Browsing by Author "Barrios, Sergio"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Embargo Dissecting the Effects of Targeted Radiation on the Bone Microenvironment(2024-04-17) Barrios, Sergio; Mikos, Antonios G; Dondossola, EleonoraRadium-223 (223Ra) is a bone-targeting, alpha particle-emitting radionuclide approved for the treatment of patients with metastatic prostate cancer that is currently being tested in a variety of clinical trials for a diverse set of bone-related disease. 223Ra has been shown to accumulate on mineralized bone tissue due to its calcium-mimetic properties and is highly enriched in areas with high bone turnover like the growth plates of long bones. Recent clinical studies have shown a significant fracture rate increase associated with the use of 223Ra, predominantly in tumor-free bones (68% of fractures). However, the biological mechanisms underlying this bone fragility are still unclear and generate a great concern in the clinical setting. Therefore, preclinical studies addressing the role of 223Ra-mediated modulation of the bone stromal components and the consequences on bone mechanical properties are much needed. In this thesis, we combined mechanical testing, micro-CT, and conventional endpoint analysis with fluorescent reporter mice for ex vivo 3D spatial biology microscopy analysis to clarify the effects of 223Ra on bone stromal components including osteoblasts, osteoclasts, adipocytes, and blood vessels. This approach assumes relevance when studying the response to 223Ra, which is spatially confined within 100 μm of the bone interface, due to the short penetration of alpha particles. Additionally, a novel tool for bone tissue image analysis was developed and validated. Overall, this thesis advances our understanding in bone biology and the unexplored impact of alpha-particle radiation on the bone microenvironment.Item Repair of complex ovine segmental mandibulectomy utilizing customized tissue engineered bony flaps(Public Library of Science, 2023) Watson, Emma; Pearce, Hannah A.; Hogan, Katie J.; Dijk, Natasja W.M. van; Smoak, Mollie M.; Barrios, Sergio; Smith, Brandon T.; Tatara, Alexander M.; Woernley, Timothy C.; Shum, Jonathan; Pearl, Craig B.; Melville, James C.; Ho, Tang; Hanna, Issa A.; Demian, Nagi; Beucken, Jeroen J.J.P. van den; Jansen, John A.; Wong, Mark E.; Mikos, Antonios G.Craniofacial defects require a treatment approach that provides both robust tissues to withstand the forces of mastication and high geometric fidelity that allows restoration of facial architecture. When the surrounding soft tissue is compromised either through lack of quantity (insufficient soft tissue to enclose a graft) or quality (insufficient vascularity or inducible cells), a vascularized construct is needed for reconstruction. Tissue engineering using customized 3D printed bioreactors enables the generation of mechanically robust, vascularized bony tissues of the desired geometry. While this approach has been shown to be effective when utilized for reconstruction of non-load bearing ovine angular defects and partial segmental defects, the two-stage approach to mandibular reconstruction requires testing in a large, load-bearing defect. In this study, 5 sheep underwent bioreactor implantation and the creation of a load-bearing mandibular defect. Two bioreactor geometries were tested: a larger complex bioreactor with a central groove, and a smaller rectangular bioreactor that were filled with a mix of xenograft and autograft (initial bone volume/total volume BV/TV of 31.8 ± 1.6%). At transfer, the tissues generated within large and small bioreactors were composed of a mix of lamellar and woven bone and had BV/TV of 55.3 ± 2.6% and 59.2 ± 6.3%, respectively. After transfer of the large bioreactors to the mandibular defect, the bioreactor tissues continued to remodel, reaching a final BV/TV of 64.5 ± 6.2%. Despite recalcitrant infections, viable osteoblasts were seen within the transferred tissues to the mandibular site at the end of the study, suggesting that a vascularized customized bony flap is a potentially effective reconstructive strategy when combined with an optimal stabilization strategy and local antibiotic delivery prior to development of a deep-seated infection.