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Adult Stem Cell Plasticity
Published in Richard K. Burt, Alberto M. Marmont, Stem Cell Therapy for Autoimmune Disease, 2019
These initial reports challenged the existing dogma of tissue specific stem cell differentiation in adults, and sparked significant debate. Many in the scientific arena have suggested alternative interpretations for these results, although some of these have not yet been strictly ruled out, the plasticity theory continues to be the best supported. The debate regarding bone marrow and other adult stem cells has spilled over into the political and public arenas as well. Opponents of human embryonic stem cell research see the plasticity of these adult cells as a means of avoiding the destruction of human blastocysts that is required to obtain pluripotent embryonic stem (ES) cells for research. The vigor with which both sides of the ES cell issue debate the worthiness of adult stem cells has contributed to the confusion over this new scientific discovery by bringing it into the mass media before science could illuminate its true nature and potential. Despite daily improvements in our knowledge, the mechanisms of cell plasticity are not yet clear, and the extent of usefulness of these cells as research tools or medical therapies remains equally enigmatic. Yet, despite the controversy and the early stage in our understanding of stem cell plasticity, hopes abound that if we can control this plasticity we may be able to use adult stem cells to produce new tissues for transplant and/or repair diseased organs. It is also hoped that these cells will provide new insights into the mechanisms of early development, cancer, and other pathologies.
Stem cell biology
Published in Christine Hauskeller, Arne Manzeschke, Anja Pichl, The Matrix of Stem Cell Research, 2019
For example, human embryonic stem cell (hESC) lines are the ‘stem’ of lineages derived from early human embryos (about five-day-old blastocysts) in vitro. hESC lines are derived by removing part of the early embryo’s inner layer and placing it in a new artificial cell culture. These details of the experimental method specify sub-variables for L: species, developmental stage, and location within the source organism. In their new environment, some of the cultured cells divide to produce colonies with specific morphological and molecular characteristics, including rapid division in culture, lack of specialized traits, flat round shape, large nuclei surrounded by correlatively thin cytoplasm, prominent nucleoli, high telomerase activity, and high expression of particular genes (Thomson et al., 1998). These details of the method specify values for the set of cell characters C. Cells with these features are selected for further in vitro culture, dividing to generate new colonies. Continuing cycles of colony formation and selection yield an ‘immortal’ cell line. The requirement for continued cell division entails that there is no upper limit for variable n. So cells resulting from this procedure are automatically self-renewing. Their differentiation potential is tested by moving them to environments conducive to differentiation, and comparing results with characters of ordinary differentiated cells. These details of the method partly specify the values of variable D – the traits that distinguish more from less differentiated cell states.
Introduction
Published in Erik Malmqvist, Kristin Zeiler, Bodily Exchanges, Bioethics and Border Crossing, 2015
Kristin Zeiler, Erik Malmqvist
In all these cases, organs and tissues are transferred for the sake of somebody else’s survival or health. However, a person’s bodily material can also be used to serve other people’s reproductive interests or to advance biomedical research. Donated sperm, eggs and embryos are used in assisted reproduction to overcome different forms of infertility, and recently the first child gestated in a transplanted uterus was born (Brännström et al. 2015). Because of how assisted reproduction attempts are performed, they typically yield more fertilized eggs than are needed for implantation in the prospective mother’s uterus. These “surplus” embryos constitute a prized resource for human embryonic stem cell research, an experimental scientific field often claimed to harbour great therapeutic potential. Further, some tissues commonly discarded as waste in clinical practice – in particular certain cancer tissues – have proven highly exploitable for scientific and commercial ends.
Investigating attitudes towards oocyte donation amongst potential donors and the general population: a systematic review
Published in Human Fertility, 2021
Sophie Platts, Timothy Bracewell-Milnes, Srdjan Saso, Benjamin Jones, Riya Parikh, Meen-Yau Thum
Kazem et al. (1995) found a significant difference in attitudes between fertile and infertile women towards OD for research, with fertile women more opposed to the idea of using oocytes in research. In one study 90% of infertile couples undergoing IVF expressed willingness to donate oocytes for research (Oskarsson et al., 1991). An Australian study looked at IVF patients’ perceptions of OD for stem cell research and found a distinct unwillingness to donate viable oocytes for research, with respondents much more willing to donate frozen embryos for human embryonic stem cell research (Waldby & Carroll, 2012). Waldby et al. (2013) explored opinions surrounding financial compensation for OD and found that people were more accepting of payment for oocytes for research rather than reproductive donation. Purewal and van den Akker (2010) found that one-third of non-patient respondents would consider donating eggs to research, with strong altruistic motives. Interestingly, 68% of potential donors reported no preference towards donating oocytes for research or an infertile couple. One study which investigated non-patient attitudes and intentions to donate oocytes for research found that women who are potentially interested in social oocyte freezing are also more open to the idea of donating oocytes for research (Stoop, Nekkebroeck, & Devroey, 2011).
Corneal Stromal Regeneration: Current Status and Future Therapeutic Potential
Published in Current Eye Research, 2020
Since the acellular porcine corneal stroma can only be used therapeutically when the corneal epithelium and endothelium are functional, attention is being given to repopulating the stromal scaffold with human cells, to enable full-thickness penetrating keratoplasty. A Chinese team from Shandong has demonstrated the ability to seed human embryonic stem cell (hESC)-derived limbal epithelial-like cells on one side of the porcine scaffold and hESC-derived corneal endothelial-like cells on the other.42 After transplantation into rabbits, corneal transparency was gradually improved through 8 weeks of follow-up, although residual haze and neovascularization were present. Nevertheless, along with vessels and inflammatory cells, stromal cells were observed to repopulate the implanted porcine stroma at only 8 weeks post-implantation. Whether stromal regeneration would eventually occur is unclear, but the given the ethical debate surrounding the use of hESC, alternatives are sought. One alternative to the use of hESC, involves a similar porcine stromal construct that was developed using human donor cornea-derived epithelial, stromal and endothelial cells that were seeded into the construct and prepared by cell culture methods.43 One week after implantation by penetrating keratoplasty in rabbits, the construct remained almost completely transparent, before an eventual immune response led to rejection and opacification of the xenogenic graft at four weeks.
Unexplained total abnormal fertilization of donor oocytes in ICSI with using spermatozoa from different patients
Published in Gynecological Endocrinology, 2019
Hripsime Grigoryan, Lev Levkov, Romualdo Sciorio, Eduard Hambartsoumian
A Spanish group Escribá et al. [14] described a technique that improves identification and removal of the extra paternal pronuclei. They microsurgically removed the pronucleus located furthest from the second polar body in 3PN human zygotes using cytoskeletal relaxing agents. The resulting embryos were diploid and developed to blastocyst stage, with the majority being heteroparental. The authors concluded that microsurgical removal of one pronucleus located at the farthest position to the second polar body from 3PN zygotes is feasible and can result, in vitro, into a morphologically normal, heteroparental diploid blastocysts. This technique of embryo recycling could be useful for reproductive purposes or human embryonic stem cell research. These could potentially be used to derive patient-specific embryonic stem cell lines, instead of using viable embryos [14]. In our case, the origin of 3PN fertilization remains unexplained. The case is more interesting because ICSI with using four different patients spermatozoa resulted in the same abnormal fertilization, which suggests rather into the reason, which derives from oocytes than from spermatozoa.