BENG0011-lecture 4.pdf

Introduction to Pluripotent Stem Cells BENG0011 – Manufacturing Regenerative Medicines: From Lab Bench to Industry Dr Rana Khalife Learning outcomes At the end of this lecture, you should: Identify and describe different types of stem cells Understand how human embryonic stem cel...

Introduction to Pluripotent Stem Cells BENG0011 – Manufacturing Regenerative Medicines: From Lab Bench to Industry Dr Rana Khalife Learning outcomes At the end of this lecture, you should: Identify and describe different types of stem cells Understand how human embryonic stem cells (hESCs) are isolated and characterised Understand how induced pluripotent stem cells (iPSCs) are generated Be able to describe and discuss the differentiation potential of different types of stem cells Why stem cells? Stem cells are a promising source for cell based therapies because: 1. Self-renewal: the ability to replicate or go through numerous cycles of cell division while maintaining the undifferentiated state. 2. Potency: the capacity to differentiate into specialized cell types. Potential of Stem Cells Who has them? Where are they? Why is self-renewal and differentiation important? Sustain the pool of stem cells throughout life Generate the progeny that sustain function of tissues. Essential to the maintenance of tissues such as: Blood Skin Gut Muscle Differentiation The process by which a cell changes from one type to another. Development of cellular specialisation Preceded by commitment to certain fate Multi-stage process proliferation 1) Specification 2) Determination differentiation Terminal differentiation When a cell can no longer change into anything other than the cell type it is. Stem Cell Potency Pros and cons of stem cells Types of Stem Cells (1) Defined by maturity/potency: Pluripotent cells: Embryonic stem cells Multipotent cells: Adult stem cells e.g. Haematopoietic stem cells and Mesenchymal stem cells Other cells (not stem cells) are known as “Somatic Cells” or “Adult Cells”. Once upon a time… At this stage, all the cells are TOTIPOTENT (totally powerful, However, as they divide the cells started and undifferentiated) to differentiate (lose power) and become A sperm met an egg… The zygote divided into 4 more specialised… identical cells… 1-2 hr X 16 cells …and together they … and formed a formed a ZYGOTE. MORULA TISSUE ENGINEERS can The cells of the inner cell When the cells reached the 50-100 cell use these PLURIPOTENT mass become more stage, they became a BLASTOCYST embryonic stem cells in specialised and begin to an attempt to differentiate into all types of Trophoblast replace/repair or cells needed in the body, regenerate tissues. they are now PLURIPOTENT ICM Development timeline Stem Cell Terminology TOTIPOTENT A cell that can divide to produce ALL differentiated (or specialised) cells in an organism, PLUS cells that are needed during early embryo development (amnion, placenta etc.). ZYGOTE Formed when the sperm joins with the egg. MORULA A solid ball of approximately 4 undifferentiated (non specialised) cells. DIFFERENTIATE To change and become more specialised. BLASTOCYST A very early embryo, approximately 50-100 cells. PLURIPOTENT A cell that can divide to produce ALL differentiated (or specialised) cells in an organism (but not cells needed during early embryo development. MULTIPOTENT A cell that can divide into somatic cells of certain lineages, e.g. Mesenchymal stem cells hESC Schematic A more complex look at the germ layers. Decreasing pluripotency Increase in specific phenotype (terminal differentiation) http://www.biotimeinc.com/technologies/purestem-progenitor-cells/#lightbox/0/ Key moments in the history of stem cells Mouse embryonic stem cells were first isolated in July 1981 by Martin Evans and Matthew Kaufman at the university of Cambridge, UK (https://www.ncbi.nlm.nih.gov/pubmed/7242681) Another paper published in December 1981 Gail Martin, University of California coined the term ‘Embryonic stem cell’ (https://www.ncbi.nlm.nih.gov/pubmed/6950406). James Thomson, University of Wisconsin-Madison, 1998, developed a technique to isolate and grow human embryonic cells in culture (https://www.ncbi.nlm.nih.gov/pubmed/9804556). Published contemporaneously with Shinya Yamanaka the derivation of human iPSC in 2007. (http://www.sciencemag.org/content/318/5858/1917.abstract), (https://www.ncbi.nlm.nih.gov/pubmed/18035408) Types of stem cells Embryonic stem cells (Pluripotent stem cells) Destruction of the embryo Ethics / Politics Destruction of the embryo August 2001 – Limit on Federal funding for hESC research Proposition 71 – State of California – Establishment of CIRM Human Embryonic Stem Cells – hESCs (Pluripotent) Jamie Thomson Paper (1998) Characterisation – …………………… – …………………… – …………………… – …………………… – …………………… – …………………… Event timeline for pluripotent stem cells 1950’s Today Induced Pluripotent Stem Cells (iPSCs) Yamanaka and Thomson Paper iPSCs Genetically reprogrammed to an embryonic stem cell–like state…“de-differentiation” Viruses currently used to introduce the reprogramming factors into adult cells Unlikely to result in immune rejection as iPSCs are near identical (if not identical!) match to donor iPSC Transcription Factors Induced Pluripotent Stem Cells