Biology 6: STEM Cells Assignment - Molecular Biology of Stem Cells

This assignment delves into the molecular characteristics that distinguish stem cells from somatic cells, highlighting differences in size and regenerative capabilities. It details the process of isolating and identifying human embryonic stem cells, including obtaining primary cell populations, maintaining them in a stem cell state through specific culture conditions, and confirming their identity using chromatin search and marker detection. The document also explores methods for obtaining embryonic-like stem cells without destroying the embryo, discusses mechanisms controlling cell fate, and addresses the validity of using any cell from a blastocyst for stem cell preparation. Furthermore, it examines the genetic implications of somatic cell nuclear transfer in generating patient-specific stem cells. Finally, the assignment outlines advantages and disadvantages of DNA microarray analysis, RT-PCR, protein expression analysis, and cell surface antigen expression studies for analyzing gene expression in stem cells.

Running head: BIOLOGY
STEM CELLS
Name of the Student
Name of the University
Author Note

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Table of Contents
Answer 1..........................................................................................................................................2
Answer 2..........................................................................................................................................2
a)..................................................................................................................................................2
b)..................................................................................................................................................2
c)..................................................................................................................................................3
Answer 3..........................................................................................................................................3
Answer 4..........................................................................................................................................3
Answer 5..........................................................................................................................................4
Answer 6..........................................................................................................................................4
Answer 7..........................................................................................................................................4
Answer 8..........................................................................................................................................5
a)..................................................................................................................................................5
b)..................................................................................................................................................5
c)..................................................................................................................................................6
References........................................................................................................................................7

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Answer 1
Stem cells have been found to vary from other types of body cells. There are three
general properties of stem cells which include their ability to divide and renew for a long period
of time, being unspecialized and producing cells of a specialized type. Somatic cells are defined
as cells other which are not associated with the reproductive system of the human body. A stem
cell is defined as an undifferentiated cell that gives rise to a large number of cells of similar
types. Somatic cells are smaller in diameter than stem cells. The diameter for stem cells is 30
microns whereas the size of somatic cells is 8 microns. Somatic cells do not have the property to
regenerate themselves and differentiate into specialized cells. These are the differences between
somatic cells and stem cells on the basis of molecular characteristics (Soldner & Jaenisch, 2018).
Answer 2
a)
Primary cell culture is obtained directly from the tissues. A biopsy sample equivalent to 1
cubic centimeter in diameter is obtained from the animal or human tissues (Kurbet & Raghavan,
2018).
b)
Primary cell isolation is done by the below-stated method:
1. The cells are gently dispersed after pipetting them. This process is named as trituration.
2. The cell suspension is filtered through the fine mesh.
3. The cells are then allowed to settle.

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4. Excess liquid with enzymes is decanted.
5. The process is repeated three times after washing.
The culture condition of stem cells should promote the formation and maintenance of
stem cells which are karyotypically stable and phenotypically well defined. The selected culture
condition must promote self-renewal and pluripotency property of stem cells. Standardization of
the culture media and usage of well-defined matrices helps in maintaining the cell culture
condition of stem cells (Mi & Lee, 2017).
c)
The two approaches for identifying a stem cell are:
1. Chromatin search for the identification of stem cells (Soldner & Jaenisch, 2018).
2. Marker detection is another method for stem cell identification.
Answer 3
The processes used by scientists for the isolation of embryonic stem cells without
destroying the stem cells are:
1. Scientists can use only a single cell instead of all the cells from the embryo consisting of 10
cells.
2. Scientists have also been found to remove a few cells from older blastocysts since they can
survive the process of embryonic stem cell extraction.
3. Turning cells from another lineage to embryonic stem cells (skin cells) (Chen et al., 2017).

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Answer 4
Fates of stem cells have been found to be decided by activating the G1 phase
developmental genes. Signaling pathways such as Notch, EGF, FGF, Wnt pathways, Hedgehog
and JAK-STAT have been found to be associate with the fate decision of cells. Notch signaling
has been observed to regulate the cells' fate of stem cells by regulating the high mortality groups
of cells. Three types of specification such as autonomous specification, conditional specification
and syncytial specification (Li et al., 2018). These are the overall mechanisms to control the fate
of cells.
Answer 5
The statement which states that any cell collected from blastocyst can be used for the
preparation of embryonic stem cells is false. This is because of the fact that during an early stage
(pre-implantation embryo), pluripotent embryonic stem cells can be derived. After 4-5 days of
post-fertilization, the blastocyst reaches the time when blastocyst consists of 50-150 cells. These
cells can be used for the preparation of stem cells. This fact has also been discussed in various
research studies. Thus, the statement can be said to be false and stem cells cannot be prepared by
any cell from the blastocyst (Rivron et al., 2018).
Answer 6
No. This is because of the fact that the embryo is formed by the somatic nuclear transfer
from a somatic cell to the donated unfertilized egg. Since embryonic stem cells are derived from
the blastocyst of the embryo, it will contain DNA of the donated unfertilized egg (Kurbet &
Raghavan, 2018). Embryonic stem cells have been found to be derived from the fertilized

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blastocyst which is derived from the fusion of nuclear contents from somatic cells and the
donated egg.
Answer 7
The five different characteristics of stem cells population are (Soldner & Jaenisch, 2018):
1. High heterogeneity.
2. The decrease in the expression of CD 146.
3. Increased inhomogeneity in the in-vitro aging stem cells.
4. Variation in the levels of CD 106.
5. The difference in phenotypic characters.
These are the five different characteristics of stem cell population which makes it
different from the somatic cell population.
Answer 8
a)
The advantages of using DNA microarray analysis for expression measurement are low
cost and increased sensitivities due to the use of long target sequences (Yang et al., 2019).
The disadvantages of using DNA microarray for the measurement of expression are a
high requirement of labor for the purification and storage of DNA (Yang et al., 2019).
The advantages of using RT-PCR for expression measurement are the ability of amplified
fragment identification during PCR and the amount of expression is identified accurately
(Kuypers & Jerome, 2017).

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The disadvantages of using RT-PCR for expression measurement are the problems
associated with complexity and sensitivity associated with reproducibility and specificity
(Kuypers & Jerome, 2017).
b)
The advantage of using protein expression analysis for the measurement of expression is
that it gives an accurate measurement of the expression levels.
The disadvantages of using protein expression analysis for the measurement of
expression are its high cost and variations in the protein expression levels.
c)
The advantage of using cell surface antigen expression study for the measurement of
expression is that it uses the pH of the cell to measure its expression levels (Tsuji et al., 2017).
The disadvantages of using cell surface antigen expression study for the measurement of
expression are the problems associated with the fluorescence level of the cell (Tsuji et al., 2017).
These are the overall advantages and disadvantages of using various techniques of molecular
biology for the isolation and characterisation of stem cells.

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References
Chen, G. Q., Zheng, C. H., HE, M. W., & Zeng, M. (2017). Isolation and culture of mouse bone
marrow mesenchymal stem cells and induced differentiation into alveolar epithelial
cells. Journal of Medical Postgraduates, 30(12), 1283-1288.
Kurbet, A. S., & Raghavan, S. (2018). Isolating Immune Cells from Mouse Embryonic Skin.
In Skin Stem Cells (pp. 299-305). Humana Press, New York, NY.
Kuypers, J., & Jerome, K. R. (2017). Applications of digital PCR for clinical microbiology.
Journal of clinical microbiology, 55(6), 1621-1628.
Li, W., Yan, Z., Ren, J., & Qu, X. (2018). Manipulating cell fate: dynamic control of cell
behaviors on functional platforms. Chemical Society Reviews, 47(23), 8639-8684.
Mi, H. W., & Lee, M. C. (2017). U.S. Patent No. 9,850,459. Washington, DC: U.S. Patent and
Trademark Office.
Rivron, N. C., Frias-Aldeguer, J., Vrij, E. J., Boisset, J. C., Korving, J., Vivié, J., ... & Geijsen,
N. (2018). Blastocyst-like structures generated solely from stem cells. Nature, 557(7703),
106-111.
Soldner, F., & Jaenisch, R. (2018). Stem cells, genome editing, and the path to translational
medicine. Cell, 175(3), 615-632.
Tsuji, K., Ojima, M., Otabe, K., Horie, M., Koga, H., Sekiya, I., & Muneta, T. (2017). Effects of
different cell-detaching methods on the viability and cell surface antigen expression of
synovial mesenchymal stem cells. Cell transplantation, 26(6), 1089-1102.

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Yang, J., Ai, Z., Yu, M., Li, J., & Li, S. (2019). Identification of key genes and transcription
factors in aging mesenchymal stem cells by DNA microarray data. Gene, 692, 79-87.