Optical projection tomography can be used to investigate spatial distribution of chondrocytes in three-dimensional biomaterial scaffolds for cartilage tissue engineering

Abstract

Biomaterial scaffolds have been used in autologous chondrocyte implantation to facilitate the repair of large lesions and to advance the formation of articular cartilage [Exp. Biol. Med. (Maywood) 237(1) (2012), 10–17]. Biomaterial scaffolds are usually three-dimensional (3-D) porous structures consisting of biodegradable materials to support articular cartilage formation. Adequate porosity of the scaffold is necessary for uniform cell distribution and cell attachment, and the density of the cells in the scaffold should be appropriate for cartilage formation [Cartilage 3(2) (2012), 108–117]. There have been only a restricted number of studies on the spatial distribution of cells in scaffolds, and on the role of this to cartilage formation [J. Biotechnol. 129 (2007), 516–531; Biotechnol. Progr. 14 (1998), 193–202; Biotechnol. Bioeng. 84 (2003), 205–214]. This may be due to the limited availability of appropriate visualization methods. Acquiring 3-D images throughout the scaffold by histology or confocal methods are not applicable to all types of scaffolds, and moreover, they are time consuming, laborious and thus not very feasible for a large scale analysis. To make the visualization of the spatial distribution of the cells easier in biomaterial scaffolds we have applied optical projection tomography (OPT). OPT microscope produces high-resolution 3-D images of both fluorescent and non-fluorescent specimens [Science 296(5567) (2002), 541–545]. Here we demonstrate that the OPT method can be used for the evaluation and visualization of the cell seeding method, spatial distribution and density of cells in biomaterial scaffolds and thus establish the OPT as a valid tool for analysis of cell distribution in cartilage tissue engineering samples.