Kinetics of in vivo bone deposition by bone marrow stromal cells within a resorbable porous calcium phosphate scaffold: An X‐ray computed microtomography study

Abstract

Resorbable ceramic scaffolds based on Silicon stabilized tricalcium phosphate (Si-TCP) were seeded with bone marrow stromal cells (BMSC) and ectopically implanted for 2, 4, and 6 months in immunodeficient mice. Qualitative and quantitative evaluation of the scaffold material was performed by X-ray synchrotron radiation computed microtomography (microCT) with a spatial resolution lower than 5 mm. Unique to these experiments was that microCT data were first collected on the scaffolds before implantation and then on the same scaffolds after they were seeded with BMSC, implanted in the mice and rescued after different times. Volume fraction, mean thickness and thickness distribution were evaluated for both new bone and scaffold phases as a function of the implantation time. New bone thickness increased from week 8 to week 16. Data for the implanted scaffolds were compared with those derived from the analysis of the same scaffolds prior to implantation and with data derived from 100% hydroxyapatite (HA) scaffold treated and analyzed in the same way. At variance with findings with the 100% HA scaffolds a significant variation in the density of the different Si-TCP scaffold regions in the pre-and post-implantation samples was observed. In particular a post-implantation decrease in the density of the scaffolds, together with major changes in the scaffold phase composition, was noticeable in areas adjacent to newly formed bone. Histology confirmed a better integration between new bone and scaffold in the Si-TCP composites in comparison to 100% HA composites where new bone and scaffold phases remained well distinct.

Micromechanics of bone tissue-engineering scaffolds, based on resolution error-cleared computer tomography

“…Numerically, the latter is defined through values related to small volume units, called voxels. Over recent years, CT has become a widely applied tool in science, technology, industry, and medicine, with a particularly strong position in the latter field [6,[11][12][13][14][15][16]. There, it supports the clinical practice, but also fundamental research devoted e.g.…”

Three-Dimensional Characterization of Tissue-Engineered Constructs by Contrast-Enhanced Nanofocus Computed Tomography

“…In particular, Xray microfocus computed tomography (micro-CT) has been frequently applied as a 3D quantitative imaging technique to assess the scaffold structure, [6][7][8] as well as bone ingrowth after in vivo implantation. 6,[9][10][11][12][13][14] Furthermore, it has been employed for time-lapsed follow-up of mineralization inside scaffolds during in vitro static [15][16][17] or bioreactor cultures. 13,18,19 In most of these studies, polymeric, ceramic, collagen scaffolds, or composites were used, in which, the mineralized extracellular matrix (ECM) could be separated from the scaffold for the purpose of volume calculations and no significant material-dependent artifacts were present.…”

Combining Coherent Hard X-Ray Tomographies with Phase Retrieval to Generate Three-Dimensional Models of Forming Bone

“…Density and the different tissue distributions in 3D presented here may help reveal the similarities and differences in bone tissue formation in these different scenarios. In recent years, a handful of studies have used holotomography and other methods in order to evaluate new biodegradable materials and treatment for healing large bone defects (Mastrogiacomo et al, 2005Papadimitropoulos et al, 2007;Langer et al, 2010b; FigUre 7 | Movat's Pentachrome stained typical histological cross-section of a paraffin-embedded 14-day-old mouse femur mid-diaphysis. Mineralized material is stained in yellow and can be clearly distinguished from the muscles (red) and the bone marrow (shades of blue).…”

“…Porous 3D scaffolds consisting of tricalcium phosphates (e.g., skalite) and/or hydroxyapatites seeded with different osteogenic cells were observed to promote bone formation during resorption. Newly formed bone was identified with holotomography used to quantify formed/resorbed volumes and to characterize the resulting 3D morphologies (Mastrogiacomo et al, 2005Papadimitropoulos et al, 2007;Langer et al, 2010b;Ruggiu et al, 2014). Growing bone in the process of mineralization contains significant non-mineralized regions.…”