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1.1.2 History of Stem Cells
The term “stem cell” was proposed for scientific use by the Russian histologist
Alexander Maximow in 1908. He postulated existence of hematopoietic stem cells.
In 1959, E. Donnall Thomas performed successful syngeneic bone marrow trans-
plant in two patients with acute lymphoblastic leukemia. He shared the Nobel Prize
in physiology in medicine with Joseph Murray, a surgeon instrumental in the devel-
opment of kidney transplantation [ 4 ]. In 1968 bone marrow transplant between two
siblings was used to successfully treat severe combined immunodeficiency. For
most of the latter half of the previous century stem cell transplant techniques focused
on hematopoietic stem cells and bone marrow transplant. It was not until 1998 when
Thomson and co-workers derived the first human embryonic stem cell line [ 5 ].
Since then several rapid strides have been made in this arena. Several new sources
of stem cells have been shown like primary teeth [ 6 ] , cord blood, amniotic fluid [ 7 ].
In 2007 Mario Capecchi, Martin Evans, and Oliver Smithies were awarded the 2007
Nobel Prize for producing genetically engineered mice (known as knockout mice)
using embryonic stem cell gene targeting.
1.1.3 Clinical Applications of Stem Cells
Stem cells can be used for a variety of applications. Some of the uses are summa-
rized below:
1.1.3.1 Understanding Genetic and Molecular Controls of Cell Division
and Differentiation
The control of cell division and differentiation is dependent on an orderly control of
the genes. Understanding how undifferentiated stem cells become differentiated to
form tissues and organs is central to the study of abnormal cell division in condi-
tions like cancer and birth defects. The information gained from the study of the
genetic and molecular mechanisms underlying cell division and differentiation may
help better understand the molecular basis of these diseases and can suggest novel
therapeutic approach.
1.1.3.2 Drug Testing
The safety and efficacy of new drugs can be tested on differentiated cells generated
from human pluripotent cell lines. Similarly, cancer cell lines are used to screen
potential anti-tumor drugs. Pluripotent cell lines can generate a number of differen-
tiated cell types, allowing a variety of cell substrate for drug testing.
T. Pa ndey