Stem cells

http://www.extremetech.com/wp-content/uploads/2014/07/stem-cells.jpg

Miltiadis-Spyridon Kitsos Platon IB Diploma

Key facts: Fertilization and first embryo stages

http://www.nature.com/nature/journal/v487/n7405/images/487043a-f1.2.jpg

https://youtu.be/jsFn-_SC2Q8

In all animals reproducing sexually, life starts with the formation of the zygote which will then undergo a series of divisions and produce consecutive stages of increasing numbers of cells (two-cell, four-cell, eight cell etc.)

These cells have the ability to divide again and again (increased division potential)

Key facts: Cell differentiationThe initial cells will eventually turn into approximately 200 different cell types.

This process where the first embryo cells change to more specialized cells, with specific morphology and functionIs called cell differentiation

http://4.bp.blogspot.com/-bw8IYEIqBWw/U0__6I0QymI/AAAAAAAAABY/7RYln5kyQmc/s1600/cell-types.bmp

Genes and cell differentiation

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All embryonic cells poses the same genes which are all activated. Cell differentiation is based on the deactivation of gene sets. The deactivation of certain genesm as well as the activation of others, lead to the development of different cell types.

Embryonic cell genes

http://res.cloudinary.com/dk-find-out/image/upload/q_80,w_1440/AW_Nerve_impulse2_tcnrmm.jpg

http://etc.usf.edu/clipart/69300/69336/69336_cell_sections_mth.gif

Stem cells Thus the specialized tissues found in multicellular organisms are a result of cell

differentiation

Differentiation involves the expression of certain genes and not others of the genome.

Differentiate cells will gradually loose their ability to switch to other cell types as well as their ability to divide.

http://outreach.mcb.harvard.edu/animations/preloaderStemCells.swf

https://youtu.be/YtvL-LQlPrU

Two animations..

Stem cells Different cell types

As all branches of a tree develop from a main stem, all cell types in human body arise from embryonic stem cells which have the ability to divide and differentiate

````` Stem cell

Cell differentiation

http://learn.genetics.utah.edu/content/stemcells/scintro/

Stem cells Categories of stem cells

Cell potency (ability to differentiate)

Totipotent Differentiate into any type of cell

Pluripotent Differentiate into many types of cells

Multipotent Can differentiate into few types of cells with functional and morphological similarities

Unipotent Have the capacity to differentiate into only one cell type

https://upload.wikimedia.org/wikipedia/commons/3/3c/Stem_cells_diagram.png

Hetmatopoiesis: A good example of shifting from multipotency to unipotency

https://upload.wikimedia.org/wikipedia/commons/thumb/6/69/Hematopoiesis_%28human%29_diagram.png/1280px-Hematopoiesis_%28human%29_diagram.png

Therapeutic use of stem cellsStargardt’s macular degeneration is a rare genetic disease related with progressive vision loss. It is the result of a mutation in the ABCA4 gene which in turn causes a malfunction in a membrane protein related with active transport in retina cells. It induces a progressive degeneration of the macula (a central area of the retina) which is related with sharp central vision. Patients also suffer with difficulties in navigating in low light. Symptoms appear at late childhood

Case study 1: Stargardt’s macular degeneration

http://ghr.nlm.nih.gov/condition/stargardt-macular-degeneration

https://www.youtube.com/watch?v=8QEYKPcD_qk

http://www.blindness.org/macular-degeneration

Learn more at: http://www.blindness.org/macular-degeneration

Normal vision Stargardt’s

Therapeutic use of stem cellsCase study 1: using stem cells to treat Stargardt’s macular degeneration

Embryonic stem cells are cultivated in the lab. They are treated with special chemical agents to differentiate into retinal pigment epithelial cells.

Patches of cells are injected in the damaged area of the eye.

Marked improvement in eyesight has been reported

Read more http://www.independent.co.uk/news/science/stem-cells-the-first-human-trial-1824099.html

http://www.theguardian.com/science/2014/oct/15/stem-cell-success-in-treating-macular-degeneration

http://www.the-scientist.com/?articles.view/articleNo/42863/title/Eye-Stem-Cell-Therapy-Moves-Ahead/

http://1.bp.blogspot.com/-GVzB16T5Jic/Tx7NeJJPavI/AAAAAAAAHfY/-7hxelmGM2M/s1600/screen-capture-4.png

Therapeutic use of stem cellsCase study 2: leukemiaLeukemia is a malignancy of blood cells. It is related with an apparent large number of changes (mutations) in the genome. Production of cancerous precursor blood cells in the bone marrow leads to the development of abnormal white blood cells which grow in vast numbers. Soon the human body is unable to fight infection, control bleeding or even transport oxygen.Leukaemia is the 12th most common cancer in Europe, with around 82,300 new cases diagnosed in 2012 (2% of the total)

http://www.medicinenet.com/leukemia/page2.htm#what_is_leukemia_what_are_the_different_types_of_leukemia

Acute lymphoblastic leukemia Acute myelogenous leukemia Chronic lymphoblastic leukemia Chronic myelogenous leukemia

Found in lymphoid cells. Grows quickly, Common in children.

Found in myeloid cells. Grows quickly, Common in adults and children.

Found in lymphoid cells. Grows slowly, Common in adults 55+.

Found in myeloid cells. Grows slowly, Common in adults.

https://blooddiseasedestination.files.wordpress.com/2014/11/leukemia1-28129.jpg?w=840

http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/leukaemia/incidence#heading-Four

Therapeutic use of stem cellsCase study 1: using stem cells to treat Leukemia

Large needle is inserted in the bone marrow of a large bone, fluid is extracted and hematopoietic stem cells are isolated

Stem cells are placed in cultures with appropriate growth media

Chemotherapy is administered to kill all bone marrow cancerous cells

Grown stem cells are introduced back to the patients bone marrow. They start multiplying and producing new white and red blood cells.

Read more: http://www.leukaemia.org.au/treatments/stem-cell-transplants/stem-cell-transplants

Therapeutic use of stem cellsMedia

https://youtu.be/2-3J6JGN-_Y

The heart makersStem cells: wonderful documentary

https://youtu.be/pd3TFB0wOI0

Stem Cell Treatment for Leukemia at UCH

https://youtu.be/FWruLa3Qsc4

http://outreach.mcb.harvard.edu/animations/thera7c.swf

http://media.hhmi.org/biointeractive/click/Stem_Cell_Therapies/01.html

http://www.sumanasinc.com/scienceinfocus/sif_stemcells.html

Sources of stem cells: ESC vs ASC vs iPSCEmbryonic

stem cells

Adult stem cells

Induced pluripotent stem

cells

Pluripotent- Almost unlimited growth potential-may differentiate into any kind of

cell

Oligopotent – Unipotent- limited cell potency

Less growth potential than embryonic stem cells

Higher risk of tumor creation Less risk of tumor creation Less risk of tumor formation

Risk of being genetically different from the recipient's cells – higher risk of rejection

Compatible with recipient’s cells – low risk of rejection.

Compatible with recipient’s cells – low risk of rejection.

Unlimited numbers of cells due to high cell potency

Limited numbers may be obtained Rather Limited numbers may be obtained

Very low probability of mutation-induced damage in the DNA

Higher probability of mutation-induced damage in the DNA – risk of diseases

Higher probability of mutation-induced damage in the DNA – risk of diseases

New scientist (The collection): Medical frontiers, 2(2): p. 73

New scientist (The collection): Medical frontiers, 2(2): p. 73

New scientist (The collection): Medical frontiers, 2(2): p. 73

Sources of stem cellsEmbryonic

stem cells

Adult stem cells

Induced pluripotent cells

Ethical issues around the use of IVF embryos for harvesting stem cells

No serious ethical issues related with their use. Adult consent is

required for harvesting the adult stem cells.

No serious ethical issues related with their use.

New scientist (The collection): Medical frontiers, 2(2): p. 73

New scientist (The collection): Medical frontiers, 2(2): p. 73

New scientist (The collection): Medical frontiers, 2(2): p. 73

Allott, Andrew, and David Mindorff. Biology: Course Companion. Oxford: OUP, 2014. 15. Print.

Ethics of stem cell use: a controversyThe Ethical Questions of Stem Cell Research

https://youtu.be/f5d0ieWfKlI

Fr. Mike McGovern on the Catholic Church's Teaching on Stem Cell Research

https://youtu.be/SZ6VSZEiiG0

Obama : Stem Cells

https://youtu.be/NZdtzNmr4gw

Countries in brown have a permissive or flexible policy on human embryonic stem cell research. With the exception of the U.S. have banned by law human reproductive cloning.

George W. Bush: On Stem Cell Research

https://youtu.be/EAiZp5jT04I

https://youtu.be/EAiZp5jT04I

Vatican finances adult stem cell reasearch led by US university

http://www.mbbnet.umn.edu/scmap.html

• Stem cell research may pave the way for future discoveries and beneficial technologies that would not have occurred if their use had been banned.

vs• Involves the creation and destruction of human embryos (at what point do we afford the

right to life?)

• Stem cells can be taken from embryos that have stopped developing and would have died anyway (e.g. abortions)

Vs• More embryos are generally produced than are needed, so excess embryos are killed.

• May be used to cure serious diseases or disabilities with cell therapy (replacing bad cells with good ones)

vs• Embryonic stem cells are capable of continued division and may develop into cancerous

cells and cause tumors

Arguments for and against Therapeutic Cloning

Slide from Chris Paine’s

http://www.slideshare.net/diverzippy/biok-notes-11-introduction-to-cells?ref=http://bioknowledgy.weebly.com/11-introduction-to-cells.html

• Transplants are less likely to be rejected as they are cells which are genetically identical to the parent. Transplants do not require the death of another human.vs

• With additional cost and effort, alternative technologies may fulfill similar roles (e.g. nuclear reprogramming of differentiated cell lines)

• Cells are taken at a stage when the embryo has no nervous system and can arguably feel no painvs

• Religious or moral objections due to the ‘playing God’ argument. • The embryo which is created could potentially be used in IVF and develop into a

human fetus, so are we creating human life to destroy it? • Although cloning humans reproductively is illegal, this has not been ratified by all

nations. Potential for a race to clone the first human.

Arguments for and against Therapeutic Cloning

Slide from Chris Paine’s

http://www.slideshare.net/diverzippy/biok-notes-11-introduction-to-cells?ref=http://bioknowledgy.weebly.com/11-introduction-to-cells.html

Looking at the future(?): Induced pluripotent cells

https://youtu.be/i-QSurQWZo0

http://learn.genetics.utah.edu/content/stemcells/quickref/ips-cells.jpg

https://vimeo.com/77546203

http://www.stepsinbiology.eu/