Değişik Kaynaklı MKH’lerin Detaylı Karakterizasyonu, Lenfohematopoezi Destekleyici Özellikleri ve İzolasyonunda CD271 Antijeninin Önemi

Abstract

Mesenchymal Stem Cells (MSCs) are multipotent cells with self-renewal ability and form the basis for regenerative treatments. CD271 antigen is an effective marker for isolation of pure populations of MSCs from bone marrow (BM). Within this thesis, the efficacy of CD271 in the isolation of MSCs from BM was assessed, cells were characterized with respect to their colony forming capacity, immunophenotype, proliferative and differentiation capacities and compared to plastic adherent BM-MSCs. In addition, the use of CD271 for isolation of MSCs from fetal tissues was assessed. Functional and lymphohematopoietic support of BM-derived MSCs and CD271 + stem cells and expression of NOTCH receptors and ligands was examined to understand their role in in vitro lymphohematopoietic differentiation. Although the CD271 was expressed at very low levels, CD271 + stem cells contained all colony forming capacity of the BM. These cells showed similar immunophenotypes and differentiation profiles, cytokine release, NOTCH receptor and ligand expression, as well as support of ex vivo hematopoietic cell expansion in comparison to BM-MSCs. However, the CD271 antigen could not be used for isolation of pure MSC populations from fetal tissues. Therefore; different isolation and/or culture conditions must be optimized for the purification of MSCs from placenta chorion (PC), placental amnion (PA) and umbilical cord (UC). CD271 + stem cells and BM-MSCs showed similar cytokine secretion and NOTCH receptor and ligand expression. However, while the profile of MSCs isolated from fetal tissues displayed high similarities, they were clearly distinct from BM-MSCs and BM-CD271+ stem cells. The importance and implications of these differences, which may have great importance for their clinical use, as well as effects on the ex vivo expansion of hematopoietic stem cells (HSCs) and lymphohematopoietic differentiation are discussed in this thesis.