Characterisation of Sr²⁺mobility in osteoporotic rat bone marrow by cryo-ToF-SIMS and cryo-OrbiSIMS

Abstract

Mass spectrometric imaging approach for ex vivo monitoring of drug transport in bone sections. Cryo-ToF-SIMS depth profiling and high-resolution imaging as well as OrbiSIMS analysis revealed inhomogeneous Sr2+ transport in rat bone marrow.

Mass Spectrometry Imaging of Biomaterials

“…Whereas red bone marrow mostly contains hematopoietic cells like blood cells, platelets, mesenchymal stem cells, fibroblasts, adipocytes, osteoblasts, osteoclasts, macrophages, or endothelial cells, the yellow bone marrow is mainly composed of bone marrow adipocytes. The percentage of yellow bone marrow increases up to 70–80% during bone maturation [ 58 ]. Bone is a highly vascular, mineralized connective tissue extraordinary for its strength and regenerative capacity.…”

“…The application of ToF-SIMS in osteoporotic bone research allows simultaneous visualization of mineralized and non-mineralized bone tissue, as well as implanted biomaterials and bone implant interphases [ 59 ]. ToF-SIMS enables the simultaneous identification of both organic and inorganic substances within the same sample in a single analysis process in 2D and 3D [ 58 ]. With ToF-SIMS the ions distribution in bone cross-sections is mapped semi-quantitatively with a lateral resolution of up to 1 μm [ 60 ].…”

“…ToF-SIMS was successfully applied for tracking pharmaceuticals in a biomaterial from in vitro to in vivo experiments, as well as for the investigation and imaging of osteoporotic bone in an animal model [ 61 ]. Usually, osteoporosis is experimentally induced in animal models by ovariectomy which can be accompanied by a deficiency diet lacking vitamins C, D2, D3, calcium, and phosphorus as well as soy- and phytoestrogen-free [ 58 ].…”

“…Since Sr 2+ ions are an effective therapeutic agent for the healing of osteoporotic bone fractures, they are often used in the form of strontium-modified bone cement. Additional studies using ToF-SIMS led to the development of the experimental protocol for transport studies in bovine bone marrow [ 58 ]. Additionally, orbitrap secondary ion mass spectrometry (OrbiSIMS) was applied for definite signal identification of lipids and fatty acid species in rat bone marrow [ 67 ].…”

“…Additionally, orbitrap secondary ion mass spectrometry (OrbiSIMS) was applied for definite signal identification of lipids and fatty acid species in rat bone marrow [ 67 ]. Comprehensive 2D and 3D mass spectrometric imaging analyses, depth profiling, as well as OrbiSIMS spectrometric analysis, discovered faster Sr 2+ diffusion in rat bone marrow areas correlated with lower intensity of lipid and fatty acid signals than in areas with higher lipid/fatty acid content [ 58 ]. Furthermore, the Authors observed that bone marrow fat consists mainly of palmitic acid, stearic acid, oleic acid, triacylglycerides, and phosphatidylcholine.…”