Overview of Infertility
Steven R. Bayer, Michael M. Alper, Alan S. Penzias in The Boston IVF Handbook of Infertility, 2017
Cloning humans may also be beneficial in fighting disease. The term therapeutic cloning refers to a situation where it is possible to differentiate normal heart cells from a stem cell line and inject them back into the diseased heart of an affected individual. This may also prove successful in treating those with spinal cord injuries, leukemia, kidney disease, and other disorders. However, there is concern that human cloning may be used for reproductive purposes. There are many ethical concerns about human reproductive cloning; many find it simply appalling. Several years ago, plans were announced to proceed with human cloning for reproductive purposes. In response, many countries throughout the world have placed a ban on this research. To date, there is no federal legislation in the United States placing a ban on the practice, but many states have enacted their own legislation.
Does Personhood Begin During Pregnancy?
Christopher Kaczor in The Ethics of Abortion, 2023
Another view is that implantation in utero marks the moment when a human being becomes a person. The importance of implantation is linked to the issue of abortion (particularly very early chemical abortion), the fate of human embryos created through in vitro fertilization not implanted in the womb (“spare” human embryos), and to therapeutic cloning, so a word about cloning is in order. A distinction is sometimes drawn between therapeutic cloning and reproductive cloning. Therapeutic cloning creates a new human embryo with the same genome as the “parent” who is cloned but destroys this human embryo in research before it is implanted in a woman's uterus. Reproductive cloning creates a human embryo for the sake of implanting the embryo in a maternal womb to be born. (In fact, both forms of cloning are “reproductive” in that they both produce an embryonic human being.) So, if human personhood begins at implantation, and not before, then therapeutic cloning would be permissible even though it destroys a human embryo. US Senator Orrin Hatch expresses this view in its most popular form when he says that a human life worthy of respect begins “in a woman's womb, not a Petri dish.”
The Dawn of GM Humans
Tina Stevens, Stuart Newman in Biotech Juggernaut, 2019
As controversy about human cloning brewed, bioentrepreneurs attempted to redefine scientific terminology for public consumption. The goal was to snuff out smoldering contention and popular challenge to professional autonomy. The method was to subdivide the definition of the term “cloning.” If the intent in producing a clonal embryo by nuclear transfer was to study it in the hope of finding cures, the recommended term was “therapeutic cloning.” If the intent in producing a clonal embryo by nuclear transfer was to bring to term a cloned infant, the recommended term became “reproductive cloning” (Kass et al., 2002; Beverly, 2003). Therapeutic cloning would be acceptable. Reproductive cloning could remain beyond the pale. The new nomenclature did not reflect existing scientific terminology, but appeared to be invented to sow confusion. More specifically, it did not correspond to how scientists in the field described their uses of SCNT. SCNT was the same technology, regardless of whether the researcher’s intent was to find cures or create a full-term human clone. Diverting attention away from the technique itself to the intentions of the scientist directing it was a political strategy. The motives of the researcher would function in place of externally imposed regulation.
Challenges and ethical considerations for using cloned primates for human brain discovery
Published in Expert Opinion on Drug Discovery, 2018
Alan O. Trounson, Andrew J. French
Ethical discussion on cloning has mainly been confined to human reproductive cloning and somatic cell nuclear transfer or therapeutic cloning [15]. There were some concerns about cloning farm animals and their entry into the human food chain but these have disappeared with regulatory approval for their use. Cloning NHP is a technical step closer to the cloning of humans and this might be an ethical concern to some people. Regulatory authorities do not require data from NHP models in preclinical medical research unless the therapeutic risks and efficacy cannot be demonstrated adequately in rodents or other large animals, or in vitro. It is difficult to completely avoid the use of NHP in neurological research because of the need to find models that represent closely human neuronal conditions. NHP research attracts increased opposition from animal activists but the degree of concern varies in different cultures. There is also a general trend by research ethics committees for reducing the number of animals used in experiments in medical research and cloned animals may be considered as supporting this trend because of their genetic homogeneity. However, other practical factors such as cost and availability will also impact on the use of cloned NHP.
What to Expect When Expecting CRISPR Baby Number Four
Published in The American Journal of Bioethics, 2019
Christopher Thomas Scott, Cynthia Selin
Hwang’s ersatz experiment, which he dropped at the 2004 International Stem Cell Society annual meeting, was a bolt from the blue. Technical hurdles, including overcoming the species barrier, had for years flummoxed researchers attempting to use somatic cell nuclear transfer (SCNT) to clone primate embryonic stem cell lines. Yet He’s CRISPR babies hardly came as a surprise. Telltales were apparent as early as 2013 when a Chinese team reported generating rats using the technology (Li et al. 2013). In January 2014, a different group in China reported twin cynomolgus monkeys born with mutations made with CRISPR/Cas9 (Niu et al. 2014).1 These experiments foreordained the eventual application of the technology in human embryos. Although it wasn’t until 2016 that two essays by scientists, inventors, and bioethicists in the journals Nature and Science detailed recommendations for how future human germline research should proceed (Baltimore et al. 2015; Lanphier et al. 2015), the future had rushed ever closer: Chinese experiments using human embryos were reported on the heels of the essays. Using CRISPR in nonviable human embryos, one research team knocked out the human gene HBB, while another introduced CCR5, an HIV-resistance allele (Kang et al. 2016; Liang et al. 2015). A third experiment in the United States successfully corrected a mutation causing heart disease in viable human embryos, which were later destroyed as part of the protocol (Ma et al. 2017).
Spermatogonial stem cell transplantation and male infertility: Current status and future directions
Published in Arab Journal of Urology, 2018
Connor M. Forbes, Ryan Flannigan, Peter N. Schlegel
Pluripotent stem cells can be obtained through multiple mechanisms. Several often-studied mechanisms are harvesting of embryonal stem cells, reprogramming adult somatic cells to make induced pluripotent stem cells, or from somatic cell nuclear transfer (SCNT) where a nucleus is inserted into an oocyte [61]. In humans, of course, the initial embryonic development is guided by centrioles from male-derived germ cells, limiting the potential success of using nuclear transfer alone (or male germ cells that have not yet initiated tail development.) The traditional pathway suggests that pluripotent stem cells must be differentiated into primordial germ cells (PGCs) prior to SSCs [61]. A review of the mechanisms for this differentiation can be found by Nikolic et al. [62].
Related Knowledge Centers
- Cloning
- Egg Cell
- Somatic Cell
- Embryo
- Oocyte
- Cell Nucleus
- Genetics
- Developmental Biology
- Dolly
- Zhong Zhong & Hua Hua