory results are obtained. With mitochondrial replacement, either human embryos are directly manipulated (pronuclear transfer) or germline cells are manipulated (maternal spindle transfer); changes in these could be transmitted to the offspring.

LAY SUMMARY

This article analyzes somatic cell nuclear transfer (cloning) and mitochondrial DNA transfer techniques, in both reproductive and therapeutic applications, and preventive methods in the transmission of mitochondrial diseases, from a bioethical perspective. The manipulation, selection, and elimination of human embryos delimits the ethical acceptability of these promising techniques.

Stepping Into and Out of the Void: Funding Dynamics of Human Embryonic Stem Cell Research in California, Sweden, and South Korea

Nonprofit organizations and philanthropists stepped into a funding void caused by controversies over public funding of human embryonic stem cell (hESC) research. Based on interviews of 83 representatives of 53 funders, we examine the motivations and accountability structures of public agencies, corporations, fundraising dependent nonprofit organizations and philanthropic organizations that funded hESC research in three jurisdictions: California, Sweden, and South Korea. While non-traditional forms of funding are essential in the early stages of research advancement, they are unreliable for the long timeframes necessary to advance cell therapies. Such funding sources may enter the field based on high expectations, but may exit just as rapidly based on disappointing rates of progress.

The Inherent Drawbacks of the Pressure to Publish in Health Sciences: Good or Bad Science

In recent years, there has been a significant increase in the number of scientific publications- it is the era of "hunting the article". This commentary discusses the drawbacks of the pressure to publish that certainly contribute to the 'dark side' of science. In fact, health science career progression greatly relies on the number of scientific publications a researcher has, and in many cases these may be more valorized than the health services provided. Of course, scientific publications help to develop the skills of health care professionals, but as Einstein highlighted " not everything that counts can be counted, and not everything that can be counted counts".

The Inherent Drawbacks of the Pressure to Publish in Health Sciences: Good or Bad Science

In recent years, there has been a significant increase in the number of scientific publications– it is the era of “hunting the article”. This commentary discusses the drawbacks of the pressure to publish that certainly contribute to the ‘dark side’ of science. In fact, health science career progression greatly relies on the number of scientific publications a researcher has, and in many cases these may be more valorized than the health services provided. Of course, scientific publications help to develop the skills of health care professionals, but as Einstein highlighted “ not everything that counts can be counted, and not everything that can be counted counts”.

Publication ethics

High-quality scientific literature is the cornerstone of scientific progress and is highly regarded by academia. However, scientific literature is often marred by plagiarism, data fabrication and falsification, redundant publication and illegitimate authorship. These problems are discussed in this article.

Data fabrication and falsification and empiricist philosophy of science

Scientists have rules pertaining to data fabrication and falsification that are enforced with significant punishments, such as loss of funding, termination of employment, or imprisonment. These rules pertain to data that describe observable and unobservable entities. In this commentary I argue that scientists would not adopt rules that impose harsh penalties on researchers for data fabrication or falsification unless they believed that an aim of scientific research is to develop true theories and hypotheses about entities that exist, including unobservable ones. This argument presents a challenge for constructive empiricists, such as van Fraassen. Constructive empiricists need to be able to explain why rules pertaining to data fabrication and falsification do not threaten their philosophy of science.

The commercialization of human eggs in mitochondrial replacement research

After the development of induced pluripotent stem cells (IPSCs) in 2007, the pressure to commercialize women's eggs for stem cell research could have been expected to lessen. However, the pressure to harvest human eggs in large quantities for research has not diminished; rather, it has taken different directions, for example in germline mitochondrial research. Yet there has been little acknowledgement of these technologies' need for human eggs, the possible risks to women and the ethical issues concerning potential exploitation. Rather, there has been a renewed campaign to legalize payment for eggs in research, although the actual scientific advances are at best modest. This article shows why a market in women's eggs is ethically problematic in terms of the doctor's duty to do no harm and the limitations of 'informed' consent.

Compounds used to produce cloned animals are genotoxic and mutagenic in mammalian assays in vitro and in vivo

The compounds 6-dimethylaminopurine and cycloheximide promote the successful production of cloned mammals and have been used in the development of embryos produced by somatic cell nuclear transfer. This study investigated the effects of 6-dimethylaminopurine and cycloheximide in vitro, using the thiazolyl blue tetrazolium bromide colorimetric assay to assess cytotoxicity, the trypan blue exclusion assay to assess cell viability, the comet assay to assess genotoxicity, and the micronucleus test with cytokinesis block to test mutagenicity. In addition, the comet assay and the micronucleus test were also performed on peripheral blood cells of 54 male Swiss mice, 35 g each, to assess the effects of the compounds in vivo. The results indicated that both 6-dimethylaminopurine and cycloheximide, at the concentrations and doses tested, were cytotoxic in vitro and genotoxic and mutagenic in vitro and in vivo, altered the nuclear division index in vitro, but did not diminish cell viability in vitro. Considering that alterations in DNA play important roles in mutagenesis, carcinogenesis, and morphofunctional teratogenesis and reduce embryonic viability, this study indicated that 6-dimethylaminopurine and cycloheximide utilized in the process of mammalian cloning may be responsible for the low embryo viability commonly seen in nuclear transfer after implantation in utero.

Preclinical stem cell therapy in Chagas Disease: Perspectives for future research

Chagas cardiomyopathy still remains a challenging problem that is responsible for high morbidity and mortality in Central and Latin America. Chagas disease disrupts blood microcirculation via various autoimmune mechanisms, causing loss of cardiomyocytes and severe impairment of heart function. Different cell types and delivery approaches in Chagas Disease have been studied in both preclinical models and clinical trials. The main objective of this article is to clarify the reasons why the benefits that have been seen with cell therapy in preclinical models fail to translate to the clinical setting. This can be explained by crucial differences between the cellular types and pathophysiological mechanisms of the disease, as well as the differences between human patients and animal models. We discuss examples that demonstrate how the results from preclinical trials might have overestimated the efficacy of myocardial regeneration therapies. Future research should focus, not only on studying the best cell type to use but, very importantly, understanding the levels of safety and cellular interaction that can elicit efficient therapeutic effects in human tissue. Addressing the challenges associated with future research may ensure the success of stem cell therapy in improving preclinical models and the treatment of Chagas disease.

Selective neuronal differentiation of neural stem cells induced by nanosecond microplasma agitation

An essential step for therapeutic and research applications of stem cells is their ability to differentiate into specific cell types. Neuronal cells are of great interest for medical treatment of neurodegenerative diseases and traumatic injuries of central nervous system (CNS), but efforts to produce these cells have been met with only modest success. In an attempt of finding new approaches, atmospheric-pressure room-temperature microplasma jets (MPJs) are shown to effectively direct in vitro differentiation of neural stem cells (NSCs) predominantly into neuronal lineage. Murine neural stem cells (C17.2-NSCs) treated with MPJs exhibit rapid proliferation and differentiation with longer neurites and cell bodies eventually forming neuronal networks. MPJs regulate ~75% of NSCs to differentiate into neurons, which is a higher efficiency compared to common protein- and growth factors-based differentiation. NSCs exposure to quantized and transient (~150 ns) micro-plasma bullets up-regulates expression of different cell lineage markers as β-Tubulin III (for neurons) and O4 (for oligodendrocytes), while the expression of GFAP (for astrocytes) remains unchanged, as evidenced by quantitative PCR, immunofluorescence microscopy and Western Blot assay. It is shown that the plasma-increased nitric oxide (NO) production is a factor in the fate choice and differentiation of NSCs followed by axonal growth. The differentiated NSC cells matured and produced mostly cholinergic and motor neuronal progeny. It is also demonstrated that exposure of primary rat NSCs to the microplasma leads to quite similar differentiation effects. This suggests that the observed effect may potentially be generic and applicable to other types of neural progenitor cells. The application of this new in vitro strategy to selectively differentiate NSCs into neurons represents a step towards reproducible and efficient production of the desired NSC derivatives.

The ups and downs of somatic cell nucleus transfer (SCNT) in humans

Achieving successful somatic cell nuclear transfer (SCNT) in the human and subhuman primate relative to other mammals has been questioned for a variety of technical and logistical issues. Here we summarize the gradual evolution of SCNT technology from the perspective of oocyte quality and cell cycle status that has recently led to the demonstration of feasibility in the human for deriving chromosomally normal stem cells lines. With these advances in hand, prospects for therapeutic cloning must be entertained in a conscientious, rigorous, and timely fashion before broad spectrum clinical applications are undertaken.

Ethical modernization: research misconduct and research ethics reforms in Korea following the Hwang affair

The Hwang affair, a dramatic and far reaching instance of scientific fraud, shocked the world. This collective national failure prompted various organizations in Korea, including universities, regulatory agencies, and research associations, to engage in self-criticism and research ethics reforms. This paper aims, first, to document and review research misconduct perpetrated by Hwang and members of his research team, with particular attention to the agencies that failed to regulate and then supervise Hwang's research. The paper then examines the research ethics reforms introduced in the wake of this international scandal. After reviewing American and European research governance structures and policies, policy makers developed a mixed model mindful of its Korean context. The third part of the paper examines how research ethics reform is proactive (a response to shocking scientific misconduct and ensuing external criticism from the press and society) as well as reactive (identification of and adherence to national or international ethics standards). The last part deals with Korean society's response to the Hwang affair, which had the effect of a moral atomic bomb and has led to broad ethical reform in Korean society. We conceptualize this change as ethical modernization, through which the Korean public corrects the failures of a growth-oriented economic model for social progress, and attempts to create a more trustworthy and ethical society.

Stem cell therapy in heart diseases: a review of selected new perspectives, practical considerations and clinical applications

Degeneration of cardiac tissues is considered a major cause of mortality in the western world and is expected to be a greater problem in the forthcoming decades. Cardiac damage is associated with dysfunction and irreversible loss of cardiomyocytes. Stem cell therapy for ischemic heart failure is very promising approach in cardiovascular medicine. Initial trials have indicated the ability of cardiomyocytes to regenerate after myocardial injury. These preliminary trials aim to translate cardiac regeneration strategies into clinical practice. In spite of advances, current therapeutic strategies to ischemic heart failure remain very limited. Moreover, major obstacles still need to be solved before stem cell therapy can be fully applied. This review addresses the current state of research and experimental data regarding embryonic stem cells (ESCs), myoblast transplantation, histological and functional analysis of transplantation of co-cultured myoblasts and mesenchymal stem cells, as well as comparison between mononuclear and mesenchymal stem cells in a model of myocardium infarction. We also discuss how research with stem cell transplantation could translate to improvement of cardiac function.

Digital images are data: and should be treated as such

The scientific community has become very concerned about inappropriate image manipulation. In journals that check figures after acceptance, 20-25% of the papers contained at least one figure that did not comply with the journal's instructions to authors. The scientific press continues to report a small, but steady stream of cases of fraudulent image manipulation. Inappropriate image manipulation taints the scientific record, damages trust within science, and degrades science's reputation with the general public. Scientists can learn from historians and photojournalists, who have provided a number of examples of attempts to alter or misrepresent the historical record. Scientists must remember that digital images are numerically sampled data that represent the state of a specific sample when examined with a specific instrument. These data should be carefully managed. Changes made to the original data need to be tracked like the protocols used for other experimental procedures. To avoid pitfalls, unexpected artifacts, and unintentional misrepresentation of the image data, a number of image processing guidelines are offered.

Successful reprogramming of differentiated cells by somatic cell nuclear transfer, using in vitro-matured oocytes with a modified activation method

Therapeutic cloning has tremendous potential for cell therapy and tissue repair in some diseases. However, the efficiency of development of cloned human embryos by somatic cell nuclear transfer is still low. In the present study, the activation of cloned human embryos was investigated while using in vitro-matured oocytes. Pseudo-pronuclear formation and the subsequent development was compared with different activation parameters, including different durations of ionomycin and 6-dimethylaminopurine treatment. The results showed that somatic cells were successfully reprogrammed by modification of activation treatments while using in vitro-matured oocytes. The activation efficiency of cloned human embryos was significantly increased at durations of ionomycin at both 5 and 7 min, despite different durations of 6-DMAP treatment. The results of blastocyst development showed that 20% of activated embryos developed to the blastocyst stage when the embryos were activated with 5 µm ionomycin for 5 min and 2 mm 6-DMAP for 5 h, which was significantly higher than those activated with other parameters. Moreover, we found that an increasing duration of 6-DMAP induced the formation of a single, large, pseudo-pronucleus in cloned human embryos and impaired subsequent development competence. In conclusion, successful reprogramming of human somatic cells was achieved using in vitro-matured oocytes by somatic cell nuclear transfer and improved with a modified activation method.

Histocompatible parthenogenetic embryonic stem cells as a potential source for regenerative medicine

Parthenogenesis is the process by which an oocyte develops into an embryo without fertilization. Parthenogenetic activation can be performed at various stages of meiosis, yielding embryos with a distinct genetic pattern of homozygousity and heterozygousity. The heterozygousity pattern specific to parthenogenetic embryonic stem (pES) cells derived from such embryos, can be predicted using genome-wide single nucleotide polymorphism (SNP) analysis to determine whether extrusion of the first or second polar body is prohibited. The heterozygous pES cells carrying the full complement of major histocompatibility complex (MHC) antigen matched to the oocyte donor, could therefore provide a potential source of MHC matched cells or tissue for cell replacement therapy. In this review, we summarized the mechanism of deriving heterozygous MHC-matched pES cells using a mouse and human models.

Aggregation of pre-implantation embryos improves establishment of parthenogenetic stem cells and expression of imprinted genes

Parthenogenetic embryonic stem cells (PgES) might advance cell replacement therapies and provide a valuable in vitro model system to study the genomic imprinting. However, the differential potential of PgES cells was limited. It could result from relative low heterology of PgES cells compared with ES cells from fertilization (fES), which produce different expression of most imprinted genes. Here, we described the establishment of PgES cells by aggregating parthenogenetic embryos at the 8-cell stage (aPgES cells), which may increase heterozygy. We found that derivation of aPgES cells in association with an increased number of inner cell mass cells by aggregating was more efficient than that of PgES cells from a single parthenogenetic blastocyst. The aPgES cells have normal karyotype, stain positive for alkaline phosphatase, express high levels of ES cell markers and can differentiate into teratomas composed of the three germ layers. Moreover, compared with PgES cells, the more highly upregulated paternally expressed imprinted genes were observed in aPgES cells, the same change was not shown in aPg blastocysts. This suggested that the aggregation induced effect could modify the expression of paternally expressed imprinted genes. Our studies showed that aPgES cells, the expression of imprinted genes in which more closely resemble fES cells than PgES cells, would contribute to all organs and avoiding immuno-rejection, which may provide invaluable material for regeneration medicine.