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Select bladder smooth muscle cell functions were enhanced on three-dimensional, nano-structured poly(ether urethane) scaffolds.

Bladder wall resection is often required as a treatment for invasive bladder cancer. When this happens, a suitable replacement material is needed. The present study, therefore, created three-dimensional, porous, nano-structured poly(ether urethane) (PU) matrices for use as bladder tissue-engineering scaffolds. Select cytocompatibility experiments (specifically adhesion and long-term growth studies) were performed on these scaffolds using human bladder smooth muscle cells (BdSMCs). In addition, the amount of total collagen and elastin present in each cell-seeded scaffold was determined since the production of these extracellular matrix (ECM) proteins is essential for the health and survival of cells and for the functionality of the replaced organ. Finally, to better understand how these scaffolds and resident cells would perform in the complex mechanical environment of the bladder wall, scaffolds and cells were subjected to 10 cmH2O pressure using a computer-controlled pressure chamber. Results provided evidence that compared to conventionally used, micro-dimensional PU scaffolds, the novel, nanodimensional scaffolds created in this research increased cell adhesion, growth, and ECM protein production. Additionally, scaffolds and resident cells were not affected by exposure to 10 cmH2O pressure (compared to controls maintained under atmospheric conditions). These results are promising and provide evidence that the nano-dimensional PU scaffolds created in this research are suitable bladder replacement materials that may outperform materials currently used for such purposes.

Animals↗

Polymeric membranes for hybrid liver support devices: the effect of membrane surface wettability on hepatocyte viability and functions.

Extracorporeal therapies based on membrane hybrid liver support devices using primary hepatocytes are an interesting approach to the treatment of acute hepatic failure. In such devices, semipermeable polymeric membranes are effectively used as immunoselective barriers between a patient's blood and the xenocytes in order to prevent the immune rejection of the graft. The membranes may act also as the substratum for cell adhesion, thus favouring the viability and functions of anchorage-dependent cells such as the hepatocytes. Membrane cytocompatibility is expected to depend on the surface properties of the polymer, such as its morphology and its physico-chemical properties. In this paper, we report our investigation on the effect of the surface wettability of membranes on hepatocyte viability and functions. Polypropylene microporous membranes were modified to increase their surface wettability and were used as substrata for rat hepatocyte adhesion culture. Isolated hepatocytes were also cultured on collagen as a reference substratum. Hepatocyte viability generally improved as the cells were cultured on more wettable membranes. In agreement with the viability data, the increasing wettability of the membrane surface also improved some metabolic functions.

Animals↗

Biodegradable nanomats produced by electrospinning: expanding multifunctionality and potential for tissue engineering.

With increasing interest in nanotechnology, development of nanofibers (n-fibers) by using the technique of electrospinning is gaining new momentum. Among important potential applications of n-fiber-based structures, scaffolds for tissue-engineering represent an advancing front. Nanoscaffolds (n-scaffolds) are closer to natural extracellular matrix (ECM) and its nanoscale fibrous structure. Although the technique of electrospinning is relatively old, various improvements have been made in the last decades to explore the spinning of submicron fibers from biodegradable polymers and to develop also multifunctional drug-releasing and bioactive scaffolds. Various factors can affect the properties of resulting nanostructures that can be classified into three main categories, namely: (1) Substrate related, (2) Apparatus related, and (3) Environment related factors. Developed n-scaffolds were tested for their cytocompatibility using different cell models and were seeded with cells for to develop tissue engineering constructs. Most importantly, studies have looked at the potential of using n-scaffolds for the development of blood vessels. There is a large area ahead for further applications and development of the field. For instance, multifunctional scaffolds that can be used as controlled delivery system do have a potential and have yet to be investigated for engineering of various tissues. So far, in vivo data on n-scaffolds are scarce, but in future reports are expected to emerge. With the convergence of the fields of nanotechnology, drug release and tissue engineering, new solutions could be found for the current limitations of tissue engineering scaffolds, which may enhance their functionality upon in vivo implantation. In this paper electrospinning process, factors affecting it, used polymers, developed n-scaffolds and their characterization are reviewed with focus on application in tissue engineering.

Absorbable Implants↗

The development of porous alginate/elastin/PEG composite matrix for cardiovascular engineering.

The development of suitable three-dimensional matrices for the maintenance of cellular viability and differentiation is critical for applications in tissue engineering and cell biology. To this end, gel matrices of different proportions of alginate/elastin/polyethylene glycol (Alg/Ela/PEG) were prepared and examined. The composite matrix membranes were evaluated for their porous scaffold using SEM, enzymatic degradation and water content. An equal blend of Alg/Ela with a ratio of Alg/Ela: PEG (7:3) was selected for fabricating Alg/Ela/PEG scaffolds for this study. The Alg/Ela/PEG membranes fabricated at 20 degrees C and - 20 degrees C had a mean surface pore size of 35-45 microm. However, their ultrastructures had shown bigger pore structures (60-75 microm) compared to their surface. It is interesting to note that the membranes of Alg/Ela/PEG prepared at 20 degrees C had larger ultrastructural pores than that of membranes prepared at -20 degrees C. Further, the SEM studies revealed that in the absence of PEG the composite membranes of Alg/Ela formed with less porous structures. The water content of membranes prepared at 20 degrees C was higher with Alg/Ela/PEG (61.6 +/- 4.8%), compared to Alg/Ela (49.9 +/- 0.3%). The enzymatic degradation and water content studies also revealed that the membranes fabricated at - 20 degrees C had high water uptake and low enzymatic degradation, as that of the membranes prepared at 20 degreees C. In other words the larger pore structured membranes had less water content and high degradation profile. This study proposes that this novel composite matrix produces a hierarchical structure that is useful for generating tissue scaffolds for repairing the failing cardiac muscles. However, more detailed investigations with cytocompatibility studies are needed to find applications.

Alginates↗

Effect of crystallographic phases of TiO2 on hepatocyte attachment, proliferation and morphology.

In this study, the effect of the crystallographic phases of titanium dioxide (TiO(2)) on hepatocyte response was investigated by culturing cells in a medium containing a dissolution of rutile TiO(2) powders, and on anatase and rutile ceramic discs. When the concentration of Ti ions exceeded 0.16 microg/mL, TiO(2) exhibited cytotoxicity. However, in a range of concentrations between 10(-6) and 10(-3)microg/mL, the Ti ion leached out from the powder stimulated cell proliferation. Cytocompatibility was also examined by the cell attachment and proliferation on the TiO(2) discs. The results show that the surface characteristic of the TiO(2) discs was the main factor influencing cell attachment, and the cells were better attached on the dense surface of the discs with high crystallinity than on the loose surface with low crystallinity. Both the surface characteristic and the crystallographic phase affected cell proliferation. In addition to the dense surface with high crystallinity, the anatase ceramics was in favor of cell proliferation as compared to the rutile ceramics sintered at the same temperature. In conclusion, the results suggest that the dense rutile ceramic with high crystallinity is a good substrate for hepatocytes.

Biocompatible Materials↗

Porous poly (DL-lactic acid) modified chitosan-gelatin scaffolds for tissue engineering.

Chitosan-gelatin (Cs-Gel) scaffolds are modified with poly (DL-lactic acid) (PDLLA) dichloromethane solution of different concentrations (0.1, 0.5, and 1.0%) and immersed in water after the evaporation of the solvent. The swollen scaffolds are freeze dried. The concentration of PDLLA has significant effects on both the physicomechanical properties and the cytocompatibility. Data reveal that only the 0.1% concentration could increase the tensile strength fourfold in comparison with the pristine Cs-Gel scaffold, while maintaining the human fibroblast adhesion, migration, and proliferation just like the Cs-Gel scaffold.

Absorption↗

The endothelialization of polyhedral oligomeric silsesquioxane nanocomposites: an in vitro study.

It has been recognized that seeding vascular bypass grafts with endothelial cells is the ideal method of improving their long-term patency rates. The aim of this study was to assess the in vitro cytocompatibility of a novel silica nanocomposite, polyhedral oligomeric silsesquioxane-poly(carbonate-urea)urethane (POSS-PCU) and hence elicit its feasibility at the vascular interface for potential use in cardiovascular devices such as vascular grafts. Using primary human umbilical vein endothelial cells (HUVEC), cell viability and adhesion were studied using AlamarBlue assays, whereas cell proliferation on the polymer was assessed using the PicoGreen dye assay. Cellular confluence and morphology on the nanocomposite were analyzed using light and electron microscopy, respectively. Our results showed that there was no significant difference between cell viability in standard culture media and POSS-PCU. Endothelial cells were capable of adhering to the polymer within 30 min of contact (Student's t-test, p < 0.05) with no difference between POSS-PCU and control cell culture plates. POSSPCU was also capable of sustaining good cell proliferation for up to 14 d even from low seeding densities (1.0 x 10(3) cells/cm(2)) and reaching saturation by 21 d. Microscopic analysis showed evidence of optimal endothelial cell adsorption morphology with the absence of impaired motility and morphogenesis. In conclusion, these results support the application of POSS-PCU as a suitable biomaterial scaffold in bio-hybrid vascular prostheses and biomedical devices.

Biocompatible Materials↗

Fibroblast and osteoblast adhesion and morphology on calcium phosphate surfaces.

Implant loosening in bone fixation is an unresolved complication associated with internal fixation. It is generally accepted that this problem can be overcome by modifying the implant/bone interface for improved osseointegration. This is achieved, in part, by hydroxyapatite (HA) or tricalcium phosphate coatings. Unfortunately, the benefits of these coatings are constrained by not only the generally low strength of their adhesion to the implant surface but also the limited cohesion within their layers. Anodic Plasma-chemical treatment (APC) has been developed to incorporate electrolytes and produce coatings with various microtopographies and strong adhesion to implants. In this in vitro study fibroblast and osteoblast morphologies and adhesion to various substrates were evaluated using qualitative and quantitative methods. The substrates were Thermanox plastic and commercially pure titanium. The latter were surface-treated using several different methods: conventional anodisation, plasma spraying of HA and anodic plasma-chemical (APC) treatment in an electrolyte solution containing either calcium and phosphate (APC-CaP) or phosphoric acid (APC-P). Both osteoblasts and fibroblasts showed extensive cell spreading, total cell area and greatest amount of adhesion, with defined adhesion patterns on the Thermanox plastic, anodised titanium, and the two APC-CaP substrates. With fibroblasts, almost no cell spreading and very low adhesion, was observed in cells cultured on the APC-P and HA surfaces. The extent of cell spreading correlated with the area of focal adhesions as assessed by the amount of vinculin labelling. The Thermanox plastic, anodised titanium, and the two APC-CaP substrates were the most cytocompatible substrates with regard to this in vitro evaluation.

Journal Article↗

Development of composite porous scaffolds based on collagen and biodegradable poly(ester urethane)urea.

Our objective in this work was to develop a flexible, biodegradable scaffold for cell transplantation that would incorporate a synthetic component for strength and flexibility and type I collagen for enzymatic lability and cytocompatibility. A biodegradable poly(ester urethane)urea was synthesized from poly(caprolactone), 1,4-diisocyanatobutane, and putrescine. Using a thermally induced phase separation process, porous scaffolds were created from a mixture containing this polyurethane and 0%, 10%, 20%, or 30% type I collagen. The resulting scaffolds were found to have open, interconnected pores (from 7 to >100 um) and porosities from 58% to 86% depending on the polyurethane/collagen ratio. The scaffolds were also flexible with breaking strains of 82-443% and tensile strengths of 0.97-4.11 MPa depending on preparation conditions. Scaffold degradation was significantly increased when collagenase was introduced into an incubating buffer in a manner that was dependent on the mass fraction of collagen present in the scaffold. Mass losses could be varied from 15% to 59% over 8 weeks. When culturing umbilical artery smooth muscle cells on these scaffolds higher cell numbers were observed over a 4-week culture period in scaffolds containing collagen. In summary, a strong and flexible scaffold system has been developed that can degrade by both hydrolysis and collagenase degradation pathways, as well as support cell growth. This scaffold possesses properties that would make it attractive for future use in soft tissue applications where such mechanical and biological features would be advantageous.

Animals↗

Hard, soft tissue and in vitro cell response to porous nickel-titanium: a biocompatibility evaluation.

Porous nickel-titanium (NiTi) alloys have demonstrated bone attachment as well as tissue ingrowth in the past. However, very few studies have compared porous NiTi soft and hard tissue reactions, and in vitro cell response. We therefore have evaluated the general muscle and bone reaction to porous nickel-titanium. The latter material was implanted in rabbit tibias and back muscle, and assessed after three, six and twelve weeks of implantation. Porous NiTi specimens did not cause any adverse effect regardless of both implantation site and post-surgery recovery time. Muscle tissue exhibited thin tightly adherent fibrous capsules with fibers penetrating into implant pores. We observed that attachment strength of the soft tissue to the porous implant seemed to increase with post-implantation time. Bone tissue demonstrated good healing of the osteotomy. There was bone remodeling characterized by osteoclastic and osteoblastic activity in the cortex. This general good in vivo biocompatibility with muscle and bone tissue corresponded very well with the in vitro cell culture results we obtained. Fibroblasts seeded on porous nickel-titanium sheets managed to grow into the pores and all around specimen edges showing an another interesting cytocompatibility behavior. These results indicate good biocompatibility acceptance of porous nickel-titanium and are very promising towards eventual NiTi medical device approbation.

Adipose Tissue↗

Interactions between chitosan and glycosaminoglycans (chondroitin sulfate and hyaluronic acid): physicochemical and biological studies.

Chitosan is a polysaccharide well known for its numerous and interesting biological properties, indeed, it is a biocompatible, bioresorbable and bioactive biopolymer. It is therefore often introduced in the human body, where it happens to be in contact with glycosaminoglycans (GAG's), especially chondroitin sulfates and hyaluronic acid which play important part in living media. Thus it seems interesting to consider systems associating chitosan and GAG's. The aim of our work is to study the mechanism of formation of biomaterials constituted of chitosan and GAG's which could have interesting biological properties such as improving the wound-healing acceleration and the cellular assistance for skin and cartilage recovery. In the same time, it was interesting to try to understand what can happen when chitosan is introduced in a natural surrounding containing GAG's. In a first part, the complexes between chitosan and GAG's were characterised by various physicochemical techniques: pH-metry, conductometry and Infra-red spectrometry. They appeared to be polyelectrolyte complexes obtained by the formation of polyanion-polycation interactions held between ammonium functions of chitosan and carboxylate and/or sulfate groups of GAG's. The complexes formed are very strong and can, in some cases, even conduct to the deprotonation of carboxylic functions. In a second part we considered the biological properties of the complexes previously obtained. The hydrolysis activity in presence of specific enzymes was investigated. We also studied the cytocompatibility of chitosan alone and its complexes with the two considered GAG's toward two kinds of cells (chondrocytes and keratinocytes). At the end of the work, a short animal experimentation on rats was performed allowing the comparison between in vitro and in vivo results.

Animals↗

Technical and biophysical aspects in prosthetic occlusal rehabilitation for edentulous teenagers.

The loss of anterior teeth may be transient solved by temporary adhesive bridges (Oslo bridge, Rochette, Ellmann, Neumann, Tschemitscheck, Armatron systems). Provisional crowns and bridges could be used for Brackets fixing. Anterior bridge with subocclusal connector permits transversal expansion. When a successful orthodontic treatment is followed by a prosthetic treatment, it is not important to change the achieved occlusion, by the occlusal framework morphology. The framework design of the metal component can contribute to the improvement of the aesthetic aspect and reduce the cost by using a small quantity of expensive alloy. Cytocompatibility of the used Cr-Co alloy is confirmed by cell culture test.

Adolescent↗

[A research on rat osteoblasts culture in vitro].

Osteoblasts were isolated from Sprague Dawley rats of 1-3 days on the frontal parietal bones and were confirmed by testing for multiple biological features. The results showed that rat osteoblasts in vitro had the same morphological feature, ALP activity, the function of synthetic BMP as in vivo and it had the ability of calcification in vitro. The results proved that these rat osteoblasts in vitro had the same function and features as in vivo and it could be used to study cytocompatibility on replacement materials of human body's hard tissues and biomedical to make experiments related to bone tissues.

Alkaline Phosphatase↗

[Piezoelectric ceramic--a novel material for bone replacement].

Based on the piezoelectric effect of nature bone, the biocompatibility of a piezoelectric ceramic and bone tissue is observed and studied in four aspects: cytocompatibility, tissue-compatibility, mechanical compatibility and electro-compatibility. The results show that the piezoelectric ceramic is biocompatible. It is not harmful to the morphology and proliferation of L929. There is osteal combination between the piezoelectric ceramic and bone. Its mechanical properties are also suitable for bone replacement. Especially, it can induce the growth of osseous tissues along the chosen direction according to the piezoelectric properties of bone. It is envisaged that the piezoelectric ceramic may be developed and used as a novel material for bone replacement.

Animals↗

Cytotoxic effects of denture base materials on a permanent human oral epithelial cell line and on primary human oral fibroblasts in vitro.

PURPOSE: The objective of this study was to determine the cytocompatibility of three different extracts of denture base resins and to compare the cytotoxic effect of these materials on a human oral epithelial KB cell line and primary human oral fibroblasts derived from buccal mucosa. MATERIALS AND METHODS: Set specimens from a heat-cured resin, a self-cured resin, and a light-cured resin were eluted with culture medium for 1, 3, and 5 days. Cytotoxicity was judged using tetrazolium bromide reduction assay. RESULTS: The eluates from self-cured, heat-cured, and light-cured denture base resins were cytotoxic to primary human buccal fibroblast cultures and KB cells. Self-cured resin was the most toxic denture base material among the chemicals tested in all cultures. The cytotoxicity decreased in the order of self-cured resin > heat-cured resin > light-cured resin for KB cells. The rank for buccal fibroblast cells was self-cured resin > heat-cured resin > light-cured resin. CONCLUSION: The influence of the cytotoxicity depended on the materials tested and the cell culture system used. The use of both permanent and primary cells is recommended for a better screening of the cytotoxic effects of denture base resins.

Acrylic Resins↗

Three-dimensional seeding of chondrocytes encapsulated in collagen gel into PLLA scaffolds.

Tissue engineering approaches have been clinically tried to repair damaged articular cartilages. It is an essential step to uniformly seed chondrocytes into 3D scaffolds in order to reconstruct tissue-engineered cartilages in vitro, but the tissue engineering could not have been provided with efficient cell seeding methods. Type I collagen is clinically used and known as a cytocompatible material, having recognition sites for integrins. Collagen gel encapsulating chondrocytes has been tried for making regenerated cartilages, but it is found difficult to have the gel keep its original shape after long-term culture, because of shrinking. On the other hand, 3D scaffolds, either of a nonwoven structure or a sponge-like structure, involve difficulty in that chondrocytes could not be uniformly seeded, although they have adequate initial mechanical properties. In this study, by combining collagen gelation with a nonwoven PLLA scaffold, we achieved uniform cell seeding into the 3D scaffold. Bovine articular chondrocytes were mixed with type I collagen solution, and the solution was poured into the nonwoven PLLA scaffold (1.5 mm thick, diameter 15 mm). The collagen-chondrocyte mixture was made into gel at 37 degrees C for 1 h. The 0.39% collagen mixture was viscous enough to prevent cells from precipitating during gelation. Almost all chondrocytes were able to be incorporated into the PLLA scaffolds by mixing with collagen solution and subsequently making into gel, while 30-40% of the chondrocytes seeded as a cell suspension were not trapped into the PLLA scaffolds. The method presented, where chondrocytes were mixed with collagen solution, and the mixture was incorporated into a 3D scaffold, then made into gel in the scaffold, could serve as an alternative for in vitro cartilage regeneration, also simultaneously having the advantages of both materials.

Animals↗

[In vitro studies about the effects of implanted materials on osteocalcin and alkaline phosphatase of rat osteoblasts].

OBJECTIVE: To evaluate the effects of the four implant materials, hydroxyl poly calcium sodium phosphate (HPA), hydroxyapatite (HA), bioglass ceramics (BGC) and titanium (Ti) on osteocalcin secreting amount and alkaline phosphatase activity of rat osteoblasts cultured in vitro, and expose the biological compatibility conditions of the implant materials as well as the index to estimate cytocompatibility. METHODS: The powders of HPA, HA, BGC and Ti were sterilized and made into extracted solutions with 199 culture medium, and the isolated osteoblasts which were taken from three-day-old Sprague-Dawley rats' calvaria, were incubated in 199 culture medium too. Then the osteoblasts were mixed and incubated into the four kinds of extracted solutions of the implant materials. After eight days of co-incubation, the cells were taken out to measure alkaline phosphatase activity with velocity analysis, and the extracellular liquid was used to estimate osteocalcin secreting amount with radioisotope analysis. RESULTS: 1. Osteocalcin secreting amount of the osteoblasts co-incubated with HPA, HA, BGC were as normal as the control, while that of other cells co-incubated with titanium was reduced (P < 0.05). 2. Alkaline phosphatase activities of all the co-incubated osteoblasts were as normal as the control. CONCLUSION: The osteocalcin secreting amount and alkaline phosphatase activity can reflect the biological compatibility of implant materials, and they may be used as indexes to evaluate biological compatibility condition of implant materials.

Alkaline Phosphatase↗

Biological characterization of experimental carbon samples.

The use of carbon is widespread in fields as wide as aeronautics, cars, electricity or electronics. The biomedical applications of carbon are also numerous. The purpose of our work is to test four experimental carbon fibers (A, B, C and D; B being the negative control) to determine the best clinical application. Four tests of cytocompatibility are carried out (cell viability, inflammatory test, cell proliferation and cell morphology). Two different cell lines are used: the L132 cell line (epithelial embryonic pulmonary human cell) and the HaCaT line (human normal spontaneously immortalized skin keratinocytes). The results of the biological tests are compared with those of a carbon fiber sample already marketed as a bandage in the treatment of infected wounds: Actisorb "Plus (J2). The various tests show us that only two experimental samples are slightly cytotoxic (A, D). On the other hand, no sample supports cell adherence. A, B, C and D do not have an inflammatory effect. J2 appears at the same time cytotoxic and inflammatory. Consequently, being given the physical presentation and the biological properties of experimental samples (A, C and D), we intend them for an application in the field of wound healing, as a bandage. Also further experimentation is needed.

Biocompatible Materials↗