人胚胎干细胞向生殖细胞分化的研究进展

小鼠胚胎干细胞体外已成功诱导分化为配子细胞,人胚胎干细胞理论上也具备分化为生殖细胞的潜能。本文从影响人胚胎干细胞体外向生殖系分化的基因调控和干细胞小生境（niche）方面进行综述,并指出胚胎干细胞在生殖医学及不孕治疗中的研究方向和应用前景。     

The problem of deception in embryonic stem cell research

Abstract.  The field of embryonic stem cell research has been plagued by exaggeration and misrepresentation, as three major journals have had to retract significant claims about progress in this field. This problem is exacerbated by the politicized climate in which the research is conducted and defended; it may also lie deeper, in a utilitarian ethic that in principle could justify unethical actions for admittedly worthwhile long-term goals. Such an ethic risks undermining the credibility of science, which must show a commitment to the facts that is independent of social and political goals.     

Cybrid human embryos--warranting opportunities to augment embryonic stem cell research

The recent vote in the British Parliament allows scientists in principle to create hybrid embryos by transferring human somatic cell nuclei into animal oocytes. This vote opens a fascinating new area of research with the central aim of generating interspecific lines of embryonic stem cells (ESCs) that could potentially be used to understand development, differentiation, gene expression and genomic compatibility. It will also promote human cell therapies, as well as the pharmaceutical industry's search for new drug targets. If this approach is to be successful, many biological questions need to be answered and, in addition, some moral and ethical aspects must be taken into account.     

A scientist's view of the ethics of human embryonic stem cell research

Scientists are rarely immoral and seldom even amoral. The ethical principles that underlie much of their own work are shared with scientists in other countries to a much greater degree than the cultural and religious differences among those countries would lead one to expect. Like me, few will have had any formal training in bioethics; so how might life scientists approach the varied ethical issues that arise in human embryo and stem cell research?     

Challenges of primate embryonic stem cell research

Embryonic stem (ES) cells hold great promise for treating degenerative diseases, including diabetes, Parkinson's, Alzheimer's, neural degeneration, and cardiomyopathies. This research is controversial to some because producing ES cells requires destroying embryos, which generally means human embryos. However, some of the surplus human embryos available from in vitro fertilization (IVF) clinics may have a high rate of genetic errors and therefore would be unsuitable for ES cell research. Although gross chromosome errors can readily be detected in ES cells, other anomalies such as mitochondrial DNA defects may have gone unrecognized. An insurmountable problem is that there are no human ES cells derived from in vivo-produced embryos to provide normal comparative data. In contrast, some monkey ES cell lines have been produced using in vivo-generated, normal embryos obtained from fertile animals; these can represent a "gold standard" for primate ES cells. In this review, we argue a need for strong research programs using rhesus monkey ES cells, conducted in parallel with studies on human ES and adult stem cells, to derive the maximum information about the biology of normal stem cells and to produce technical protocols for their directed differentiation into safe and functional replacement cells, tissues, and organs. In contrast, ES cell research using only human cell lines is likely to be incomplete, which could hinder research progress, and delay or diminish the effective application of ES cell technology to the treatment of human diseases.     

The derivation of clinical-grade human embryonic stem cell lines

The pluripotent nature of human embryonic stem cells (hESC) has attracted great interest in using them as a source of cells or tissue in cell therapy. However, in order to be used in regenerative medicine, the pluripotent hESC lines should be established and propagated according to good manufacturing practice quality requirements. The cultures should be animal substance free in order to exclude the risk of infections and immunogenity. They should also be genetically and epigenetically normal. The detailed molecular mechanisms of their pluripotency are still not defined. Using human feeder cells, a medium containing only human proteins, the mechanical isolation of the inner cell mass and mechanical passaging of hESC, is a safe option until a functional defined medium containing physiological concentrations of regulatory factors is available.     

The generation of GLP-grade human embryonic stem cell banks from four clinical-grade cell lines for preclinical research

The Singapore Stem Cell Bank has generated human embryonic stem cell banks from clinical-grade cell lines ESI-017, ESI-035, ESI-049, and ESI-053. All banks were prepared and characterized according to principles of Good Laboratory Practice for quality assurance. Importantly, each cell line has clearly documented and approved ethical provenance and meets recognized standards for performance and safety. The banks are intended to facilitate the translation of stem cell research to clinical medicine by enabling early phase research and development with high-quality, low-cost cells that are also available as clinical-grade stocks.