Archive of Medical Research

Controlled release of bisphosphonate from a calcium phosphate biomaterial inhibits osteoclastic resorption in vitro.

Calcium phosphate biomaterials such as calcium deficient apatite (CDA) have been contemplated as carrier for delivery of bisphosphonate in bone tissues. In the present work, we have investigated the in vitro biological properties of Zoledronate-loaded CDA. CDA was loaded with zoledronate according to a previously described coating process. (31)P MAS NMR spectra demonstrated the effective loading of zoledronate onto CDA. Using (14)C labeled zoledronate, we then demonstrated the in vitro release of zoledronate from CDA. In a first set of experiments, we confirmed that Zoledronate reduced the number of TRAP-, vitronectin receptor-, and F-actin ring-positive cells as well as the resorption activity of osteoclasts obtained from a total rabbit bone cell culture. Interestingly, Zoledronate-loaded CDA and its extractive solutions decreased the osteoclastic resorption. Finally, zoledronate-loaded CDA did not affect the viability and alkaline phosphatase activity of primary osteoblastic cells. These data demonstrate that CDA is effective for loading and release of zoledronate. The released zoledronate inhibited osteoclastic resorption without affecting osteoblasts. Our findings therefore suggest that such a drug delivery system would allow an increase in the efficiency of bisphosphonates by being locally available. Further experiments are now required to evaluate the in vivo antiresorptive activity of this concept. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Faucheux C, Verron E, Soueidan A, Josse S, Arshad MD, Janvier P, Pilet P, Bouler JM, Bujoli B, Guicheux J.

INSERM, U791, LIOAD, Nantes, F‐44042, France.

Cationic supramolecules consisting of oligoethylenimine-grafted alpha-cyclodextrins threaded on poly(ethylene oxide) for gene delivery.

In this study, three cationic polyrotaxanes composed of multiple oligoethylenimine-grafted alpha-cyclodextrin rings threaded on a poly(ethylene oxide) chain have been synthesized and characterized, and investigated for gene delivery. All three cationic polyrotaxanes could efficiently compact pDNA into small nanoparticles, with diameters ranging from 100 to 200 nm. In both BHK-21 and MES-SA cell lines, the transfection efficiency mediated by the cationic polyrotaxanes were comparable or even higher than that of branched polyethylenimine (PEI) with a molecular weight of 25 kDa, which is one of the most efficient gene-delivery vectors to date. Moreover, the cationic polyrotaxanes showed much lower cytotoxicity than branched PEI (25 kDa). Hence, these cationic poly rotaxanes have high potentials as new carriers for gene delivery. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Yang C, Li H, Wang X, Li J.

Division of Bioengineering, Faculty of Engineering, National University of Singapore, 7 Engineering Drive 1, Singapore 117574, Singapore.

Recombinant human bone morphogenetic protein-2/atelocollagen composite as a new material for ossicular reconstruction.

Ossicular reconstruction is the rebuilding of the damaged middle ear. There are many different prosthesis and techniques used to reconstruct the middle ear ossicles. However, precision in the surgical procedures and prostheses used for ossiculoplasty are still imperfect. The objective of this study was to evaluate the potential of recombinant human bone morphogenetic protein-2 (rhBMP-2)/ atelocollagen composite for ossicular reconstruction implanted in the tympanic cavity of rat. The ossicles were extirpated by perforating the tympanic membranes of rats. rhBMP-2/atelocollagen composite was implanted as substitute of ossicles in intimate contact with the tympanic membrane. Composites were subjected to histological, immunohistochemical, and radiological examination. To evaluate the auditory function, auditory brainstem response (ABR) was measured. rhBMP-2/atelocollagen composites showed good stability and durability without any inflammatory reaction within the tympanic cavity. The process of new bone formation was similar to intramembranous ossification. They also demonstrated that the hearing ability was re-established by ABR threshold shifts. rhBMP-2/atelocollagen composite exhibited excellent potential for ossicular reconstruction, maintaining their vibratory function. This ossicular tissue engineering may be considered as a future therapeutic strategy for ossiculoplasty. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Takeuchi A, Tsujigiwa H, Murakami J, Kawasaki A, Takeda Y, Fukushima K, Rodriguez AP, Nagatsuka H, Yamada M, Nishizaki K.

Department of Otolaryngology‐Head and Neck Surgery, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.

PLGA doping of PCL affects the plastic potential of human mesenchymal stem cells, both in the presence and absence of biological stimuli.

A range of poly epsilon-caprolactone (PCL) films mixed/doped with poly(lactide-co-glycolide) (PLGA) (65:35) in 0, 10, 20, and 30 wt % were produced, sterilized using ethylene oxide, and analyzed using FTIR. Characterized human mesenchymal stem cells (hMSCs) were cultured in contact with the materials in basal, chondrogenic, and osteogenic medium for time periods up to 28 days, to determine if the materials could induce differentiation of MSC both in the presence and absence of biological stimuli. Viable cell adhesion was analyzed under all conditions. Collagen I, collagen II, sox-9, osteocalcin, osteopontin, osteonectin, and CBFA1 were evaluated at both the mRNA (real-time PCR) and protein production levels (fluorescent immunohistochemistry) and used to identify cell differentiation. Pure PCL and PCL mixed with PLGA demonstrated a chondrogenic potential. Only PCL 8 (80 wt % PCL, 20 wt % PLGA) facilitated osteogenic differentiation of MSCs under osteogenic conditions. This was attributed to the increased hydrophilic nature of the surface allowing sufficient homogeneous cell attachment and the formation of filamentous F-actin in the cells, allowing osteogenic differentiation. Of all materials tested, PCL 7 (70 wt % PCL, 30 wt % PLGA) demonstrated the greatest chondrogenic differentiation potential under basal and stimulated conditions at both the mRNA and protein production level. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Curran JM, Tang Z, Hunt JA.

Division of Clinical Engineering (UK CTE), UK BioTEC, University of Liverpool, Liverpool, United Kingdom.

Proteomic analysis of Staphylococcus aureus biofilms grown in vitro on mechanical heart valve leaflets.

The in vitro colonization of three commercial heart valve leaflets by Staphylococcus aureus was investigated. The leaflets, made of pyrolytic carbon alloyed with or without silicon, displayed similar surface properties (wettability, roughness) and were readily colonized by S. aureus that formed patchy biofilms on the three supports. A proteomic approach was used to assess the physiological status of biofilm populations by comparing their protein maps to those of bacteria cultured as free cells in the presence or absence of biofilm substratum. Principal component analysis (PCA) revealed, for each tested leaflet, statistical relationships between the protein maps of the biofilm and free-floating microbial populations. A spot-by-spot comparison of protein levels on two-dimensional electropherograms showed that many proteins were accumulated or underproduced by microbial populations grown in the presence of a leaflet compared with protein levels in control free populations. The number of accumulated proteins was noticeably higher than that of underproduced polypeptides. This protein overproduction was emphasized in biofilm populations. Several proteins, some of which were identified, were differentially produced by both surface-associated planktonic and biofilm-grown cell populations compared with control free-cell ones cultured in the absence of leaflet, whatever the leaflet tested. The potential of this proteomic approach for fighting against microbial adhesion and biofilm formation is discussed. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Bénard L, Litzler PY, Cosette P, Lemeland JF, Jouenne T, Junter GA.

Research Group on Antimicrobials and Microorganisms, EA 2656, Charles Nicolle University Hospital, Rouen, France.

An in vitro comparison of possibly bioactive titanium implant surfaces.

The aim of the study was to compare Ca and P formation (CaP) and subsequent bone cell response of a blasted and four different possibly bioactive commercially pure (cp) titanium surfaces; 1. Fluoride etched (Fluoride), 2. Alkali-heat treated (AH), 3. Magnesium ion incorporated anodized (TiMgO), and 4. Nano HA coated and heat treated (nano HA) in vitro. Furthermore, to evaluate the significance of the SBF formed CaP coat on bone cell response. The surfaces were characterized by Optical Interferometry, Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). CaP formation was evaluated after 12, 24 and 72 h in simulated body fluid (SBF). Primary human mandibular osteoblast-like cells were cultured on the various surfaces subjected to SBF for 72 h. Cellular attachment, differentiation (osteocalcin) and protein production (TGF-beta(1)) was evaluated after 3 h and 10 days respectively. Despite different morphological appearances, the roughness of the differently modified surfaces was similar. The possibly bioactive surfaces gave rise to an earlier CaP formation than the blasted surface, however, after 72 h the blasted surface demonstrated increased CaP formation compared to the possibly bioactive surfaces. Subsequent bone cell attachment was correlated to neither surface roughness nor the amount of formed CaP after SBF treatment. In contrast, osteocalcin and TGF-beta(1) production were largely correlated to the amount of CaP formed on the surfaces. However, bone response (cell attachment, osteocalcin and TGF-F production) on the blasted controls were similar or increased compared to the SBF treated fluoridated, AH and TiMgO surface. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Göransson A, Arvidsson A, Currie F, Franke-Stenport V, Kjellin P, Mustafa K, Sul YT, Wennerberg A.

Department of Biomaterials, Institute of Surgical Science, Sahlgrenska Academy at Göteborg University, Göteborg, Sweden.

Supramolecular hydrogels based on self-assembly between PEO-PPO-PEO triblock copolymers and alpha-cyclodextrin.

This article reports a detailed study on the hydrogel formation of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers with alpha-cyclodextrin (alpha-CD) in aqueous solutions. The gelation kinetics and the gel rheological properties were studied using viscometry. The sol-gel phase transitions were studied using phase diagrams, while the gelation mechanism was studied using differential scanning calorimetric analysis. It was concluded that the gelation was induced by the complex formation between the PEO segments of the PEO-PPO-PEO triblock copolymer and alpha-CD, and the further self-assembly of the partially formed inclusion complexes. The addition of alpha-CD largely reduced the concentration of the copolymer needed for gel formation. The gels were thixotropic and reversible, and potentially suitable for use as an injectable drug-delivery system. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Ni X, Cheng A, Li J.

Institute of Materials Research and Engineering, National University of Singapore, 3 Research Link, Singapore 117602, Singapore.

Studies of the cellular uptake of hydrogel nanospheres and microspheres by phagocytes, vascular endothelial cells, and smooth muscle cells.

Intensive research efforts have been placed on the development of nanospheres for targeted drug delivery for treating a variety of diseases, including coronary restenosis, cancer, and inflammatory reactions. Although most of these drug-bearing spheres are delivered via intravenous administration, little is known about the effect of sphere physical characteristics on the responses of vascular and blood cells. To find the answer, this work was aimed to investigate the cellular uptake of nanosized (100 nm) and microsized hydrogel spheres (1 mum) made of poly(N-isopropylacrylamide) by vascular cells and phagocytes under various flow conditions in vitro. We found that the cellular uptake of nanospheres depended on incubation times and sphere concentrations as well as on the introduced shear stress levels of the medium. Measurements of the intracellular-released fluorescence and confocal fluorescence microscopy revealed that nanospheres were internalized by endothelial cells and smooth muscle cells more than microspheres, whereas microspheres were rapidly taken up by phagocytes, especially at high concentration. Our results strongly suggest that hydrogel nanospheres are more effective as an intravascular delivery system compared to microspheres in the terms of vascular cellular uptake and biocompatibility. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Nguyen KT, Shukla KP, Moctezuma M, Braden AR, Zhou J, Hu Z, Tang L.

Department of Bioengineering, The University of Texas at Arlington, Arlington, Texas 76019.

Electrosynthesis of hydrogel films on metal substrates for the development of coatings with tunable drug delivery performances.

Novel polyacrylates-based hydrogel thin films were prepared by electrochemical polymerization, a new method to obtain hydrogels directly onto metal substrates. 2-Hydroxy-ethyl-methacrylate (HEMA), a macromer poly (ethylene-glycol diacrylate) (PEGDA) and PEGDA copolymerized with acrylic acid (AA) were used to obtain hydrogels. The electrosynthesized coatings were characterized by X-ray photoelectron spectroscopy, to assess their surface chemical composition, and by water content determination measurements, to characterize the swelling behavior. In particular, quartz crystal microbalance with dissipation monitoring was used to evaluate the pH-dependency of the swelling for AA-containing hydrogels. Moreover, a model protein (bovine serum albumin) and a model drug (caffeine) were entrapped within the hydrogel coatings during electrosynthesis, to examine the release performances and mechanisms of the electrosynthesized hydrogels. It was observed that all the examined polymers showed significant release properties and, in particular, AA-containing hydrogel films confirmed a strong pH-dependence as expected. These coatings seem to be promising in orthopedic field for in situ drug delivery applications. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

De Giglio E, Cometa S, Satriano C, Sabbatini L, Zambonin PG.

Department of Chemistry, University of Bari, Via E. Orabona 4 I‐70126 Bari, Italy.

Enhancing neurite outgrowth from primary neurones and neural stem cells using thermoresponsive hydrogel scaffolds for the repair of spinal cord injury.

In this study, thermoresponsive xyloglucan hydrogel scaffolds were investigated as candidates for neural tissue engineering of the spinal cord. The hydrogels were optimized to provide similar mechanical properties to that of native spinal cord, although also being functionalized through the immobilization of poly-D-lysine to promote neurone adhesion and neurite outgrowth. Under 2D and 3D culture conditions, xyloglucan scaffolds supported the differentiation of primary cortical neurones. Furthermore, functionalization provided a means of controlling and optimizing the cell diameter, number, migration and the neurite density, and the direction of growth. The interaction of neural stem cells (NSCs) was also investigated on the xyloglucan scaffolds in vitro. The survival of the NSCs and the axonal extensions on the scaffolds were similar to that of the primary cortical neurones. These findings suggest that xyloglucan-based materials are suitable for providing a neurotrophic milieu. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Nisbet DR, Moses D, Gengenbach TR, Forsythe JS, Finkelstein DI, Horne MK.

Department of Materials Engineering, Division of Biological Engineering, Monash University, Victoria 3800, Australia.