Papers by Michael Woeltje
In vivo (Athens, Greece)
The purpose of the present study was to find inexpensive and non-toxic additives enhancing and ac... more The purpose of the present study was to find inexpensive and non-toxic additives enhancing and accelerating the osteogenesis of mesenchymal stem cells in vitro, which can be used for tissue engineering of bone material. Osteogenic differentiation of rat mesenchymal stem cells was carried-out using classic differentiation medium containing or lacking purmorphamine, statins or oxysterols, respectively. Cell proliferation, alkaline phosphatase activity, calcium sedimentation and expression of bone matrix protein genes were measured to monitor differentiation. Purmorphamine substantially suppressed proliferation, enhanced and accelerated alkaline phosphatase activity and calcium sedimentation and increased the expression of osteopontin and osteocalcin in rat mesenchymal stem cells in vitro. A similar osteogenesis-promoting effect was observed for oxysterols but not for the two statins. Purmorphamine and oxysterols promote and accelerate osteogenesis of mesenchymal stem cells in vitro su...
In vivo (Athens, Greece)
The present study aimed to find bone substitutes to enhance osteogenic differentiation of mesench... more The present study aimed to find bone substitutes to enhance osteogenic differentiation of mesenchymal stem cells in three-dimensional scaffolds in the absence of dexamethasone. Seven commercial bone substitutes were added to a three-dimensional fibrin-matrix containing rat mesenchymal stem cells in a biocompatible poly-L-lactic-acid mesh. Cell viability, cytotoxicity and alkaline phosphatase activity were followed for three weeks. Expression of bone markers was examined by qualitative evaluation of corresponding transcripts. Six out of the seven bone derivatives exhibited an osteogenic-enhancing effect. The osteogenic-enhancing effect of the evaluated bone substitutes suggests their potential clinical application for preparation of autologous bone replacement material in three-dimensional carriers.
Bioengineering in Cell and Tissue Research
Zentralblatt für Chirurgie, 2009
PLoS ONE, 2011
Background: Mesenchymal stem cells (MSC) represent a particularly attractive cell type for bone t... more Background: Mesenchymal stem cells (MSC) represent a particularly attractive cell type for bone tissue engineering because of their ex vivo expansion potential and multipotent differentiation capacity. MSC are readily differentiated towards mature osteoblasts with well-established protocols. However, tissue engineering frequently involves three-dimensional scaffolds which (i) allow for cell adhesion in a spatial environment and (ii) meet application-specific criteria, such as stiffness, degradability and biocompatibility. Methodology/Principal Findings: In the present study, we analysed two synthetic, long-term degradable polymers for their impact on MSC-based bone tissue engineering: PLLA-co-TMC (ResomerH LT706) and poly(e-caprolactone) (PCL). Both polymers enhance the osteogenic differentiation compared to tissue culture polystyrene (TCPS) as determined by Alizarin red stainings, scanning electron microscopy, PCR and whole genome expression analysis. ResomerH LT706 and PCL differ in their influence on gene expression, with ResomerH LT706 being more potent in supporting osteogenic differentiation of MSC. The major trigger on the osteogenic fate, however, is from osteogenic induction medium. Conclusion: This study demonstrates an enhanced osteogenic differentiation of MSC on ResomerH LT706 and PCL compared to TCPS. MSC cultured on ResomerH LT706 showed higher numbers of genes involved in skeletal development and bone formation. This identifies ResomerH LT706 as particularly attractive scaffold material for bone tissue engineering.
Neuroscience Letters, 2010
Mesenchymal stromal cells are promising candidate donor cells for promoting functional tissue rep... more Mesenchymal stromal cells are promising candidate donor cells for promoting functional tissue repair following traumatic spinal cord injury (SCI), however, the mechanism(s) of action remain poorly defined. Here, we describe an in vitro study of the axon growth-promoting properties of highly enriched populations of adult human mesenchymal stromal cells (hMSC). A random, non-oriented pattern of neuritic outgrowth was observed from dissociated adult rat DRG neurons seeded onto confluent A431 cells and PLL/laminin positive control substrata. Confluent hMSC formed arrays of similarly orientated cell bodies and processes which supported the regeneration of significantly more primary neurites but a slightly lower overall neuritic length than was observed over the PLL/laminin control substrate. The hMSC exerted a strong influence on the direction of neuritic outgrowth, with many regenerating processes following the orientation of underlying hMSC. The production of extracellular matrix appeared to be responsible for neuritic directionality, but the release of growth factors was a significant promoter for DRG neuritic outgrowth. This suggests that further investigations into the properties of hMSC may be of particular interest in the development of transplant-mediated strategies intending to promote functional axonal regeneration after SCI.
Nephrology Dialysis Transplantation, 2011
Background. Post-transplantation bone disease is associated with a high degree of morbidity inclu... more Background. Post-transplantation bone disease is associated with a high degree of morbidity including pain and fractures. Glucocorticoid-induced osteoporosis on top of pre-existing renal osteodystrophy is considered the major pathogenic factor, while the role of non-glucocorticoid immunosuppressants is less well defined. Methods. In this study, we investigated the influence of sirolimus (SRL) versus calcineurin inhibitor (CI)-based immunosuppressive regimens on biomarkers of bone resorption in renal transplant patients. In addition, the impact of SRL, tacrolimus and mycophenolate mofetil (MMF) on osteoclast activation and function was assessed in cell culture systems. Results. Using this approach, we demonstrated reduced serum levels of bone resorption markers in patients treated with SRL after kidney transplantation compared to a CIbased regimen. In line with this observation, we detected profoundly reduced osteoclast differentiation and subsequently diminished hydroxyapatite resorption in the presence of SRL compared to MMF and tacrolimus in vitro. Moreover, SRL significantly reduced osteoclast precursor proliferation in vitro compared to tacrolimus and led to augmented apoptosis in osteoclast precursors. Conclusions. Taken together, SRL was shown to inhibit osteoclast formation in vivo and in vitro. SRL thus may have the potential to balance osteoclast promoting effects of glucocorticoids and CI, thereby counteracting the development of accelerated osteoporosis in renal transplant recipients.
Journal of Wound, Ostomy & Continence Nursing, 2011
The aim of this study was to investigate the influence of oxidized regenerated cellulose/collagen... more The aim of this study was to investigate the influence of oxidized regenerated cellulose/collagen matrix on the concentration and activity of gelatinases, elastase, and plasmin in wound exudate. SUBJECTS AND SETTING: The study included 32 patients with diabetic foot ulcers. Ten patients with a mean age of 66 Ϯ 9 years (mean Ϯ SD) were treated with hydrocolloid dressings; 22 patients with a mean age of 57 Ϯ 12 years were treated with oxidized regenerated/collagen matrix and hydrocolloid dressings. METHODS: Wound exudate was collected on days 0, 5, 14, and every 14 days thereafter for 12 weeks. Total protein was determined according to Bradford's technique. The levels of elastase and plasmin were measured spectrofluorometrically. Besides, gelatinase activity and matrix metalloproteinase-2 concentration were analyzed. The surface area of all ulcers was measured by planimetry. RESULTS: Patients treated with oxidized regenerated cellulose/ collagen matrix showed a significant decrease in elastase, plasmin, and gelatinase activities in wound exudates. The matrix metalloproteinase-2 concentration was significantly reduced on days 14, 28, 42, and 56 in comparison to day 0. Furthermore, wound size was significantly reduced at days 14 and 28 in oxidized regenerated cellulose/collagen matrix-treated patients (P Ͻ .05). CONCLUSION: Our results showed a significant and immediate reduction in the levels of all tested proteases in the wound exudate of diabetic foot ulcer patients treated with oxidized regenerated cellulose/collagen matrix. These patients also experienced a significantly greater reduction in wound size.
Journal of the American College of Cardiology, 2003
We sought to test the hypothesis that cytokines would be expressed in the myocardium of infants w... more We sought to test the hypothesis that cytokines would be expressed in the myocardium of infants with congenital cardiac defects and to identify the signaling pathways involved. BACKGROUND Mechanical stress upregulates pro-inflammatory cytokines in the myocardium. METHODS Fifteen infants with tetralogy of Fallot (TOF) (n ϭ 7) or with ventricular septal defects (VSDs) (n ϭ 8) were investigated. Concentrations of pro-and anti-inflammatory cytokines and of the inducible nitric oxide synthase (iNOS) were measured by enzyme-linked immunosorbent assay and/or Western blotting in the right ventricular myocardium taken during cardiac surgery. Activation of the nuclear factor-kappa-B (NF-kappa-B) and p38 mitogen-activated protein kinase (MAPK) pathways was assessed by electrophoretic mobility shift assay with supershift and/or Western blotting, respectively. RESULTS The pro-inflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-1-beta, and IL-6 and the anti-inflammatory cytokine IL-10 were detected in the myocardium of all patients. Concentrations of the pro-inflammatory cytokines and also of phosphorylated p38 MAPK were higher in patients with TOF than in those with VSD and correlated with the degree of pressure overload of the right ventricle. Levels of phosphorylated I-kappa-B-alpha, iNOS, and IL-10 were similar in patients with TOF and in those with VSD. CONCLUSIONS Our results show intramyocardial synthesis of pro-inflammatory cytokines in infants with congenital cardiac defects. This is associated with activation of both the NF-kappa-B and p38 MAPK pathways. The latter could be particularly important for the transduction of mechanical signals in the infant's myocardium. Synthesis of IL-10 indicates an intramyocardial anti-inflammatory potential in this age group.
Journal of Plastic, Reconstructive & Aesthetic Surgery, 2007
Journal of Neurochemistry, 2000
Prodynorphin, the precursor of the dynorphin opioid peptides, has been shown to play an important... more Prodynorphin, the precursor of the dynorphin opioid peptides, has been shown to play an important role in several aspects of human diseases and complex traits, e.g., drug abuse, epilepsy, and mood disorders. The objective of this study was to identify polymorphisms in the 5' control region of the human prodynorphin gene and to relate these polymorphisms to prodynorphin gene expression. Within the core promoter region, a 68-bp sequence was found to occur as a polymorphic element, either singular or as tandemly repeated element two, three, or four times. This 68-bp repeat element contains an AP-1 transcription factor binding site as demonstrated by electrophoretic mobility shift assay. Reporter gene assays were performed and provided evidence for allele dependent different promoter activity. Dynorphin was found to be involved in many pathophysiological processes so that the described prodynorphin alleles may correlate with the occurrence of several diseases, for example, drug addiction. However, prodynorphin allelic distributions were not significantly different in heroin addicts and control subjects.
Journal of Neurochemistry, 2002
ABSTRACT The aim of this study was to examine the effects of the phorbol ester O-tetradecanoylpho... more ABSTRACT The aim of this study was to examine the effects of the phorbol ester O-tetradecanoylphorbol 13-acetate (TPA) and forskolin on δ-opioid receptor gene transcription. Treatment of NG 108-15 cells with TPA (100 nM) for 48 h increased δ-opioid receptor mRNA levels, whereas different concentrations of forskolin induced a transient down-regulation of mRNA 5 h after treatment, followed by increased mRNA levels after 48 h. Reporter gene assays in transiently transfected NG 108-15 cells in combination with electrophoretic mobility shift assays indicate that the increase of δ-opioid receptor mRNA after stimulation with TPA is mediated by transcription factor AP-1, which binds 355 bp upstream of the start codon within the gene promoter. The forskolin-induced mRNA increase is mediated neither by a cyclic AMP-response element nor indirectly by AP-1 up-regulation. Reporter gene assays, mutational analysis, and electrophoretic mobility shift assays revealed that δ-opioid receptor gene regulation by forskolin is mediated by transcription factor AP-2, which binds to an element 157 bp upstream of the start codon.
Journal of Molecular Endocrinology, 2006
Alpha2HS-glycoprotein/fetuin-A (Ahsg) is a serum protein preventing soft tissue calcification. In... more Alpha2HS-glycoprotein/fetuin-A (Ahsg) is a serum protein preventing soft tissue calcification. In trauma and inflammation, Ahsg is down-regulated and therefore considered a negative acute phase protein. Enhancement of Ahsg expression as a protective serum protein is desirable in several diseases including tissue remodelling after trauma and infection, kidney and heart failure, and cancer. Using reporter gene assays in hepatoma cells combined with electrophoretic mobility shift assays we determined that dexamethasone up-regulates hepatic Ahsg. A steroid response unit at position −146/−119 within the mouse Ahsg promoter mediates the glucocorticoid-induced increase of Ahsg mRNA. It binds the hepatocyte nuclear factor 3β and CCAAT enhancer binding protein β (C/EBP-β). The up-regulation is mediated indirectly via glucocorticoid hormone-induced transcriptional up-regulation in C/EBP-β protein. A high degree of sequence identity in mouse, rat and human Ahsg promoters suggests that the prom...
Journal of Cranio-Maxillofacial Surgery, 2008
International Wound Journal, 2008
Oxidised regenerated cellulose/collagen matrix (ORC/collagen matrix) modifies wound microenvironm... more Oxidised regenerated cellulose/collagen matrix (ORC/collagen matrix) modifies wound microenvironments by binding and inactivating excess levels of proteases such as elastase, plasmin and gelatinases in wound exudates. To compare levels of the gelatinases matrix metalloproteinase 2 (MMP-2), elastase and plasmin in wound exudates collected from chronic venous insufficiency patients with venous leg ulcers treated with either an ORC/collagen matrix or a standard control therapy. During a 12-week treatment period, wound exudate samples were obtained from a control group of 10 patients treated with a hydrocolloid dressing and a treatment group of 17 patients treated with a combination of ORC/collagen matrix and hydrocolloid dressing. On admission and days 5, 14 and every subsequent 14th day, ulcers were photographed to determine healing rate and changes in ulcer appearance, and MMP-2 concentration and the gelatinase, elastase and plasmin activities were analysed from wound exudates. The patients treated with ORC/collagen matrix showed a significant decrease in elastase, plasmin and gelastinase activity as compared with the control group, with no significant difference in the MMP-2 concentrations between the two groups. The results show a significant and immediate reduction in protease activity in wound exudates from venous leg ulcers treated with ORC/collagen.
FEBS Letters, 1998
We have cloned the 5P upstream regulatory region of the mouse somatostatin receptor 2 gene. Its g... more We have cloned the 5P upstream regulatory region of the mouse somatostatin receptor 2 gene. Its genomic organization is novel among all somatostatin receptor genes. It contains two previously unrecognized exons, separated by introns larger than 25 kb, and three tissue and cell specific alternative promoters. The first promoter in front of exon 1 is active only in AtT-20 tumor cells. The second promoter, located 5P to exon 2, is used in brain, pituitary, adrenals, pancreas, NG 108-15 and AtT-20 cells. Furthermore, it contains putative DNA elements for regulation by glucocorticoids, estradiol and cAMP. A third promoter, located in exon 3, is additionally used in lung, kidney and spleen.
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Papers by Michael Woeltje