Novel Approach to Creation of Biomimetic Scaffolds for Tissue Engineering
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Novel Approach to Creation of Biomimetic Scaffolds for Tissue Engineering Bronislava Belenkaya1, Aleksey Shepelev2 and Valentina Sakharova1 1 2
3S Corporation, Campbell, CA 95008, U.S.A. The Karpov Institute of Physical Chemistry, Moscow, Russia
ABSTRACT In tissue engineering, a successful tissue scaffold is not simply a 3D-micro/nanofibered, highly porous environment that mimics a native extra cellular matrix (ECM). To maintain an ideal medium for cells to grow and proliferate, the biodegradable scaffold should be generally hydrophilic and should serve as a reservoir of cell nutrients, growth factors and other components present in the blood flow. Synthetic biodegradable polymers have found wide applications in micro/nanofibered scaffolding materials because of their proven biocompatibility, availability of established processing techniques, good mechanical properties and controlled, regulated biodegradation time. But, high hydrophobicity of these polymers does not allow to realize a moist environment in the scaffold typical for native ECM and favorable for the cells. We have recently found that electrospun polymeric blends of polyvinylpyrrolidone (PVP) and poly-d,l-lactide (PDLL) provide mechanically strong micro/nanofibered materials of high hydrophilicity. These materials have a regulated absorption ability of blood or other biological liquids of up to ~8-10 g/g without swelling or changing the shape of the fibers. As demonstrated by spectroscopy and differential scanning calorimetry, strong polymer chains assembly of PDLL-PVP occurs when the corresponding blends are processed into micro/nanofibers by electrospinning or casted into films. The polymer chain assembly is not affected by absorbed liquids. The matrices preserve their liquid absorption ability after drying. Preliminary testing of matrices in humans demonstrated a high efficacy of the scaffolds for wound healing acceleration. INTRODUCTION Three main common strategies of tissue regeneration are: (1) using tissue inducing substances (e.g., growth factors); (2) application of isolated cells or cell substitutes and (3) using combination of cells on or within matrices [1]. Among these strategies, the cell-matrix combination is of special interest for regenerating and healing lost or damaged tissues, or for creating a new engineered tissue or organs. The scaffold that is used as a temporary substituent for the natural extra-cellular matrix and as „bridge‟ between healthy and damaged tissue or organ should simulate a site-specific optimal microenvironment for in vivo or in vitro cell deposition and should stimulate cell normal proliferation in a desired direction as a natural ECM does. And like a natural ECM, the scaffold should provide:1) physical and mechanical support provided by a matrix of micro /nanofibered 3D-architecture, which allows cells to populate the „body‟ of the scaffold; 2) a supporting ability until it is replaced by a new tissue; 3) a high hydrophilicity and the capability to communicate with blood flow and the neighboring tissues, so as
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