Fig 4.
Development stage, cell type and source of cells currently used in cellular therapy. Cellular source can come from human and animals at different stages of development including embryonic, embryonic-foetal, foetal and adult involving different beginning tissue sources ranging from zygotes to specific tissues (bone marrow, adipose, amniotic fluid, skin, liver, bone, cartilage etc.). Embryonic stem cells are derived from embryos at early stage where less than 100 cells are present, followed by foetal stem cells that are taken from the genital ridge section from 5 to 8 weeks of gestation (drawing modified from http://commons.wikimedia.org/wiki/Image:10_weeks_pregnant.jpg donated by wouter.vengeer@tribal.nl with a free license). Tissue-specific foetal cells are taken following 9 weeks of gestation usually up to 14–16 weeks from normal tissue. Adult stem cells can be isolated from most tissue sources but are rare with only 1 in every 104 to 105 of total cell volume.