Commentary: Bioceramics and Scaffolds: A Winning Combination for Tissue Engineering

We read with interest the review published by Baino et al. (2015) about bioceramics and scaffolds. We would like to add some information as we produce a porous alumina ceramic (CERAMIL ®) which present almost all the criteria that characterize an ideal scaffold as presented in table 1 of the article. Converse to the assertion that porous alumina is only used in the fabrication of orbital implants, our ceramic is widely implanted as vertebra cages and gap filling during opening wedge high tibial osteotomy. It has been recently implanted for the replacement of a tumor sternum. The ceramic used is an alumina porous one processed thanks to a patented process [Patent FR2823674 (2006)]. Our technic seems to be in accordance to every point listed by the authors: Geometry: several shapes are designed such as cubes, roof tiles, cylinders, trapezoidal parallelepi-ped, spheres, and complex one such as the sternum with holes for stitching. 3D complex shapes can be designed and small bones can easily be done (Figure 1). Bioactivity: the porous characteristic (see below) allows a rapid attachment of osteoblasts to the ceramic, and its integration has been studied by histopathology showing in-growth bone cell in pores. This characteristic leads to long-term bonding between ceramic and surrounding bone. Biocompatibility: more than 5,000 implantations have been performed with vertebra cages, and the long-term follow-up does not show any case of local or systemic toxic effect. Studies are ongoing to analyze activity of bone cell in contact with the ceramic. Furthermore, alumina ceramic are classified as inert with no interaction with the surrounding tissues (Patel and Gohil, 2012; Baino et al., 2015). Chemical and biological stability: as said by the authors, alumina has a very good bioinertness and good long-term mechanical properties without degradation (Baino et al., 2015). Porous structure: with the technic used to fabricate our ceramic, the size of the interconnected pores is ranging from 100 to 900 μm with a vast majority of pore of about 600 to 900 μm. Moreover, all the pores are interconnected, without dead-end. This structure allows colonization with bone cells and thus the stability of the ceramic in the bone (Bignon et al., 2003; Hing, 2005; Lew et al., 2012). Moreover, pore's size ranging from 600 to 1,250 μm seems to be the ones that allow the best colonization by bone cells (Bignon et al., 2003). Mechanical competence: the ceramic possess a mechanical compressive resistance …