Fig. 9.4 Embryonic stem cells

Fig. . Embryonic stem cells In mammals there are two main types of stem cells – Embryonic Stem Cells (ES Cells) and adult stem cells. ES cells are both pluripotent (can produce the three primary germ layers ectoderm, mesoderm and endoderm) and multipotent (can differentiate into a number of types of cells (Fig. . )) . ES Cells are isolated from the epiblast tissue of the inner cell mass of a blastocyst. When stimulated, ES Cells can develop into more than cells types of the adult body. ES Cells are immortal i.e., they can proliferate in a sterile culture medium and maintain their undifferentiated state. Adult stem cells are found in various tissues of children as well as adults. An adult stem cell or somatic stem cell can divide and create another cell similar to it. Most of the adult stem cells are multipotent and can act as a repair system of the body, replenishing Bacterium carrying plasmid with cloned normal human ADA gene Genetically disabled retrovirus T cells with disabled ADA gene isolated from SCID patient Cloned ADA gene is incorporated into virus Genetically altered cells are reimplanted to produce ADA Cells are grown in culture to ensure ADA gene is active Retrovirus infects T cells, transfer ADA gene to cells