TY - THES A1 - Mickler, Johannes T1 - Veränderungen von mesenchymalen Stammzellen des Fettgewebes auf DNA- und Chromatidebene während ihrer Expansion in vitro T1 - Alterations in adipose-derived stem cells at DNA- and chromosomal level during expansion in vitro N2 - Stammzellbasierte Therapieverfahren versprechen neue Lösungen für bisher nur unzureichend behandelbare Erkrankungen. In der Hals-, Nasen- und Ohrenheilkunde ist die Herstellung von Knorpel im Rahmen des Tissue Engineering von besonderem Interesse. Die mesenchymalen Stammzellen des Fettgewebes (ASC) stellen eine vielversprechende Zellpopulation als Ausgangspunkt für die Erzeugung von Gewebe dar. Auf Grund der hohen Zahl an Zellteilungen, oxidativem und mechanischem Stress sowie enzymatischer Verdauung steigt im Rahmen der in vitro Expansion das Risiko für DNA-Schäden. Diese können wiederum der Ausgangspunkt für die maligne Transformation einer Zelle sein. Ziel unserer Studie war es, zu zeigen, ob die Expansion und mehrfache Passagierung zu einer zunehmenden genetischen Instabilität der ASC führt. Es wurden frische ASC aus Liposuktionsaspirat von 8 verschiedenen Patienten isoliert. Mit ASC der Passagen 1, 2, 3, 5 und 10 wurde zur Detektion von Schäden auf DNA-Ebene jeweils eine alkalische Einzelzellgelelektrophorese(Comet Assay) und ein Mikrokerntest durchgeführt. Zur Erfassung von Schäden auf Chromatidebene erfolgte darüber hinaus mit Zellen der selben Passage ein Chromosomenaberrationstest. Mit dem Comet Assay und dem Mikrokerntest konnte keine signifikante Progression der genetischen Instabilität mit zunehmender Passage nachgewiesen werden. Beim Chromosomenaberrationstest zeigte sich im Friedman-Test eine signifikante Zunahme an strukturellen Chromosomenaberrationen mit steigender Passage. Der Wilcoxon-Test hingegen erbrachte kein signifikantes Ergebnis. Die im Rahmen dieser Arbeit gewonnen Daten zeigen, dass eine zunehmende genetische Instabilität der ASC mit zunehmender Dauer der Expansion und steigender Passage nicht vollständig ausgeschlossen werden kann. Aus diesem Grund sollten vor einer Transplantation regelhaft Untersuchungen wie beispielsweise ein Chromosomenaberrationstest oder ein Screening auf typische malignitätsfördernde Mutationen erfolgen. N2 - Stem-cell based therapies promise new solutions for diseases which are insufficiently treatable up to now. In Otorhinolaryngology, the in vitro production of cartilage for tissue engineering approaches is of particular interest. Mesenchymal adipose-derived stem cells (ASCs) are a promising cell population for the production of tissue. Due to a high number of cell divisions, oxidative and mechanical stress as well as enzymatic digestion there is an increasing risk of DNA-damage during in vitro expansion. This DNA-damage can lead to a malignant transformation of the ASCs. The aim of our study was to show whether prolonged in vitro expansion leads to an increased genetic instability of ASCs. Human ASCs were isolated from subcutaneous adipose tissue of different donors (n = 8) undergoing liposuction surgery for aesthetic reasons. To detect DNA-damage, an alkaline single-cell microgel electrophoresis (comet) assay and a micronucleus assay were performed with cells of passage 1,2,3,5 and 10. Moreover, to assess chromosomal damage, a chromosomal aberration test was carried out with cells of the same passage. With the comet assay and the micronucleus assay, no significant progress of DNA-damage could be demonstrated. However, the chromosomal aberration test showed a significant increase of structural chromosomal damage. The results of our study underline the fact that an increasing genetic instability of ASCs during prolonged in vitro expansion cannot be completely excluded. Consequently, tests monitoring malignant transformations or genetic instability should be implemented before transplantation of ASCs. KW - Stammzelle KW - Fettgewebe KW - Comet Assay KW - Chromosomenaberration KW - Mikrokern KW - Fettgewebsstammzellen KW - ASC KW - Chromosomenaberrationstest KW - Comet Assay KW - Mikrokerntest Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-122291 ER - TY - JOUR A1 - Wohlleben, Gisela A1 - Scherzad, Agmal A1 - Güttler, Antje A1 - Vordermark, Dirk A1 - Kuger, Sebastian A1 - Flentje, Michael A1 - Polat, Buelent T1 - Influence of hypoxia and irradiation on osteopontin expression in head and neck cancer and glioblastoma cell lines JF - Radiation Oncology N2 - Background Tumor hypoxia is a known risk factor for reduced response to radiotherapy. The evaluation of noninvasive methods for the detection of hypoxia is therefore of interest. Osteopontin (OPN) has been discussed as an endogenous hypoxia biomarker. It is overexpressed in many cancers and is involved in tumor progression and metastasis. Methods To examine the influence of hypoxia and irradiation on osteopontin expression we used different cell lines (head and neck cancer (Cal27 and FaDu) and glioblastoma multiforme (U251 and U87)). Cells were treated with hypoxia for 24 h and were then irradiated with doses of 2 and 8 Gy. Osteopontin expression was analyzed on mRNA level by quantitative real-time RT-PCR (qPCR) and on protein level by western blot. Cell culture supernatants were evaluated for secreted OPN by ELISA. Results Hypoxia caused an increase in osteopontin protein expression in all cell lines. In Cal27 a corresponding increase in OPN mRNA expression was observed. In contrast the other cell lines showed a reduced mRNA expression under hypoxic conditions. After irradiation OPN mRNA expression raised slightly in FaDu and U87 cells while it was reduced in U251 and stable in Cal27 cells under normoxia. The combined treatment (hypoxia and irradiation) led to a slight increase of OPN mRNA after 2 Gy in U251 (24 h) and in U87 (24 and 48 h) cell lines falling back to base line after 8 Gy. This effect was not seen in Cal27 or in FaDu cells. Secreted OPN was detected only in the two glioblastoma cell lines with reduced protein levels under hypoxic conditions. Again the combined treatment resulted in a minor increase in OPN secretion 48 hours after irradiation with 8 Gy. Conclusion Osteopontin expression is strongly modulated by hypoxia and only to a minor extent by irradiation. Intracellular OPN homeostasis seems to vary considerably between cell lines. This may explain the partly conflicting results concerning response prediction and prognosis in the clinical setting. KW - glioblastoma multiforme KW - head and neck cancer KW - irridation KW - hypoxia KW - osteopontin Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-125746 VL - 10 IS - 167 ER -