A novel method for segmenting and aligning the pre- and post-implantation scaffolds of resorbable calcium-phosphate bone substitutes

In vivo osseointegration and erosion of nacre screws in an animal model

The use of resorbable devices for osteosynthesis has become a subject of interest. Nacre has been proposed as a resorbable and osteoconductive material favoring bone apposition without triggering an inflammatory reaction. We compared the in vivo osseointegration and erosion of nacre screws in an animal model with titanium screws. Implantation of similar nacre and titanium screws was performed in the femoral condyles of adult rats. Animals (n = 41) were randomized in four groups sacrificed at day one, 1, 6, and 12 months. Microcomputed tomography (microCT) allowed 3D morphometry of erosion of nacre. Osseointegration was measured as the volume of trabecular bone bone volume/tissue volume (BV/TV) in a standardized volume of interest around each screw. Undecalcified bone histology was also done. Gross examination revealed a similar clinical osseointegration for titanium and nacre screws. A progressive erosion of nacre screws, but no erosion of titanium screws, was observed in microCT. The volume of nacre screws progressively decreased over time whereas no modification occurred for titanium. For titanium screws, BV/TV remained stable throughout the study. For nacre screws, the BV/TV decrease was not statistically different. A significant difference was found between nacre and titanium screws at 6 months but not at 12 months. The screw heads, outside the bone shaft, were not eroded even after 12 months. Erosion of nacre occurred during the entire study period, only within the bone shaft in direct contact with bone marrow. Bone apposition was observed on nacre surfaces without signs of erosion. Nacre is a promising biomaterial in maxillofacial surgery.

Micro-CT - a digital 3D microstructural voyage into scaffolds: a systematic review of the reported methods and results

BACKGROUND

Cell behavior is the key to tissue regeneration. Given the fact that most of the cells used in tissue engineering are anchorage-dependent, their behavior including adhesion, growth, migration, matrix synthesis, and differentiation is related to the design of the scaffolds. Thus, characterization of the scaffolds is highly required. Micro-computed tomography (micro-CT) provides a powerful platform to analyze, visualize, and explore any portion of interest in the scaffold in a 3D fashion without cutting or destroying it with the benefit of almost no sample preparation need.

MAIN BODY

This review highlights the relationship between the scaffold microstructure and cell behavior, and provides the basics of the micro-CT method. In this work, we also analyzed the original papers that were published in 2016 through a systematic search to address the need for specific improvements in the methods section of the papers including the amount of provided information from the obtained results.

CONCLUSION

Micro-CT offers a unique microstructural analysis of biomaterials, notwithstanding the associated challenges and limitations. Future studies that will include micro-CT characterization of scaffolds should report the important details of the method, and the derived quantitative and qualitative information can be maximized.

Multimodal analysis of in vivo resorbable CaP bone substitutes by combining histology, SEM, and microcomputed tomography data

This study introduced and demonstrated a new method to investigate the repair process of bone defects using micro- and macroporous beta-tricalcium phosphate (β-TCP) substitutes. Specifically, the new method combined and aligned histology, SEM, and preimplantation microcomputed tomography (mCT) data to accurately characterize tissue phases found in biopsies, and thus better understand the bone repair process. The results included (a) the exact fraction of ceramic remnants (CR); (b) the fraction of ceramic resorbed and substituted by bone (CSB); and (c) the fraction of ceramic resorbed and not substituted by bone (CNSB). The new method allowed in particular the detection and quantification of mineralized tissues within the 1-10 µm micropores of the ceramic ("micro-bone"). The utility of the new method was demonstrated by applying it on biopsies of two β-tricalcium phosphate bone substitute groups with two differing macropore sizes implanted in an ovine model for 6 weeks. The total bone deposition and ceramic resorption of the two substitute groups, having macropore sizes of 510 and 1220 μm, were 25.1 ± 8.1% and 67.5 ± 3.2%, and 24.4 ± 4.1% and 61.4 ± 6.5% for the group having the larger pore size. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1567-1577, 2018.