Strontium substitution of gelatin modified calcium hydrogen phosphates as porous hard tissue substitutes

Aiming at the generation of a high strontium-containing degradable bone substitute, the exchange of calcium with strontium in gelatin-modified brushite was investigated. The ion substitution showed two mineral groups, the high-calcium containing minerals with a maximum measured molar Ca/Sr ratio of 80%/20% (mass ratio 63%/37%) and the high-strontium containing ones with a maximum measured molar Ca/Sr ratio of 21%/79% (mass ratio 10%/90%). In contrast to the high-strontium mineral phases, a high mass loss was observed for the calcium-based minerals during incubation in cell culture medium (alpha-MEM), but also an increase in strength owing to dissolution and re-precipitation. This resulted for the former in a decrease of cation concentration (Ca + Sr) in the medium, while the pH value decreased and the phosphate ion concentration rose significantly. The latter group of materials, the high-strontium containing ones, showed only a moderate change in mass and a decrease in strength, but the Ca + Sr concentration remained permanently above the initial calcium concentration in the medium. This might be advantageous for a future planned application by supporting bone regeneration on the cellular level. © 2020 The Authors. Journal of Biomedical Materials Research Part A published by Wiley Periodicals LLC

Data on TOF-SIMS analysis of Cu2+, Co2+ and Cr3+ doped calcium phosphate cements

This article contains data of time of flight secondary ion mass spectrometry (TOF-SIMS) analysis of brushite-forming calcium phosphate cements doped with biologically active metal ions. This data are related to the research article “Cu2+, Co2+ and Cr3+ doping of a calcium phosphate cement influences materials properties and response of human mesenchymal stromal cells” (Schamel et al., 2017) [1]. Cu2+, Co2+ and Cr3+ doped β-tricalcium phosphate precursor powders were used to prepare cement samples. The incorporation and distribution of the metal ions in the cement matrix was visualized by imaging mass spectrometry

Strontium release from Sr 2+ -loaded bone cements and dispersion in healthy and osteoporotic rat bone

Drug functionalization of biomaterials is a modern and popular approach in biomaterials research. Amongst others this concept is used for the functionalization of bone implants to locally stimulate the bone healing process. For example strontium ions (Sr2+) are administered in osteoporosis therapy to stimulate bone growth and have recently been integrated into bone cements. Based on results of different analytical experiments we developed a two-phase model for the transport of therapeutically active Sr2+-ions in bone in combination with Korsmeyer-Peppas kinetics for the Sr2+ release from bone cement. Data of cement dissolution experiments into water in combination with inductively coupled plasma mass spectrometry (ICP-MS) analysis account for dissolution kinetics following Noyes-Whitney rule. For dissolution in ??-MEM cell culture media the process is kinetically hindered and can be described by Korsmeyer-Peppas kinetics. Time of flight secondary ion mass spectrometry (ToF-SIMS) was used to determine the Sr2+ diffusion coefficient in healthy and osteoporotic trabecular rat bone. Therefore, bone sections were dipped in aqueous Sr2+-solution by one side and the Sr2+-profile was measured by classical SIMS depth profiling. The Sr2+ mobility can be described by a simple diffusion model and we obtained diffusion coefficients of (2.28??2.97)???10-12cm2/s for healthy and of (1.55??0.93)???10-10cm2/s for osteoporotic bone. This finding can be explained by a different bone nanostructure, which was observed by focused ion beam scanning electron microscopy (FIB-SEM) and transmission electron microscopy (TEM). Finally, the time and spatially resolved drug transport was calculated by finite element method for the femur of healthy and osteoporotic rats. The obtained results were compared to mass images that were obtained from sections of in vivo experiments by ToF-SIMS. The simulated data fits quite well to experimental results. The successfully applied model for the description of drug dispersion can help to reduce the number of animal experiments in the future.Copyright ?? 2017 Elsevier B.V. All rights reserved

Postembedding Decalcification of Mineralized Tissue Sections Preserves the Integrity of Implanted Biomaterials and Minimizes Number of Experimental Animals

Bone histology of decalcified or undecalcified samples depends on the investigation. However, in research each method provides different information to answer the scientific question. Decalcification is the first step after sample fixation and governs what analysis is later feasible on the sections. Besides, decalcification is favored for immunostaining and in situ hybridization. Otherwise, sample decalcification can be damaging to bone biomaterials implants that contains calcium or strontium. On the other hand, after decalcification mineralization cannot be assessed using histology or imaging mass spectrometry. The current study provides a solution to the hardship caused by material presence within the bone tissue. The protocol presents a possibility of gaining sequential and alternating decalcified and undecalcified sections from the same bone sample. In this manner, investigations using histology, protein signaling, in situ hybridization, and mass spectrometry on the same sample can better answer the intended research question. Indeed, decalcification of sections and grindings resulted in well-preserved sample and biomaterials integrity. Immunostaining was comparable to that of classically decalcified samples. The study offers a novel approach that incites correlative analysis on the same sample and reduces the number of processed samples whether clinical biopsies or experimental animals