FFP1-Cellular Differentiation and Stem Cells1 (2).pptx

Royal College of Surgeons in Ireland – Medical University of Bahrain FFP1-18 Cellular Differentiation & Stem Cells Module :FFP1 Code :FFP1 Class : MedYear1 semester 1 Lecturer : Dr Jeevan Shetty Date : 30th Sep 2023 Pre class • Please watch these short videos • 15-minute film, “A Stem Cell Stor...

Royal College of Surgeons in Ireland – Medical University of Bahrain FFP1-18 Cellular Differentiation & Stem Cells Module :FFP1 Code :FFP1 Class : MedYear1 semester 1 Lecturer : Dr Jeevan Shetty Date : 30th Sep 2023 Pre class • Please watch these short videos • 15-minute film, “A Stem Cell Story” provides an excellent introduction to stem cells. See www.eurostemcell.org/films • Video tutorials: – (Khan Academy): – https://www.youtube.com/watch?v=yCIMk1x0Pk&ab_channel=KhanAcademy https://www.youtube.com/watch? v=uUH5YI5dTOg&ab_channel=khanacademymedicine 2 Learning Objectives 1. Define cellular differentiation. 2. Define the unique properties of stem cells. 3. Describe the different sources of stem cells including embryonic, tissue and induced pluripotent (iPS) stem cells. 4. Compare and contrast the types of stem cells. 5. Describe the potential applications of stem cells. 6. Discuss the ethical issues surrounding stem zygote Human Development… inner cell mass (ICM) morula trophectoderm blastocyst embryo fetus 8th week See also Anatomy lectures 3 Fundamental Aspects of Developmental Biology 1. Cell division • Growth of cell populations, where one cell grows and divides to produce two ‘daughter cells’. 2. Cell differentiation • Process by which a less specialized cell becomes a more specialized cell type. 3. Morphogenesis • Process controls the organized spatial Cellular Differentiation • Complex organism requires many different cell types to form structures and carry out specific functions. zygote • If all the cells arise from a single fertilised egg cell and all contain the same DNA in their nuclei, how do they become different or ‘differentiate’? • This is what we call cellular differentiation. CONTROL OF CELLULAR DIFFERENTIATION • By differential gene expression: cells become different because they express different genes. Same DNA if cells from one individual  express myosin genes X express globin gene  express globin gene X express myosin genes • Different cell types follow different differentiation programmes. • Common process in adults as well: adult stem cells divide and create fully differentiated daughter cells during tissue repair and normal cell turnover. Stem cell biology basics 8 cell are different from other cells of the Stem cell 1. SELF-RENEWAL (copying) Stem cell 2. DIFFERENTIATI ON (specializing) specialized cell Identical stem cells -e.g. muscle cell, nerve cell - cannot divide to make Self renewal Differentiation - replaces dead or dama copies of themselves maintains the stem cells throughout your life Maintain the pool of stem cells STEM CELLS Undifferentiat ed cells that divide and give rise to cells that differentiate into specialized cells Self-renewal Differentiation Replacing damaged cells Developme nt of embryo Stem cell niches Niche Microenvironment around stem cells that provides support and signals regulating self-renewal and differentiation Direct contact Soluble factors stem cell niche Intermediate cell Where are stem cells found? 2. tissue stem cells fetus, baby and throughout lif 1. embryonic stem cells blastocyst - a very early embryo 3. induced pluripotent stem cells haematopoietic (blood) stem cells umbilical cord blood Stem cell Terms Potency: A measure of how many types of specialized cell a stem cell can make Multipotent Can make multiple types of specialized cells, but not all types Tissue stem cells are multipotent Pluripotent Can make all types of specialized cells in the body Lack potential to (extensively) contribute to extraembryonic tissue, such as the placenta Embryonic stem cells from ICM are pluripotent Totipotent Can make all types of cells in the body PLUS cells that are needed during Types of stem cell: 1) Embryonic stem cells Embryonic stem (ES) cells: Where we find them blastocyst cells inside = ‘inner cell mass’ outer layer of cells = ‘trophectoderm’ fluid with nutrients culture in the lab embryonic stem cells taken from to grow more cells the inner cell mass Embryonic stem (ES) cells: What they can do differentiation embryonic stem cells PLURIPOTENT all possible types of specialized cells Embryonic stem (ES) cells: Challenges A s n o i ndit o c der n u grow embryonic stem cells grow under con ditions B grow und er c ond ition gro sC w un de rc on dit ion sD ? Controls not skin neuro ns blood live r Types of stem cell: 2) Tissue stem cells Tissue stem cells: Where we find them surface of the eye skin testicles muscles brain breast intestines (gut) bone marrow Tissue stem cells: What they can do blood stem cell found in bone marrow MULTIPOTENT differentiation only specialized types of blood cell: red blood cells, white blood cells, platelets Tissue stem cells can ONLY make the kinds of cell found in the tissue they belong to. Tissue stem cells: Principles of renewing tissues Stem cell stem cell:  self renew  divide rarely  higher potency  rare committed progenitors:  “transient amplifying cells”  multipotent  divide rapidly  no self-renewal specialized cells:  work  no division Tissue stem cell examples: 1. Haematopoietic stem cells (HSCs) NK cell T cell B cell dendritic cell megakaryocyteplatelet s erythrocytes HSC macrophage neutrophil bone marrow eosinophil basophil committed progenitors specialized cells Tissue stem cell examples: 2. Mesenchymal stem cells (MSCs) Bone (osteoblasts) Cartilage (chondrocytes) MSC bone marrow Fat (adipocytes) committed progenitors specialized cells Types of stem cell: 3)Induced pluripotent (iPS) stem cells Induced pluripotent stem cells (iPS cells) ‘genetic reprogramming’ = add certain genes to the cell adult cell Shinya Yamanaka and John Gurdon- 2012 Nobel induced pluripotent stem (iPS) cell behaves like an embryonic stem cell differentiation culture iPS cells in the lab all possible types of vantage: No need for embryos specialized cells Genetically identical advantages: Large numbers of somatic cells needed Long term studies still required. Induced pluripotent stem cells (iPS cells) genetic reprogramming adult cell (skin) Oct4, Sox2, Klf4 and c-Myc pluripotent stem cell (iPS) differentiation http://www.youtube.com/watch?v=cPvidAvzmx0&feature=player_embedded http://www.youtube.com/watch?v=i-QSurQWZo0&feature=related Cloning Number of different processes used to produce genetically identical copies of a biological entity. 27 Cloning There are three VERY different types of cloning: Reproductive cloning Therapeutic cloning Molecular cloning gene 1 gene 2 Live birth cloning. Use to make two identical Experimental cloning. individuals Use to make patientspecific cell lines Very difficult to do isolated from an embryo (not intended Illegal to do on humansfor transfer in utero) DNA cloning. Use to study what a gene does Routine in the biology lab Reproductive cloning adult cell egg remove nucleus and take the rest of the cell take the cell (containing DNA) Clone identical to the individual that gave the nucleus Dolly the sheep How many attempts? Somatic-Cell Transfer (SCT) • laboratory technique for creating a cloned embryo with a donor nucleus Therapeutic cloning Definition: Transfer of nuclear material from a somatic cell into an enucleated oocyte in the goal of deriving embryonic cell lines with the same genome as the nuclear donor. Little to no risk of rejecting transplanted cells/tissues - immunologically compatible with patient. ? SCT in human cells ? - ethical concerns(egg procurement) & technical challenges Applications of Stem Cells • Regenerative Medicine – Potential to treat diseases by replacing cells which are irreversibly lost, and for which there are currently no therapies, – E.g. Parkinson’s, heart disease, diabetes, spinal cord injury… – Bone marrow transplants and skin grafting are established examples of therapeutic use of stem cells. • Drug testing and screening - stem cells directed to produce a specific cell type in lab, huge amounts of identical cells. • Study disease processes - most cases its extremely difficult to obtain cells damaged due to the disease in order to study them in detail – diseased cells used to model the disease. Stem Cell Success Stories Regulation of stem cell research • • Legislation regarding use of ES cells varies around the globe. Many countries (US, UK, Australia), new cell lines can be created from spare embryos from fertility clinics with consent from donors. Laws prohibit the creation of embryos for research. • Ireland - one of few countries in Europe that has no regulation for stem cell research. • Link to regulations in other European countries: http://www.eurostemcell.org/stem-cell-regulations Stem cell research raises many questions: Does life begin at fertilization, in the womb, or at birth? Since ES cells can grow indefinitely in a dish and can, in theory, still grow into a human being, is the embryo really destroyed? Is a human embryo equivalent to a human child? Might the destruction of a single embryo be justified if it provides a cure for a countless number of patients? Should the laws that govern iPS cells differ from those for hES Since iPS cells are not cells? If so, what exactly the same as hESlegislation is needed? cells, and hES cells still provide important controls, should hES research continue? Does a human embryo have any rights? With iPS cells now available as an alternative to hES cells, is the debate over stem cell research irrelevant? iPS cells have the potential to develop into a human embryo, in effect producing a clone of the donor – is this ethical? Key Points • Cellular differentiation: cells become different (specialized) because they express different genes • Stem cells – 2 properties – Self renewal – Differentiation • Types of stem cells – Embryonic stem cells (pluripotent) – Tissue stem cells (multipotent) – Induced pluripotent stem cells • Somatic-Cell Transfer (SCT) – Reproductive cloning – Therapeutic cloning Further information and resources • 15-minute film, “A Stem Cell Story” provides an excellent introduction to stem cells. See www.eurostemcell.org/films • Video tutorials: – (Khan Academy): – https://www.youtube.com/watch?v=yCIMk1x0Pk&ab_channel=KhanAcademy https://www.youtube.com/watch? v=uUH5YI5dTOg&ab_channel=khanacademymedicine • Acknowledgements EuroStem Cell Slides (selected slides) - Dr Christele Gonneau, Freddy Radtke of EPFL, Switzerland, Keisuke Kaji, University of Edinburgh, UK, Jonas Larsson, Lund University, Sweden, Hans Clevers and Nick Barker, Hubrecht Institute. Post session Knowledge Check (fill the boxes) Name 3 types of stem cells Sources Potency Ethical concerns /limitations 1. 2. 3. Knowledge Check (answers) 3 types of stem cells Embryonic Sources Cells from the inner Fetus, baby, cell mass of a umbilical and blastocyst throughout Genetic reprogramming involving the introduction of 4 transcription factors (Oct4, Sox2, Klf4 and c-Myc) to a somatic cell Potency Pluripotent Multipotent Pluripotent Ethical concerns /limitations Requires destruction of embryo. Difficult to identify, isolate & maintain in lab. Stem cells can be genetically matched to patient. No major ethical concerns. Long term effects unknown. Stem cells could be genetically matched to patient. Donation requires informed consent. Tissue Induced pluripotent