Embryo Project Encyclopedia Articles

Edward Donnall Thomas, an American physician and scientist, gained recognition in the scientific community for conducting the first bone marrow transplant, a pioneering form of hematopoietic stem cell transplantation (HSCT). Bone marrow transplants are considered to be the first successful example of tissue engineering, a field within regenerative medicine that uses hematopoietic stem cells (HSCs) as a vehicle for treatment. Prior to Thomas's groundbreaking work, most blood-borne diseases, including certain inherited and autoimmune diseases, were considered lethal.

Tissue engineering is a field of regenerative medicine that integrates the knowledge of scientists, physicians, and engineers into the construction or reconstruction of human tissue. Practitioners of tissue engineering seek to repair, replace, maintain, and enhance the abilities of a specific tissue or organ by means of living cells. More often than not stem cells are the form of living cells used in this technology. Tissue engineering is one of the disciplines involved in translating knowledge of developmental biology into the clinical setting. One focus that this field has taken is the understanding of tissue and organ development during embryogenesis, as this knowledge will open avenues to new applications of this technology.

The purpose of regenerative medicine, especially tissue engineering, is to replace damaged tissue with new tissue that will allow the body to resume normal function. The uniqueness of tissue engineering is that it can restore normal structure in addition to repairing tissue function, and is often accomplished using stem cells. The first type of tissue engineering using stem cells was hematopoietic stem cell transplantation (HSCT), a surgical procedure in which hematopoietic stem cells (HSCs) are infused into a host to treat a variety of blood diseases, cancers, and immunodeficiencies. While there is a standard procedure for the infusion of these cells into a donor, variations in the sources of hematopoietic stem cells, and in the relationship between donor and recipient, do produce some variability in the procedure.

The discovery of hematopoietic stem cells (HSCs) provided a pioneering step in stem cell research. HSCs are a type of multipotent adult stem cell, characterized by their ability to self-renew and differentiate into erythrocyte (red blood cell) and leukocyte (white blood cell) cell lineages. In terms of function, these cells are responsible for the continual renewal of the erythrocytes, leukocytes, and platelets in the body through a process called hematopoiesis. They also play an important role in the formation of vital organs such as the liver and spleen during fetal development. The early biological knowledge obtained from the studies of HSCs established the base of knowledge for understanding other stem cell systems. In addition, these cells have a vital role in furthering stem cell research for clinical applications. Regenerative medicine is a field of medicine that has applied HSCs to the treatment of blood-borne diseases such as leukemia and lymphoma and of cancer patients undergoing chemotherapy.

Renowned physician and scientist William Harvey is best known for his accurate description of how blood circulates through the body. While his published work on the circulation of blood is considered the most important of his academic life, Harvey also made significant contributions to embryology with the publication of his book Exercitationes de Generatione Animalium in 1651. In this book he established several theories that would set the stage for modern embryology and addressed many embryological issues including conception, embryogenesis, and spontaneous generation.

Birth Control or the Limitation of Offspring was written by American eugenics and birth control advocate William J. Robinson. First published in 1916, the final edition (forty-eighth) was published in 1936, the same year that Robinson died. As a medical doctor and author, Robinson used his influence to promote propaganda for "fewer and better babies," by focusing on contraception. Even Margaret Sanger, another prominent eugenics and birth control advocate, took great interest in this book. Robinson had three goals in mind when writing Birth Control. First, he advocated for limiting the number of children to parental financial means through prevention of conception. Second, he addressed the various forms of preventing conception, and suggested the best and most harmless way of doing such. Last, Robinson wanted information about birth control to be readily available to anyone who sought it.

Robert Alan Good was an American physician and scientific researcher who explored the cellular mechanisms of immunity. His research and discoveries earned him the label of "father of modern immunology." Though his work in immunology is considered his greatest scientific achievement, Good is also well known for his work with tissue engineering. From his research on immunology, Good was able to perform the first successful allogeneic (donor and recipient are unrelated) bone marrow transplant. A bone marrow transplant is a form of hematopoietic stem cell transplant in which hematopoietic stem cells are infused into a patient to treat various diseases of the blood including some autoimmune and inherited conditions, and cancer. Following his success with bone marrow transplants, Good established a bone marrow transplantation program for children at the University of South Florida.

Pope Pius IX, born Giovanni Maria Mastai-Ferretti, marked his contribution to the abortion debate by removing the distinction between an "animated" and "unanimated" fetus from Catholic doctrine, and established the edict that a human should be protected starting from the moment of conception onward. This proclamation made abortion at any time of gestation punishable by excommunication. Pope Pius IX's decision became Canon Law of the Catholic Church.

Pope Gregory XIV, born Nicolo Sfondrati, reversed the bull of Pope Sixtus V, Effraenatum, under which an abortion at any time of gestation can be punished by excommunication. He supported the Aristotelian distinction between an "animated" and "unanimated" fetus, making abortion of an unanimated fetus punishable by lesser means. This decision contributed to the historical debates within the Roman Catholic Church on when a fetus has a soul, and when abortion was punishable by excommunication.

Umbilical cord blood (UCB) stem cells are hematopoietic stem cells (HSC) that are recovered from the blood of the umbilical cord and placenta after birth. Umbilical cord blood is rich in cells that express the CD34 molecule, a surface protein that identifies cells as stem cells. Prior to the discovery of UCB stem cells, it was standard procedure to discard the umbilical cord and placenta; now much effort is devoted to raising public awareness and to encouraging people to store or donate cord blood. The importance of these cells lies in potential clinical treatments of blood-borne diseases, as well as the possibility of restoring cells of other lineages, such as cardiac and neural cells. These possible uses have given rise to cord blood stem cell banking, both private and public, where cells can be frozen and stored for later use.