Cell adhesion is dependent on the presence of extracellular matrix proteins, which present specific cues for cellular adhe- sion receptors, such as integrins. Adsorption of proteins from surrounding liquids as well as their biological activity is con- trolled by the physicochemical surface properties of materials. However, the majority of polymeric biomaterials are hydropho- bic, which may cause alterations of protein conformation and hence their biological activity. We have explored different techniques to modify the surface of biomaterials to maintain the biological activity of proteins like fibronectin and observed improved cell contacting properties of these materials. In the studies presented here, we applied physical principles to modify the surface of hydrophobic or charged (polymeric) materials. A first approach was based on the immobilisation of poly (ethylene oxide) on hydrophobic materials. Amphiphilic poly (ethylene oxide) block copolymers (Pluronics) were adsorbed from aqueous solutions on material surfaces. In con- trast to other studies low coating concentrations of Pluronics were applied. It was demonstrated that adsorption of low quan- tities of Pluronics improve adhesion and spreading of cells on hydrophobic materials. This effect was attributed to a stabilisa- tion of conformation of proteins such as fibronectin by neigh- bouring PEG molecules. In further studies we explored also the ability of the layer-by-layer technique to assemble charged bio- genic macromolecules (polyelectrolytes) as ECM-like struc- tures on material surfaces. Here we used chitosan, heparin and fibronectin, which were alternating adsorbed. We obtained control over the adhesive properties of the substratum indicated by adhesion and spreading of cells by the selection of polyelec- trolytes, but also the pH of assembly and the number of layers. Overall, the techniques we described herein can be applied to different types of biomaterials. The selection and arrangement of molecules may be used as a means to control adsorption of proteins and thus the adhesion of cells. 4 Construction and validation of a carrier to shuttle nucleic acid-based drugs from biocompatible polymers to living cells C. Lande b , M. Evangelista a , L. Tedeschi a , G. Rainaldi a , L. Citti a a CNR, Institute of Clinical Physiology, via Moruzzi, 1, 56124 Pisa, Italy b Pharmacy Faculty, University of Pisa, via Bonanno, 33, 56122 Pisa, Italy Antisense, ribozyme, siRNA and DNA decoys are nucleic- acid-based molecules able to inhibit gene expression at either the transcriptional or post-transcriptional level. For that, they are considered very promising tools in molecular gene medi- cine. In case of tissues and organs must be targeted, the deliv- ery and release of nucleic acids are the main problems to be solved. A carrier made of a positively charged polymer (poly- cation) bound to a cell-penetrating peptide (CPP) to be loaded of an oligonucleotide could bypass these difficulties. Firstly, we synthesized two carriers (polycation + CPP) and measured their ability to complex oligonucleotides. The result- ing complexes were administered to different types of cultured cells including porcine vascular smooth muscle cells. One of the synthesized carriers was able to shuttle a fluorescein- labelled oligonucleotide in living cells. Secondly, we tested matrices of PLLA, PLGA and PCL. The in vitro results showed that the nature of employed sol- vents, the thickness of resulting film, the drying techniques and polymer-solvent ratios were crucial to obtain an efficient release of the embedded complex oligonucleotide-carrier. In vivo experiments are in progress to test the release in living cells. 5 A bioreactor for the electromechanical stress of cells to address towards the cardiac phenotype F. Lotti a , G. Vassura a , C. Melchiorri b , L. Biagotti b , C. Muscari c,e , E. Giordano c,d,e , M. Govoni c,d,e , F. Bonafé e , M. Carboni e , C.M. Caldarera e , S. Cavalcanti b,d,e a Dipartimento di Ingegneria delle Costruzioni Meccaniche, Nucleari, Aeronautiche e di Metallurgia, Unibo b Dipartimento di Elettronica, Informatica e Sistemistica, Unibo c Dipartimento di Biochimica, “G. Moruzzi”, Unibo d Laboratorio di Ingegneria Cellulare e Molecolare per lo Sudio dei Bionanossistemi, Unibo e Istituto Nazionale per la Ricerda Cardiovascolare, Unibo The aim of this work is the development of a bioreactor useful for the commitment of competent cells—such as rat neo- natal cardiac muscle cells and rat femur bone marrow mesenchimal cells—towards the mature cardiomyocyte pheno- type. It is expected that transferring a controlled mechanical stress to a polymeric scaffold bearing the cells could improve their (trans)differentiation, in presence of appropriate growth factors and of a concurrent electrical field stimulation. Obtain- ing an engineered 3D tissue patch, with spontaneous and coherent contractile activity, will be an initial step critical for further studies addressing the effectiveness of this strategy to induce a regenerative response in ischemic myocardial disease. Indeed, this approach is intended to mimic the cardiac environ- ment in vitro, to foster the cellular (trans)differentiation pro- cess. Aspecific feature of the cardia muscle is in fact the coor- dinated electromechanical coupling among its cells, which is however hard to reproduce in standard static culture conditions. A controlled cyclic stretch can be applied to a cell population in culture when it is seeded onto an elastic and deformable bioploymer. Chemical and structural properties of such a sup- port to be used within a bioreactor are a first critical point to face, as a bio- and cyto-compatible biomaterial with appropri- ate mechanical performances is a specific requirement. In this study we will use a biopolymer showing both these specific features. Biocompatibility of patches of a polymeric matrix can be enhanced by introducing specific surface functional chemical groups and a 3D environment can be created by Abstracts / Biomedicine & Pharmacotherapy 60 (2006) 468–479 469