@phdthesis{Heitmann2014,
  author    = {Heitmann, Maximilian},
  title     = {Vergleich der genetischen Eigenschaften von Bone Marrow derived Mesenchymal Stem Cells und Trabecular Bone derived Mesenchymal Stem Cells},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-108612},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {Technische Neuerungen und steigende Anspr{\"u}che an die Gesundheit stellen die moderne Medizin immer wieder vor neue Herausforderungen und f{\"u}hren zur Entwicklung von neuen Therapiekonzepten wie dem Tissue Engineering. Vielfach kommen dabei adulte pluripotente Stammzellen zum Einsatz. Bei der Regeneration mesenchymalen Gewebes wie Knochen, Knorpel und Muskulatur leisten Mesenchymale Stammzellen (MSCs) einen entscheidenden Beitrag. Diese lassen sich aus allen mesenchymalen Geweben des K{\"o}rpers gewinnen und stellen daher zwar keine homogene Zellpopulation dar, doch sie lassen sich aufgrund ph{\"a}notypischer und molekularbiologischer Gemeinsamkeiten charakterisieren. In großer Zahl lassen sich MSCs aus dem Knochenmark gewinnen und werden als stromale MSCs bzw. mhMSCs (marrow-derived human MSCs) bezeichnet. Auf der Suche nach homogenen Subpopulationen von MSCs wurde in dieser Arbeit eine Zellpopulation aus Knochentrabekeln gewonnen, sogenannte bhMSCs (trabecular bone-derived MSCs), und anhand ihrer Genexpression mit mhMSCs verglichen. Daf{\"u}r wurde RNA aus beiden Populationen in einem Microarray mit anschließender SAM (significance analysis of microarrays) analysiert um unterschiedliche Expressionsmuster zwischen mhMSCs und bhMSCs aufzuzeigen. Diese Ergebnisse wurden durch konventionelle Reverse Transkriptase Polymerase Kettenreaktion (RT-PCR) best{\"a}tigt, wobei das Augenmerk vor allem auf solche Gene gerichtet wurde, die differentiell exprimiert waren und zudem als Markergene ein Differenzierungspotential in bestimmte Gewebe wie Muskel und Knochen vorhersagen. Dabei konnte sowohl eine gute {\"U}bereinstimmung zwischen Microarray und RT-PCR demonstriert als auch die Hoffnung auf eine homogene (trabekul{\"a}re) MSC-Population mit anderen Differenzierungseigenschaften geweckt werden. Im Verlauf weitergehender Untersuchungen der SAM fiel eine unerkl{\"a}rlich hohe Expression von Immunglobulinketten in der mhMSC-Kultur (Passage 0) auf, die letztlich auf eine Kontamination der Zellkultur mit Plasmazellen schließen ließ. Da die Ergebnisse des Microarrays (Passage 0 Kultur) somit zu hinterfragen waren, wurde die Kontamination der Plasmazellen durch Passagieren der mhMSC-Zellkultur (Passage 1) beseitigt und erneut ein Microarray mit SAM durchgef{\"u}hrt. Dabei relativierten sich fast alle Expressionsunterschiede, die somit auf die Kontamination der Plasmazellen zur{\"u}ckgef{\"u}hrt werden mussten. Einzig drei Gene (CD24, TRIB2, AHNAK) wurden in diesem zweiten Array differentiell exprimiert, was sich bei CD24 und TRIB2 auch durch RT-PCR untermauern ließ. Es l{\"a}sst sich also schlussfolgern, dass bhMSCs wahrscheinlich in der Zukunft des Tissue Engineering keinen Stellenwert haben werden, zumal ihre Gewinnung im Vergleich zu mhMSC deutlich aufwendiger ist.},
  subject      = {Mesenchymale Stammzelle},
  language  = {de}
}
@phdthesis{Simann2015,
  author    = {Simann, Meike},
  title     = {Aufkl{\"a}rung der Effekte von Fibroblasten-Wachstumsfaktor 1 und 2 auf die Adipogenese und Osteogenese von prim{\"a}ren humanen Knochenmark-Stroma-Zellen},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119322},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {Regulating and reverting the adipo-osteogenic lineage decision of trabecular human bone marrow stromal cells (hBMSCs) represents a promising approach for osteoporosis therapy and prevention. Fibroblast growth factor 1 (FGF1) and its subfamily member FGF2 were scored as lead candidates to exercise control over lineage switching processes (conversion) in favor of osteogenesis previously. However, their impact on differentiation events is controversially discussed in literature. Hence, the present study aimed to investigate the effects of these FGFs on the adipogenic and osteogenic differentiation and conversion of primary hBMSCs. Moreover, involved downstream signaling mechanisms should be elucidated and, finally, the results should be evaluated with regard to the possible therapeutic approach. This study clearly revealed that culture in the presence of FGF1 strongly prevented the adipogenic differentiation of hBMSCs as well as the adipogenic conversion of pre-differentiated osteoblastic cells. Lipid droplet formation was completely inhibited by a concentration of 25 ng/µL. Meanwhile, the expression of genetic markers for adipogenic initiation, peroxisome proliferator-activated receptor gamma 2 (PPARg2) and CCAAT/enhancer binding protein alpha (C/EBPa), as well as subsequent adipocyte maturation, fatty acid binding protein 4 (FABP4) and lipoprotein lipase (LPL), were significantly downregulated. Yet, the genetic markers of osteogenic commitment and differentiation were not upregulated during adipogenic differentiation and conversion under FGF supplementation, not supporting an event of osteogenic lineage switching. Moreover, when examining the effects on the osteogenic differentiation of hBMSCs and the osteogenic conversion of pre-differentiated adipocytic cells, culture in the presence of FGF1 markedly decreased extracellular matrix (ECM) mineralization. Additionally, the gene expression of the osteogenic marker alkaline phosphatase (ALP) was significantly reduced and ALP enzyme activity was decreased. Furthermore, genetic markers of osteogenic commitment, like the master regulator runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein 4 (BMP4), as well as markers of osteogenic differentiation and ECM formation, like collagen 1 A1 (COL1A1) and integrin-binding sialoprotein (IBSP), were downregulated. In contrast, genes known to inhibit ECM mineralization, like ANKH inorganic pyrophosphate transport regulator (ANKH) and osteopontin (OPN), were upregulated. ANKH inhibition revealed that its transcriptional elevation was not crucial for the reduced matrix mineralization, perhaps due to decreased expression of ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) that likely annulled ANKH upregulation. Like FGF1, also the culture in the presence of FGF2 displayed a marked anti-adipogenic and anti-osteogenic effect. The FGF receptor 1 (FGFR1) was found to be crucial for mediating the described FGF effects in adipogenic and osteogenic differentiation and conversion. Yet, adipogenic conversion displayed a lower involvement of the FGFR1. For adipogenic differentiation and osteogenic differentiation/conversion, downstream signal transduction involved the extracellular signal-regulated kinases 1 and 2 (ERK1/2) and the mitogen-activated protein kinase (MAPK)/ERK kinases 1 and 2 (MEK1/2), probably via the phosphorylation of FGFR docking protein FGFR substrate 2a (FRS2a) and its effector Ras/MAPK. The c-Jun N-terminal kinase (JNK), p38-MAPK, and protein kinase C (PKC) were not crucial for the signal transduction, yet were in part responsible for the rate of adipogenic and/or osteogenic differentiation itself, in line with current literature. Taken together, to the best of our knowledge, our study was the first to describe the strong impact of FGF1 and FGF2 on both the adipogenic and osteogenic differentiation and conversion processes of primary hBMSCs in parallel. It clearly revealed that although both FGFs were not able to promote the differentiation and lineage switching towards the osteogenic fate, they strongly prevented adipogenic differentiation and lineage switching, which seem to be elevated during osteoporosis. Our findings indicate that FGF1 and FGF2 entrapped hBMSCs in a pre-committed state. In conclusion, these agents could be applied to potently prevent unwanted adipogenesis in vitro. Moreover, our results might aid in unraveling a pharmacological control point to eliminate the increased adipogenic differentiation and conversion as potential cause of adipose tissue accumulation and decreased osteoblastogenesis in bone marrow during aging and especially in osteoporosis.},
  subject      = {Mesenchymzelle},
  language  = {en}
}