Can we grow a fetus in a lab?
Embryogenesis, a complex process in the development of the embryo, is set to the first eight weeks of gestation after fertilization. First, the egg is fertilized by a sperm to create a zygote. The zygote starts to cleave, or rapidly divide, by 2,4, 8, 16, 32 cells.. and so on... At 32 cells, the clump is now called a morula. The cells of the morula begin to migrate outward to create a hallow ball which is now called a blastula. At this time, all the cells are pluripotent, meaning that they do not have signals to become specialized cells, or mature cells that form specific organs. After blastulation, or the formation of the blastula, gastrulation begins. In gastrulation, the cells start to form cavities, implant onto the uterine wall and differentiate into different germ layers, which are categorized as the ectoderm, endoderm and the mesoderm. The three categories then continue to “mold” into the organs needed for human life in nine months. The ectoderm, which is the outer layer, forms the neural crest, central nervous system and skin. The mesoderm, which is the middle layer, forms the notochord, skeleton, kidney, heart and muscles. The endoderm, which is the inner layer of cells, created the gastrointestinal system, liver and lungs.
We have developed artificial ways to become pregnant. In vitro fertilization (IVF), a state-of-the-art technology, offering hope to families struggling with fertility is commonly used to increase chance of human pregnancy. Unfortunately, there are still high failure rates with IVF that are not clearly understood and the first 14 days of embryogenesis is still considered a “black box”.
To better understand embryogenesis, and the early developmental stages, scientists have pursued developing artificial embryos. Researchers have figured out a way to use pluripotent stem cells, also called human naive stem cells, into embryo models without the need for an egg, sperm or womb. Artificial embryo models can be made in unlimited numbers compared to the limited number of natural embryos that can be obtained and has less ethical restrictions. After having to make induced pluripotent stem cells myself and differentiate them into specialized cells, I can tell you that the process is extremely sensitive and that both the de-differentiating and differentiating process is extremely difficult. As difficult as it may be, however, these embryo models can be used to conduct research in support of genetic and gestational research to continue improving early human development.
On the latter end of fetal development, scientists have created artificial wombs to grow a fetus outside of the human body with high scientific success displaying that we can mimic the womb environment to provide the oxygen and neutrients a fetus needs to grow. In 2019, Children’s hospital of Philadelphia published a fantasy paper on conceiving a baby lamb in a lab. Since then, after extensive pre-clinical studies on animals and good endpoints, with animal results showing that pre-28 week fetus can be carried to full term in an artificial womb, the first human clinical trials on Extra-uterine Environment for Newborn Development, or EXTEND, is under FDA discussion and will begin soon.
While we can artificially inseminate, artificially grow embryos, and have an artificial womb, we are still not at a point where we can artificially create a fetus. Artificial embryos can be implanted successfully into humans to form a healthy and living fetus. However, through the extensive research in the use and longevity of synthetic embryos and continuous innovative medical technology research on artificial wombs, I believe that one day we might just be able to bridge the gap to grow real humans in a lab.
