Mesenchymal stem cells (MSC) originate in the human embryo and are considered to be multipotent — a type of stem cells that have not yet adopted a specific cellular phenotype. Such cells have the ability to differentiate into various types of cells found within the human body, including fibroblasts, adipose cells, muscle cells, bone cells, and skin cells. Once MSCs differentiate, the cells mature and will fulfill the functions of the phenotypes until they die. While mesenchymal stem cells play an important role in studying the behavior of cellular development, critics claim collection of MSCs from human embryos is unethical and morally wrong.
MSCs are derived from the mesenchyme, an early developmental tissue of the embryo that will develop into various types of connective tissue. Although MSCs are primarily derived from embryos, they may also be extracted from umbilical cord tissue as well. While primarily found in the human embryo, mesenchymal stem cells may also be found in the soft tissue of adult teeth. Cells known as mulitpotent stromal cells have similar properties as mesenchymal stems cells but are found in the adult body, particularly in bone marrow and connective tissue surrounding vasculature.
Mesenchymal stem cells have various applications in the field of cell and tissue engineering. Specifically, MSCs are easily extracted, isolated, and maintained in vitro, allowing for effective studies into cellular behavior with little concern over cell viability. MSC cell lines are eternal — under the appropriate growth conditions, the cells will divide indefinitely provided they have adequate space. During experimentation, MSC cell lines are often kept in a controlled environment in which the temperature is held at 98.6 degrees Fahrenheit (37 degrees Celsius) and a 5 percent carbon dioxide (CO2) gaseous environment is maintained.
MSCs are especially important in studies aiming to determine the effects of various external stimuli, both chemical and mechanical, on cellular behavior. As multipotent cells, MSCs will adopt their final phenotypes based on such external stimuli. Therefore, researchers may determine the causative factors in cell differentiation through the use of MSCs.
In addition, research has been performed using MSCs to investigate the mechanisms of cancer cell growth and proliferation. Such studies hope to employ MSCs to better understand key stages in cancer cell development so that these stages of development may be interrupted to prevent further cancerous behavior. Techniques investigating more efficient derivation of MSCs from umbilical cord and connective tissues have sought to alleviate moral and ethical concerns with derivation of stem cells from human embryos.