HUMAN MESENCHYMAL STEM CELLS AND THEIR, CLINICAL AAPPLICATION

There are two main categories for stem cells according to their origin: Embryonic Stem Cells and Adult Stem Cell. Mesenchymal stem cell, supporting hematopoetic stem cells in bone marrow, can regenerate tissues such as bone, cartilage, muscle, tendon and fatty tissue. Mesenchymal Stem Cells can be obtained easily from bone marrow although they can be isolated from other tissues such as fetal blood, cord blood and amnion fluid and membrane. The frequency of these cells in bone marrow is 0.001- 0.1 % of cell population. Aspiration of bone marrow from iliac crest, femur and tibia contains of mesenchymal stem cells which can be easily expanded In Vitro. These cells isolated from bone marrow according to their ability to adhere culture area and can be expanded according to the standard protocols. There is still no known marker(s) for mesenchymal stem cells; however, recent studies showing some specific marker for these cells. They lack hematopoetic stem cells marker such as CD14, CD45, CD34; endothelial markers such as CD34, CD31 and von-Willberand (VWF) factor. Mesenchymal stem cells express a few of adherent molecules such as CD44, CD29, CD90 and stromal cell markers SH-2, SH-3, SH-4 and also receptors like IL-1 and TNF receptors. These kinds of cells can be transdifferentiated to cells of three lineages such as neuron, hepatocyte and cardiomyocyte like cells. The accessible sources and easily expansion of these cells and also being autologe make them ideal for therapeutic usage, but low frequency of these cells in the bone marrow and need of additional componenet such as serum (especially animal based serum) for good expansion in the culture media is the main problem in this field, however researchers are trying to expand mesenchymsl stem cell in serum free medium. In this article we will first talk about the biology of mesenchymal stem cell, their Immunologic properties, their application in regenerative medicine and clinical application and at the end we will talk about isolation and expansion of these cells in a protocol manner.