Embryonic stem cell research
and in vitro fertilization
In the normal development of a human being, the single cell formed at the moment of fertilization contains all the genetic material necessary to develop the organs and tissue of an adult human being. The single cell of the newly conceived human being divides and becomes a two-celled organism about 30 hours after conception. Cell division continues as the new human being floats down the fallopian tube toward the uterus.
As a single cell, he or she is called a zygote, after the first cell division he or she becomes a morala, and, at day 4 or 5, he or she has developed into a blastocyst. All of these are stages of the embryonic period of human development.
With the first cell divisions, the developing embryo takes the form of a simple cluster of balls, like a berry, but by the blastocyst stage the embryo has the form of a hollow sphere with a mass of cells lumped against one of the inner sides. The inner mass will continue to develop into the body of the embryo while the outer sphere will develop into the placenta - an organ he or she needs while living in the womb, but will discard at birth.
The embryo embeds in the wall of the uterus between 7 and 13 days after conception.
About 14 days after conception, a crease forms in the inner mass of cells. This crease is the beginning of the body’s axis. Cells migrate from the crease to form three layers of cells that will develop into the organs.
The neural tube begins to form along the crease at around 21 days after conception and brain waves are measurable at around 42 days. The heart begins to beat rhythmically around day 22.
Normally, fertilization and this early development happen inside the mother’s reproductive system. However, by the early 1900s, scientists were collecting sperm and oocytes, or eggs, from small animals and allowing them to fertilize in dishes in their labs. Soon afterward, they were successfully implanting the embryos in the female animals to gestate and deliver full-term.
In 1978 the first full-term human baby was born after being conceived in a petri dish and implanted in her mother’s uterus. The process of causing conception to happen in a lab is called in vitro fertilization, or IVF.
The capacity of early embryonic cells to develop into any organ makes them extremely attractive to researchers.
In the early 2000s, under the Clinton and Bush administrations, the National Institutes of Health (NIH) published guidelines for federal funding of embryo-destructive research. During the development of the guidelines, a group of researchers admitted to creating embryos via IVF in order to extract their cells for research, killing the embryos in the process.(1)
The new NIH guidelines prohibited federal funding of embryo-destructive research, but permitted funding of research from already established cell lines, even if the original source of the cell line was a human embryo.(2)
Scientists can keep certain types of cells alive and dividing for months and even years. The first cells die, but the new cells created by division live long enough to divide and make new cells. These are called cell lines. The cells are not alive in the same sense that a complete organism is alive, but they have a capacity to be rejoined to a living organism. Just as a severed finger may be reattached to a hand if done quickly, before the finger “dies,” so the cells are alive and may be reintroduced into a living organism. In the same way, organ transplants rely on the organ being alive.(3)
The human body has many different types of cells with specialized structures and forms: blood cells, muscle cells, brain cells, etc. It also has stem cells, which are unspecialized and can create different types of specialized cells through division. Most of the cells in an early embryo are stem cells.
In the early 2000s, there was a stem cell research craze, especially embryonic stem cell research. Academia and the media promised cures for diabetes, Alzheimer's, spine injuries, and more - from embryo-destructive research with embryonic stem cells. Since the federal government would not fund such research, California passed a state constitutional amendment, approved by voters in 2004, that created the California Institute for Regenerative Medicine (CIRM) to fund stem cell research, including embryo-destructive stem cell research.(4)
The amendment specifies that the embryos used for research are only to be leftovers from fertility treatments at IVF clinics. Clients of IVF clinics can donate the embryos they do not want to implant and raise.
The initial funding for the Institute was supplied by the sale of $3 billion in bonds.
Since 2004, the furor surrounding embryonic stem cell research has faded. No research with embryonic stem cells has resulted in approved cures or therapies, although some vaccines and medications have been tested on or developed using cell lines derived from the tissue of aborted babies.
Research with non-embryonic stem cells, however, often called adult stem cells, extracted from bone marrow, fat cells, or umbilical cord blood after a baby is born, have shown much promise.(5) For example, adult stem cells have been introduced into patients’ diseased tissues or organs and repaired the injury.
In 2020, California voters approved another 5.5 billion dollars in bond sales to continue funding research through the California Institute for Regenerative Medicine, including embryo-destructive research.
In 2021, the International Society for Stem Cell Research dropped its ethical recommendation that embryos be cultivated and experimented on for no more than the first 14 days of their lives.
The in vitro fertilization (IVF) process is often used to conceive children for infertile couples, same-sex couples, single people, or anyone who does not want to be pregnant and give birth. If the prospective parents cannot or do not want to contribute sperm and/or oocytes to create their children, donated or purchased sperm and/or oocytes are used to conceive embryos in a lab.
The embryos may then be screened for genetic defects and the sex of each embryo may be determined. The prospective parents choose which embryo or embryos to transfer to the uterus.
Sometimes the embryo or embryos are transferred to the uterus of the mother who intends to raise them. However, single males, same-sex male couples, and women who do not wish to be pregnant may enter into a contract with a woman, called a surrogate, to carry the unborn child or children to term.
Only a fraction of the embryos transferred to a uterus survive to birth. Those not transferred are frozen indefinitely, donated to researchers, destroyed, or placed for frozen embryo adoption. No one knows how many embryos are frozen in storage. Estimates range from tens of thousands to over a million in the United States.