Biology subjects

Onnerfjord, P.

Publications and source records attributed to Onnerfjord, P..

3 recordsLinked to original sources

bioRxiv2025

Characterization of calcifications in posterior horn of human meniscus using micro-computed tomography

ObjectiveMeniscal calcifications are associated with meniscal degeneration and osteoarthritis (OA). We investigated micro-computed tomography ({micro}CT) imaging for identification of calcification patterns caused by basic calcium phosphate (BCP) and calcium pyrophosphate (CPP). DesignPosterior horns of human medial and lateral menisci from 19 individuals with medial compartment knee OA and 21 deceased donors were imaged with high-resolution {micro}CT. Raman spectroscopy characterized the calcification types from histological sections, adjacent to {micro}CT piece. Qualitative and quantitative analysis, visualization, and grading were performed using 3D {micro}CT images of meniscal calcifications. ResultsDifferent calcification patterns were observed with BCP and CPP. BCP was found at the borders of meniscal tissue and inside complex tears or fibrillation. In contrast, CPP accumulated as circumferential rod-like structures between collagen bundles, mainly inside the meniscal tissue, and lacked the porous 3D structure observed in BCP calcifications. Quantitatively, CPP samples had a higher calcification volume compared to BCP with a geometric mean ratio of 14 (95%CI; 3,73), and larger particle sizes with a ratio of 7 (95%CI; 2,8). Additionally, BCP calcifications had an organized porous structure with a closed porosity range of 6-19, while a similar structure was not seen in CPPs (range 1-3.5). ConclusionsWe qualitatively and quantitatively identified volumetric and morphological differences in the calcification deposition patterns between BCP and CPP calcifications in human meniscus. The calculated differences may help distinguish the calcification types with in vivo imaging modalities in the future, as well as provide a better understanding of their role in OA.

bioengineering↗

bioRxiv2025

Characterizing meniscal calcifications with photon counting-based dual-energy computed tomography

Meniscal calcifications are associated with meniscal degeneration and osteoarthritis (OA). However, differentiating between calcification types, such as basic calcium phosphate (BCP) and calcium pyrophosphate (CPP), remains challenging in vivo. Therefore, assessing new imaging possibilities is crucial in understanding the calcification pathologies and their relationship with OA. This study investigated dual-energy computed tomography combined with a photon counting detector (PCD-DECT) to identify calcifications in human meniscal samples ex vivo, using Raman spectroscopy as reference. 82 meniscus samples from 41 donors were imaged using PCD-DECT at 120kVp. Data were collected in two energy bins (20-50keV and 50-120keV) with an isotropic resolution of 37{micro}m. Raman spectroscopy was used to classify the calcifications as BCP or CPP. Among 82 samples, Raman spectroscopy identified 36 samples with only either BCP or CPP calcifications, that were included in the subsequent analysis. Regression models were used to compare the dual-energy index (DEI) and to assess the low energy values for corresponding high energy values between calcification types. The highest difference observed between BCP and CPP in comparison of low energy values for corresponding high energy values was 166HU (95%CI: 73, 259) at high energy value of 500HU and the difference between DEI values was 0.035 (95%CI: 0.011, 0.059), suggesting a potential difference in the measured parameters of calcification types. To conclude, PCD-DECT allowed the measurement of BCP and CPP calcifications ex vivo, offering new potential in vivo applications in the future, which could help understand calcification processes and evaluate the efficacy of disease-modifying drugs targeting calcification inhibition.

bioengineering↗

bioRxiv2023

Altered co-expression patterns of synovial fluid proteins related to the immune system and extracellular matrix organization in late stage OA, compared to non-OA controls

ObjectiveSynovial fluid contains proteins that may have been released from surrounding tissues, our aim was to gain new insights into the proteomic profiles of human synovial fluid in knees with and without osteoarthritis (OA). MethodsWe used synovial fluid from 11 patients with end-stage medial compartment knee OA, aspirated during total knee replacement, and from 13 deceased donors who had no prior history of knee OA (healthy controls). These samples were analyzed using high-multiplex immunoassays Olink(R). The differential expression of proteins between the groups was analyzed using a linear mixed effects model. The linear associations between pairs of protein expressions were estimated with a linear regression model. ResultsWe found that almost half of the detected proteins were differentially expressed between the OA and non-OA controls. The proteins that were most elevated in the OA group compared to controls were tartrate-resistant acid phosphatase type 5 (fold change 10.6, 95% CI [6.6-17.0]), coagulation factor XI (4.3 [2.6-6.8]) and urokinase-type plasminogen activator (4.3 [2.3-6.8]). The proteins with lower levels in OA compared to controls were fatty acid-binding protein, adipocyte (0.03 [0.02-0.05]), myocilin (0.05 [0.03-0.08]) and carbonic anhydrase 3 (0.14 [0.09-0.23]). The protein-protein co-expression analysis suggests an overall lower number of protein pairs that show co-expression in OA. ConclusionThere is a substantial change in protein abundance in synovial fluid in end-stage knee OA, suggesting that global joint homeostasis is severely deranged. Our findings suggest altered co-expression between the immune response and extracellular matrix organization in end-stage knee OA, in comparison to non-OA controls.

molecular biology↗