Publications by authors named "Viktorija Rumenovic"

2 Publications

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Iron overload in aging mice induces exocrine pancreatic injury and fibrosis due to acinar cell loss.

Int J Mol Med 2021 Apr 2;47(4):1-8. Epub 2021 Mar 2.

Laboratory for Mineralized Tissues, Center for Translational and Clinical Research, School of Medicine, University of Zagreb, HR‑10000 Zagreb, Croatia.

The relationship between hemochromatosis and diabetes has been well established, as excessive iron deposition has been reported to result in impaired function of the endocrine and exocrine pancreas. Therefore, the objective of the present study was to analyze the effects of iron accumulation on the pancreata and glucose homeostasis in a bone morphogenetic protein 6‑knockout () mouse model of hemochromatosis. The sera and pancreatic tissues of wild‑type (WT) and mice (age, 3 and 10 months) were subjected to biochemical and histological analyses. In addition, F‑fluorodeoxyglucose biodistribution was evaluated in the liver, muscle, heart, kidney and adipose tissue of both animal groups. The results demonstrated that 3‑month‑old mice exhibited iron accumulation preferentially in the exocrine pancreas, with no signs of pancreatic injury or fibrosis. No changes were observed in the glucose metabolism, as pancreatic islet diameter, insulin and glucagon secretion, blood glucose levels and glucose uptake in the liver, muscle and adipose tissue remained comparable with those in the WT mice. Aging mice presented with progressive iron deposits in the exocrine pancreas, leading to pancreatic degeneration and injury that was characterized by acinar atrophy, fibrosis and the infiltration of inflammatory cells. However, the aging mice exhibited unaltered blood glucose levels and islet structure, normal insulin secretion and moderately increased α‑cell mass compared with those in the age‑matched WT mice. Additionally, iron overload and pancreatic damage were not observed in the aging WT mice. These results supported a pathogenic role of iron overload in aging mice leading to iron‑induced exocrine pancreatic deficiency, whereas the endocrine pancreas retained normal function.
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April 2021

Synthetic ceramic macroporous blocks as a scaffold in ectopic bone formation induced by recombinant human bone morphogenetic protein 6 within autologous blood coagulum in rats.

Int Orthop 2020 Oct 14. Epub 2020 Oct 14.

Laboratory for Mineralized Tissues, Center for Translational and Clinical Research, University of Zagreb School of Medicine, Zagreb, Croatia.

Purpose: We have recently developed an autologous bone graft substitute (ABGS) containing recombinant human bone morphogenetic protein 6 (rhBMP6) in autologous blood coagulum (ABC) that induces new bone formation in vivo. In order to improve biomechanical properties of the implant, compression resistant matrix (CRM) consisting of synthetic ceramics in the form of macroporous cylinders was added to the ABGS and we evaluated the biomechanical properties and the quantity and quality of bone formation following subcutaneous implantation in rats.

Methods: ABGS implants containing rhBMP6 in ABC with cylindrical ceramic blocks were implanted subcutaneously (n = 6 per time point) in the axillary region of Sprague-Dawley rats and removed at specified time points (7, 14, 21, 35, and 50 days). The quantity and quality of newly formed bone were analyzed by microCT, histology, and histomorphometric analyses. Biomechanical properties of ABGS formulations were determined by employing the cut test.

Results: MicroCT analyses revealed that ABGS implants induced formation of new bone within ceramic blocks. Histological analysis revealed that on day seven following implantation, the endochondral ossification occupied the peripheral part of implants. On days 14 and 21, newly formed bone was present both around the ceramic block and through the pores inside the block. On both days 35 and 50, cortical bone encircled the ceramic block while inside the block, bone covered the ceramic surface surrounding the pores. Within the osseous circles, there were few trabeculae and bone marrow containing adipocytes. ABGS containing cylindrical ceramic blocks were more rigid and had significantly increased stiffness compared with implants containing ceramic particles as CRM.

Conclusion: We demonstrated that macroporous ceramic blocks in a form of cylinders are promising CRMs with good handling and enhanced biomechanical properties, supporting bone formation with ABGS containing rhBMP6 within autologous blood coagulum. Hence, ABGS containing ceramic blocks should be tested in preclinical models including diaphyseal segmental defects and non-unions in larger animals.
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October 2020