Chapter 1 Answers to Select Review Questions
1. Who first coined the term "stem cell" and what was his background?
Alexander A. Maximow first coined the term "stem cell" in 1908 while addressing a hematologic society congress in Berlin (see Focus Box 1.1). Maximow was a scientist and histologist who spent several years around the turn of the 20th century contemplating the existence of a unique cell type that would allow for generation of many differentiated, mature phenotypes. Maximow's main focus was on blood cell type identity and what drives the generation of the terminally differentiated cells in the hematopoietic system. It was as a professor at the Imperial Military Academy in Saint Petersburg, Russia from 1903 to 1922 where he refined his theories on the existence of a common hematopoietic precursor cell.
3. What contribution did Joseph Altman and Gopal Das make to the field of stem cell research?
They demonstrated neurogenesis, defined as the generation of neurons and glial cells, occurring in the adult brain.
5. How were hematopoietic stem cells discovered?
Gregor Prindull's team extracted cord blood from newborn infants 8-10 days old. Cells from the blood samples were processed by sedimentation and clearing of non-lymphoid cells and subsequently cultured in a methylcellulose cell culture system. By the tenth day of cell culture the researchers identified a small subpopulation of cells (1 in 1678 on average) in a sample of non-adherent mononuclear cells that represented myelocytic colony forming units (CFUs), cells that have the ability to divide and form a clonal colony in tissue culture.
7. From what region of the brain were the first neural progenitor and stem cells isolated and who accomplished this?
Brent A. Reynolds and Samuel Weiss in the Department of Pathology at the University of Calgary School of Medicine first successfully isolated neural progenitor and stem cells from the subventricular zone (a neurogenic region) of adult mouse brain tissue.
12. What is the difference between therapeutic and reproductive cloning?
Therapeutic cloning can be defined as reproduction of a genetically identical cell for purposes of cell therapy such as cellular replacement while reproductive cloning involves a somatic cell nuclear transfer derived cell that may be either propagated in tissue culture or allowed to develop into an embryo and transplanted into a surrogate mother.
17. What two factors aggravate spinal cord injury repair?
The adult central nervous system (CNS) has a very limited capacity to regenerate itself and, as a consequence, injuries to the spinal cord often result in partial or complete irreversible paralysis. Secondary degeneration of the CNS post-injury also aggravates this scenario.
24. How did Andrew French's group successfully clone human embryos?
It was accomplished through SCNT of nuclei from adult fibroblasts into enucleated oocytes. Mature oocytes obtained from donors were enucleated either via extrusion or aspiration and nuclei transferred into these oocytes from adult male fibroblasts.
29. Why does the mitochondria drive innate immunity rejection?
iPS cells generated from host donor cells have accumulated mitochondrial DNA mutations throughout the aging process. These mutations result in desired differentiated lineages that are different from the host donor, which may contribute to immune rejection by the host recipient of any derived cell therapy.