Browsing by Author "Watson, Emma"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Customizable Bone Constructs and Tunable Scaffolds for Craniofacial Tissue Engineering(2020-07-28) Watson, Emma; Mikos, Antonios GThe repair of large craniofacial defects remains a challenge, and repair with the clinical gold standard of a fibular flap can lead to donor site morbidity. In cases of tumor removal, growth factors may be contraindicated, and in trauma an infection may prevent immediate definitive reconstruction. A two-stage approach to craniofacial tissue engineering involves the implantation of a space maintainer within the defect site to optimize the site for receiving a customized bone graft grown elsewhere within the body adjacent to periosteum. The space maintainers can be loaded with antibiotics to clear infections and fabricated from novel polymers with varied mechanical properties to create a robust tissue pocket for transfer. In this dissertation, we sought to develop tissue engineering and biomaterials-based strategies for the reconstruction of large, complicated craniofacial defects. In the first specific aim, the two-stage strategy for mandibular repair is further challenged with two complex ovine models. We tested the ability of an antibiotic-loaded space maintainer to treat a mandibular infection, while simultaneously determining the effects of an untreated mandibular infection on the bone growth within the bioreactors. We showed that the antibiotic-loaded space maintainer was capable of clearing or preventing a Staphyloccus aureus mandibular infection, and that an untreated mandibular infection led to increased bone growth of more mature bone within the bioreactor chambers. We also showed that autograft-filled bioreactors led to increased new bone formation with more robust mechanical properties than commercially available cancellous bone chips. In another sheep model, we increased our defect size to the entire height of the mandible, creating a defect that was more exposed to mechanical forces than previously tested. Using fixation considered standard for a human with a similar defect, several animals experienced dehiscence and hardware failure. Radiographic analysis of the bioreactor tissue from implantation to transfer to integration within the mandible showed remodeling over time, but the tissue did not reach the same radiographic values as the unoperated contralateral side. Taken together, these two studies demonstrated that a space maintainer and bioreactor two-stage strategy is promising if fixation of the mandible is adequate to prevent hardware failure, micromotion, and mucosal dehiscence. For the second aim, we worked to commercialize our porous space maintainer through submissions to and interactions with the Food and Drug Administration (FDA). Our device was to proceed along the 510(k) pathway for a significant risk device, requiring an early feasibility study (EFS) and investigational device exemption (IDE) approval. To acquire the appropriate approvals, we developed protocols and created specimens for a battery of biocompatibility testing, proving that our device was cytocompatible, non-mutagenic, non-sensitizing, non-irritating, and non-toxic. We further worked with clinical collaborators to draft a clinical protocol for approval from the FDA to begin our EFS. Finally, the third specific aim involved the investigation of a class of novel polymers, synthesized from potentially antimicrobial monomers. These polymers were created from differing lengths of diols reacted with diacids to create polymers with tunable mechanical properties. We performed a main effects analysis on molecular weight, thermal characteristics, and mechanical properties to determine how they were impacted by the feed ratios of the polymers. We further expanded the tested ratios of the diacids and demonstrated that the mechanical properties could be varied predictably. However, the cytotoxicity also varied across groups, with high succinic acid incorporation leading to high levels of cell death. Although this platform was tunable, the effects of mechanical properties of the substrate and release of cytotoxic compounds on cell fate would be difficult to dissect. The overall goal of this thesis was to expand on the two-stage strategy of utilizing a space maintainer and bioreactor to repair craniofacial defects and to develop and investigate the applicability of a novel polymer system as a tunable tissue engineering platform. We demonstrated that antibiotic-loaded space maintainers are efficacious at clearing mandibular infection and that the two-stage approach to bone tissue engineering is promising even in larger, load-bearing defects. We worked to commercialize this technology and to create a polymer system with tunable mechanical properties. The translation of tissue engineering strategies has great potential to assist in patient treatment.Item ERIN WATSON Composer MASTER'S RECITAL Wednesday, November 19, 2003 8:00 p.m. Hirsch Orchestra Rehearsal Hall(Shepherd School of Music, Rice University, 2003-11-19) Watson, Emma; Watson, Erin (composer, accordion); Starz, Claire (flute); Gustin, Elizabeth (clarinet); Koiner, Francis (cello); Mimaki, Kana (piano); Remick, Heidi (viola); Samson, William (tuba); Bertrand, Evan (percussion); Wightman, David (percussion); Lee, Christopher (miscellany); Beecher, Lembit (conductor); Chan, Ning (violin); Millner, Angela (violin); Koiner, Francis (cello)Program: 4' / Emma Watson -- 10' / Emma Watson -- Inhale / Emma Watson -- 8' / Emma Watson -- Hold / Emma Watson -- 6' / Emma Watson -- Exhale / Emma Watson -- 3' / Emma Watson.Item Poly(diol fumarates) and poly(diol fumarate-co-succinates)(2020-11-17) Tatara, Alexander Mitchell; Watson, Emma; Mikos, Antonios G.; Kontoyiannis, Dimitrios P.; Rice University; Board of Regents, The University of Texas System; United States Patent and Trademark OfficeThe disclosure relates to a class of diol-based, unsaturated aliphatic polyesters that biodegrade into monomers capable of mitigating infection. These poly(diol fumarates) (PDFs) and poly(diol fumarate-co-succinates) (PDFSs), can be crosslinked to form networks of scaffolds with antimicrobial degradation products. Both the diol carbon length and the degree of available double bonds are tunable, resulting in a highly controllable class of antimicrobial polymers useful for cell scaffolds and drug delivery systems and devices.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.