Anatomical meniscus construct with zone specific biochemical composition and structural organization.

A PCL/hydrogel construct that would mimic the structural organization, biochemistry and anatomy of meniscus was engineered. The compressive (380 ±â€¯40 kPa) and tensile modulus (18.2 ±â€¯0.9 MPa) of the PCL scaffolds were increased significantly when constructs were printed with a shifted design and circumferential strands mimicking the collagen organization in native tissue (p < 0.05). Presence of circumferentially aligned PCL strands also led to elongation and alignment of the human fibrochondrocytes. Gene expression of the cells in agarose (Ag), gelatin methacrylate (GelMA), and GelMA-Ag hydrogels was significantly higher than that of cells on the PCL scaffolds after a 21-day culture. GelMA exhibited the highest level of collagen type I (COL1A2) mRNA expression, while GelMA-Ag exhibited the highest level of aggrecan (AGG) expression (p < 0.001, compared to PCL). GelMA and GelMA-Ag exhibited a high level of collagen type II (COL2A1) expression (p < 0.05, compared to PCL). Anatomical scaffolds with circumferential PCL strands were impregnated with cell-loaded GelMA in the periphery and GelMA-Ag in the inner region. GelMA and GelMA-Ag hydrogels enhanced the production of COL 1 and COL 2 proteins after a 6-week culture (p < 0.05). COL 1 expression increased gradually towards the outer periphery, while COL 2 expression decreased. We were thus able to engineer an anatomical meniscus with a cartilage-like inner region and fibrocartilage-like outer region.

Square prism micropillars improve osteogenicity of poly(methyl methacrylate) surfaces.

Osteogenicity and osteointegration of materials is one of the key elements of the success of bone implants. Poly(methyl methacrylate) (PMMA) is the basic compound of bone cement and has been widely investigated for other orthopedic applications, but its poor osteointegration and the subsequent loosening of implant material limits its widespread use as bone implants. Micropillar features on substrate surfaces were recently reported to modulate cell behavior through alteration of cell morphology and promotion of osteogenesis. Utilization of this pillar-decorated topography may be an effective approach to enhance osteogenicity of polymeric surfaces. The aim of this study was to investigate the effect of cell morphology on the micropillar features on attachment, proliferation, and osteogenic activity of human osteoblast-like cells. A series of solvent cast PMMA films decorated with 8 µm high square prism micropillars with pillar width and interpillar distances of 4, 8 and 16 µm were prepared from photolithographic templates, and primary human osteoblast-like cells (hOB) isolated from bone fragments were cultured on them. Micropillars increased cell attachment and early proliferation rate compared to unpatterned surfaces, and triggered distinct morphological changes in cell body and nucleus. Surfaces with pillar dimensions and gap width of 4 µm presented the best osteogenic activity. Expression of osteogenic marker genes was upregulated by micropillars, and cells formed bone nodule-like aggregates rich in bone matrix proteins and calcium phosphate. These results indicated that micropillar features enhance osteogenic activity on PMMA films, possibly by triggering morphological changes that promote the osteogenic phenotype of the cells.

Effects of microarchitecture and mechanical properties of 3D microporous PLLA-PLGA scaffolds on fibrochondrocyte and L929 fibroblast behavior.

There are several reports studying cell behavior on surfaces in 2D or in hydrogels in 3D. However, cell behavior in 3D microporous scaffolds has not been investigated extensively. In this study, poly(L-lactic acid)/poly(lactic acid-co-glycolic acid) (PLLA/PLGA)-based microporous scaffolds were used to study the effects of scaffold microarchitecture and mechanical properties on the behavior of two different cell types, human meniscal fibrochondrocytes and L929 mouse fibroblasts. In general, cell attachment, spreading and proliferation rate were mainly regulated by the strut (pore wall) stiffness. Increasing strut stiffness resulted in an increase in L929 fibroblast attachment and a decrease in fibrochondrocyte attachment. L929 fibroblasts tended to get more round as the strut stiffness increased, while fibrochondrocytes tended to get more elongated. Cell migration increased for both cell types with the increasing pore size. Migrating L929 fibroblasts tended to get more round on the stiff scaffolds, while fibrochondrocytes tended to get more round on the soft scaffolds. This study shows that the behavior of cells on 3D microporous scaffolds is mainly regulated by pore size and strut stiffness, and the response of a cell depends on the stiffness of both cells and materials. This study could be useful in designing better scaffolds for tissue engineering applications.

Peripheral nerve conduits: technology update.

Peripheral nerve injury is a worldwide clinical problem which could lead to loss of neuronal communication along sensory and motor nerves between the central nervous system (CNS) and the peripheral organs and impairs the quality of life of a patient. The primary requirement for the treatment of complete lesions is a tension-free, end-to-end repair. When end-to-end repair is not possible, peripheral nerve grafts or nerve conduits are used. The limited availability of autografts, and drawbacks of the allografts and xenografts like immunological reactions, forced the researchers to investigate and develop alternative approaches, mainly nerve conduits. In this review, recent information on the various types of conduit materials (made of biological and synthetic polymers) and designs (tubular, fibrous, and matrix type) are being presented.

In vitro and transdermal penetration of PHBV micro/nanoparticles.

The purpose of this study was to develop micro and nano sized drug carriers from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and study the cell and skin penetration of these particles. PHBV micro/nanospheres were prepared by o/w emulsion method and were stained with a fluorescent dye, Nile Red. The particles were fractionated by centrifugation to produce different sized populations. Topography was studied by SEM and average particle size and its distribution were determined with particle sizer. Cell viability assay (MTT) was carried out using L929 fibroblastic cell line, and particle penetration into the cells were studied. Transdermal permeation of PHBV micro/nanospheres and tissue reaction were studied using a BALB/c mouse model. Skin response was evaluated histologically and amount of PHBV in skin was determined by gas chromatography-mass spectrometry. The average diameters of the PHBV micro/nanosphere batches were found to be 1.9 µm, 426 and 166 nm. Polydispersity indices showed that the size distribution of micro sized particles was broader than the smaller ones. In vitro studies showed that the cells had a normal growth trend. MTT showed no signs of particle toxicity. The 426 and 166 nm sized PHBV spheres were seen to penetrate the cell membrane. The histological sections revealed no adverse effects. In view of this data nano and micro sized PHBV particles appeared to have potential to serve as topical and transdermal drug delivery carriers for use on aged or damaged skin or in cases of skin diseases such as psoriasis, and may even be used in gene transfer to cells.

Effects of ethylene oxide resterilization and in-vitro degradation on mechanical properties of partially absorbable composite hernia meshes.

BACKGROUND AND AIM: Prosthetic mesh repair for abdominal wall hernias is widely used because of its technical simplicity and low hernia recurrence rates. The most commonly used material is pure polypropylene mesh, although newer composite materials are recommended by some centers due to their advantages.However, these meshes are more expensive than pure polypropylene meshes. Resterilization of a pure polypropylene mesh has been shown to be quite safe, and many centers prefer slicing a large mesh into smaller pieces, suitable for any hernia type or defect size. Nevertheless there is no data about the safety after resterilization of the composite meshes. The present study was carried out to investigate the effects of resterilization and in vitro degradation in phosphate buffered saline solution on the physical structure and the mechanical properties of partially absorbable lightweight meshes. METHODS: Two composite meshes were used in the study: One mesh consists of monofilament polypropylene and monofilament polyglecaprone -a copolymer of glycolide and epsilon(ε)- caprolactone - (Ultrapro®, 28 g m2, Ethicon, Hamburg,Germany), and the other one consisted of multifilament polypropylene and multifilament polyglactine (Vypro II®, 30g m2, Ethicon, Hamburg, Germany). Two large meshes were cut into rectangular specimens sized 50 x 20 mm for mechanical testing and 20 x 20 mm for in vitro degradation experiments.Meshes were divided into control group with no resterilization and gas resterilization. Ethylene oxide gas sterilization was performed at 55°C for 4.5 hours. In vitro degradation in 0.01M phosphate buffered saline (PBS, pH 7.4) solution at 37 ± 1°C for 8 weeks was applied to one subgroup in each mesh group. Tensiometric measurements and scanning electronmicroscopic evaluations were completed for control and resterilization specimens. RESULTS: Regardless of resterilization, when the meshes were exposed to in vitro degradation, all mechanical parameters decreased significantly. Highest reduction in mechanical properties was observed for Ultrapro due to the degradation of absorbable polyglecaprone and polyglactin parts of these meshes. It was observed that resterilization by ethylene oxide did not determine significant difference on the degradation characteristics and almost similar physical structures were observed for resterilized and non-resterilized meshes. For VyproII meshes, no significant mechanical difference was observed between resterilized and non-resterilized meshes after degradation while resterilized Ultrapro meshes exhibited stronger characteristics than non-resterilized counterparts, after degradation. CONCLUSION: Resterilization with ethylene oxide did not affect the mechanical properties of partially absorbable compositemeshes. No important surface changes were observed inscanning electron microscopy after resterilization.

An in vivo study on the effect of scaffold geometry and growth factor release on the healing of bone defects.

The hypothesis of this study was that the extent of bone regeneration could be enhanced by using scaffolds with appropriate geometry, and that such an effect could be further increased by mimicking the natural timing of appearance of bone morphogenetic proteins BMP-2 and BMP-7 after fracture. Bioplotted poly(ε-caprolactone) (PCL) disks with four different fibre organizations were used to study the effect of 3D scaffold architecture on the healing of bone defects in a rat pelvis model. Moreover, one PCL construct was further modified by introducing a nanoparticulate sequential BMP-2/BMP-7 delivery system into this scaffold. Scaffolds and functionalized construct along with free nanocapsules were implanted using a rat iliac crest defect model. Six weeks post-implantation, the defects were evaluated by CT scan and histology. Analysis revealed that the basic architecture, having the highest pore volume for tissue ingrowth, presented the highest bone formation as determined by the bone mineral density (BMD) within the defect (144.2 ± 7.1); about four-fold higher than that of the empty defect (34.9 ± 10.7). It also showed the highest histological analysis scores with a high amount of bone formation within the defect, within the scaffold pores and along the outer surfaces of the scaffold. The basic scaffold carrying the BMP-2/BMP-7 delivery system showed significantly higher bone formation than the growth factor-free basic scaffold at 6 weeks (BMD 206.8 ± 15.7). Histological analysis also revealed new bone formation in close to or in direct contact with the construct interface. This study indicates the importance of open and interconnecting pore geometry on the better healing of bone defects, and that this effect could be further increased by supplying growth factors, as is the case in nature.

EFFECTS OF ETHYLENE OXIDE RESTERILISATION AND IN-VITRO DEGRADATION ON MECHANICAL PROPERTIES OF PARTIALLY ABSORBABLE COMPOSITE HERNIA MESHES.

BACKGROUND: Prosthetic mesh repair for abdominal wall hernias is widely used because of its technical simplicity and low hernia recurrence rates. The most commonly used material is pure polypropylene mesh, however newer composite materials are recommended by some centers because of their advantages. However, these meshes are more expensive than pure polypropylene meshes. Resterilisation of a pure polypropylene mesh has been shown to be quite safe, and many centers prefer slicing a large mesh into smaller pieces that suitable for hernia type or defect size. Nevertheless there is no data about the safety after resterilisation of the composite meshes. OBJECTIVE: To search the effects of resterilisation and In vitro degradation in phosphate buffered saline solution on the physical structure and the mechanical properties of partially absorbable lightweigth meshes. DESIGN: Laboratory-based research. SUBJECTS: Two composite meshes were used in the study: One mesh is consisted of monofilament polypropylene and monofilament polyglecaprone--a copolymer of glycolide and epsilon (ε)-caprolactone--(Ultrapro®, 28 g/m2, Ethicon, Hamburg, Germany),andthe otherone consisted of multifilamentpolypropyleneandmultifilament polyglactine (Vypro II®, 30 g/m2,Ethicon, Hamburg, Germany). Two large meshes were cut into rectangular specimens sized 50x20 mm for mechanical testing and 20x20 mm for In vitro degradation experiments. Meshes were divided into control group with no resterilisation and gas resterilisation. Ethylene oxide gas sterilisation was performed at 55°C for 4.5 hours. In vitro degradation in 0.01 M phosphate buffered saline (PBS, pH 7.4) solution at 37 ± 1°C for 8 weeks was applied to one subgroup in each mesh group. Tensiometric measurements and scanning electron microscopyic evaluations were completed for control and resterilisation specimens. RESULTS: Regardless of resterilisation, when meshes were exposed to In vitro degradation, all mechanical parameters decreased significantly. Highest reduction in mechanical properties was observed for Ultrapro due to the degradation of absorbable polyglecaprone and polyglactin parts of these meshes. It was observed that resterilisation by ethylene oxide did not have significant difference on the degradation characteristics and almost similar physical structures were observed for resterilised and non-resterilised meshes. For Vypro II meshes, no significant mechanical difference was observedbetweenresterilised andnon-resterilised meshes after degradationwhile resterilised Ultrapro meshes exhibited stronger characteristics than non-resterilised counterparts, after degradation. CONCLUSION: Resterilisation with ethylene oxide did not affect the mechanical properties of partially absorbable composite meshes. No important surface changeswere observed in scanning electron microscopy after resterilisation.

Development of porous chitosan-gelatin/hydroxyapatite composite scaffolds for hard tissue-engineering applications.

Composite scaffolds prepared from natural polymers and hydroxyapatite (HA) are expected to have enhanced osteoconductive properties and as a result gained much attention in recent years for use in bone tissue-engineering applications. Although there are various natural polymers available for this purpose, chitosan (C) and gelatin (G) are commonly studied because of their inherent properties. The aim of this study was to prepare three-dimensional (3D) scaffolds using these two natural polymers and to add either non-sintered hydroxyapatite (nsHA) or sintered hydroxyapatite (sHA) to compare their influence on physical, chemical and mechanical properties of the scaffolds and on their affinities towards Saos-2 cells. For this purpose, nsHA and sHA were synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and particle size analyses. Then nsHA and sHA particles, with average sizes of 16 µm and 6 µm, respectively, were added to the solutions of C and G during the preparation step and the resultant 3D scaffolds were characterized. Compression tests indicated that presence of nsHA or sHA increased the Young's modulus and compressive strength of the scaffolds, and the values were very similar to those of human spongy bone. MTS assays, confocal microscopy and SEM analysis showed that cell attachment and proliferation were higher on C-G/sHA composite scaffolds compared to the other scaffolds. It was shown that the scaffolds prepared from chitosan, gelatin and HA are appropriate cell carriers for bone tissue engineering, especially those with sHA incorporated.

Porous Agarose-Based Semi-IPN Hydrogels: Characterization and Cell Affinity Studies.

Hydrogels are frequently considered for medical applications due to the ease of preparation in different forms and high water content that makes them comparable to natural tissues. However, these general properties are not sufficient to make any hydrogel suitable for cell attachment and growth which are necessary for their use in tissue regeneration. Besides, the high water content makes the hydrogels mechanically weak. The formation of semi-interpenetrating networks (semi-IPNs) can be used in attempts to enhance physical, mechanical and thermal properties. In this study, semi-IPNs of agarose were prepared with chitosan and alginate, two polyelectrolytes that are positively and negatively charged under physiological conditions, respectively. Zeta potential was used to confirm the formation of charged hydrogels. All hydrogels had ultimate compression strengths in the range of 91-210 Pa where the value for pure agarose was about 103 Pa. Chitosan increased the compressive strength about two folds whereas the alginate had opposite effects. The amount of strongly bound water present in the hydrogels were estimated from TGA and DSC analysis and the highest value was found for alginate-agarose hydrogels as about 15%. The attachment and the migration of L929 fibroblasts were monitored in vitro using the MTS assay and confocal microscopy. The highest cell proliferation and penetration were observed for positively charged chitosan-agarose semi-IPN hydrogels.

Microfabrication of PDLLA scaffolds.

This study aimed to comprehend the potentialities of the microfabrication to produce tissue-engineering scaffolds. Structures presenting homogeneously distributed pores of size 100 and 200 µm were fabricated through layer-by-layer deposition of filaments of poly(D,L-lactic acid) (PDLLA) prepared from dichloromethane/dimethylformamide solutions. Rheological tests on the solution and molecular weight distributions of PDLLA, solvent cast films and microfabricated scaffolds were performed to determine which material conditions are optimal for the microfabricated system and to identify any possible material modification induced by the process. In vitro qualitative preliminary cell culture studies were conducted using MG63 osteoblast cell lines after assuring the non-cytotoxicity of the scaffold material by the lactate dehydrogenase in vitro toxicology assay; biological evaluations were initially performed using scaffolds with the smaller (100 µm) pore size. Scanning electron microscopy imaging was used to determine cell morphology distribution. A second cell culture test was performed, using the scaffold with the higher (200 µm) porosity. Confocal laser microscopy (CLM) was utilized to examine cell morphology and growth behaviour. Cellular metabolic activity and viability were also examined using Alamar Blue assay and further verifications were performed using CLM. Cell culture studies indicated homogeneous distribution, high viability and metabolic activity. Pore dimension affects cell distribution: pores < 100 µm acted as barrier structures for the MG63 osteoblast cell line; penetration inside the matrix was hindered and cells grew on the outer part. Increasing pore size resulted in a more homogeneous cell distribution and penetration of cells inside the structure was achieved.

Sequential BMP-2/BMP-7 delivery from polyester nanocapsules.

The aim of this study was to develop a nanosized, controlled growth factor release system to incorporate into tissue engineering scaffolds and thus activate the cells seeded in the scaffold. Nanocapsules of poly(lactic acid-co-glycolic acid) (PLGA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were loaded with the bone morphogenetic proteins BMP-2 and BMP-7, respectively, and with bovine serum albumin (BSA), the model protein. BSA-loading efficiency and release kinetics were used to determine the most appropriate nanocapsule pair to achieve the delivery of growth factors in a sequential manner, as occurs in natural processes. BSA-encapsulation efficiency was highest when the polymer concentration used in the preparation of PLGA and PHBV nanocapsules was 10% (w/v) (84.75% and 16.72%, respectively). Release of BSA was faster from PLGA than it was from PHBV. Based on the encapsulation efficiency and release data, 10% PLGA and 10% PHBV nanocapsules were chosen to provide the early BMP-2 and later BMP-7 release, respectively. Simultaneous, sequential delivery and individual release of the BMPs were studied for 7, 14, and 21 days, using rat bone marrow mesenchymal stem cells. Individual BMP-2 release suppressed cell proliferation while providing higher alkaline phosphatase activity with respect to BMP-7. The sequential delivery of BMP-2 and BMP-7 provided slightly lower proliferation than did simultaneous delivery, but the highest alkaline phosphatase activity of all indicated a synergistic effect on the osteogenic differentiation of mesenchymal stem cells caused by the use of the two growth factors in a sequential fashion.

Basic fibroblast growth factor loaded polypropylene meshes in repair of abdominal wall defects in rats.

BACKGROUND AND AIM: Incisional hernia following laparotomy and recurrent herniation after its repair are still common problems in spite of mesh augmentation. The underlying biological mechanism may be related to collagen metabolism. Recently, some members of growth factors family have been tested in the prevention of wound failure and incisonal hernia formation. Growth factors may promote fibroblast proliferation and collagen deposition. In the present study, we searched the effects of basic fibroblast growth factor (bFGF) loaded polypropylene meshes in an incisional hernia model in rats. METHODS: A total of 80 Wistar albino rats were randomly divided into five groups. A uniform surgical procedure was employed in all groups: a 5 cm skin incision was made at the midline and a full segment of the abdominal wall sized 3 x 2 cm was excised. Abdominal wall was closed with rapidly absorbable 3/0 catgut. Following this standard surgery, five different procedures were applied to the groups before closing the skin with 4/0 monofilament polypropylene sutures. Control subjects (Group 1) received no extra procedure after abdominal wall suturing. Polypropylene meshes were used in onlay position by fixing 4/0 monofimalent polypropylene interrupted sutures in other four groups. A standard mesh with no chemical treatment was used in Group 2. Gelatin coated meshes were used in Group 3, while Group 4 and 5 received bFGF loaded meshes with 1 microgram (microg) and 5 microg doses respectively. All the groups then divided into 1st month (early: E) and 2nd month (late: L) subgroups (n=8 each) according to sacrification dates. Tensiometric and histopathological evaluations were done. The specimens for histopathology were obtained from the interface area of the meshes and stained with hematoxylin and eosin, and also Masson trichrome. The variables were examined and evaluated by a single blinded pathologist under light microscopy in respect of inflammation, vascularization, fibroblast activity, collagen fibers and connective tissue organization. The avidin-biotin-peroxidase method was performed using the primary monooclonal antibodies against collagen type I and collagen Type III. RESULTS: bFGF loaded meshes showed higher tensile strength values in comparison with a standard polypropylene mesh after 2 months. Histopathological and immunohistochemistry studies also revealed somewhat better scores in favor of bFGF loaded mesh over a standard polypropylene mesh. These limited effects of bFGF did not seem to be dose dependent. CONCLUSIONS: The use of bFGF loaded polypropylene mesh in the abdominal wall healing may cause somewhat higher tensile strength values in comparison with a standard polypropylene. However, histopathological and immunohistochemistry studies revealed only a slightly better healing in favor of bFGF loaded mesh over a standard polypropylene mesh.

Epidermal growth factor-containing wound closure enhances wound healing in non-diabetic and diabetic rats.

BACKGROUND: This study was designed to elucidate the in vivo efficacy of epidermal growth factor (EGF) on wound healing in non diabetic and diabetic rats. METHODS: Ninety-six male Wistar-Albino rats were randomly divided into six groups. Saline-moistened gauze, pure gelatin or EGF in gelatin-microsphere dressings were used in a dermal excision model in both normal and streptomycin-induced diabetic rats. Wound healing was evaluated on day 7 and 14. Reduction in wound area, hydroxypyroline content and tensile strength of the wound were evaluated in each rat. Tissue samples taken from the wounds were examined histopathologically for reepithelialisation, cellular infiltration, number of fibroblasts, granulation and neovascularisation. RESULTS: On day 7, the use of EGF-containing dressing was observed to reduce the wound area better when compared with the other dressings tested. This effect was significant in normal rats rather than diabetic rats. The difference in reduction of wound area did not persist on day 14. No significant effect on hydroxyproline content of the wound was found with EGF-containing dressing in either normal or diabetic rats. There was a statistically significant increase in tensile strength values of EGF-applied non diabetic rats over the 14 day period. An increase in tensile strength was prominent in also EGF-applied diabetic rats on day 14. Histological examination revealed higher histopathologic scores in EGF-applied diabetic and non diabetic rats. CONCLUSION: These findings implicate that use of EGF in gelatin-microsphere dressings improves wound healing both in normal and diabetic rats.

Nanopatterned collagen tubes for vascular tissue engineering.

Nanopatterned (330 nm wide channels) type I collagen films were prepared by solvent casting on poly(dimethyl siloxane) (PDMS) templates. These films were rolled into tubular constructs and crosslinked. Tubular constructs were incubated under cell culture conditions for 28 days and examined by stereomicroscopy and scanning electron microscopy (SEM) for the integrity of the structure. The nanopatterned films were also seeded with human vascular smooth muscle cells (VSMCs) and examined after immunostaining with fluorescence microscopy and SEM to assess the cell phenotype and alignment on the nanopatterns on the films.

Reduction of peritoneal adhesions by sustained and local administration of epidermal growth factor.

Previous studies have shown epidermal growth factor (EGF) facilitate peritoneal membrane healing by augmenting cell adhesion and migration. The objective of this study was to show the effect of sustained and local administration of EGF on peritoneal adhesion. Fourty-two rats were divided into six groups: control 7 and 14, gelatin 7 and 14, and EGF 7 and 14. Adhesions were created by scraping the cecum with mesh gause followed by application of absolute alcohol and placement of silk suture in the parietal peritoneum. The anterior walls of the intestines were covered with 5 x 5 cm unloaded, and EGF loaded gelatin films in the gelatin and EGF groups, respectively. The rats were killed on days 7 and 14 to assess the adhesion occurring, and for biochemical examination. The mean adhesion grades of EGF groups were significantly lower than in the other groups (P < 0.008). The mean adenosine deaminase (ADA) measurements of EGF 7 group were lower than in the gelatin 7 and control 7 groups but the difference was not significant (P > 0.008). The mean ADA measurements in the 14 days groups were as follows: control 14 < EGF 14 < gelatin 14 groups. The mean ADA measurements between 14 days groups did not significantly differ from each other (P > 0.008). The mean hydroxyproline measurements did not differ among the groups (P > 0.008). EGF decreased intestinal adhesion in our study. EGF has important roles in DNA synthesis and cell proliferation. Further studies are required to determine the exact mechanism by which EGF lowers the efficiency of intestinal adhesion.

Adsorption of human salivary mucin MG1 onto glow-discharge plasma treated acrylic resin surfaces.

It has been suggested that altering the surface properties of acrylic resin material may change the nature of the adsorbed pellicle affecting denture retention and microbial adherence. This study aimed at evaluating the adsorption of salivary high molecular-weight mucins, a major component of denture pellicle, onto modified acrylic resin surfaces. (Poly) methylmethacrylate specimens were treated by glow discharge plasma technique, using hydrophilic 2-Hydroxyethylmethacrylate monomer or oxygen (O(2)) gas and hydrophobic Hexamethyldisiloxane monomer, at different discharge powers. Acrylic samples were incubated with high-molecular weight mucin, MG1 purified from saliva, the adsorbed fractions were transferred to nitrocellulose membranes by slot-blot technique, stained by periodic acid-Schiff and colour intensities were analysed by a colour densitometer. Higher amounts of mucins were adsorbed on all the surfaces modified by glow-discharge plasma treatment. Within the limitations of this study, it was concluded that glow-discharge plasma altered the surfaces of acrylic resin denture base materials and significantly increased the adsorption of high molecular-weight mucins at varying levels depending on plasma parameters.

Adherence of Candida albicans to glow-discharge modified acrylic denture base polymers.

An important aetiologic factor in the pathogenesis of denture-induced stomatitis, is the presence of numerous yeasts, usually Candida albicans, on the fitting surfaces of dentures. In the present study, effect of glow-discharge plasma, a technique applied to increase surface wettability of acrylic resins, on candidial adherence was evaluated. The durability of glow-discharge modification with saliva coating was also evaluated. Samples including control and experimental groups were prepared by using heat compression mould technique. To create a hydrophobicity gradient, experimental groups were exposed to a radiofrequency glow discharge in an O2 atmosphere under different discharge powers. To characterize the wetting properties, an expression of surface hydrophobicity, contact angle measurements were performed by the sessile drop method. The organism used was C. albicans (ATTC10321). Acrylic samples were coated with unstimulated whole saliva collected from a healthy man. The fungal suspension was poured on saliva-inoculated samples and incubated at 37 degrees for 2 h. The samples were then fixed with glutaraldehyde and Gram stained. Adhered candidial cells were examined by light microscope. Diffuse Reflectance FTIR (DRIFT) and scanning electron-microscope examinations were also performed to evaluate the surface composition and roughness of the test groups. Glow-discharge plasma was found to be an effective means of increasing surface wettability even with salivary pellicle. Amounts of candida cells adhered were significantly higher in all the plasma treated surfaces than the unmodified control group (P < 0.001). It was concluded that improving the surface wettability of acrylic resins by glow-discharge plasma in O2 atmosphere increased the adherence of the C. albicans.

The effect of sustained and local administration of epidermal growth factor on improving bilateral testicular tissue after torsion.

Epidermal growth factor (EGF) modulates Leydig cell proliferation, steroidogenesis, spermiogenesis, and Sertoli cell activity. It plays an important role in repairing ischemia-reperfusion injury in different tissues. The aim of this study was to evaluate the effects of sustained and local administration of EGF on improving bilateral testicular tissue after torsion. A total of 57 Wistar albino rats were used. For the EGF transport system, 1x2 cm gelatin films containing 2 microg EGF were used. Torsion was created by rotating the right testis 720 degrees in a clockwise direction for 4 h in all groups except the control group. Then, in the torsion group, bilateral orchiectomy was performed. After returning the torsioned ipsilateral testes to their normal state, the bilateral testes were wrapped by 1x2 cm unloaded gelatin films in the gelatin (G7 and G21) groups and, by 2 microg EGF loaded gelatin films in the EGF 7 and EGF 21 groups. The testes were removed on the seventh and 21st days, respectively, for biochemical and histological examination. Histologically, Johnsen's spermatogenesis criteria and mean seminiferous tubule diameter (MSTD) measurements were used. The EGF7 group did not show significant loss of Sertoli cells, while in the G7 group the number of these cells decreased. The ipsilateral ischemic testis of the EGF21 group showed Leydig cell hyperplasia, and the contralateral non-ischemic testes in this group were similar to the control group. In the G21 group, the bilateral testes showed Sertoli cell only syndrome in some sections, and most of the cells were undergoing apoptosis. The mean spermatogenesis scores and MSTD in the EGF7 and EGF21 groups were higher than in the G7 and G21 groups ( P<0.05). Malondialdehyde levels were significantly lower in the EGF groups than in the G groups ( P<0.05). Glutathione peroxidase (GSH-Px) levels in the G21 group were significantly higher than in the EGF21 group. Our study shows that local and sustained EGF release after testicular torsion improves bilateral testicular injury. EGF administration may be a new treatment choice for bilaterally injured testis after detorsion without removing the twisted testis.

Cytotoxicity of 5-fluorouracil entrapped in gelatin microspheres.

Gelatin microspheres were prepared by water/oil emulsion polymerization and by cross-linking with glutaraldehyde. For the microsphere preparation procedure, two different gelatin (5 or 10% w/v) and three different glutaraldehyde (5, 0.5 or 0.1% v/v) concentrations were used. The influence of preparation compositions on microsphere recovery, particle size and morphology, swelling and degradation, 5-fluorouracil loading and release, and cytotoxicity were investigated. The concentrations of gelatin and glutaraldehyde influenced the size and surface properties of microspheres. The decrease in gelatin concentration and the increase in glutaraldehyde concentration resulted in the formation of smaller (140.82-71.47 microm for gelatin microspheres with a 5% gelatin content; 297.67-97.44 microm for gelatin microspheres with a 10% gelatin content) microspheres with smoother surface properties. Swelling values were decreased as the amount of glutaraldehyde was increased. In particular, for microspheres with a high glutaraldehyde content (5% v/v), only about 15% were degraded in 12 days, whereas for those with 0.5% (v/v) glutaraldehyde, almost 97% degradation occurred in the same period. The most rapid 5-fluorouracil release was observed from uncross-linked microspheres (about 88% in 4 h), whereas a particular slower release (about 36% in 4 h) profile was obtained for the highly cross-linked ones. Cytotoxicity tests of free and entrapped 5-fluorouracil were carried out with MCF-7 breast cancer cell line. Free 5-fluorouracil produced an immediate effect, whereas entrapped 5-fluorouracil showed a prolonged cytotoxic effect.