151 research outputs found
Bone Healing Gone Wrong : Pathological Fracture Healing and Non-Unions—Overview of Basic and Clinical Aspects and Systematic Review of Risk Factors
Bone healing is a multifarious process involving mesenchymal stem cells, osteoprogenitor
cells, macrophages, osteoblasts and -clasts, and chondrocytes to restore the osseous tissue. Particularly
in long bones including the tibia, clavicle, humerus and femur, this process fails in 2–10% of all
fractures, with devastating effects for the patient and the healthcare system. Underlying reasons for
this failure are manifold, from lack of biomechanical stability to impaired biological host conditions
and wound-immanent intricacies. In this review, we describe the cellular components involved in
impaired bone healing and how they interfere with the delicately orchestrated processes of bone
repair and formation. We subsequently outline and weigh the risk factors for the development of
non-unions that have been established in the literature. Therapeutic prospects are illustrated and put
into clinical perspective, before the applicability of biomarkers is finally discussed
TGF-β1 As Possible Link between Loss of Bone Mineral Density and Chronic Inflammation
and their possible role in bone homeostasis in primary human osteoblasts. application.
Monocytes Do Not Transdifferentiate into Proper Osteoblasts
Recent publications suggested that monocytes might be an attractive cell type to transdifferentiate into various cellular phenotypes. Aim was, therefore, to evaluate the potential of blood monocytes to transdifferentiate into osteoblasts. Monocytes isolated from peripheral blood were subjected to two previously published treatments to obtain unique, multipotent cell fractions, named programmable cells of monocytic origin (PCMOs) and monocyte-derived mesenchymal progenitor cells (MOMPs). Subsequently, MOMPs and PCMOs were treated with osteogenic differentiation medium (including either vitamin D or dexamethasone) for 14 days. Regarding a variety of surface markers, no differences between MOMPs, PCMOs, and primary monocytes could be detected. The treatment with osteogenic medium neither resulted in loss of hematopoietic markers nor in adoption of mesenchymal phenotype in all cell types. No significant effect was observed regarding the expression of osteogenic transcription factors, bone-related genes, or production of mineralized matrix. Osteogenic medium resulted in activation of monocytes and appearance of osteoclasts. In conclusion, none of the investigated monocyte cell types showed any transdifferentiation characteristics under the tested circumstances. Based on our data, we rather see an activation and maturation of monocytes towards macrophages and osteoclasts
EGF and HB-EGF enhance the proliferation of programmable cells of monocytic origin (PCMO) through activation of MEK/ERK signaling and improve differentiation of PCMO-derived hepatocyte-like cells
Cilostazol promotes blood vessel formation and bone regeneration in a murine non-union model
Non-unions represent a major complication in trauma and orthopedic surgery. Many factors contribute to bone
regeneration, out of which an adequate vascularization has been recognized as crucial. The phosphodiesterase-3
(PDE-3) inhibitor cilostazol has been shown to exert pro-angiogenic and pro-osteogenic effects in a variety of
preclinical studies. Hence, we herein investigated the effects of cilostazol on bone regeneration in an atrophic
non-union model in mice. For this purpose, a 1.8 mm femoral segmental defect was stabilized by pin-clip fixation
and the animals were treated daily with 30 mg/kg body weight cilostazol or saline (control) per os. At 2, 5 and 10
weeks after surgery the healing of femora was analyzed by X-ray, biomechanics, photoacoustic imaging, and
micro-computed tomography (µCT). To investigate the cellular composition and the growth factor expression of
the callus tissue additional histological, immunohistochemical and Western blot analyses were performed.
Cilostazol-treated animals showed increased bone formation within the callus, resulting in an enhanced bending
stiffness when compared to controls. This was associated with a more pronounced expression of vascular
endothelial growth factor (VEGF), a higher number of CD31-positive microvessels and an increased oxygen
saturation within the callus tissue. Furthermore, cilostazol induced higher numbers of tartrate-resistant acidic
phosphate (TRAP)-positive osteoclasts and CD68-positive macrophages. Taken together, these findings demonstrate that cilostazol is a promising drug candidate for the adjuvant treatment of atrophic non-unions in clinical
practice
Radiographic, Biomechanical and Histological Characterization of Femoral Fracture Healing in Aged CD-1 Mice
With a gradually increasing elderly population, the treatment of geriatric patients represents
a major challenge for trauma and reconstructive surgery. Although, it is well established that aging
affects bone metabolism, it is still controversial if aging impairs bone healing. Accordingly, we
investigated fracture healing in young adult (3–4 months) and aged (16–18 months) CD-1 mice using
a stable closed femoral fracture model. Bone healing was analyzed by radiographic, biomechanical
and histological analysis at 1, 2, 3, 4 and 5 weeks after fracture. Our results demonstrated an increased
callus diameter to femoral diameter ratio in aged animals at later time points of fracture healing
when compared to young adult mice. Moreover, our biomechanical analysis revealed a significantly
decreased bending stiffness at 3 and 4 weeks after fracture in aged animals. In contrast, at 5 weeks
after fracture, the analysis showed no significant difference in bending stiffness between the two study
groups. Additional histological analysis showed a delayed endochondral ossification in aged animals
as well as a higher amounts of fibrous tissue at early healing time points. These findings indicate a
delayed process of callus remodeling in aged CD-1 mice, resulting in a delayed fracture healing when
compared to young adult animals. However, the overall healing capacity of the fractured femora was
not affected by aging
Induction of active demethylation and 5hmC formation by 5-azacytidine is TET2 dependent and suggests new treatment strategies against hepatocellular carcinoma
Background: Global deregulation of DNA methylation is one of the crucial causes of hepato cellular carcinoma (HCC). It has been reported that the anti-cancer drug 5-azacytidine (5-AZA) mediates the activation of tumor suppressor genes through passive demethylation by inhibiting DNMT1. Recent evidence suggests that active demethylation which is mediated by ten-eleven translocation (TET) proteins may also be an important step to control global methylation. However, there exists a controversial discussion in which TET proteins are involved in the demethylation process in HCC. Therefore, we firstly wanted to identify which of the TETs are involved in demethylation and later to study whether or not 5-AZA could trigger the TET-dependent active demethylation process in HCC. HCC cell lines (Huh-7, HLE, HLF), primary human hepatocytes (hHeps), and tissues from both healthy (55 patients) and HCC patients (55 patients) were included in this study; mRNA levels of isocitrate dehydrogenase (IDH1, 2) and TETs (TET1–3) were studied via qPCR and confirmed by Western blot. The expression of 5hmC/5mC was determined by immunohistochemistry in human HCC tissues and the corresponding adjacent healthy liver. HCC cell lines were stimulated with 5-AZA (0–20 μM) and viability (Resazurin conversion), toxicity (LDH release), proliferation (PCNA), and 5hmC/5mC distribution were assessed. In addition, knockdown experiments on TET proteins in HCC cell lines using short interference RNAs (siRNAs), in the presence and absence of 5-AZA, were performed. Results: Our data applying qPCR, immunofluorescence, and Western blotting clearly show that TET2 and TET3 but not TET1 were significantly decreased in HCC tissue and different HCC cell lines compared to non-tumor liver tissues and hHeps. In addition, we show here for the first time applying knockdown experiments that 5-AZA is able to trigger an active TET2-dependent demethylation process with concomitant significant changes in 5hmC/5mC in HCC cell lines and hHeps. Conclusions: Our data clearly show that the expression and activity of TET2 and TET3 proteins but not TET1 are impaired in hepatocellular carcinoma leading to the reduction of 5hmC in HCCs. Furthermore, this study identified a novel function of 5-azacytidine in promoting a TET-mediated generation of 5hmC suggesting that the availability of 5-AZA in cancer cells will have various effects on different epigenetic targets. These findings may open new therapeutic strategies for epigenetic drugs to treat HCC
Quercetin Protects Primary Human Osteoblasts Exposed to Cigarette Smoke through Activation of the Antioxidative Enzymes HO-1 and SOD-1
Smokers frequently suffer from impaired fracture healing often due to poor bone quality and stability. Cigarette smoking harms bone cells and their homeostasis by increased formation of reactive oxygen species (ROS). The aim of this study was to investigate whether Quercetin, a naturally occurring antioxidant, can protect osteoblasts from the toxic effects of smoking. Human osteoblasts exposed to cigarette smoke medium (CSM) rapidly produced ROS and their viability decreased concentration- and time-dependently. Co-, pre- and postincubation with Quercetin dose-dependently improved their viability. Quercetin increased the expression of the anti-oxidative enzymes heme-oxygenase- (HO-) 1 and superoxide-dismutase- (SOD-) 1. Inhibiting HO-1 activity abolished the protective effect of Quercetin. Our results demonstrate that CSM damages human osteoblasts by accumulation of ROS. Quercetin can diminish this damage by scavenging the radicals and by upregulating the expression of HO-1 and SOD-1. Thus, a dietary supplementation with Quercetin could improve bone matter, stability and even fracture healing in smokers
Разработка автоматизированной системы управления блока подготовки газа факельного сепаратора
Объектом исследования является блок подготовки газа (сепаратор факельной системы) установки комплексной подготовки газа.
Цель работы – разработка автоматизированной системы управления сепаратора факельной системы УКПГ с использованием ПЛК, на основе выбранной SCADA-системы.
В данном проекте была разработана система контроля и управления технологическим процессом на базе промышленных контроллеров Siemens, с применением SCADA-системы CodeSys.The object of the study is the gas treatment unit (the separator of the flare system) of the complex gas treatment unit.
The purpose of the work is to develop an automated control system of the separator of the flare system of the UCP using PLC, based on the selected SCADA – system.
This project was a developed system of control and management of technological process on the basis of industrial controllers of Siemens, with the use of SCADA-system CodeSys
Diclofenac, a NSAID, delays fracture healing in aged mice
Nonsteroidal anti-inflammatory drugs (NSAIDs), such as diclofenac, belong to the most prescribed analgesic
medication after traumatic injuries. However, there is accumulating evidence that NSAIDs impair fracture
healing. Because bone regeneration in aged patients is subject to significant changes in cell differentiation and
proliferation as well as a markedly altered pharmacological action of drugs, we herein analyzed the effects of
diclofenac on bone healing in aged mice using a stable closed femoral facture model. Thirty-three mice (male n
= 14, female n = 19) received a daily intraperitoneal injection of diclofenac (5 mg/kg body weight). Vehicletreated mice (n = 29; male n = 13, female n = 16) served as controls. Fractured mice femora were analyzed
by means of X-ray, biomechanics, micro computed tomography (μCT), histology and Western blotting. Biomechanical analyses revealed a significantly reduced bending stiffness in diclofenac-treated animals at 5 weeks after
fracture when compared to vehicle-treated controls. Moreover, the callus tissue in diclofenac-treated aged animals exhibited a significantly reduced amount of bone tissue and higher amounts of fibrous tissue. Further
histological analyses demonstrated less lamellar bone after diclofenac treatment, indicating a delay in callus
remodeling. This was associated with a decreased number of osteoclasts and an increased expression of osteoprotegerin (OPG) during the early phase of fracture healing. These findings indicate that diclofenac delays
fracture healing in aged mice by affecting osteogenic growth factor expression and bone formation as well as
osteoclast activity and callus remodeling
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