Bio-Medical Materials and Engineering - Volume 16, issue 4

Authors: Stoltz, J.F. | Bensoussan, D. | Decot, V. | Netter, P. | Ciree, A. | Gillet, P.

Article Type: Research Article

Abstract: Most human tissues do not regenerate spontaneously; this is why cell therapies and tissue engineering are promising alternatives. The principle is simple: cells are collected in a patient and introduced in the damaged tissue or in a tridimentional porous support and harvested in a bioreactor in which the physico-chemical and mechanical parameters are controlled. Once the tissues (or the cells) are mature they may be implanted. In parallel, the development of biotherapies with stem cells is a field of research in turmoil given the hopes for clinical applications that it brings up. Embryonic stem cells are potentially more interesting since …they are totipotent, but they can only be obtained at the very early stages of the embryo. The potential of adult stem cells is limited but isolating them induces no ethical problem and it has been known for more than 40 years that bone marrow does possess the regenerating functions of blood cells. Finally, the properties of foetal stem cells (blood cells from the umbilical cord) are forerunners of the haematopoietic system but the ability of these cells to participate to the formation of other tissues is more problematic. Another field for therapeutic research is that of dendritic cells, antigen presenting cells. Their efficiency in cell therapy relies on the initiation of specific immune responses. They represent a promising tool in the development of a protective immune response against antigens which the host is usually unable to generate an efficient response (melanomas, breast against cancer, prostate cancer, …). Finally, gene therapy, has been nourishing high hopes but few clinical applications can be envisaged in the short term, although potential applications are multiple (haemophilia, myopathies, …). A large number of clinical areas stand as candidates for clinical applications: leukaemia and cancers, cardiac insufficiency and vascular diseases, cartilage and bone repair, ligaments and tendons, liver diseases, ophthalmology, diabetes, neurological diseases (Parkinson, Huntington disease, …), … Various aspects of this new regenerative therapeutic medicine are developed in this work. Show more

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S3-S18, 2006

Authors: Du, Rui Lin | Chang, Jiang

Article Type: Research Article

Abstract: To evaluate the influence of Zn on the formation of hydroxyapatite (HA), zinc-containing glass 58S4Z was prepared by substitution of CaO with 4 wt% ZnO in 58S bioactive glass, and Zn-containing simulated body fluid (ZnSBF) was prepared as soaking fluid. During the soaking, all samples could induce the deposition of HA, but 58S4Z in SBF and 58S in ZnSBF showed lower formation rate of HA than 58S in SBF, which suggests that both the Zn in glass and the Zn2+ in soaking fluid retarded the deposition of HA. The ICP and EDS analysis results indicated that the main factor …was the preferential reaction of Zn2+ with PO4 3− , which resulted in a decrease of the PO4 3− concentration in soaking fluid and the nucleation of HA. Besides the inhibitory effect of Zn2+ in the soaking fluid, Zn in 58S4Z glass caused a lower release rate of Ca2+ in the initial soaking periods because of the lower CaO content as compared with 58S, and resulted in a lower nucleation rate of HA. The results suggested that small amount of Zn in bioactive glass retarded the nucleation of HA, but with the exhaustion of Zn2+ by PO4 3− , it did not affect the long-term deposition of HA in SBF. Show more

Keywords: Zinc, hydroxyapatite, bioactive glass

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. 229-236, 2006

Authors: Gray, G.B. | Kataria, V. | McManus, S. | Jagger, D.C.

Article Type: Research Article

Abstract: The aim of this study was to investigate the effect of one step adhesives on the shear bond strength of a compomer restorative material to both enamel and dentine. Human extracted teeth were used for the study. Ten samples were prepared for both enamel and dentine specimens for each of the five groups: Tooth, no etch, Prime and Bond NT (P+B NT); tooth, Non-Rinse Conditioner (NRC), P+B NT; tooth, NRC, Prime and Bond 2.1 (P+B 2.1); tooth, etch, P+B NT; tooth, etch, P+B 2.1. The specimens were subjected to bond testing. The shear bond strength was measured using an Inston …1193 testing machine using a cross head speed of 1 mm/minute. The specimens were tested to destruction. The results show that for the enamel specimens the highest bond strength was recorded for those specimens subjected to Etch, P+B 2.1 (22.1 MPa) and Etch P+B NT (20.0 MPa). The groups of specimens which did not undergo etching had very low bond strengths ranging from 11.4 MPa for NRC, P+B 2.1, 8.5 MPa for NRC P+B NT to 6.9 MPa for P+B NT. For the dentine specimens, for all of the groups, the shear bond strengths were low. Those groups subjected to etching produced the highest values of 7.9 MPa for NRC P+B 2.1 with the lowest value of 6.1 MPa for NRC P+B NT. These bond strengths were significantly lower than those achieved for bonding to enamel. Prime and Bond NT and Prime and Bond 2.1, used in conjunction with acid etching, produce satisfactory bond strengths of compomer restorative material to enamel. Bond strengths to dentine were low. Show more

Keywords: Compomer, bond strength, enamel, dentine

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. 237-241, 2006

Authors: Ozeki, K. | Okuyama, Y. | Fukui, Y. | Aoki, H.

Article Type: Research Article

Abstract: Hydroxyapatite (HA) was coated onto titanium implants using radio frequency magnetron sputtering. The HA films were crystallized in an autoclave tube using low temperature hydrothermal treatment. The average film thickness on the implant was 1.1 μm. HA-coated and pure-titanium implants were inserted into canine mandibles for up to 24 weeks. Forty-eight implants were placed in eight beagles. After 2, 4, 12 and 24 weeks, implants were retrieved and prepared for histological observation, and the HA film thickness was determined using energy-dispersive X-ray spectroscopy. Light microscopy revealed that, after two weeks, the bone response to the HA-coated implants was much better …than to the pure titanium implants, and osteoblasts were observed at the bone–implant interface. After four weeks, the screw threads of the HA-coated implants were almost completely covered with bone. The HA film thickness rapidly decreased up to four weeks of implantation, then gently decreased, reaching 0.40±0.03 μm at the upper region of the implant after 12 weeks. That indicates that about 80% of the HA film had dissolved after 12 weeks of implantation. The rate of decrease in the HA film thickness was greater with increasing implant depth. Show more

Keywords: Sputtering, hydroxyapatite, dental implant

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. 243-251, 2006

Authors: Beaupied, Hélène | Dupuis, Aurélie | Arlettaz, Alexandre | Brunet-Imbault, Barbara | Bonnet, Nicolas | Jaffré, Christelle | Benhamou, Claude-Laurent | Courteix, Daniel

Article Type: Research Article

Abstract: The bone samples used in clinical and experimental trials must be the less damaged as possible to avoid alterations of their properties. However, the mode of storage might possibly alter the bone properties, particularly microarchitecture and strength. The aim of our study was to analyze the effects of deep-freezing and alcohol conservation techniques on the densitometric, microarchitectural and biomechanical parameters of rat femurs. The left femurs were elongated in uniaxial tension up to breakdown in order to calculate biomechanical parameters. The densitometric and microarchitectural properties of right femurs were evaluated using dual-energy X-ray absorptiometry and microcomputed tomography, respectively. Results showed …no significant difference in the parameters investigated between deep-freezing, alcohol storage and fresh femurs when comparing each parameter separately. Therefore, one month storage in alcohol or deep-freezing seemed to induce no harmful effect on densitometric, microarchitectural and biomechanical parameters of rat femurs. Show more

Keywords: Storage, femur, biomechanics, densitometry, microarchitecture

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. 253-259, 2006

Authors: Chen, Lih-Huei | Lai, Po-Liang | Tai, Ching-Lung | Niu, Chi-Chien | Fu, Tsai-Sheng | Chen, Wen-Jer

Article Type: Research Article

Abstract: Eight fresh porcine lumbar spines received a posterior instrumentation at L4–L5 using pedicle screw–rod system. Each specimen was tested utilizing laminectomies of varying extent. Group A (Integrity) preserved the spinous process and interspinous ligament; Group B (Partial laminectomy) removed the inferior portion of L4 spinous process and preserved the interspinous ligament of L3–L4; Group C (Complete laminectomy) removed the entire L4 spinous process. Hydraulic testing machine was used to generate an increasing moment up to 8400 N mm in flexion and extension. The intervertebral displacement on the superior adjacent disc between L3–L4 was measured using an extensometer. Under extension, no significant …difference in the intervertebral displacement was observed among three different models of laminectomy. However, under flexion, the intervertebral displacement on adjacent disc with complete laminectomy was statistically larger than those of integrity and partial laminectomies (P=0.000976 and P=0.0363, respectively). No difference was found between integrity and partial laminectomy groups (P>0.05). This study implies that an instrumented spine with integrity of posterior complex is less likely to develop adjacent instability than a spine with destruction of the anchoring point for supraspinous ligament. Show more

Keywords: Spinal fusion, adjacent segment, interspinous ligament, pedicle screw fixation, porcine model

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. 261-267, 2006

Authors: Kara, Sadık | Dirgenali, Fatma

Article Type: Research Article

Abstract: The purpose of this study was to evaluate principal component analysis method to power spectral density acquired with autoregressive modeling (AR) of carotid artery Doppler signals. Carotid artery Doppler signals from patient with atherosclerosis and healthy subjects were recorded. Afterwards, power spectral densities of these signals were obtained using AR method. The basic differences between the healthy and patients were obtained with 1st principal component obviously. These results could be extrapolated to situations involving noninvasive measurement where PCA can be extremely time saving. As a result the patient and healthy groups are separated clearly from each other via an arbitrary …power function y=ax with perfect accuracy resulting in a precision sensitivity and specificity of 100 percent and the use of PCA of physiological waveform is presented as a powerful method likely to be incorporated in future medical signal processing. Show more

Keywords: Atherosclerosis, carotid artery, power spectral density, principal component analysis, autoregressive

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. 269-277, 2006

Authors: Yang, Cheng-Huei | Huang, Hsiu-Chen | Yang, Cheng-Hong

Article Type: Research Article

Abstract: This paper aims to develop an enhanced rehabilitation and assessment system for people with impaired leg muscles, and for people who need to improve their leg muscle function. Through interactive design and real time evaluation, medical staff can totally control the training situation for patients and therefore provide a better training program, so that overall a better treatment performance can be achieved. The system consists of four major parts. Sensory and signal conversion circuits convert the lever arm lengths and muscle strengths of the leg into a proper electronic signal and then deliver this to the computer. Then, the intelligent …and interactive interface design lets a trainee complete the training process independently without the involvement of medical staff. In addition, the trainee can see the training results at the end of the training process on the computer screen. The training protection and evaluation mechanism effectively monitors the training situation, based on the individual status settings by the medical staff, and thus any further impairment can be avoided. The database management system is developed to store related personal data, system settings and training results, which can then be retrieved for control and assessment. In comparison to similar equipment the proposed system demonstrates a much better performance, particularly in system functions, accuracy, operation and costs. Show more

Keywords: Leg muscle, assessment, signal conversion

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. 279-286, 2006

Authors: Pulkkinen, Hertta | Tiitu, Virpi | Lammentausta, Eveliina | Laasanen, Mikko S. | Hämäläinen, Eija-Riitta | Kiviranta, Ilkka | Lammi, Mikko J.

Article Type: Correction

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. 287-287, 2006

Authors: Auger, François A.

Article Type: Research Article

Keywords: Tissue engineering, transplantation, grafts, skin, blood vessels, ligament

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S19-S25, 2006

Authors: Pulkkinen, Hertta | Tiitu, Virpi | Lammentausta, Eveliina | Hämäläinen, Eija-Riitta | Kiviranta, Ilkka | Lammi, Mikko J.

Article Type: Research Article

Abstract: One goal of functional tissue engineering is to manufacture scaffolds infiltrated with chondrocytes which are suitable for transplantation into the lesion areas of articular cartilage. Various research strategies are used to fabricate cartilage transplants which would have the correct phenotype, contain enough extracellular matrix components, and have structural and biomechanical properties equivalent to normal articular cartilage. We have investigated the suitability of viscose cellulose sponges as a scaffold for cartilage tissue engineering. The sponges were tested alone, or with recombinant human type II collagen cross-linked inside the material. Scanning electron microscopy and confocal microscopy were used to study the structure …of the scaffold during four weeks of cultivation. Cellulose and cellulose/recombinant type II collagen sponges were biocompatible for at least four weeks in cultivation, and gradual filling of the scaffold was observed. However, the constructs remained soft during the observation period, and were devoid of extracellular matrix composition typical for normal articular cartilage. Show more

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S29-S35, 2006

Authors: Schumann, D. | Kujat, R. | Nerlich, M. | Angele, P.

Article Type: Research Article

Abstract: Articular cartilage possesses little capacity for endogenous repair after having been damaged by disease or trauma. Various surgical procedures depending on ingrowth of mesenchymal stem cells into the defects showed repair with fibrocartilage which is of minor quality and less resistant against physical forces. New treatment options using Tissue Engineering strategies for cartilage repair showed intriguing results. Human mesenchymal stem cells (MSC) isolated from bone marrow are becoming increasingly recognized for their potential to generate different cell types and thereby function effectively in vitro or in vivo in tissue repair. Incorporation of MSCs in suitable tissue engineering scaffolds and culture …in chondrogenic medium can produce cartilage-like tissue. MSCs can be harvested from bone marrow by a small puncture of the iliac crest of patients. In contrast to chondral based repair this small procedure creates no additional harvest defect in the knee joints of the patient. Numerous publications show the beneficial influence of mechanobiological conditioning (e.g. mechanical compression, hydrostatic pressure, osmotic, shear, ultrasound) on the chondrogenic differentiation of dedifferentiated chondrocytes. In contrast to chondrocytes and cartilage explants there are few studies that examine the influence of mechanobiological stress on mesenchymal progenitor cells undergoing chondrogenesis. Using an in vitro aggregate culture system enhanced chondrogenesis of mesenchymal progenitor cells, detected by an increased extracellular matrix deposition of collagen and aggrecan, could be shown under repeated cyclic hydrostatic pressure. Similar results, with an increase in chondrogenic differentiation of mesenchymal progenitor cells could be detected, when the cells were loaded in three-dimensional matrices and subjected to cyclic, compressive load or low-intensity pulsed ultrasound. This review will summarize the current state of knowledge in the field of mechanobiological conditioning of mesenchymal stem cells and its possible clinical application. Show more

Keywords: Chondrogenesis, stem cells, bone marrow, mechanobiology, cartilage

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S37-S52, 2006

Authors: Amédée, J. | Guillotin, B. | Pallu, S. | Bareille, R. | Guignandon, A. | Bourget, Ch. | Durrieu, M.C. | Bordenave, L.

Article Type: Research Article

Abstract: In the field of osseous substitution, the possibilities being offered to the surgeons prove sometimes difficult to apply in particular in the case of great losses of osseous substance. For these reasons, it is necessary to develop innovative techniques to satisfy the request increasing for substitutes and to see appearing on the market solutions combining availability, perenniality and biosecurity of the implants. The implantation of stem cells in a biomaterial opens a way of development of therapeutic substitute. Moreover, in order to optimize the rehabitation of the biomaterials by the cells and the host tissues, the second approach consists in …modifying the surface of materials by the coating or the grafting of adhesive factors in order to stimulate their colonization. At least, one cannot consider a tissue mechanism of repair without a better knowledge of the respective role of the various cell populations implied in the rebuilding of this tissue and their cell to cell communication processes. Show more

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S53-S60, 2006

Authors: Matoušková, Eva | Brož, Ludomír | Štolbová, Vlasta | Klein, Leo | Kőnigová, Radana | Veselý, Pavel

Article Type: Research Article

Abstract: The tissue engineered skin should be composed of both dermal and epidermal layers. We combined cultured human allogeneic keratinocytes with acellular xenodermis prepared from pig xenografts. The resulting composite skin was termed recombined human/pig skin (RHPS), and could be cultured in both, undifferentiated and differentiated phenotype. The undifferentiated RHPS was grown submerged and formed 1–2 layers of keratinocytes. The differentiated phenotype (D-RHPS) was grown at the air-liquid interface and formed 5–20 cell layers similar to the normal epidermis, including the granular and horny layers. Undifferentiated RHPS has skin-like consistency and has been successfully used for treatment of burns and skin …defects using “upside-down” application. Donor sites and deep dermal burn wounds prepared by tangential excision or deep dermabrasion grafted with RHPS healed in the course of about one week after keratinocyte transplantation. Simple acellular xenodermis without keratinocytes can also be used as temporary cover for donor sites, small to medium leg ulcers and other skin defects. Xenodermis can be fully sterilized and stored at the room temperature. Show more

Keywords: Acellular xenodermis, human keratinocytes, recombined human/pig skin, wound grafting, burns

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S63-S71, 2006

Authors: Auxenfans, C. | Colloud, M. | Debard, A.L. | Braye, F.M. | Amini, M. | Allombert-Blaise, V. | Builles, N. | Claudy, A. | Damour, O.

Article Type: Research Article

Abstract: The clinical interest of using allogenic epidermal sheets (AES) has largely been shown [1,2,3]. As well as covering, they also stimulate healing, by simultaneously secreting numerous growth factors (GFs), although little is known on their mechanism of action. Our objectives were to: (a) devise a test for the efficacy of AES release, (b) select keratinocyte-secreting strains and optimal culture conditions. Three GFs were selected: IL-1α, IL-8 and VEGF. Three different keratinocyte strains were cultured for 3 and 6 days after confluence for 3 passages. Assays were performed after 3 h and 24 h+3 h after dispase treatment (AES conservation for …24 h then change of medium and sampling after 3 h). AES were found to secrete GFs in DMEM and the amounts were greater when cultured for 6 rather than 3 days after confluence. Each strain had different secretory patterns depending on passage and time in culture, this variability being explained by inter-individual heterogeneity. Show more

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S73-S83, 2006

Authors: Dezutter-Dambuyant, C. | Black, Annie | Bechetoille, Nicolas | Bouez, Charbel | Maréchal, Sylvie | Auxenfans, Céline | Cenizo, Valérie | Pascal, Pascale | Perrier, Eric | Damour, Odile

Article Type: Research Article

Abstract: The development of human skin models that have the same properties as genuine human skin is of particular significance. Very promising skin models are the three-dimensional artificial skin constructs, which, similar to genuine skin, consist of an epidermis of differentiated keratinocytes and a dermis. A skin equivalent based on a collagen–glycosaminoglycan–chitosan dermal substrate has been developed to meet the growing demand in tissue engineered skin equivalents. We used this model to investigate whether CD34-generated Langerhans/dendritic cell precursors could be integrated into this skin equivalent model and pursue their differentiation without addition of cytokine and growth factor. To address the issue …of dendritic cell (DC) differentiation, an endothelialized skin equivalent coculture model was used to study the behaviour of haematopoietic progenitor cells (HPC) in epidermal and dermal environments. CD34+ HPC were cultured for 6 days with GM-CSF, TGFβ1 and TNFα and seeded in the endothelialized skin equivalent at different time points to favour dermal or epidermal integration. This integration (after keratinocyte seeding, only and in absence of exogenous GM-CSF, TNFα, TGFβ1) gave rise both cutaneous DC, i.e. epidermal Langerhans cells (CD1a+ , HLA-DR+ ) and dermal DC (DC-SIGN+ , HLA-DR+ ) while endothelial cells are sufficiently activated to acquire HLA-DR expression. For the first time, the presence of a living dermal equivalent could provide a more complex environment integrating vascular components to study the differentiation of interstitial DC in a dermis equivalent. Such sophisticated skin equivalent may clarify some intriguing aspects of the numerous regulatory mechanisms controlling skin homeostasis. Show more

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S85-S94, 2006

Authors: Builles, Nicolas | Bechetoille, Nicolas | Justin, Virginie | Ducerf, Amélie | Auxenfans, Céline | Burillon, Carole | Sergent, Michèle | Damour, Odile

Article Type: Research Article

Abstract: Our objective was to formulate a medium for monolayer culture optimising both keratocyte growth and preservation of the keratocyte phenotype. Methods: An experimental matrix selected 14 media to test, using 7 components. Selection criteria were growth rates over 5 passages and expression of the CD34 marker. Results: Acetylcholine, insulin and vitamin C had no effect on growth and differentiation. The DMEM + Ham F12 1 : 1 based medium was selected for its initial effect on growth. At concentrations of 5 ng/ml, b-FGF improved the percentage of CD34+ cells without reducing growth rates. New-born calf serum (NCS) had a greater effect on …growth than foetal calf serum (FCS). We showed three major interactions: between b-FGF and IGF-1, FCS and IGF-1 and NCS and b-FGF. Conclusion: We selected the following medium, which provides optimal growth and preservation of the CD34+ phenotype: DMEM/HAM-F12 + 10% NCS + 5 ng/ml b-FGF + antibiotics. Show more

Keywords: Keratocytes, culture, medium

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S95-S104, 2006

Authors: Vinatier, C. | Guicheux, J. | Daculsi, G. | Layrolle, P. | Weiss, P.

Article Type: Research Article

Abstract: Tissue engineering is an emerging field of regenerative medicine which holds promise for the restoration of tissues and organs affected by chronic diseases, age-linked degeneration, congenital deformity and trauma. During the past decade, tissue engineering has evolved from the use of naked biomaterials, which may just replace small area of damaged tissue, to the use of controlled three-dimensional scaffolds in which cells can be seeded before implantation. These cellularized constructs aims at being functionally equal to the unaffected tissue and could make possible the regeneration of large tissue defects. Among the recently developed scaffolds for tissue engineering, polymeric hydrogels have …proven satisfactory in cartilage and bone repair. Major technological progress and advances in basic knowledge (physiology and developmental biology) are today necessary to bring this proof of concept to clinical reality. The present review focuses on the recent advances in hydrogel-based tissue engineered constructs potentially utilizable in bone and cartilage regenerative medicine. Show more

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S107-S113, 2006

Authors: Boura, C. | Kerdjoudj, H. | Moby, V. | Vautier, D. | Dumas, D. | Schaaf, P. | Voegel, J.-C. | Stoltz, J.-F. | Menu, P.

Article Type: Research Article

Abstract: Polyelectrolyte multilayer films were recently investigated to favour attachment of Human Vein Umbilical Endothelial Cells (HUVECs) on non-adhesive surfaces. In this study, we evaluated the initial adhesion of HUVECs after 3 h of seeding on two polyelectrolyte multilayer films ending by poly(D-lysine) (PDL) or poly(allylamine hydrochloride) (PAH). In order to obtain information about initial adhesion of HUVECs, cell morphology as well as the expression of β1 integrins, specific receptors of adhesion, were evaluated after 3 h of seeding on polyelectrolyte multilayer films. The data were also compared to PDL or PAH monolayers (polyelectrolytes terminating the multilayer architecture). The expression of …β1 integrins was not different, whatever are the studied surfaces. However, HUVECs spreading on polyelectrolyte multilayer films, in particular on PAH ending film, was more important as compared to polyelectrolyte monolayers or glass. In conclusion, the best initial adhesion conditions of HUVECs on polyelectrolyte films could not be elucidated, moreover the results suggested also that β1 integrins could only play a limited role. Show more

Keywords: Polyelectrolyte multilayers, endothelial cells, cell adhesion, atomic force microscopy, β1 integrins

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S115-S121, 2006

Authors: Kerdjoudj, H. | Boura, C. | Marchal, L. | Dumas, D. | Schaff, P. | Voegel, J.-C. | Stoltz, J.-F. | Menu, P.

Article Type: Research Article

Abstract: Decellularized allograft tissues have been identified as a potential extracellular matrix scaffold for tissue-engineered vascular substitutes. In order to improve the thromboresistance, it is necessary to pre-coat the intra-luminal vessel surface. Recently a new surface modification technique appeared, based on the alternate adsorption of positive and negative charged polyelectrolytes. Our objective was to develop an alternative vascular scaffold made of decellularized human umbilical arteries treated with a PAH/PSS polyelectrolyte multilayered film. The vessels luminal surfaces covered with the multilayer film were observed by electronic scanning microscopy. Our observations showed that the luminal surface is completely devoid of ECs following treatment …with trypsin. A top view of the coated artery indicated that the multilayer uniformly covered internal surface of the vessels. The successful of the multilayer correct deposition and retention on the arterial wall were controlled by confocal microscopy using a fluorescent polyelectrolyte (rhodamine-PAH). The data suggest that decellularized cryopreserved arteries represent a potential scaffold for further vascular tissue engineering efforts. Moreover, the multilayer films can be used to coat biological surfaces and following the terminated layer (PAH or PSS), favour the cell adhesion or cell resistance. Show more

Keywords: Cardiovascular engineering, vascular grafts, umbilical arteries, surface modification, thin polyelectrolyte multilayer film

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S123-S129, 2006

Authors: Vaquette, C. | Fawzi-Grancher, S. | Lavalle, P. | Frochot, C. | Viriot, M.-L. | Muller, S. | Wang, X.

Article Type: Research Article

Abstract: Nowadays, synthetic biodegradable polymers, such as aliphatic polyesters, are largely used in tissue engineering. They provide several advantages compared to natural materials which use is limited by immunocompatibility, graft availability, etc. In this work, poly(L-lactic) acid (PLLA), poly(DL-lactic) acid (PDLA), poly-ε-caprolactone (PCL), poly(L-lactic)-co-caprolactone (molar ratio 70/30) (PLCL) were selected because of their common use in tissue engineering. The membranes were elaborated by solvent casting. Membrane morphology was investigated by atomic force microscopy. The membranes were seeded with human fibroblasts from cell line CRL 2703 in order to evaluate the biocompatibility by the Alamar blue test. The roughness of the membranes …ranged from 4 nm for PDLA to 120 nm and they presented very smooth surface except for PCL which beside a macroscopic structure due to its hydrophobicity. Human fibroblasts proliferated over 28 days on the membranes proving the non-in vitro toxicity of the materials and of the processing method. A further step will be the fabrication of three-dimensional scaffold for tissue engineering and the treatment of the scaffolds to augment cell adhesion. Show more

Keywords: Biocompatibility, fibroblast, biodegradable polymer, proliferation, scaffold

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S131-S136, 2006

Authors: Shalaw, Fawzi-Grancher | Slimani, Said | Kolopp-Sarda, M.N. | Marchand, Michel | Faure, G. | Stoltz, Jean-François | Muller, Sylvaine

Article Type: Research Article

Abstract: It is well known today that mechanical forces are one of the important factors that induce a variety of cellular responses including morphological changes, protein synthesis, and gene expression and which are involve in tissue remodelling. We studied the effect of uniaxial cyclic stretching on the proliferation, collagens, and tenascin C mRNA expression of fibroblasts under different concentrations of foetal bovine serum. Proliferation was studied by cell cycle analysis, mRNA expression of collagen and tenascin C was studied by RT-PCR. Human fibroblasts were grown in silicon sheet coated with 1% gelatin. Cyclic stretching (5% elongation) was applied at 0.5 Hz …(30 cycle/min), for 24 h with two concentrations of the serum (0.5%, 10% FBS). We showed that stretching enhances the synthesis of collagen and tenascin C, but do not act on the proliferation. In contrast, higher concentration of serum enhances the proliferation. These findings suggest that both mechanical stretching and serum concentration can modulate proliferation and extra cellular matrix synthesis in human fibroblasts. Show more

Keywords: Cyclic stretching, FBS, proliferation, extracellular matrix synthesis

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S137-S144, 2006

Authors: Silva, João N. | Filipe, Paulo | Morlière, Patrice | Mazière, Jean-Claude | Freitas, João P. | Cirne de Castro, José L. | Santus, René

Article Type: Research Article

Abstract: Photodynamic therapy (PDT) by porphyrins and related tetrapyrrole derivatives is an emerging new treatment modality of tumors of lung, eosophagus and skin and of age-related macular degeneration. Phase III clinical trials for other applications such as re-stenosis after angioplasty are also underway. Under systemic conditions, the transport of porphyrin photosensitizers by serum low density lipoproteins and their specific delivery to tumor cells and vasculature is a determinant of treatment effectiveness. However, this effectiveness can be improved by increasing the selectivity of the photosensitizer uptake by tumors and by using photosensitizers absorbing light in the 660–800 nm range where tissues have …the highest transmittance. Another treatment showing great promise is the PDT of skin cancers after topical application of the protoporphyrin IX precursor delta-aminolevulinic acid (or its ester forms). In all the cases, the photosensitizers should be rapidly excreted to avoid a long lasting skin photosensitivity. Show more

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S147-S154, 2006

Authors: Cattan, Valérie | Kakou, Augustine | Louis, Huguette | Lacolley, Patrick

Article Type: Research Article

Abstract: Stiffening of large arteries is considered as an independent predictor of cardiovascular events. This article summarizes recent theories on the mechanisms contributing to arterial stiffness involving extracellular matrix proteins, endothelial and smooth muscle cells, cell–matrix interactions, and genetic background. Despite the important role of genetic factors in essential hypertension, little is known about the genetic of arterial stiffness. In the future, candidate genes approaches will allow to determine the cellular and molecular mechanisms of arterial stiffness. A review of different strategies aimed at lowering arterial stiffness and potentially reducing cardiovascular risk are presented. Lifestyle changes and antihypertensive drugs have showed …beneficial effects in reversing stiffness. New emerging tools as gene therapy and molecules involved in matrix attachments or crosslink of collagen may be promising. Therapeutic trials using such strategies will be necessary to demonstrate their impact on morbidity and mortality. Show more

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S155-S161, 2006

Authors: Li, Yin-Ping | Latger-Canard, Véronique | Marchal, Luc | Li, Na | Ou-Yang, Jing-Ping | Stoltz, Jean-François

Article Type: Research Article

Abstract: Immune homeostasis is important for the protection of a host from pathogen aggression, as well as for preventing autoimmunity. Dendritic cells (DCs), the most potent antigen presenting cells, are critical in innate, adaptive immunity and in central tolerance. Recently, their involvement in peripheral tolerance has been shown. Whether DCs induce immunity or tolerance depends on their state of maturation. Different subsets of tolerogenic DCs have been identified in vivo, either in physiological, or pathological conditions, such as tumors, or GVHD. Moreover, tolerogenic DCs can be generated in vitro, by using different culture conditions, such as IL-10 or TGF-β. In our …study, we obtained tolerogenic DCs, by culturing them in the presence of human mesenchymal stem cells (MSCs). Show more

Keywords: Dendritic cells (DCs), tolerogenic DCs, immunity, tolerance, mesenchymal stem cells (MSCs)

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 4, pp. S163-S170, 2006