3D Distribution of Cells Seeded Onto a Polymeric Scaffold for Bone Regeneration

Aims In orthopedic surgery the tissues damaged by injury or disease could be replaced using constructs based on biocompatible materials, cells and growth factors. Scaffold design, porosity and early colonization are key components for the implant success. From biological point of view, attention may be also given to the number, type and size of seeded cells, as well as the seeding technique and cell morphological and volumetric alterations. The most common method for examining cells in scaffolds is still microscopy. Based on embedding the sample, sectioning and finally histological staining, this technique is destructive and only semiquantitative. The present paper describes the use of the microCT approach (to date used principally for mineralized matrix quantification) to observe construct colonization in terms of cell localization, and make a direct comparison of the microtomographic sections with SEM images and CLSM analysis. Cells do not have the intrinsic X-ray attenuation ability to be clearly visualized by microCT thus it becomes necessary to use a contrast agent [1] The studies that have approached 3D cellular distribution analysis by microCT used osmium tetroxide as contrast agent [2-3] because of its great affinity with lipids: it reacts with unsaturated lipids by forming black compounds containing hexavalent osmium that are visible by microCT.