Tissue engineering, stem cells, cloning, and parthenogenesis: new paradigms for therapy

Extracellular Vesicles in Musculoskeletal Regeneration: Modulating the Therapy of the Future

Tissue regeneration is a hot topic in health sciences, particularly because effective therapies promoting the healing of several cell types are lacking, specifically those of the musculoskeletal system. Mesenchymal Stem/Stromal Cells (MSCs) have been identified as crucial players in bone homeostasis, and are considered a promising therapy for diseases such as osteoarthritis (OA) and Rheumatoid Arthritis (RA). However, some known drawbacks limit their use, particularly ethical issues and immunological rejections. Thus, MSCs byproducts, namely Extracellular Vesicles (EVs), are emerging as potential solutions to overcome some of the issues of the original cells. EVs can be modulated by either cellular preconditioning or vesicle engineering, and thus represent a plastic tool to be implemented in regenerative medicine. Further, the use of biomaterials is important to improve EV delivery and indirectly to modulate their content and secretion. This review aims to connect the dots among MSCs, EVs, and biomaterials, in the context of musculoskeletal diseases.

Healing of Artificially Created Gap Non-union Using Autologous Cultured Osteoblasts Impregnated Over Three-Dimensional Biodegradable Scaffold: An Experimental Study (Rabbit)

BACKGROUND

The large bone defect often require bone transplant or its substitutes to restore bone integrity which have some limitations. The study was conducted to analyze role of autologous osteoblast that are amplified in vivo and impregnated in a synthesized three-dimensional gelatin hydroxyapatite scaffold for treating artificially created critical size defect in rabbit's iliac crest.

METHODS

In this research, 4-month-old ten healthy white male rabbits of average weight 2-3 kg were chosen. Osteoblasts cells were isolated from the rabbit iliac crest and were taken in transfer medium to the laboratory and cultured for 2-3 weeks. These osteoblast cells were seed on 3-dimensional scaffold and culture the construct for 2 weeks. The cultured autologous osteoblasts over the scaffold were transplanted into the defect by reopening the iliac crest of the same rabbit from which is cells were extracted. Serial radiograph of pelvis was done to see progressive signs of union.

RESULTS

Out of ten rabbits chosen for study two rabbits were passed during study. Gross and radiological examination of rabbits was done at 0, 4, 8 and 12 weeks. Features of union was seen in six rabbits on follow-up. There is no signs of union or minimal new bone formation around the implant material were seen in two case.

CONCLUSION

The study demonstrated using autologous cultured osteoblasts impregnated over three-dimensional biodegradable scaffold for large bone defect is a good option. The importance of three-dimensional biodegradable scaffold is that it provide scaffolding for sufficient interval for new bone formation.

Electrofusion Stimulation Is an Independent Factor of Chromosome Abnormality in Mice Oocytes Reconstructed via Spindle Transfer

Oocytes reconstructed by spindle transfer (ST) are prone to chromosome abnormality, which is speculated to be caused by mechanical interference or premature activation, the mechanism is controversial. In this study, C57BL/6N oocytes were used as the model, and electrofusion ST was performed under normal conditions, Ca²⁺ free, and at room temperature, respectively. The effect of enucleation and electrofusion stimulation on MPF activity, spindle morphology, γ-tubulin localization and chromosome arrangement was compared. We found that electrofusion stimulation could induce premature chromosome separation and abnormal spindle morphology and assembly by decreasing the MPF activity, leading to premature activation, and thus resulting in chromosome abnormality in oocytes reconstructed via ST. Electrofusion stimulation was an independent factor of chromosome abnormality in oocytes reconstructed via ST, and was not related to enucleation, fusion status, temperature, or Ca²⁺. The electrofusion stimulation number should be minimized, with no more than 2 times being appropriate. As the electrofusion stimulation number increased, several typical abnormalities in chromosome arrangement and spindle assembly occurred. Although blastocyst culture could eliminate embryos with chromosomal abnormalities, it would significantly decrease the number of normal embryos and reduce the availability of embryos. The optimum operating condition for electrofusion ST was the 37°C group without Ca²⁺.

Proteomic analysis demonstrates that parthenogenetically activated swamp buffalo embryos have dysregulated energy metabolism

The comprehensive understanding of early embryo development is essential to optimize in vitro culture conditions. Protein expression landscape of parthenogenetically produced embryo remains unexplored. This study aimed to investigate the protein expression dynamics with a particular focus on energy metabolism throughout the early developmental stages of parthenogenetic buffalo embryos. For this purpose, we performed iTRAQ-based quantitative mass spectrometry and identified 280 proteins common in all stages. A total of 933 proteins were identified during the proteomics analysis. The data depicted that morula and blastocyst had distinct protein expression dynamics as compared to 2- to 16-cell-stage embryo. KEGG pathway analysis showed 23 proteins belonging to energy metabolism appeared in the data. Study of energy metabolism-related protein's expression pattern demonstrated that there was asynchrony in proteins related to glycolysis throughout the examined developmental stages. The expression pattern of pyruvate kinase mutase (PKM), an essential protein of glycolysis, indicated a slightly decreasing trend from 2-cell-stage embryo to blastocyst, and it was supported by expression of proteins involved in lactate production (LDHA and LDHB) suggesting the decreasing rate of aerobic glycolysis (Warburg Effect) at morula and blastocyst stage. The increased Warburg Effect is considered as the hallmark of proliferating cells or embryo at the blastocyst stage. Furthermore, the proteins involved in the citric acid cycle also showed down-regulation at the blastocyst stage, indicating a lesser role of oxidative phosphorylation at this stage. Therefore, it could be divulged from the study that there may be an irregular pattern of energy metabolism in early parthenogenetic embryos. Further studies are recommended to understand this phenomenon.

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.

Intercellular bridges are essential for human parthenogenetic cell survival

Parthenogenetic cells, obtained from in vitro activated mammalian oocytes, display multipolar spindles, chromosome malsegregation and a high incidence of aneuploidy, probably due to the lack of paternal contribution. Despite this, parthenogenetic cells do not show high rates of apoptosis and are able to proliferate in a way comparable to their biparental counterpart. We hypothesize that a series of adaptive mechanisms are present in parthenogenetic cells, allowing a continuous proliferation and ordinate cell differentiation both in vitro and in vivo. Here we identify the presence of intercellular bridges that contribute to the establishment of a wide communication network among human parthenogenetic cells, providing a mutual exchange of missing products. Silencing of two molecules essential for intercellular bridge formation and maintenance demonstrates the key function played by these cytoplasmic passageways that ensure normal cell functions and survival, alleviating the unbalance in cellular component composition.

In vivo and in vitro differentiation of uniparental embryonic stem cells into hematopoietic and neural cell types

The biological role of genomic imprinting in adult tissue is central to the consideration of transplanting uniparental embryonic stem (ES) cell-derived tissues. We have recently shown that both maternal (parthenogenetic/gynogenetic) and paternal (androgenetic) uniparental ES cells can differentiate, both in vivo in chimeras and in vitro, into adult-repopulating hematopoietic stem and progenitor cells. This suggests that, at least in some tissues, the presence of two maternal or two paternal genomes does not interfere with stem cell function and tissue homeostasis in the adult. Here, we consider implications of the contribution of uniparental cells to hematopoiesis and to development of other organ systems, notably neural tissue for which consequences of genomic imprinting are associated with a known bias in development and behavioral disorders. Our findings so far indicate that there is little or no limit to the differentiation potential of uniparental ES cells outside the normal developmental paradigm. As a potentially donor MHC-matching source of tissue, uniparental transplants may provide not only a clinical resource but also a unique tool to investigate aspects of genomic imprinting in adults.

The implications of stem cell applications for diseases of the respiratory system

Stem cells possess the unique properties of unlimited self-renewal capability and a broad differentiation spectrum to produce multiple different cell types. This provides many platforms to explore novel multidisciplinary approaches to create and/or restore functional three-dimensional tissues or organs for the treatment of a range of diseases. In this chapter, in the context of respiratory diseases, we review the unique properties of stem cells, and how they have been studied for their therapeutic potential in cell therapy and tissue engineering. In addition, we give a brief overview of the current clinical studies on the use of stem cells for both acute and chronic respiratory diseases.

Stem cells in alginate bioscaffolds

The immobilization of cells into polymeric scaffolds releasing therapeutic factors, such as alginate microcapsules, has been widely employed as a drug-delivery system for numerous diseases for many years. As a result of the potential benefits stem cells offer, during recent decades, this type of cell has gained the attention of the scientific community in the field of cell microencapsulation technology and has opened many perspectives. Stem cells represent an ideal tool for cell immobilization and so does alginate as a biomaterial of choice in the elaboration of these biomimetic scaffolds, offering us the possibility of benefiting from both disciplines in a synergistic way. This review intends to give an overview of the many possibilities and the current situation of immobilized stem cells in alginate bioscaffolds, showing the diverse therapeutic applications they can already be employed in; not only drug-delivery systems, but also tissue engineering platforms.

An improved transplantation strategy for mouse mesenchymal stem cells in an acute myocardial infarction model

To develop an effective therapeutic strategy for cardiac regeneration using bone marrow mesenchymal stem cells (BM-MSCs), the primary mouse BM-MSCs (1^st BM-MSCs) and 5^th passage BM-MSCs from β-galactosidase transgenic mice were respectively intramyocardially transplanted into the acute myocardial infarction (AMI) model of wild type mice. At the 6^th week, animals/tissues from the 1^st BM-MSCs group, the 5^th passage BM-MSCs group, control group were examined. Our results revealed that, compared to the 5^th passage BM-MSCs, the 1^st BM-MSCs had better therapeutic effects in the mouse MI model. The 1^st BM-MSCs maintained greater differentiation potentials towards cardiomocytes or vascular endothelial cells in vitro. This is indicated by higher expressions of cardiomyocyte and vascular endothelial cell mature markers in vitro. Furthermore, we identified that 24 proteins were down-regulated and 3 proteins were up-regulated in the 5^th BM-MSCs in comparison to the 1^st BM-MSCs, using mass spectrometry following two-dimensional electrophoresis. Our data suggest that transplantation of the 1^st BM-MSCs may be an effective therapeutic strategy for cardiac tissue regeneration following AMI, and altered protein expression profiles between the 1^st BM-MSCs and 5^th passage BM-MSCs may account for the difference in their maintenance of stemness and their therapeutic effects following AMI.

An obscure rider obstructing science: the conflation of parthenotes with embryos in the Dickey-Wicker amendment

In 1996 Congress passed the Dickey-Wicker Amendment (DWA) as part of an appropriations bill; it has been renewed every year since. The DWA bans federal funding for research using embryos and parthenotes. In this paper, we call for a public discussion on parthenote research and a questioning of its inclusion in the DWA. We begin by explaining what parthenotes are and why they are useful for research on reproduction, cancer, and stem cells. We then argue that the scientific difference between embryos and parthenotes translates into ethical differences, and claim that research on parthenotes is much less ethically problematic. Finally, we contextualize the original passage of the DWA to provide an explanation for why the two were possibly conflated in this law. We conclude by calling for a public discussion on reconsidering the DWA in its entirety, starting with the removal of parthenogenesis from this prohibition of National Institutes of Health (NIH) funding.

Ethical aspects of tissue engineering: a review

Tissue engineering (TE) is a promising new field of medical technology. However, like other new technologies, it is not free of ethical challenges. Identifying these ethical questions at an early stage is not only part of science's responsibility toward society, but also in the interest of the field itself. In this review, we map which ethical issues related to TE have already been documented in the scientific literature. The issues that turn out to dominate the debate are the use of human embryonic stem cells and therapeutic cloning. Nevertheless, a variety of other ethical aspects are mentioned, which relate to different phases in the development of the field. In addition, we discuss a number of ethical issues that have not yet been raised in the literature.

Aerodynamically assisted jetting and threading for processing concentrated suspensions containing advanced structural, functional and biological materials

In recent years material sciences have been interpreted right across the physical and the life sciences. Essentially this discipline broadly addresses the materials, processing, and/or fabrication right up to the structure. The materials and structures areas can range from the micro- to the nanometre scale and, in a materials sense, span from the structural, functional to the most complex, namely biological (living cells). It is generally recognised that the processing or fabrication is fundamental in bridging the materials with their structures. In a global perspective, processing has not only contributed to the materials sciences but its very nature has bridged the physical with the life sciences. In this review we discuss one such swiftly emerging fabrication approach having a plethora of applications spanning the physical and life sciences.

Whole-blastocyst culture followed by laser drilling technology enhances the efficiency of inner cell mass isolation and embryonic stem cell derivation from good- and poor-quality mouse embryos: new insights for derivation of human embryonic stem cell lines

The optimization of human embryonic stem (hES) cell line derivation methods is challenging because many worldwide laboratories have neither access to spare human embryos nor ethical approval for using supernumerary human embryos for hES cell derivation purposes. Additionally, studies performed directly on human embryos imply a waste of precious human biological material. In this study, we developed a new strategy based on the combination of whole-blastocyst culture followed by laser drilling destruction of the trophoectoderm for improving the efficiency of inner cell mass (ICM) isolation and ES cell derivation using murine embryos. Embryos were divided into good- and poor-quality embryos. We demonstrate that the efficiency of both ICM isolation and ES cell derivation using this strategy is significantly superior to whole-blastocyst culture or laser drilling technology itself. Regardless of the ICM isolation method, the ES cell establishment depends on a feeder cell growth surface. Importantly, this combined methodology can be successfully applied to poor-quality blastocysts that otherwise would not be suitable for laser drilling itself nor immunosurgery in an attempt to derive ES cell lines due to the inability to distinguish the ICM. The ES cell lines derived by this combined method were characterized and shown to maintain a typical morphology, undifferentiated phenotype, and in vitro and in vivo three germ layer differentiation potential. Finally, all ES cell lines established using either technology acquired an aneuploid karyotype after extended culture periods, suggesting that the method used for ES cell derivation does not seem to influence the karyotype of the ES cells after extended culture. This methodology may open up new avenues for further improvements for the derivation of hES cells, the majority of which are derived from frozen, poor-quality human embryos.

Pilot study to investigate the possibility of cytogenetic and physiological changes in bio-electrosprayed human lymphocyte cells

Background: We recently pioneered the ability to directly electrospray and electrospin living cells without compromising their viability. These protocols, now referred to as ‘bio-electrosprays’ and ‘cell electrospinning’, are rapidly emerging bio-techniques with a plethora of promising applications within the life sciences, in particular to regenerative and therapeutic medicine. Our studies to date, with both bio-electrosprays and cell electrospinning, have demonstrated that a large population of viable cells exist post-treatment, in comparison to controls over both short and long periods as assessed by flow cytometry. Methods: Post-treated mammalian cells are investigated in comparison to controls (culture and needle controls) at a cytogenetic and physiological level. In particular, the study addresses chromosome integrity following these protocols to assess any protocol-inflicted aberrations. Results: The procedures explored failed to inflict any process-driven gross chromosomal aberrations post-treatment. Conclusions: Our preliminary investigations demonstrate no significant compromising affects on the cell’s structure at a cytogenetic or physiological level, post-treatment. Thus, further establishing these protocols as unique direct cell-engineering approaches with a host of biological and medical applications, from the development of tissues to perhaps even organs in the future.

Advanced jet protocols for directly engineering living cells: a genesis to alternative biohandling approaches for the life sciences

Processing methodologies possessing the ability to directly handle living cells imply tremendous possibilities for a whole host of applications in the regenerative and therapeutic medicinal themes of R&D. Most cell-handling techniques have, in the past, been unearthed in the physical sciences, which have subsequently undergone rapid development for a plethora of applications within the life sciences. In this review, the author wishes to introduce current and swiftly emerging direct cell-handling jet protocols whilst identifying their advantages and disadvantages in comparison to each approach. The article extends to elucidating their applicability for a few life science-based research themes, where these protocols are currently undergoing intense investigation. It is the opinion of this author that these protocols generate a range of opportunities for the life sciences, which have previously not been explored and hence could have an overwhelming affect in a biological and clinical standpoint. These methods and protocols have evidently bridged the physical with the life sciences during this endeavor.

Embryonic stem cells for cardiac muscle engineering

The aim of cardiac tissue engineering is twofold: (1) to provide three-dimensional cardiac tissue to restore the function of diseased hearts and (2) to develop improved test beds for target validation and substance screening. Both concepts have been successfully demonstrated by several groups using immature primary heart cells, but these cells are essentially postmitotic, precluding clinical and large-scale in vitro applications. Identification of a renewable cell source is therefore one of the key objectives in the field. Embryonic stem (ES) cells are attractive candidates because they can be propagated in large quantities, have a robust capacity to differentiate into cardiac myocytes, and can be obtained from humans. Classic isolation of ES cells from the inner cell mass is associated with destruction of the respective embryo. Thus, alternative technologies to generate stem cell lines with ES cell properties are inevitably called for. This review discusses the usefulness of ES cells in cardiac tissue engineering and alternative, embryo-sparing technologies to derive ES cells.

Aerodynamically assisted bio-jets: the development of a novel and direct non-electric field-driven methodology for engineering living organisms

We recently demonstrated the ability to use electrified jets under stable conditions for the generation of cell-bearing droplets to the formation of composite threads which are biologically active. Our studies established that processed cells were viable over several generations post-jetting and -threading. These harmless and successful techniques for jet-based cell handling to deployment for precision deposition have great potential and widespread applications in bioengineering and biotechnology. Nonetheless, our investigations into 'bio-electrosprays' and 'cell electrospinning' have elucidated these jets having direct applicability in regenerative and therapeutic medicine to studies in developmental biology. For these very reasons, jet methodologies having the capability to safely handle living organisms for drop and placing are increasingly gaining the interests of life scientists. We now demonstrate yet another technique (a non-electric field-driven approach, previously never explored with jetting living cells), possessing the ability to directly handle the processing of primary living organisms by means of the flow of a cell suspension within a needle placed in a pressure chamber in the presence of an applied pressure difference. The technique we introduce here is referred to as 'aerodynamically assisted bio-jets/-jetting' which is driven completely by aerodynamic forces applied over an exit orifice by way of a differential pressure. Our investigations present an operational window in which stable jetting conditions are achieved for the formation of a near-monodispersed distribution of cell-bearing droplets and droplet residues. Finally, the aerodynamically bio-jetted living primary organisms are assessed (over both short and long time points) for cellular viability by means of FACScan, a flow cytometry technology which quantifies the percentage of living and dead cells. These advanced biophysical and bioengineering studies elucidate the emergence of a non-electric field-driven bio-jetting technology which now joins the cell jetting race.

Alternative sources of adult stem cells: a possible solution to the embryonic stem cell debate

The complex moral and ethical debate surrounding the definition of the origins of human life, together with conflicting current and proposed legislation on state and federal levels, is hindering the course of research into the therapeutic uses of human embryonic stem cells. However, newly identified sources of adult stem cells, free from many of the ethical and legal concerns attached to embryonic stem cell research, may offer great promise for the advancement of medicine. These alternative sources may alleviate the need to resolve the stem cell debate before further therapeutic benefits of stem cell research can be realized. While legislation and ethics evolve to address the legal and moral issues of embryonic stem cell research, innovative researchers will continue to search for and find real and present solutions for cell-based therapies using adult stem cells.

In vitro development of human oocytes after parthenogenetic activation or intracytoplasmic sperm injection

OBJECTIVE

To compare directly in vitro developmental competence between parthenogenetically activated and intracytoplasmic sperm injection (ICSI)-fertilized oocytes.

DESIGN

For each patient, three metaphase II oocytes were randomized to the ICSI procedure, while n-3 were allocated to parthenogenetic activation.

SETTING

University hospital infertility unit.

PATIENTS

Thirty-eight patients, aged 35.2 +/- 3.3 years (mean +/- SD) selected for ICSI.

INTERVENTIONS

After 1 hour from denudation, oocytes were either fertilized by ICSI (n = 114) or chemically activated (n = 104). Fertilized and activated oocytes were cultured for up to 3 and 5 days, respectively.

MAIN OUTCOME MEASURES

Development rate, cell number, and morphological grade during culture.

RESULTS

The two groups showed no significant differences between rates of fertilization and parthenogenetic activation, development, and blastomere number on days 2 and 3 of culture. However, parthenotes showed a lower morphological grade, and a significantly lower proportion went on cleaving to day 3, when only activated rather than total numbers of oocytes were considered. On day 5 after activation, nine oocytes (8.6%) reached the blastocyst stage, representing 12.9% of parthenotes.

CONCLUSIONS

Since most parameters examined in this study were similar between activated and fertilized oocytes, parthenogenetic activation may be a useful tool for the preclinical evaluation of experimental procedures.

Laser-assisted blastocyst dissection and subsequent cultivation of embryonic stem cells in a serum/cell free culture system: applications and preliminary results in a murine model

Background

To evaluate embryonic stem cell (ESC) harvesting methods with an emphasis on derivation of ESC lines without feeder cells or sera. Using a murine model, laser-assisted blastocyst dissection was performed and compared to conventional immunosurgery to assess a novel laser application for inner cell mass (ICM) isolation.

Methods

Intact blastocysts or isolated ICMs generated in a standard mouse strain were plated in medium with or without serum to compare ESC harvesting efficiency. ESC derivation was also undertaken in a feeder cell-free culture system.

Results

Although ICM growth and dissociation was comparable irrespective of the media components, an enhanced ESC harvest was observed in our serum-free medium (p < 0.01). ESC harvest rate was not affected by ICM isolation technique but was attenuated in the feeder cell-free group.

Conclusion

Achieving successful techniques for human ESC research is fundamentally dependent on preliminary work using experimental animals. In this study, all experimentally developed ESC lines manifested similar features to ESCs obtained from intact blastocysts in standard culture. Cell/sera free murine ESC harvest and propagation are feasible procedures for an embryology laboratory and await refinements for translation to human medical research.

Nanomedicine: techniques, potentials, and ethical implications

Nanotechnology is concerned with materials and systems whose structures and components exhibit novel physical, chemical, and biological properties due to their nanoscale size. This paper focuses on what is known as nanomedicine, referring to the application of nanotechnology to medicine. We consider the use and potentials of emerging nanoscience techniques in medicine such as nanosurgery, tissue engineering, and targeted drug delivery, and we discuss the ethical questions that these techniques raise. The ethical considerations involved in nanomedicine are related to risk assessment in general, somatic-cell versus germline-cell therapy, the enhancement of human capabilities, research into human embryonic stem cells and the toxicity, uncontrolled function and self-assembly of nanoparticles. The ethical considerations associated with the application of nanotechnology to medicine have not been greatly discussed. This paper aims to balance clear ethical discussion and sound science and so provide nanotechnologists and biotechnologists with tools to assess ethical problems in nanomedicine.

What's in a name? Embryos, entities, and ANTities in the stem cell debate

This paper discusses two proposals to the US President's Council on Bioethics that try to overcome the issue of killing embryos in embryonic stem (ES) cell research and argues that neither of them can hold good as a compromise solution. The author argues that (1) the groups of people for which the compromises are intended neither need nor want the two compromises, (2) the US government and other governments of countries with restrictive regulation on ES cell research have not provided a clear and sound justification to take into account minority views on the protection of human life to such a considerable extent as to constrain the freedom of research in the area of stem cell research, and (3) the best way to deal with these issues is to accept that many people and most governments adopt a gradualist and variable viewpoint on the human embryo which implies that embryos can be sacrificed for good reasons and to try to find other, less constraining, ways to take into account minority views on the embryo. Finally, another more efficient and time and money sparing compromise will be proposed for those who accept IVF, a majority in most societies.

Identification and isolation of embryonic stem cells in reproductive endocrinology: theoretical protocols for conservation of human embryos derived from in vitro fertilization

BACKGROUND

Embryonic stem cells (ESC) are pluripotent cells obtained from the inner cell mass (ICM) of blastocysts derived from in vitro culture associated with reproductive endocrinology therapy. Human ESCs are regarded as highly significant since they retain the capacity to differentiate into any of approximately 200 unique cell types. Human ESC research is controversial because to acquire such cells, the ICM of human blastocysts must be manipulated in a way that renders embryos nonviable and unsuitable for transfer in utero. Techniques to yield competent ESCs with conservation of source blastocysts would satisfy many objections against ESC research, but at present such approaches remain largely untested.

RESULTS AND DISCUSSION

We contrast experimental culture of single blastomeres obtained by 1) non-destructive biopsy of embryos destined for transfer, and 2) isolation of karyotypically normal blastomeres from disaggregated ("dead") embryos considered unsuitable for transfer, and evaluate these approaches with regard to production of ESCs. Pluripotency was confirmed by morphological criteria and by quantification of divergent homeodomain proteins specific to undifferentiated cell development. Following ESC isolation and identification, assessment was conducted according to a novel ESC grading system, also proposed here.

CONCLUSION

The role of reproductive endocrinology in ESC research remains paramount. In this report, we hypothesize new and expand on existing strategies having the potential to enhance human ESC isolation, identification and in vitro maintenance.