14 research outputs found
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
Pantoprazole impairs fracture healing in aged mice
Proton pump inhibitors (PPIs) belong to the most common medication in geriatric medicine. They are known to reduce osteoclast activity and to delay fracture healing in young adult mice. Because differentiation and proliferation in fracture healing as well as pharmacologic actions of drugs markedly differ in the elderly compared to the young, we herein studied the effect of the PPI pantoprazole on bone healing in aged mice using a murine fracture model. Bone healing was analyzed by biomechanical, histomorphometric, radiological and protein biochemical analyses. The biomechanical analysis revealed a significantly reduced bending stiffness in pantoprazole-treated animals when compared to controls. This was associated with a decreased amount of bone tissue within the callus, a reduced trabecular thickness and a higher amount of fibrous tissue. Furthermore, the number of osteoclasts in pantoprazole-treated animals was significantly increased at 2Â weeks and decreased at 5Â weeks after fracture, indicating an acceleration of bone turnover. Western blot analysis showed a lower expression of the bone morphogenetic protein-4 (BMP-4), whereas the expression of the pro-angiogenic parameters was higher when compared to controls. Thus, pantoprazole impairs fracture healing in aged mice by affecting angiogenic and osteogenic growth factor expression, osteoclast activity and bone formation
Profiling microRNA expression in murine bone healing and non-union formation: Role of miR-140 during the early stage of bone healing
Although cellular and molecular mechanisms during the course of bone healing have been
thoroughly investigated, the regulation of gene expression by microRNA during bone regen eration is still poorly understood. We hypothesized that nonunion formation is associated
with different microRNA expression patterns and that target proteins of these microRNAs
are differently expressed in callus tissue of nonunions compared to physiologically healing
bones. In a well-established femoral osteotomy model in CD-1 mice osteotomies were
induced which result either in healing or in nonunion formation. MicroRNA and target protein
expression was evaluated by microarray, quantitative real-time polymerase chain reaction
(qrt-PCR) and Western blot. Microarray analyses demonstrated 44 microRNAs to be rele vant for nonunion formation compared to physiological bone healing. In nonunions qrt-PCR
could validate a higher expression of microRNA-140-3p and microRNA-140-5p. This was
associated with a reduced expression of Dnpep and stromal cell-derived factor (SDF)-1α,
which are both known to be target proteins of microRNA-140 and also to be involved in the
process of bone healing. These data suggest that an increased expression of microRNA 140-3p and microRNA-140-5p markedly contributes to the development of nonunions, most
probably by affecting bone morphogenetic protein (BMP)-2 function during the early stage
of healing due to a reduced SDF-1α expression
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 (ÎĽCT), 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
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
Sildenafil, a phosphodiesterase-5 inhibitor, stimulates angiogenesis and bone regeneration in an atrophic non-union model in mice
Abstract Non-union formation represents a major complication in trauma and orthopedic surgery. The phosphodiesterase-5 (PDE-5) inhibitor sildenafil has been shown to exert pro-angiogenic and pro-osteogenic effects in vitro and in vivo. Therefore, the aim of the present study was to analyze the impact of sildenafil in an atrophic non-union model in mice. After creation of a 1.8 mm segmental defect, mice femora were stabilized by pin-clip fixation. Bone regeneration was analyzed by means of X-ray, biomechanics, photoacoustic and micro-computed tomography (µCT) imaging as well as histological, immunohistochemical and Western blot analyses at 2, 5 and 10 weeks after surgery. The animals were treated daily with either 5 mg/kg body weight sildenafil (n = 35) or saline (control; n = 35) per os. Bone formation was markedly improved in defects of sildenafil-treated mice when compared to controls. This was associated with a higher bending stiffness as well as an increased number of CD31-positive microvessels and a higher oxygen saturation within the callus tissue. Moreover, the bone defects of sildenafil-treated animals contained more tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts and CD68-positive macrophages and exhibited a higher expression of the pro-angiogenic and pro-osteogenic markers cysteine rich protein (CYR)61 and vascular endothelial growth factor (VEGF) when compared to controls. These findings demonstrate that sildenafil acts as a potent stimulator of angiogenesis and bone regeneration in atrophic non-unions
Increased Levels of BAMBI Inhibit Canonical TGF-β Signaling in Chronic Wound Tissues
Chronic wounds affect more than 2% of the population worldwide, with a significant burden on affected individuals, healthcare systems, and societies. A key regulator of the entire wound healing cascade is transforming growth factor beta (TGF-β), which regulates not only inflammation and extracellular matrix formation but also revascularization. This present work aimed at characterizing wound tissues obtained from acute and chronic wounds regarding angiogenesis, inflammation, as well as ECM formation and degradation, to identify common disturbances in the healing process. Serum and wound tissues from 38 patients (N = 20 acute and N = 18 chronic wounds) were analyzed. The patients’ sera suggested a shift from VEGF/VEGFR to ANGPT/TIE2 signaling in the chronic wounds. However, this shift was not confirmed in the wound tissues. Instead, the chronic wound tissues showed increased levels of MMP9, a known activator of TGF-β. However, regulation of TGF-β target genes, such as CTGF, COL1A1, or IL-6, was absent in the chronic wounds. In wound tissues, all three TGF-β isoforms were expressed with increased levels of TGF-β1 and TGF-β3 and a reporter assay confirmed that the expressed TGF-β was activated. However, Western blots and immunostaining showed decreased canonical TGF-β signaling in the respective chronic wound tissues, suggesting the presence of a TGF-β inhibitor. As a potential regulatory mechanism, the TGF-β proteome profiler array suggested elevated levels of the TGF-β pseudo-receptor BAMBI. Also, tissue expression of BAMBI was significantly increased not only in chronic wounds (10.6-fold) but also in acute wounds that had become chronic (9.5-fold). In summary, our data indicate a possible regulatory role of BAMBI in the development of chronic wounds. The available few in vivo studies support our findings by postulating a therapeutic potential of BAMBI for controlling scar formation