title: The anti-calcification potential of a silsesquioxane nanocomposite polymer under in vitro conditions: potential material for synthetic leaflet heart valve.
abstract: Calcification currently represents a major cause of failure of biological tissue heart valves. It is a complex phenomenon influenced by a number of biochemical and mechanical factors. Recent advances in material science offer new polymers with improved properties, potentially suitable for synthetic leaflets heart valves manufacturing. In this study, the calcification-resistance efficacy and mechanical and surface properties of a new nanocomposite polymeric material (polyhedral oligomeric silsesquioxane-poly(carbonate-urea)urethane; POSS-PCU) which has been developed by our group are assessed by means of in vitro testing. In particular, thin sheets of nanocomposite, glutaraldehyde-fixed bovine pericardium (BP) and polyurethane (PU) were exposed to a calcium solution into a specially designed in vitro accelerated physiological pulsatile pressure system for a period of 31days and a total of 4×10(7) cycles. The samples were investigated for signs of calcification after exposure to calcium solution by means of X-ray, microscopic and chemical inspections. Mechanical and surface properties were also studied using stress-strain behaviour and surface morphology and hydrophobicity. Comparison shows that, in the experimental conditions, the level of calcification for the nanocomposite is considerably lower than for the fixed BP (p=0.008) and PU samples (p=0.015). Also, mechanical properties were unchanged in POSS-PCU, while there was a significant deterioration in PU samples (p<0.05). Hydrophobicity was significantly reduced in both the POSS-PCU and PU samples (p<0.0001). However, the POSS-PCU nanocomposite remained more hydrophobic than the PU sample (p<0.0001). Less platelet adhered to the POSS-PCU compared to the PU (p<0.0001). These results indicate that the use of this nanocomposite in synthetic leaflets heart valves may lead to potential advantages in terms of long-term performances and durability.
authors.affiliation: Centre for Nanotechnology & Regenerative Medicine, UCL Division of Surgery & Interventional Sciences, University College London, London, UK.
authors.forename: Hossein
authors.initials: H
authors.lastname: Ghanbari
authors.forename: Asmeret G
authors.initials: AG
authors.lastname: Kidane
authors.forename: Gaetano
authors.initials: G
authors.lastname: Burriesci
authors.forename: Bala
authors.initials: B
authors.lastname: Ramesh
authors.forename: Arnold
authors.initials: A
authors.lastname: Darbyshire
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Seifalian
mesh_terms: D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects; D002113:Calcification, Physiologic / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D002152:Calorimetry, Differential Scanning; D002448:Cell Adhesion / Q000187:drug effects; D006350:Heart Valve Prosthesis; D006801:Humans; D008422:Materials Testing / Q000379:methods*; D018613:Microscopy, Confocal; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D017646:Organosilicon Compounds / Q000737:chemistry / Q000494:pharmacology*; D011108:Polymers / Q000737:chemistry / Q000494:pharmacology*; D013499:Surface Properties / Q000187:drug effects; D013718:Tensile Strength / Q000187:drug effects; D014965:X-Rays
chemical_list: D017646:Organosilicon Compounds; D011108:Polymers; D002118:Calcium