Biodegradation of porous calcium phosphate scaffolds in an ectopic bone formation model studied by X-ray computed microtomograph

Abstract

Three types of ceramic scaffolds with different composition and structure [namely synthetic 100% hydroxyapatite (HA; Engipore), synthetic calcium phosphate multiphase biomaterial containing 67% silicon stabilized tricalcium phosphate (Si-TCP; Skelite™) and natural bone mineral derived scaffolds (Bio-oss®)] were seeded with mesenchymal stem cells (MSC) and ectopically implanted for 8 and 16 weeks in immunodeficient mice. X-ray synchrotron radiation microtomography was used to derive 3D structural information on the same scaffolds both before and after implantation. Meaningful images and morphometric parameters such as scaffold and bone volume fraction, mean thickness and thickness distribution of the different phases as a function of the implantation time, were obtained. The used imaging algorithms allowed a direct comparison and registration of the 3D structure before and after implantation of the same sub-volume of a given scaffold. In this way it was possible to directly monitor the tissue engineered bone growth and the complete or partial degradation of the scaffold. Further, the detailed kinetics studies on Skelite™ scaffolds implanted for different length of times from 3 days to 24 weeks, revealed in the X-ray absorption histograms two separate peaks associated to HA and TCP. It was therefore possible to observe that the progressive degradation of the Skelite™ scaffolds was mainly due to the resorption of TCP. The different saturation times in the tissue engineered bone growth and in the TCP resorption confirmed that the bone growth was not limited the scaffold regions that were resorbed but continued in the inward direction with respect to the pore surface.

Phase Composition and Crystallinity of Hydroxyapatite With Various Heat Treatment Temperatures

“…Calcium phosphate-based phases are having a molar ratio of Ca/P <1.7, such as tricalcium phosphate, have shown to be more degradable. Studies showed that biphasic structure of HA and tricalcium phosphate (HA/TCP) have drawn considerable attention because they are able to show better degradation [3,10,11]. In fact, most studies of biphasic HA/TCP scaffold employed commercially available HAs.…”

Bone fibrillogenesis and mineralization: Quantitative analysis and implications for tissue elasticity

“…Bone tissue engineering has become a huge field, both in terms of scientific production and medical potential [Cancedda et al, 2007], and ever since the pioneering work of Langer and Vacanti [1993], a great variety of different material systems have been explored for their potential use as bone tissue engineering scaffolds [Karageorgiou and Kaplan, 2005;Perry, 2002;Komlev et al, 2010;Verma et al, 2008]. Quite naturally among all these materials, such based on the actual elementary components of bone, i.e.…”

Synchrotron Radiation and Nanotechnology for Stem Cell Research

“…This methodology offers major advantages, including the possibility of investigating the influence of scaffold parameters, such as porosity and spatial distribution of the structure thickness, on the bone growth within the implant. Very recently, different ceramic scaffolds with high porosity were characterized (Komlev et al, 2010) and it was evaluated the bone growth into the tissue engineering constructs ex vivo at different implantation times, by using synchrotron radiation micro-CT. In this study, three types of ceramic scaffolds with different composition and structure (namely synthetic 100% hydroxyapatite (HA; Engipore), synthetic calcium phosphate multiphase biomaterial containing 67% silicon stabilized tricalcium phosphate (Si-TCP; Skelite™) and natural bone mineral derived scaffolds (Bio-oss®), were seeded with mesenchymal stem cells (BMSC) and ectopically implanted for 8 and 16 weeks in immunodeficient mice.…”

“…The analysis proposed in the manuscript (Komlev et al, 2010) is, therefore, a major improvement as compared to the imaging procedure adopted in our previous work , where only a comparison between different subvolumes of the implants before and after implantation was made. Fig.…”