O-PTIR Data for "Label-Free Optical Photothermal Infrared Imaging Reveals Age-Dependent Matrix Remodeling in SPARC-Deficient Murine Intervertebral Discs"

This dataset contains optical photothermal infrared (O-PTIR) spectroscopic data and corresponding microscope images from intervertebral disc (IVD) tissue of SPARC-deficient (SPARC-KO) and wild-type (WT) mice at young and advanced ages. The data were generated to investigate age- and genotype-associated biochemical remodeling of the intervertebral disc extracellular matrix at micrometer-scale spatial resolution. Study design The underlying experimental cohort comprised 24 mice distributed across four age/genotype groups: young wild-type (WT), 3–4 months of age (n = 6) young SPARC-deficient (KO), 3–4 months of age (n = 6) aged wild-type (WT), 15 months of age (n = 6) aged SPARC-deficient (KO), 15 months of age (n = 6) Each group included three female and three male animals. Spectra acquired from multiple regions within an individual animal represent nested measurements and should therefore not be considered independent biological replicates. Spinal tissue was fixed, decalcified using EDTA, paraffin embedded, and sectioned for histological and spectroscopic analysis. O-PTIR measurements were performed directly on standard glass-mounted tissue sections using a Mirage-R O-PTIR system with a 785 nm probe laser. Spectroscopic sampling O-PTIR spectroscopy was used to obtain spatially resolved infrared signatures from defined anatomical compartments of the intervertebral disc and adjacent tissues. Investigated regions included, where available: nucleus pulposus (NP) inner annulus fibrosus (iAF) outer annulus fibrosus (oAF) adjacent vertebral bone marrow The spectra provide information on the biochemical composition and organization of the tissue matrix, including protein- and collagen-associated spectral features as well as signals arising from other organic matrix constituents. Because the tissue sections were decalcified before spectroscopic analysis, spectral features in mineral- or phosphate-associated regions should not be interpreted as direct measures of tissue mineralization. Dataset contents The deposited data are organized into separate archives according to age, genotype, and data type: 3months_KO_spc – O-PTIR spectra from young SPARC-deficient mice 3months_WT_spc – O-PTIR spectra from young wild-type mice 15months_KO_spc – O-PTIR spectra from aged SPARC-deficient mice 15months_WT_spc – O-PTIR spectra from aged wild-type mice Average OPTIR spectra – averaged O-PTIR spectra derived from the investigated groups and/or tissue regions IR spectra reference biomolecules – infrared reference spectra of selected biomolecules used to facilitate interpretation of tissue-associated spectral signatures Microscope images KO 3 months – microscope images corresponding to young SPARC-deficient samples Microscope images WT 3-months – microscope images corresponding to young wild-type samples Microscope images WT 15-months – microscope images corresponding to aged wild-type samples The combination of individual spectra, averaged spectra, reference spectra, and accompanying microscope images enables comparison of biochemical signatures between SPARC-deficient and wild-type tissue and across age groups. The dataset may also be useful for independent spectral preprocessing, multivariate analysis, biomolecular band assignment, and methodological evaluation of O-PTIR spectroscopy in musculoskeletal and extracellular-matrix research. Biological context SPARC (secreted protein acidic and rich in cysteine) is an extracellular matrix-associated protein involved in matrix organization and tissue homeostasis. Loss of SPARC provides an experimental model for studying alterations in intervertebral disc matrix composition and organization during aging. The present dataset enables investigation of spatially resolved biochemical differences within defined disc compartments and comparison of age-dependent matrix changes between SPARC-deficient and wild-type animals. Complementary histopathological data Complementary histopathological whole-slide images from this experimental context, including hematoxylin and eosin (HE), Calcium–Alcian Blue, and SPARC immunohistochemistry, are available as a separate Zenodo record: Pallua, J., Klosterhuber, M., Lindtner, R., Arora, R., Huck, C., Popp, J., Krafft, C., Cael, S., Zelger, B., & Jöbstl, S. (2026). Histopathological Whole-Slide Images of SPARC-Deficient Murine Intervertebral Discs: HE, Calcium–Alcian Blue, and SPARC Immunohistochemistry [Graphic]. Zenodo. https://doi.org/10.5281/zenodo.21679929