Lecture - Stem Cells: Difference between revisions

Revision as of 14:04, 12 October 2011

Introduction

Week 1 human development

Blastocyst development

Embryology is all about stem cells, a single cell (zygote) divides and differentiates to form all the tissues throughout the body. Furthermore within some tissues, stem cells remain to continuously replace cells that are lost through the life of that tissue. In recent years Scientific and general interest in this topic has increased due to the many issues that surround this specialised cell type. This lecture will introduce the various types/sources of stem cells as well as their practical and therapeutic potentials. A brief discussion of the pros and cons of different types of stem cells currently investigated in the field of medical research will be discussed.

Textbooks

Moore, K.L. & Persuad, T.V.N. (2008). The Developing Human: clinically oriented embryology (8^th ed.). Philadelphia: Saunders.

(chapter links only work with a UNSW connection).

Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R. and Francis-West, P.H. (2009). Larsen’s Human Embryology (4^th ed.). New York; Edinburgh: Churchill Livingstone.

(chapter links only work with a UNSW connection).

Hill, M.A. (2011) UNSW Embryology (11^th ed.). Sydney:UNSW.

Links: Embryology Textbooks | NIH - Regenerative Medicine 2006

Why Stem Cells

Why are they in the News?

Scientific and Ethical
Therapeutic uses
Issues relating to human cloning
Use of excess human eggs/sperm for research purposes
Availability of human stem cell lines

What are their uses?

Generation of “knock out” mice
Studying regulation of cell differentiation in development
Therapeutic uses?
Genetic disease
Neurodegenerative
Injury

Medline Search stem cell 2002 - 110,920 | 2004 - 128,485 | 2005 - 140,966 | 2006 - 154,176 | 2011 - 190,069

Research that led to Stem Cells

Human Diseases - Generation of “knock out” mice
Human Development - Studying regulation of cell differentiation in development
Human Reproduction - Disorders, sterility

Stem Cell Types

Tissue Stem Cells

differentiated cells have short life spans continually replaced
blood cells, epithelial cells of skin and digestive tract
fully differentiated cells do not proliferate
proliferation of less differentiated- stem cells
produce daughter cells that either differentiate or remain as stem cells

Blood Cells

Hematopoietic and stromal cell differentiation

All different types of blood cells develop from a pluripotent stem cell in bone marrow
Precursors of differentiated cells undergo several rounds of cell division as they mature
- proliferation ceases at terminal stages of differentiation

Embryonic Stem Cells

File:Progenitor and stem cell cartoon.jpg

Difference between a Progenitor and Stem Cell

NIH - What are embryonic stem cells?

What is a stem cell - Pluripotent (totipotent)
Pluripotent - to describe stem cells that can give rise to cells derived from all 3 embryonic germ layers (Ectoderm, Mesoderm, Endoderm)
layers are embryonic source of all cells of the body

Blastocyst

hollow structure composed of about 100 cells surrounding an inner cavity
Only ES cells, which form inner cell mass, actually form the embryo.
ES cells can be removed from the blastocyst and grown on lethally irradiated “feeder cells.” (See E. Robertson et al., 1986, Nature 323:445)

Stem Cell Definition

cell that has ability to divide for indefinite periods
self replicate
throughout life of organism
stem cells can differentiate
- conditions, signals
to the many different cell types

Chimeric Mouse

ES or teratocarcinoma - shows that stem cells can combine with cells of a normal blastocyst to form a healthy chimeric mouse

Embryoid Bodies

spheroid cellular tissue culture structure
mouse and human ES cells have the capacity to undergo controlled differentiation
recapitulate some aspects of early development
- regional-specific differentiation program
- derivatives of all three embryonic germ layers

Historic References

Mouse

Pig and Sheep

Primate

Human

Stem Cell Lines ATCC - Embryonic Stem cell lines

Cord Blood Stem Cells

Cord blood induced stem cell differentiation

Blood collected from the placental umbilical cord of a newborn baby shortly after birth
- total amount of blood about 90 ml
blood stem cells that can be used to generate red blood cells and cells of the immune system
collected, typed, stored in Cord Blood Bank
- Both public and private Banks have arisen
- available for use by the donor and compatible siblings

suggested use to treat a range of blood disorders and immune system conditions such as leukaemia, anaemia and autoimmune diseases
cells provide a resource for bone marrow replacement therapy in many diseases.

Adult Stem Cells

Connective Tissue
Bone marrow - Blood Cells, Osteoclasts, blasts
Epithelia - Gut, Skin (Epidermis: Immortal Stem Cell)
Neural?

Epithelium Stem Differentiation

Epidermis stem cell models

each generation at least 1 "immortal" stem cell - descendants present in patch in future
Other basal cells - leave basal layer and differentiate
Committed, born different or may be stem cells
- equivalent to immortal stem cell in character
- mortal in sense that their progeny jostled out of basal layer and shed from skin

Amplifying Cells

Stem cells in many tissues divide only rarely
give rise to transit amplifying cells
daughters committed to differentiation that go through a limited series of more rapid divisions before completing the process.
each stem cell division gives rise in this way to eight terminally differentiated progeny

Stem Cell Production - Stem Cell Daughter Fates

Environmental asymmetry
- daughters are initially similar
- different pathways according to environmental influences that act on them after they are born
- number of stem cells can be increased or reduced to fit niche available
Divisional asymmetry
- stem cell has an internal asymmetry
- divides in such a way two daughters are already have different determinants at time of their birth

Links: NIH - What are adult stem cells?

Induced Pluripotent Cells

non-pluripotent cells engineered to become pluripotent (iPSC), a cell with a specialized function ‘reprogrammed’ to an unspecialized state

Human iPS cell clones^[1]

embryonic stem cell signalling regulation

Yamanaka Factors

A set of 4 transcription factors when introduced into cells induces stem cell formation.^[2] These four transcription factors can be expressed from doxycycline (dox)-inducible lentiviral vectors. The only culture difference in iPS cells and human embryonic stem cell culture is that iPS cell culture require 100ng/ml of bFGF in the culture media.

Outline of the MEF reprogramming protocol 1 Outline of the MEF reprogramming protocol 2 | stained with anti-Rex1, Sox2 and SSEA1 antibodies

OCT4 Transcription factors containing the POU homeodomain
MYC The MYC protooncogene encodes a DNA-binding factor that can activate and repress transcription. Ectopic expression of c-Myc can also cause tumorigenicity in offspring.
SOX2 SRY-RELATED HMG-BOX GENE 2
KLF4 Kruppel-like factor 4, zinc finger protein, transcription factor which acts as both an activator and repressor.

More recently shown that Oct4 together with either Klf4 or c-Myc is sufficient to generate iPS cells from neural stem cells.^[3]

Thompson Factor

NANOG

Links: Generating iPS Cells from MEFS through Forced Expression of Sox-2, Oct-4, c-Myc, and Klf4

Embryonic vs Adult Stem Cells

Early lineage markers in morulae and blastocysts

Embryonic Stem Cell Advantages

Pluripotency - ability to differentiateinto any cell type.
Immortal - one cell can supply endless amounts of cells.
Easily available - human embryos from fertility clinics.

Embryonic Stem Cell Disadvantages

Unstable - difficult to control differentiation into specific cell type.
Immunogenic - potential immune rejection when transplanted into patients.
Teratomas - tumor composed of tissues from 3 embryonic germ layers.
Ethical Controversy - unethical for those who believes that life begins at conception.

Adult Stem Cell Advantages

Already ‘specialised’ - induction of differentiation into specific cell types will be easier.
Plasticity - Recent evidences suggest wider than previously thought ranges of tissue types can be derived.
No Immune-rejection - if used in autologous transplantations.
No Teratomas - unlike ES cells.
No Ethical Controversy - sourced from adult tissues.

Adult Stem Cell Disadvantages

Minimal quantity - number of isolatable cells may be small.
Finite life-span - may have limited lifespan in culture.
Ageing - stem cells from aged individuals may have higher chance of genetic damage due to ageing.
Immunogenic - potential immune rejection if donor cells are derived from another individual.

Current stem cell research

File:NIH stem cell cartoon.jpg

NIH - stem cell cartoon

How to:

Isolate
Grow
Maintain, store
Differentiate
Therapeutic uses

References

Textbooks

Molecular Biology of the Cell Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter New York and London: Garland Science; c2002 Figure 22-4. The definition of a stem cell | Figure 22-19. Renewal of the gut lining | [http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?db=Books&rid=mboc4.figgrp.4092 Figure 22-5. Two ways for a stem cell to produce daughters with different fates

Molecular Cell Biology Lodish, Harvey; Berk, Arnold; Zipursky, S. Lawrence; Matsudaira, Paul; Baltimore, David; Darnell, James E New York: W. H. Freeman & Co.; c1999 Figure 24-8. Formation of differentiated blood cells from hematopoietic stem cells in the bone marrow

The Cell- A Molecular Approach Cooper, Geoffrey M. Sunderland (MA): Sinauer Associates, Inc.; c2000 Stem Cells

Search

Online Textbooks "stem cell" Molecular Biology of the Cell | Molecular Cell Biology | The Cell- A molecular Approach

Entrez stem cell | stem cell marker | embryonic stem cell | mesenchymal stem cell

Images

Inner cell mass
Hematopoietic and stromal cell differentiation
Blood stem cell
Stem cell therapy.jpg

Stem cell therapy
stem cell signalling regulation
Epidermis stem cell models
Human embryonic_stem_cell_defined_conditions_01
Human embryonic_stem_cell_defined_conditions_02
Different tissues
Human induced pluripotent_stem_cells
Early lineage markers in morulae and blastocysts
Morula cell lines express ES markers

References

↑ <pubmed>20525219</pubmed>| BMC Dev Biol.
↑ <pubmed>16904174</pubmed>
↑ <pubmed>18594515</pubmed>

Journals

Stem Cell Research & Therapy

Co-ordinator Note

Dr Mark Hill

ANAT2341 Embryology S2 2011

Lecture content is made available on the Monday of the associated lecture week.
Some guest lecturers will provide additional handouts or lecture notes.
For background information see Embryonic Development and Systems Notes
2011 Timetable | 2011 Students

--Mark Hill 06:47, 20 July 2011 (EST)

Course Content 2011

Glossary Links

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Cite this page: Hill, M.A. (2024, April 16) Embryology Lecture - Stem Cells. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Lecture_-_Stem_Cells

What Links Here?

[1] <pubmed>20525219</pubmed>| BMC Dev Biol.

[2] <pubmed>16904174</pubmed>

[3] <pubmed>18594515</pubmed>

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[2]

[3]

@@ Line 129: / Line 129: @@
 ==Cord Blood Stem Cells ==
+[[File:Cord blood induced stem cells 02.jpg|thumb|Cord blood induced stem cell differentiation]]
 * Blood collected from the placental umbilical cord of a newborn baby shortly after birth
 ** total amount of blood about 90 ml