Stem Cells – An Overview

Subhajit Hazra* [02]Department of Pharmacology

Gupta College of Technological SciencesAsansol – 713301 ; WB.

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Chronology of Stem Cell Research Stem Cell Introduction Classification & Age of stem Cells A Brief Review on the 4 major Kinds of Stem Cells Induced Pluripotent Stem Cells – A Short Study Cloning in context of Stem Cells The Question - Are We Alone ? Chimera and its Implications Cancer Stem Cells Noble Laureates of Stem Cell Research Stem Cell Application Strategies for transplantation of Stem Cells Clinical Trials Undertaken in Stem Cell Research Ethical Considerations'

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James Alexander ThomsonIs an American developmental biologist

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1868 — The term “stem cell” appears in scientific literature, when German biologist Ernst Haeckel.June 1, 1909 — Russian academic Alexander Maximow lectures at the Berlin Hematological Society on a theory that all

blood cells come from the same ancestor cell. This introduces the idea of blood stem cells1981 — Two scientists, Martin Evans of the University of Cambridge and Gail Martin of the University of California, San

Francisco, conduct separate studies and derive pluripotent stem cells from the embryos of mice1998 - Researchers first extract stem cells from human embryos 2001 - President Bush restricts federal funding for embryonic stem-cell research2002 - Juvenile Diabetes Research Foundation International creates $20 million fund-raising effort to support stem-cell

research.Dec. 10, 2003 — George Q. Daley and his team publish findings on converting stem cells from mice into germ cells and,

eventually, primitive sperm cells that are able to fertilize egg cells.2004 - Harvard researchers grow stem cells from embryos using private funding.May 19, 2005 — South Korean scientists under the direction of Woo-Suk Hwang announce that they’ve used therapeutic

cloning to create 11 stem cell lines.Aug. 25, 2006 — Japanese scientists Shinya Yamanaka and Kazutoshi Takahashi announce the creation of rodent induced

pluripotent cells (iPS cells).November/December, 2007 — Three independent teams in Japan, Wisconsin and Boston, led by Shinya Yamanaka,

James Thomson, and George Q. Daley, respectively, announce that they have created human iPS cells.Aug. 6, 2008 – The Stem Cell Program at Boston Children’s Hospital announces the creation of 10 disease-specific lines

of iPS cells.2010 - A person with spinal injury becomes the first to receive a medical treatment derived from human embryonic stem

cells as part of a trial by Geron of Menlo Park, California, a pioneering company for human embryonic stem cell therapies.

History of Stem Cell Research

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Stem Cell History Cont.2012 Another Nobel - Yamanaka wins a Nobel prize for creating induced pluripotent stem cells,

which he shares with John Gurdon of the University of Cambridge.2013 Therapeutic cloning - Shoukhrat Mitalipov at the Oregon National Primate Research Center

in Beaverton and his colleagues produce human embryonic stem cells from fetal cells using therapeutic cloning – the breakthrough falsely claimed in 2005.

2014 Pre-embryonic state - Charles Vacanti of Harvard Medical School together with Haruko Obokata at the Riken Center for Developmental Biology in Kobe, Japan, and colleagues announced a revolutionary discovery that any cell can potentially be rewound to a pre-embryonic state – using a simple, 30-minute technique.

2014 Therapeutic cloning – with adult cellsTeams led by Dieter Egli of the New York Stem Cell Foundation and Young Gie Chung from CHA University in Seoul, South Korea, independently produce human embryonic stem cells from adult cells, using therapeutic cloning. Egli’s team use skin cells from a woman with diabetes and demonstrate that the resulting stem cells can be turned into insulin-producing beta cells. In theory, the cells could be used to replace those lost to the disease.

AND THE LIST STILL GROWS ....

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What makes stem cells so valuable?

Cell Therapy

Research

New Drugs

Pluripotent stem cells

Tissue stem cells

No one stem cell type fits all applications. Research must continue using all types of stem cells.

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Stem Cell – Definition

• A cell that has the ability to continuously divide and differentiate (develop) into various other kind(s) of cells/tissues

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Stem cells can:• Self-renew to make

more stem cells• Differentiate into a

specialized cell type

Embryonic stem cells (pluripotent)

Stem cells that can become many types of cells in the body

are called Pluripotent.

Tissue stem cells (multipotent)

Stem cells that can become only a few types of cells are

called Multipotent.

Why are Stem Cells Special?

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This cellCan form the

Embryo and placenta

This cellCan just form the

embryo

Totipotent

Pluripotent

Multi-potent

Fully mature

Classification of Stem Cells

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Age of Stem Cells

Stem cell type Description Age

Totipotent Each cell can develop into a new individual

Cells from early (1-3 days) embryos

Pluripotent Cells can form any (over 200) cell types

Some cells of blastocyst (5 to 14 days)

MultipotentCells differentiated, but can form a number of other tissues

Fetal tissue, cord blood, and adult stem cells

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Kinds of Stem Cells & their Origin

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Embryonic Stem Cells

• Derived from donated IVF embryos

• Can be grown indefinitely in the laboratory in an unspecialised state

• Retain ability to specialise into many different tissue types – know as Totipotent.

• Can restore function in animal models following transplantation

Human embryonic stem cells can become any cell in the body including these beating heart cells

A Embryonic Stem Cell

Blastocyst

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8-cell blastocystfertilised egg 2-cellegg

Day 0 Day 1 Day 2 Day 3 Day 6

• Donated excess IVF (in vitro fertilization)embryos

Images from www.advancedfertility.com

Where do embryonic stem cells come from?

Inner cell mass

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Foetal Stem Cell

3 Sources of Foetal Stem Cells :

Trophoblast Stem Cells (TS Cells) (Discovery that led to the successful lab culcure of TS Cells is Fibroblast Growth factor 4 –

Required to maintain TS Cells at Undifferentiated State)

Premodial Stem Cells (Embryonic Stem Cells)

Are Pluripotent in nature

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Umbilical Cord Stem Cells

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What’s in ?

• Also Known as Wharton’s Jelly

• Adult stem cells of infant origin

• Isolated prior to/ immediately following birth

• Haematopoietic stem cells (Majority)

• 100,000 Pluripotent or Multipotent stem cells per mL in UCB

• Alternate to bone marrow stem cells

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Types divided in:

Three important functions of UCS cells:

- Plasticity: Potential to change into other cell types like nerve cells

- Homing: To travel to the site of tissue damage

- Engraftment: To unite with other tissues

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Applications

• Hematopoietic cell transplantation (HCT) - Is curative for malignant and nonmalignant diseases like aplastic anemia, leukemias, metabolic and other congenital disorders.

• HLA (Human leukocyte antigen) mismatch may be better tolerated in the UCBT (Umbilical cord blood transplantation) setting than Bone Marrow Transplantation.

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Tissue Stem Cells• Often known as Adult Stem Cells• They are Unipotent • Also includes stem cells isolated from fetal and cord blood• Reside in most tissues of the body where they are involved in

repair and replacement

• Generally very difficult to isolate• Already used to treat patients (haematological malignancies,

diseases of the immune system)

Bone marrow Kidney Lungs

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Induced Pluripotent Stem Cells (IPSC’s)

• Derived from adult cells in 2007 - very recent discovery!

• Can be grown indefinitely in culture in an undifferentiated state

• Similar properties to embryonic stem cells as can differentiate into many different tissue types –Pluripotent

• Can create stem cells directly from a patient for research

Induced change in gene expression

Pluripotent stem cells

Starting cells from donor tissue

iPS Cells

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Cloning

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Cloning

Cloning means making an organism identical to another.

Production of one or more individual plants or animals(whole/in part) that are genetically identical

In nature :- Identical Twins

Occurs naturally in single celled organisms

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Types of Cloning

Embryo Cloning

Reproductive cloning

Therapeutic Cloning

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Therapeutic cloning (research cloning) is when stem cells are extracted to grow into a piece of human tissue which is encouraged to grow into a human organ for transplant

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Human Stem Cells

Are We Alone ?

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Plant Stem Cells ?• They are

undifferentiated cells• Located in root

meristem, shoot meristem, and vascular meristem

• Create all differentiated cell types

• Self-renew, In this microscopy of root meristem, the stem cells are

located within zone 1

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Chimera ? A chimera is a single organism composed of cells from different zygotes.

Types of Chimera : Animal Chimera Plant Chimera Human to Animal Chimera (Of most impact to the society)

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Animal Chimera

Human to Animal Chimera

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Implication of Human to Animal Chimera

Researchers are pursuing a number of strategies to make pigs into human-organ donors that could cause an immune response in primates.

The advantage of chimaeras as said by Izpisua Belmonte is that researchers could one day use a patient’s own cells to create a pig chimaera with a human organ that has been grown for that individual.

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Cancer Stem Cells

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Cancer stem cells

Rare cells within tumors with the ability to self-renew and give rise to the phenotypically diverse tumor cell

population to drive tumorigenesis

Normal stem cells

Rare cells within organs with the ability to self-renew and give rise to all types of cells within the organ to

drive organogenesis

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Therapeutic implications of Cancer Stem Cells

• Most therapies fail to consider the difference in drug sensitivities of cancer stem cells compared to their non-tumorigenic progeny.

• Most therapies target rapidly proliferating non-tumorigenic cells and spare the relatively quiescent cancer stem cells.

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Future Directions

- Need to characterize cancer stem cells at the single cell level

- Understand the genetic and biochemical mechanisms that control the self-renewal phenotype, asymmetric subdivision, and the role of the stem cell niche in regulating the biological properties of both normal and cancer stem cells.

- Characterize the response of cancer stem cells to chemotherapeutic regimens.

- Develop therapeutic strategies to target cancer stem cells to prevent tumor recurrence.

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Nobel Prize Winning Experiments

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Stem Cells Applications

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Strategies for transplantation of Stem Cells

1.Undifferentiated or partially differentiated stem cells may be injected directly in the target organ or intravenously.(i.e Hematopoietic stem cells)

2. Stem cells may be differentiated ex vivo prior to injection into the target organ. (Beta cells, Cardiomyocyte)

3. Growth factors or other drugs may be injected to stimulates endogenous stem cell populations.

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Key Ethical Issues• Use of fetal tissue is ethically controversial because it is

associated with abortion, which many people object to.

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References Mitalipov S, Wolf D (2009). "Totipotency, pluripotency and nuclear reprogramming". Adv. Biochem. Eng.

Biotechnol. Advances in Biochemical Engineering/Biotechnology. 114: 185–99. Bubela T, Li MD, Hafez M, Bieber M, Atkins H (2012). "Is belief larger than fact: Expectations, optimism

and reality for translational stem cell research. BMC Med. 10: 133. Oh Young Banga, Eun Hee Kim, Jae Min Cha, Gyeong Joon Moon (2016). Adult Stem Cell Therapy for

Stroke: Challenges and Progress. J Stroke > Volume 18(3). Simona Delia Nicoară, Sergiu Șușman, Oana Tudoran, et al. (2016), “Novel Strategies for the

Improvement of Stem Cells’ Transplantation in Degenerative Retinal Diseases,” Stem Cells International, vol. 2016.

Alan Trounson and Courtney McDonald (2015). Stem Cell Therapies in Clinical Trials: Progress and Challenges, Cell Stem Cell 17, July 2.

Strain, Lisa; John C.S. Dean; Mark P. R. Hamilton; David T. Bonthron (1998). "A True Hermaphrodite Chimera Resulting from Embryo Amalgamation after in Vitro Fertilization". The New England Journal of Medicine. 338 (3): 166–169.

Jun Wu et al. (2017) Interspecies Chimerism with Mammalian Pluripotent Stem Cells. Cell 168, 473–486. Irma Virant-Klun & Martin Stimpfel (2016). Novel population of small tumour-initiating stem cells in the

ovaries of women with borderline ovarian cancer. Scientific Reports 6, Article number: 34730. Ran Lu et al. (2017)Neurons generated from carcinoma stem cells support cancer progression. Signal

Transduction and Targeted Therapy 2, Article number: 16036. Wei Guo, Joseph L Lasky and Hong Wu (2006). Cancer Stem Cells. Pediatric Research (2006) 59, 59R–

64R.