An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres. The blastomeres are arranged as a solid ball that when reaching a certain size, called a morula, takes in fluid to create a cavity called a blastocoel. The structure is then termed a blastula, or a blastocyst in mammals.
Cellular differentiation is the process in which a stem cell changes from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellular organism as it changes from a simple zygote to a complex system of tissues and cell types. Differentiation continues in adulthood as adult stem cells divide and create fully differentiated daughter cells during tissue repair and during normal cell turnover. Some differentiation occurs in response to antigen exposure. Differentiation dramatically changes a cell's size, shape, membrane potential, metabolic activity, and responsiveness to signals. These changes are largely due to highly controlled modifications in gene expression and are the study of epigenetics. With a few exceptions, cellular differentiation almost never involves a change in the DNA sequence itself. However, metabolic composition does get altered quite dramatically where stem cells are characterized by abundant metabolites with highly unsaturated structures whose levels decrease upon differentiation. Thus, different cells can have very different physical characteristics despite having the same genome.
Oct-4, also known as POU5F1, is a protein that in humans is encoded by the POU5F1 gene. Oct-4 is a homeodomain transcription factor of the POU family. It is critically involved in the self-renewal of undifferentiated embryonic stem cells. As such, it is frequently used as a marker for undifferentiated cells. Oct-4 expression must be closely regulated; too much or too little will cause differentiation of the cells.
A designer baby is a baby whose genetic makeup has been selected or altered, often to exclude a particular gene or to remove genes associated with disease. This process usually involves analysing a wide range of human embryos to identify genes associated with particular diseases and characteristics, and selecting embryos that have the desired genetic makeup; a process known as preimplantation genetic diagnosis. Screening for single genes is commonly practiced, and polygenic screening is offered by a few companies. Other methods by which a baby's genetic information can be altered involve directly editing the genome before birth, which is not routinely performed and only one instance of this is known to have occurred as of 2019, where Chinese twins Lulu and Nana were edited as embryos, causing widespread criticism.
In biology, reprogramming refers to erasure and remodeling of epigenetic marks, such as DNA methylation, during mammalian development or in cell culture. Such control is also often associated with alternative covalent modifications of histones.
Rudolf Jaenisch is a Professor of Biology at MIT and a founding member of the Whitehead Institute for Biomedical Research. He is a pioneer of transgenic science, in which an animal’s genetic makeup is altered. Jaenisch has focused on creating genetically modified mice to study cancer, epigenetic reprogramming and neurological diseases.
The inner cell mass (ICM) or embryoblast is a structure in the early development of an embryo. It is the mass of cells inside the blastocyst that will eventually give rise to the definitive structures of the fetus. The inner cell mass forms in the earliest stages of embryonic development, before implantation into the endometrium of the uterus. The ICM is entirely surrounded by the single layer of trophoblast cells of the trophectoderm.
Janet Rossant, is a developmental biologist well known for her contributions to the understanding of the role of genes in embryo development. She is a world renowned leader in developmental biology. Her current research interests focus on stem cells, molecular genetics, and developmental biology. Specifically, she uses cellular and genetic manipulation techniques to study how genes control both normal and abnormal development of early mouse embryos. Rossant has discovered information on embryo development, how multiple types of stem cells are established, and the mechanisms by which genes control development. In 1998, her work helped lead to the discovery of the trophoblast stem cell, which has assisted in showing how congenital anomalies in the heart, blood vessels, and placenta can occur.
Genetically modified animals are animals that have been genetically modified for a variety of purposes including producing drugs, enhancing yields, increasing resistance to disease, etc. The vast majority of genetically modified animals are at the research stage while the number close to entering the market remains small.
Edith Heard is a British-French researcher in epigenetics who has been serving as the Director General of the European Molecular Biology Laboratory (EMBL) since January 2019. She is also Professor at the Collège de France, holding the Chair of Epigenetics and Cellular Memory.
The International Society for Stem Cell Research (ISSCR) is an independent 501(c)(3) nonprofit organization based in Evanston, Illinois, United States. The organization's mission is to promote excellence in stem cell science and applications to human health.
Sir James Cuthbert Smith is Director of Science at the Wellcome Trust, Senior Group Leader at the Francis Crick Institute and President of the Council at Zoological Society of London.
The Centre for Genomic Regulation is a biomedical and genomics research centre based on Barcelona. Most of its facilities and laboratories are located in the Barcelona Biomedical Research Park, in front of Somorrostro beach.
Magdalena Żernicka-Goetz is a Polish-British developmental biologist. She is Professor of Mammalian Development and Stem Cell Biology in the Department of Physiology, Development and Neuroscience and Fellow of Sidney Sussex College, Cambridge. She also serves as Bren Professor of Biology and Biological Engineering at California Institute of Technology (Caltech).
Human germline engineering is the process by which the genome of an individual is edited in such a way that the change is heritable. This is achieved by altering the genes of the germ cells, which then mature into genetically modified eggs and sperm. For safety, ethical, and social reasons, there is broad agreement among the scientific community and the public that germline editing for reproduction is a red line that should not be crossed at this point in time. There are differing public sentiments, however, on whether it may be performed in the future depending on whether the intent would be therapeutic or non-therapeutic.
Davor Solter is a Yugoslavian-born developmental biologist, particularly known for his pioneering work on mammalian genomic imprinting. He is Emeritus Member and Director, Max Planck Institute of Immunobiology and Epigenetics; Visiting International Professor, Siriraj Center for Excellence in Stem Cell Research, Mahidol University, Thailand; and Visiting Professor, University of Zagreb Medical School.
Antonio Jesus Giraldez is a Spanish developmental biologist and RNA researcher at Yale University School of Medicine, where he serves as chair of the department of genetics and Fergus F. Wallace Professor of Genetics. He is also affiliated with the Yale Cancer Center and the Yale Stem Cell Center.
The He Jiankui affair is a scientific and bioethical controversy concerning the use of genome editing following its first use on humans by Chinese scientist He Jiankui, who edited the genomes of human embryos in 2018. He became widely known on 26 November 2018 after he announced that he had created the first human genetically edited babies. He was listed in the Time's 100 most influential people of 2019. The affair led to ethical and legal controversies, resulting in the indictment of He and two of his collaborators, Zhang Renli and Qin Jinzhou. He eventually received widespread international condemnation.
He Jiankui is a Chinese biophysicist who was an associate professor in the Department of Biology of the Southern University of Science and Technology (SUSTech) in Shenzhen, China. Earning his Ph.D. from Rice University in Texas on protein evolution, including that of CRISPR, He learned gene-editing techniques (CRISPR/Cas9) as a postdoctoral researcher at Stanford University in California.
CRISPR gene editing is a genetic engineering technique in molecular biology by which the genomes of living organisms may be modified. It is based on a simplified version of the bacterial CRISPR-Cas9 antiviral defense system. By delivering the Cas9 nuclease complexed with a synthetic guide RNA (gRNA) into a cell, the cell's genome can be cut at a desired location, allowing existing genes to be removed and/or new ones added in vivo.
