Infrared Spectroscopy-Determined Bone Compositional Changes Associated with Anti-Resorptive Treatment of the oim/oim Mouse Model of Osteogenesis Imperfecta

Abstract

Applications of vibrational spectroscopy to assess bone disease and therapeutic interventions are continually advancing, with tissue mineral and protein composition frequently investigated. Here, we used two spectroscopic approaches for determining bone composition in a mouse model of the brittle bone disease osteogenesis imperfecta (OIM) with and without antiresorptive agent treatment (alendronate (ALN) and RANK-Fc). Near infrared (NIR) spectral analysis via a fiber optic probe and Fourier transform infrared spectroscopy using attenuated total reflection (FTIR-ATR) mode were applied to investigate bone composition, including water, mineral and protein content. Spectral parameters revealed differences among the control wildtype (WT) and OIM groups. NIR spectral analysis of protein and water showed that OIM mouse humerii had ~ 50% lower protein and ~ 50% higher overall water content compared to WT bone. Moreover, some OIM treated groups showed a reduction in bone water compared to OIM controls, approximating values observed in WT bone. Differences in bone quality based on increased mineral content and reduced carbonate content were also found between some groups of treated OIM and WT bone, but crystallinity did not differ among all groups. The spectroscopically-determined parameters were evaluated for correlations with gold-standard mechanical testing values to gain insight into how composition influenced bone strength. As expected, bone mechanical strength parameters were consistently up to three-fold greater in WT mice compared to OIM groups, except for stiffness in the ALN-treated OIM groups. Further, bone stiffness, maximum load and post-yield displacement showed the strongest correlations with NIR-determined protein content (positive correlations) and bound-water content (negative correlations). These results demonstrate that in this study, NIR spectral parameters were more sensitive to bone composition differences than ATR parameters, highlighting the potential of this nondestructive approach for screening of bone diseases and therapeutic efficacy in pre-clinical models.

The recombinant BMP-2 loaded silk fibroin microspheres improved the bone phenotype of mild osteogenesis imperfecta mice

“…Drug therapy is relatively more practical and convenient in clinical practice. Multiple anti-resorptive and anabolic agents have improved the phenotype of OI bones ( Datta, Vila & Tuck, 2021 ; Shanas et al, 2022 ). However, the length of these medications’ half-life frequently results in undesirable side effects or inconveniences.…”

Application of Optical Photothermal Infrared (O-PTIR) Spectroscopy for Assessment of Bone Composition at the Submicron Scale

“…Attenuated total reflection (ATR) and O-PTIR spectroscopies were used to investigate several tissue compositional properties of the bone powder and intact femoral neck samples, as detailed below, and previously described. 33,35,43,44 Attenuated Total Reflection. Demineralized bone and intact tissue sections were lyophilized and analyzed using a Nicolet iS5 FT-IR spectrometer coupled to an iD7 ATR accessory with a ∼2 mm diameter diamond crystal (Thermo Scientific).…”

“…Attenuated total reflection (ATR) and O-PTIR spectroscopies were used to investigate several tissue compositional properties of the bone powder and intact femoral neck samples, as detailed below, and previously described. 33,35,43,44…”

Bone hydration: How we can evaluate it, what can it tell us, and is it an effective therapeutic target?

“…In pre-clinical testing, NIR spectral analysis in the oim/oim (OIM) mouse model of moderate-to-severe OI demonstrated that cortical bone had a 50% higher overall water content in OIM compared to wildtype controls ( Fig. 10 A) ( Shanas et al, 2021 ). The authors postulate this was a result of more matrix space in OIM bone for water to ‘loosely associate with’.…”

“…C) Mineral and matrix-bound water relative to total protein was negatively correlated to stiffness (r = −0.44, p < 0.05) and D) maximum load (r = −0.60, p < 0.05). Figures from Shanas et al adapted with permission ( Shanas et al, 2021 ). …”