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This presentation provides a flexible tool for scientists, science communicators, and educators to discuss stem cell biology. It includes slides for different audience levels, from school students to informed non-specialist audiences.
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Dear speaker… This presentation is intended as a flexible tool for scientists, science communicators and educators. Not all the slides will be useful for any one occasion. Choose the ones most suitable for your audience, mix them with your own slides, or just use the diagrams. Contents • Stem cell biology basics: For school students aged 16+, or adult public with little or no scientific knowledge • Cloning: For adult public with little or no scientific knowledge; initial slides also suitable for students aged 16+ • Stem cell biology in more detail: For informed non-specialist audiences, e.g. clinicians, scientists working in fields other than stem cell biology. Presenter’s notes Each slide in the Basics and Cloning sections includes notes that give a simple, jargon-free explanation of the key points. The more detailed slides in the last section have much briefer notes and assume some knowledge of stem cell science. Further information and resources The 15-minute film, “A Stem Cell Story” provides an excellent introduction to stem cells and covers many of the concepts presented here. See www.eurostemcell.org/films Got a question or a comment? Contact us at http://www.eurostemcell.org/contact
What is a stem cell? stem cell SELF-RENEWAL (copying) DIFFERENTIATION (specializing) specialized cell e.g. muscle cell, nerve cell stem cell
What is a stem cell? Stem cell Stem cell DIFFERENTIATION (specializing) SELF-RENEWAL (copying) Identical stem cells Specialized cells
Why self-renew AND differentiate? 1 stem cell 4 specialized cells 1 stem cell Differentiation - replaces dead or damaged cells throughout your life Self renewal - maintains the stem cell pool
Where are stem cells found? tissue stem cells fetus, baby and throughout life embryonic stem cells blastocyst - a very early embryo
Types of stem cell: 1) Embryonic stem cells
Embryonic stem (ES) cells: Where we find them blastocyst cells inside = ‘inner cell mass’ fluid with nutrients culture in the lab to grow more cells embryonic stem cells taken from the inner cell mass outer layer of cells = ‘trophectoderm’
Embryonic stem (ES) cells: What they can do differentiation embryonic stem cells PLURIPOTENT all possible types of specialized cells
Embryonic stem (ES) cells: Challenges skin grow under conditions A grow under conditions B neurons embryonic stem cells grow under conditions C blood grow under conditions D ? liver
Types of stem cell: 2) Tissue stem cells
Tissue stem cells: Where we find them surface of the eye brain skin breast intestines (gut) testicles bone marrow muscles
Tissue stem cells: What they can do blood stem cell differentiation found in bone marrow only specialized types of blood cell: red blood cells, white blood cells, platelets MULTIPOTENT
Types of stem cell: 3)Induced pluripotent (iPS) stem cells
Induced pluripotent stem cells (iPS cells) ‘genetic reprogramming’ = add certain genes to the cell cell from the body induced pluripotent stem (iPS) cell behaves like an embryonic stem cell differentiation culture iPS cells in the lab all possible types of specialized cells Advantage: no need for embryos!
Induced pluripotent stem cells (iPS cells) genetic reprogramming pluripotent stem cell (iPS) cell from the body (skin) differentiation
Stem cell jargon PotencyA measure of how many types of specialized cell a stem cell can make PluripotentCan make all types of specialized cells in the body Embryonic stem cells are pluripotent MultipotentCan make multiple types of specialized cells, but not all types Tissue stem cells are multipotent
Cloning Reproductive cloning Use to make two identical individuals Very difficult to do Illegal to do on humans Molecular cloning Use to study what a gene does Routine in the biology labs gene 1 gene 2 There are two VERY different types of cloning:
Reproductive cloning cell from the body remove nucleus and take the rest of the cell take the nucleus (containing DNA) Clone identical to the individual that gave the nucleus Dolly the sheep egg
Molecular cloning: Principles 1) Take DNA out of the nucleus gene 2 gene 1 cell 1 cell 2 2) Make a new piece of DNA gene 1 gene 1 gene 2 gene 2 3) Put new DNA into a test cell and grow copies Daughter cells contain same DNA: Genes 1 and 2 have been cloned gene 2 gene 1 cell divides insert new DNA
Molecular cloning: Applications Loss of function Reporter gene Lineage tracing remove a gene to see if anything works differently add a gene that shows us when another gene is working mark a group of cells to see where their daughter cells end up eye Normal mouse embryo gene A missing gene is involved in giving the eye its colour gene is active in blue areas only gene is passed on to cells all over the body
Tissue stem cell types and hierarchies
Tissue stem cells: Principles of renewing tissues Stem cell • stem cell: • self renew • divide rarely • high potency • rare • committed progenitors: • “transient amplifying cells” • multipotent • divide rapidly • no self-renewal • specialized cells: • work • no division
Tissue stem cells: Haematopoietic stem cells (HSCs) neutrophil NK cell T cell B cell dendritic cell HSC platelets megakaryocyte erythrocytes bone marrow macrophage eosinophil basophil specialized cells committed progenitors
Tissue stem cells: Neural stem cells (NSCs) Neurons Interneurons Oligodendrocytes Type 2 Astrocytes Type 1 Astrocytes NSC brain committed progenitors specialized cells
Tissue stem cells: Gut stem cells (GSCs) Paneth cells Goblet cells GSC Endocrine cells Columnar cells Small intestine committed progenitors specialized cells
Tissue stem cells: Mesenchymal stem cells (MSCs) Bone (osteoblasts) Cartilage (chondrocytes) MSC bone marrow Fat (adipocytes) committed progenitors specialized cells
Stem cells at home: The stem cell niche
Stem cell niches Niche Microenvironment around stem cells that provides support and signals regulating self-renewal and differentiation stem cell niche Intermediate cell Soluble factors Direct contact
Credits Picture credits Many thanks to the following people for permission to reproduce images: Slide 17, iPS cells: Keisuke Kaji, University of Edinburgh, UK Slide 27, blood cell diagrams: Jonas Larsson, Lund Univeristy, Sweden Slide 29, intestinal cell diagrams: Hans Clevers and Nick Barker, Hubrecht Institute, The Netherlands Should you wish to re-use any of the images listed above, please contact the owner. All other images in this presentation can be re-used freely. Acknowledgements Particular thanks to Dr Christele Gonneau for creating these slides and working tirelessly to help ensure the notes are correct. Thanks also to Freddy Radtke of EPFL, Switzerland, whose slide we copied to make slide 27 on tissue stem cells.