: 1 Concept of Stem Cells: Embryonic and Adult Stem Cells 1. 2. 1) (Totipotent stem cell) 2) (Pluripotent stem cell) 3) (Multipotent stem cell) 3. (Embryonic stem cells) (Adult stem cells) 4. 5. 1. 60 100,., 35,000.,, 210. (stem cell). 1981 (embryonic stem cell). 1988.., : 13
Fig. 1. Development of embryonic stem cells from the differentiated cells of an adult.., (Fig. 1). ( ; totipotent),,... 2., (self-renewal), (Table 1).,, (Fig. 2). 14
Table 1. Capability of stem cell i) Proliferation ii) Self-renewal iii) Production of a large number of differentiated progeny iv) Regeneration and maintainence of tissues Fig. 2. Human stem cells. (totipotent stem cell). (blastocyst)..,. (pluripotent stem cells),, (Table 2). : 15
Table 2. Stem cells and organogenesis during embryonic development Germ layer Endoderm Mesoderm Ectoderm Differentiated organ/tissue Thymus Thyroid, parathyroid glands Epithelial lining of larynx, trachea, lung, respiratory tract Epithelial lining of urinary bladder, vagina, urethra Liver, pancreas, lining of gastrointestinal tract Cardiac, skeletal and smooth muscle Heart and blood vessels Bone marrow (blood) Lymphatic tissue Connective tissues, e.g. bone, cartilage, fibroblast, lipocyte Adrenal cortex Urogenital system Skin Neural tissue Adrenal medulla Pituitary gland Eyes, ears, connective tissue of head/face (hematopoietic stem cells),,, (multipotent stem cells).. 2,000, 100, 4,000. (totipotent stem cells) (pluripotent stem cells), (multipotent stem cells) (Fig. 2). 1) (Tot ipote nt ste m ce ll),. ( ). 16
(Fig. 2). 2. 2 ) (Pluripote nt ste m ce ll) (blastocyst) inner cell mass (ICM). ICM (trophoblast). ICM, ICM (pleuripotency). ICM,., 1998 Thomson.,. 3 ) (Multipote nt ste m cell),.,,. (hematopoietic stem cell),..,. (Table 3). (hematopoietic stem cell), (neural stem cell), (mesenchymal stem : 17
Table 3. Companies for stem cell research and development Company Location Specialization Aastrom Biosciences Geron Corp. Layton BioScience Neural Stem Biopharmaceuticals Neuronyx Inc Nexell Therapeutics Inc. Osiris Therapeutics ReNeuron Stem Cell Sciences 6Stem Cells Inc. Ann Arbor, MI Menlo Park, CA Atherton, CA Bethesda, MD Malvern, PA irvine, CA Baltimore, MD London Melbourne, Australia Sunnyvale, CA Hematopoietic stem cells Embryonic, fetal stem cells Fetal neural stem cells Fetal neural stem cells Neural stem cells Hematopoietic stem cells Mesenchymal stem cells Neural stem cells Embronic stem cells Adult neural stem cells cell).,,.,,.. Table 4. Markers for tissue- specific stem cells Organ Stem cell type Markers Bone marrow Brain Cornea Gut Heart Liver Lung Breast Pancreas Retina Skin Testes HSC MSC NSC/ependymal cells Corneal epithelial stem cells Intestinal stem cells No known stem cell Oval cells Likely to exist Mammary epithelial stem cells Pancreatic stem cells Retinal stem cells Epidermal stem cells Spermatogonial stem cells Mouse: Sca-1, c-kit, CD34: Human: KDR, CD34 Human: SH2 +, SH3 +, CD34 -, CD45 - Nestin, Notch-1 No known specific markers No known specific markers Rat: OV6, OC2, OC3, Thy-1, c-kit, CD34 Unknown Human: CALLA, MUC1 Mouse: Nestin, Neurogenin-3 Mouse and chicken: Nestin, CHX-10 Mouse: 6 bri, CD71 dim 6- and 1-integrin 18
,.,,,,,,.,,,,,. (marker) (Table 4). 3. (embryonic stem cells) (adult stem cells). (embryo) 8 (Fig. 3). 8-12..,,. Fig. 3. Development of embryonic and adult stem cells : 19
Table 5 20
(Fig. 3).,. (Table 5)., (cord boold),. (Table 6). Table 6. Differences between embryonic and adult stem cells Feature Embryonic stem cells Adult stem cells Source Develop in tissue culture (in vitro) from inner cell of early embryo mass Exist in many tissue sin adult human body (in vivo) Abundance in tissues High Very low-difficult to identify, isolate and purify Ability to spontaneously differentiate Yes, in favourable tissue culture conditions Not observed, some circumstantial evidence, e.g. in the olfactory bulb Pluripotency High, i.e. can form all cells of the body Low, e.g. haematopoietic and gut Capacity to specialize into various cell and tissue types High-can develop into specialized cells from all three embryonic layers Limited-increasing evidence, e.g. bone marrow cells developing into liver cells, neurons 4. in vitro model. : 21
,.,,. (Fig. 4).,.,,.., 1..,,.,, Heart disease (e.g. replace muscle and arteries) Spinal cord injuries (e.g. replace nerve cells) Burn injuries (e.g. provide new skin tissue) Stem cells Parkinson's disease (e.g. replace nerve cells) Alzheimer's disease (e.g. replace damaged nerve cells) Type-1 diabetes (e.g. add healthy pancreatic cells) Fig. 4. Therapeutic use of stem cells in human disease 22
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