Vergleich der Differenzierungspotentiale humaner mesenchymaler Stammzellen aus dem Knochenmark und aus der Nabelschnur auf kollagenen Matrices
The present dissertation compares the differentiation and migration potential as well as the functional behaviour of human bone marrow- and umbilical cord mesenchymal stem cells on three dimensional collagen scaffolds during osteogenic induction. We could draw conclusions from the in vitro characteristics of the stem cell-biomaterial-hybrids as to the in vivo integration of both stem cell types in human tissue. Both the perinatal and adult bone marrow stem cells exhibited all characteristics of mature osteoblasts, as it could be demonstrated by histology, immunhistochemistry, electron microscopy and molecular biology via RT-PCR. However, the BM-hMSC showed a stronger osteogenic transformation under two-dimensional culture conditions, whereas the UC-hMSC with contact to the collagenous matrix were superior to extracellular mineralisation and synthesis of extracellular matrix. In addition the UC-hMSC just like the BM-hMSC are able to boost fracture healing comparable with in vivo osteoblasts by the MMP-mediated migration and the associated colonization of the collagen scaffolds and by their great contractive potential. Insofar the mesenchymal stem cells from the umbilical cord will play a decisive role in the field of bone reconstruction in future. In order to realize their commitment not only in the field of mesodermal but also ectodermal tissues in long term, we tried to induce a differentiation of the UC-hMSC beyond the blastodermic layer. Therefore we cultivated the mesenchymal stem cells with air contact on dermal equivalents composed of collagen I/III with fibroblasts under epidermal differentiation stimuli. After isolation nearly 10% of the stem cells expressed the epithelial marker pan-cytoceratin, while this proportion increased to more than 30% after 21 days of three-dimensional culture conditions of skin, but after osteogenic stimulation there was no expression detectable. This underlinded the influence of the culture conditions. But except for the concomitant coexpression of the mesenchymal marker vimentin a complete epidermal differentiation of umbilical cord stem cells could also be refuted by the missing epithelial stratification and expression of further markers typical of epithel. The pan-cytokeratin- expression can be attributed to the transformation of the UC-hMSC in myofibroblasts, which could be supported by their alpha-SMA-positivity and typical morphology in electron microscopy, the synthesis of extracellular matrix and their characteristic functional behaviour in terms of a collagen contraction. There were no significant changes concerning differentiation in cells of epidermis respectively myofibroblasts detectable under modification of the culture conditions with 5-azacytidin and all-trans-retinoic acid. Nevertheless mesenchymal stem cells from umbilical cord will play a major role in the near future in the field of wound healing and therapy of hereditary dermatosis because of their differentiation in myofibroblasts and their great capacity of synthesis.
info:eu-repo/classification/ddc/610, Zelldifferenzierung, Adulte Stammzelle, Medizin, Differenzierungspotential, Migrationspotential, Transdifferenzierung, Nabelschnurstammzellen, Knochenmarkstammzellen, stem cells, differentiation potential, transdifferentiation
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