Biology subjects

Mieczkowska, A.

Publications and source records attributed to Mieczkowska, A..

4 recordsLinked to original sources

bioRxiv2026

GL-0001, a first-in-class dual GIP/GLP-2 analogue, reduces bone fragility by enhancing bone material properties in a murine model of type III osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a severe heritable skeletal disorder characterized by bone fragility, short stature, and increased fracture risk. Currently, no pharmacological treatment has been approved for OI, and bisphosphonates are commonly used off label. While bisphosphonates increase bone mass, their effects on bone quality and fracture reduction remain limited. GL-0001, a first-in-class dual glucose-dependent insulinotropic polypeptide (GIP)/glucagon-like peptide-2 (GLP-2) compound that targets bone material properties, may offer alternative skeletal benefits. We evaluated the effects of 9 weeks of GL-0001 treatment in the oim/oim murine model of severe OI, a well-established model carrying a homozygous Col1a2 mutation resulting in abnormal type I collagen formation and compared outcomes with zoledronic acid (100 g/kg) or saline. Analyses included longitudinal growth, fracture incidence, bone biomechanics, microarchitecture, turnover markers, and bone material properties. OI mice exhibited reduced body weight, impaired femoral growth, severe trabecular and cortical deficits, altered bone turnover, and compromised biomechanical properties compared with WT controls. GL-0001 increased femur length by 5% (p=0.015) and reduced spontaneous fracture incidence by 90% (p=0.004), whereas zoledronic acid had no significant effect on fracture burden. Bone microarchitecture was not significantly altered by GL-0001, whereas zoledronic acid improved trabecular and cortical parameters. At the tissue level, GL-0001 improved bone strength, increasing ultimate stress (+26%, p=0.022) and yield stress (+30%, p=0.014), and reducing brittleness (-32%, p=0.002). These changes were associated with increased collagen maturity (+12%, p<0.001). In contrast, zoledronic acid had limited effects on bone material properties. These findings demonstrate that GL-0001 improves skeletal fragility in the oim/oim murine model of severe OI through mechanisms primarily involving enhancement of bone material properties and longitudinal growth, rather than changes in bone mass or microarchitecture. GL-0001 may therefore represent a novel therapeutic strategy targeting bone quality in OI.

physiology↗

bioRxiv2026

Bone Material Properties Distributions from quantitative Raman analysis: a distribution-based approach to human bone matrix characterization

Background: Bone mechanical competence depends not only on bone mass but also on the spatial organization of mineral and organic matrix properties. Whereas quantitative backscattered electron imaging (qBEI) characterizes mineral heterogeneity using Bone Mineral Density Distributions (BMDDs), no equivalent framework currently exists for describing the biochemical heterogeneity of the bone matrix by Raman microspectroscopy. Methods: We developed a quantitative Raman analysis (qRA) workflow to generate Bone Material Properties Distributions (BMPDs). Raman spectra were acquired along full-thickness line scans crossing successive bone structural units in human trabecular and cortical bone. Pixel-wise Raman-derived biochemical parameters describing collagen organization, advanced glycation end-products, glycosaminoglycans, mineral-to-matrix ratios, carbonate substitution, and mineral crystallinity were converted into normalized frequency distributions and modeled using gaussian functions. BMPDs were generated from undecalcified pMMA-embedded iliac biopsies (n=38) and routinely processed decalcified paraffin-embedded osteomedullary biopsies (n=21). The analytical framework was validated against conventional two-dimensional Raman mapping, and reproducibility, interindividual variability, and demographic influences were evaluated. Results: BMPDs were consistently well described by gaussian functions (typically R2 > 0.95), allowing extraction of three descriptors for each biochemical parameters: Mean, Peak, and Width. One-dimensional line scans showed excellent agreement with conventional two-dimensional Raman mapping while reducing acquisition time approximately 100-fold. Technical variability remained substantially lower than biological variability for all parameters, and a single trabecular line scan provided reliable estimates of BMPD descriptors for nearly all Raman-derived indices. Cortical bone exhibited narrower BMPDs than trabecular bone, indicating lower biochemical heterogeneity. Comparable BMPDs were obtained from undecalcified and routinely decalcified specimens, demonstrating robustness to tissue processing. No significant associations with age or sex were observed after correction for multiple testing. Reference BMPDs further enabled visualization and standardized quantification of deviations in representative pathological bone biopsies. Conclusions: Quantitative Raman analysis introduces BMPDs as a novel framework for assessing the spatial heterogeneity of bone extracellular matrix composition. By extending Raman microspectroscopy beyond conventional mean measurements, BMPDs provide robust, reproducible descriptors of bone material organization and establish a methodological foundation for investigating alterations of bone quality in metabolic bone diseases.

physiology↗

bioRxiv2024

The GLP-1 analogue, exendin-4, improves bone material properties and strength through a central relay in ovariectomized mice

Glucagon-like peptide-1 (GLP-1) has previously been shown to be indispensable for optimal bone strength by acting at the bone material level. However, it was not fully clear whether the effects of GLP-1 were mediated by direct or indirect actions on bone cells. In the present study, we were unable to demonstrate the expression of the GLP-1 receptor (GLP-1r) in bone tissue at the gene expression level using qPCR and in situ hybridization, or at the protein level. Furthermore, the peripheral administration of exendin-4, a specific GLP-1r agonist, in ovariectomized (OVX) BALB/c mice enhanced post-yield displacement (18%) and energy-to-fracture (24%), as well as bone volume/total volume (BV/TV) (11%), trabecular number (Tb.N) (6%), and collagen maturity (18%). These bone effects were still observed when exendin-4 was centrally administered into the lateral cerebral ventricle. On the other hand, the peripheral administration of exendin-4 coupled to bovine serum albumin, a GLP-1r agonist that cannot penetrate the brain, failed to replicate the positive effects on bone despite increased calcitonin secretion. Altogether, these data confirm that GLP-1r agonists represent an interesting approach for managing bone fragility due to ovariectomy, but also suggest that GLP-1r agonists require a central relay yet to be identified to exert positive effects on bone physiology. Further studies are needed to decipher the mechanisms of action of GLP-1 and GLP-1r agonists on bone physiology.

physiology↗

bioRxiv2023

Validation of Fourier transform infrared microspectroscopy for the evaluation of enzymatic cross-linking of bone collagen

Enzymatic cross-linking of the bone collagen is important to resist to crack growth and to increased flexural strength. In the present study, we proposed a new method for assessment of enzymatic cross-link based on FTIR microspectroscopy that takes into account secondary structure of type I collagen. Briefly, femurs were collected from sham or ovariectomized mice and subjected either to LC-MS or embedded in polymethylmethacrylate, cut and analyzed by FTIR microspectroscopy. FTIR acquisition were recorded before and after UV exposure or acid treatment. In addition, femurs from a second animal study were used to compare gene expression of Plod2 and Lox enzymes and enzymatic cross-links determined by FTIR microspectroscopy. We evidenced here that intensities and areas of subbands located at [~]1660 cm-1, [~]1680 cm-1 and [~]1690 cm-1 were positively and significantly associated with the concentration of pyridinoline (PYD), deoxypyridinoline (DPD) or immature dihydroxylysinonorleucine (DHLNL) / hydroxylysinonorleucine (HLNL) cross-links. Seventy-two hours exposure to UV light significantly reduced by [~]86% and [~]89% the intensity and area of the [~]1660 cm-1 subband. Similarly, 24 hours of acid treatment significantly reduced by 78% and 76% the intensity and area of the [~]1690 cm-1 subband. Plod2 and Lox expression were also positively associated to the signal of the [~]1660 cm-1 and [~]1690 cm-1 subbands. In conclusion, our study provided a new method for decomposing the amide I envelope of bone section that positively correlates with PYD and immature collagen cross-links. This method allows for investigation of tissue distribution of enzymatic cross-links in bone section.

biochemistry↗