Collagen-based membranous materials of various shapes (gel, film, sponge) are known to be the most promising materials in terms of facilitating the regeneration of dermal defects. In this study, dense and porous collagen membranes were fabricated using air-drying and freeze-drying processes, respectively, and the effect of ultraviolet (UV) radiation on the degree of membrane crosslinking was evaluated by in vitro biodegradation and mechanical testing. A non-irradiated membrane group was used as the negative control and a glutaraldehyde (GA) treated group as the positive control. Scanning electron microscopy showed that, as the freezing temperature decreased to -196 degrees C, the resultant mean pore sizes also decreased; optimal pore size was obtained at a freezing temperature of -70 degrees C. In vitro biodegradation and mechanical testing demonstrated that GA treatment or 4 hours of exposure to UV radiation significantly increased both resistance to collagenase and mechanical strength versus the untreated controls, regardless of the collagen membrane type (dense or porous). Our results suggest that UV treatment is a useful tool for the fabrication of collagen membranes designed to be used as dermal dressings.
Animal ; Cattle ; Collagen/ultrastructure ; Collagen/radiation effects* ; Collagen/metabolism ; Elasticity ; Membranes, Artificial* ; Microscopy, Electron, Scanning ; Porosity ; Tensile Strength ; Ultraviolet Rays*

OBJECTIVETo investigate the effect on intramuscular connective tissue and passive range of joint motion by the stress produced in limb lengthening.

METHODSAn animal model of limb lengthening was established in the tibia of rabbits. Distraction was initiated at a rate of 1 mm/d and 2 mm/d in two steps respectively, and both proceeded until 10% and 20% of the tibia length was achieved. Muscle samples were harvested at the time when distraction ended and at the 4th week of consolidation after the distraction. Scanning electron microscope was applied to observe the morphological changes of the perimysium. The goniometer, which we made for this study, was used to measure the passive range of joint motion.

RESULTSThe collagen fibers were partitioned in bundles, crimped and interconnected closely and orderly. In the regime of 1 mm/d distraction with 10% lengthening, no apparent changes of the collagen fiber and passive range of joint motion was demonstrated. When tibia was increased to 20%, the crimped fibers showed a tendency of being straightened while the passive range of joint motion was reduced. The findings remained the same at the 4th week of consolidation. In the regime of 2 mm/d distraction with 10% lengthening, the crimped structure of the collagen fibers in the perimysium disappeared and the fibers were almost straightened. Additionally, the interconnection of the collagen fibers became loosened and interstice was presented among the fibers. At the 4th week of consolidation, the restoration to the original crimped structure was not completed. When the lengthening ratio was increased to 20%, the collagen fibers were straightened completely. This condition remained unchanged throughout all 4 weeks. The passive range of joint motion was reduced dramatically in the regime of 2 mm/d distraction.

CONCLUSIONThe ultrastructure of perimysium and the passive range of joint motion in the regime of 1mm/d lengthening shows the condition closest to the normal ones. The regime of 2 mm/d lengthening may cause an apparent change in the ultrastructure of perimysium and passive range of joint motion.

Animals ; Bone Lengthening ; Collagen ; ultrastructure ; Connective Tissue ; injuries ; physiology ; ultrastructure ; Male ; Osteogenesis, Distraction ; Rabbits ; Range of Motion, Articular ; physiology ; Regeneration ; physiology

BACKGROUNDThe pathogenesis of hypersplenism and the immune function of the spleen in patients with portal hypertension (PH) remain obscure. This study aimed to evaluate the morphological changes of blood spleen barrier in spleen with hypersplenism due to PH and provide evidence for an in-depth investigation of the immune function of the spleen with hypersplenism and the mechanism of hypersplenism.

METHODSSpleen samples from 12 portal hypertensive patients and 4 patients with traumatic ruptures of spleen were examined. The samples of spleen were made into pathological sections, stained with Masson trichrome stain, Gomori stain, and CD68, CD34 immunohistochemistry, and were examined microscopically for the changes in the distribution of collagen fibers, reticular fibers, macrophages, and vascular endothelial cells. The changes in ultrastructure of macrophages and endothelial cells in marginal zone were also evaluated by transmission electron microscopy.

RESULTSAs compared to the normal spleen, the density of macrophage in the PH spleen was decreased, but the macrophages were mainly located in the marginal zone and distributed around the splenic corpuscle, with many villi and pseudopodium-like protrusion on the cell surface. The accrementition of collagen fibers was obvious around the splenic corpuscle and central artery. The increased reticulate fibers encircled the splenic corpuscle with more connection between the fibers. The vascular endothelial cells were in diffused distribution, without any regionality in PH spleen, but the vessel with enlarged lumina increased in red pulp.

CONCLUSIONSThe morphological changes of the blood spleen barrier can be one of the pathological fundaments for the abnormality of the immune function and the increased destruction of blood cells located in the spleens of patients with PH. However, this still entails clarification.

Adult ; Collagen ; analysis ; Endothelial Cells ; pathology ; ultrastructure ; Female ; Humans ; Hypertension, Portal ; immunology ; pathology ; Macrophages ; pathology ; ultrastructure ; Male ; Microscopy, Electron ; Middle Aged ; Spleen ; blood supply ; immunology ; pathology ; ultrastructure

OBJECTIVETo investigate the structure and degradation property of the polyvinyl alcohol (PVA)-collagen complex drug membrane.

METHODSDrug collagen membrane was complexed with PVA. The physical and chemical properties of the membrane were characterized by transmission electron microscopy, scanning electron microscope, forier transform-infrared spectroscopy and differential scanning calorimetry. Degradation experiment was performed to determine the degradation property of membrane and a degradation curve was therefor drawn.

RESULTSThe thermodynamic stability of collagen membrane was not destroyed by adding PVA. Collagen had good compatibility with PVA. Compared with collagen membrane, collagen-PVA complex membrane had smaller and evener pores. Adding PVA decreased the degradation rate of membrane.

CONCLUSIONSPVA-collagen membrane has better microstructure and antidegradation property than collagen membrane.

Biocompatible Materials ; chemistry ; Collagen ; chemistry ; ultrastructure ; Humans ; Membranes ; Polyvinyl Alcohol ; chemistry ; Spectroscopy, Fourier Transform Infrared

BACKGROUNDIn the process of hepatic fibrosis, the accumulation of collagen fibers is strongly related to the hepatic function. The aim of this study was to investigate the three-dimensional architecture of the collagen network in the liver of rats with hepatic fibrosis.

METHODSHealthy adult male Wistar rats (n = 32) were randomly divided into a control group (n = 16) and a hepatic fibrosis group (n = 16). In the control group, the rats were treated with peanut oil while the rats in hepatic fibrosis group were treated for 10 weeks with 60% CCl(4) diluted in peanut oil. The quantity of collagen fibers was detected by Western blotting; distribution of the collagen was detected by sirius red staining and polarized microscope; the three-dimensional architecture of collagen in the liver was observed under the scanning electron microscope after fixed tissues were treated with cell-maceration using NaOH. Statistical analysis was performed using the u test.

RESULTSThe quantity of collagen fibers increased significantly in the hepatic fibrosis group. With the aggravation of hepatic fibrosis, collagen fibers gradually accumulated. They interlaced the reticulation compartment and formed a round or ellipse liver tissue conglomeration like a grape framework that was disparate and wrapped up the normal liver lobule. The deposition of collagen fibers was obvious in adjacent hepatic parenchyma, especially around the portal tracts.

CONCLUSIONOur experiment showed the collagen proliferation and displays clearly the three-dimensional architecture of collagen fibers in rat liver with hepatic fibrosis by scanning electron microscope. It can provide a morphological foundation for the mechanisms of changed haemodynamics and portal hypertension in hepatic fibrosis.

Animals ; Blotting, Western ; Collagen ; ultrastructure ; Liver Cirrhosis, Experimental ; pathology ; Male ; Microscopy, Electron, Scanning ; Rats ; Rats, Wistar

The preparation of collagen sponges was studied in order to develop tissue engineering scaffolds. Collagen solutions with varying concentrations were obtained by condensing the initial collagen with polyethylene glycol (PEG) at 4 degrees C for different periods of time, and then were freeze-dried to make collagen scaffolds. The porous characteristics of the prepared scaffolds were characterized by use of different methods, including laser scanning confocal microscopy (LSCM), scanning electron microscopy (SEM) and tensile tests. All collagen sponges were shown to have similar interconnected porous structures but were found to have different pore size, porosity, water capacity and the mechanical property, depending on the concentration of collagen solutions. These findings indicate that the way of controlling the concentration of collagen solutions with PEG permits the freeze-drying fabrication of collagen sponges with varying porous features suitable for different tissue engineering purposes.
Collagen ; chemistry ; ultrastructure ; Freeze Drying ; Polyethylene Glycols ; chemistry ; Porosity ; Tissue Engineering ; Tissue Scaffolds

BACKGROUNDOsteosarcoma is characterized by high neovascularization and a high propensity for metastasis through bloodstream. This study was to examine whether there is evidence for vasculogenic mimicry in osteosarcoma and to illustrate mechanism of tumor blood vessels formation in osteosarcoma.

METHODSOsteosarcoma cell lines (U-2OS) were tested for their ability to form tubular networks in three-dimensional culture containing type I collagen. The structures of the tubular networks were observed with phase contrast microscope and transmission electron microscope (TEM). Morphometric studies using hematoxylin and eosin (HE) stain and CD31 immunohistochemical stain to show tumor-lined channels in human osteosarcoma were also performed.

RESULTSObservation with light microscope and TEM showed that highly aggressive osteosarcoma cell lines (U-2OS) formed networks containing channels when grown in three-dimensional culture containing type I collagen, in the absence of endothelial cells or fibroblasts. Morphometric observation using HE stain and CD31 immunohistochemical stain showed that tumor cell-lined channels were also detected in vivo in osteosarcoma; by comparison, all vascular areas in the pedicle of osteochondroma or outside osteochondroma were endothelial-lined.

CONCLUSIONThese observations strongly suggest that aggressive osteosarcoma cells may generate vascular channels that facilitate tumor perfusion independent of tumor angiogenesis and have the ability of vasculogenic mimicry.

Bone Neoplasms ; pathology ; ultrastructure ; Cell Line, Tumor ; Collagen ; biosynthesis ; Humans ; Immunohistochemistry ; Neovascularization, Pathologic ; pathology ; Osteosarcoma ; pathology

OBJECTIVETo investigate the long-term changes of expanded skin after transplantation.

METHODSThe expanded skin in dogs at 0 week, 3 weeks, 6 weeks, 3 months and 6 months after transplantation was observed through areas, histomorphological, electron microscopic, collagen content, biomechanical, and immunohistochemical methods.

RESULTSThe expanded skin was close to the control groups in all observations.

CONCLUSIONThe biological changes after expansion remain in 3 months. The expanded skin will gradually recover to normal in 3-6 months. It is similar to a wound repair process.

Animals ; Collagen ; analysis ; Dogs ; Female ; Male ; Skin ; chemistry ; ultrastructure ; Skin Transplantation ; Tissue Expansion

This study aims at the mechanism of foveola formation in bovine trabecular bone under fatigue process and its relation with biomechanical pathogenesis of senile osteoporosis. The scanning electron microscope equipped with fatigue stage was used to observe fatigue micro injury accumulation of cancellous bone. The massive foveola formation in the laminal bone of vertical trabeculae was found in the tensile fatigue test. There existed the collagen avulsion in the foveola. The massive foveola formation was also observed in the lamina bone of the horizontal trabeculae in the compressive fatigue test. The bone collagen fibers were protracted, debound with hydroxyapatite crystal, and then avulsed under tensile and bending stresses. Finally the retraction of the avulsed collagen fibers brought on the massive formation of foveolae in lamina bone. The mechanical capacity of bone also declined greatly. We infer that the direct mineralization of avulsed collagen and foveola in lamina bone would be one of the main processes of self repair in vivo, which brings on the increase in fragility and stiffness of trabeculae of senile osteoporotic bone along with the agelong accumulation of collagen fatigue injury and foveola formation in the lamina bone.
Animals ; Bone and Bones ; pathology ; ultrastructure ; Cattle ; Collagen ; ultrastructure ; Compressive Strength ; Durapatite ; chemistry ; In Vitro Techniques ; Microscopy, Electron, Scanning ; Models, Biological ; Stress, Mechanical ; Tensile Strength

Dentin matrix metalloproteinases (MMPs) are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. After bonding with resins to dentin there are usually some exposed collagen fibrils at the bottom of the hybrid layer owing to imperfect resin impregnation of the demineralized dentin matrix. Exposed collagen fibrils might be affected by MMPs inducing hydrolytic degradation, which might result in reduced bond strength. Most MMPs are synthesized and released from odontoblasts in the form of proenzymes, requiring activation to degrade extracellular matrix components. Unfortunately, they can be activated by modem self-etch and etch-and-rinse adhesives. The aim of this review is to summarize the current knowledge of the role of dentinal host-derived MMPs in dentin matrix degradation. We also discuss various available MMP inhibitors, especially chlorhexidine, and suggest that they could provide a potential pathway for inhibiting collagen degradation in bonding interfaces thereby increasing dentin bonding durability.
Chlorhexidine ; pharmacology ; Collagen ; metabolism ; ultrastructure ; Dental Bonding ; Dentin ; enzymology ; ultrastructure ; Dentin-Bonding Agents ; chemistry ; Enzyme Inhibitors ; pharmacology ; Humans ; Hydrolysis ; Matrix Metalloproteinase Inhibitors ; Matrix Metalloproteinases ; metabolism ; Resin Cements ; chemistry