Browsing by Author "Pearce, Hannah A."

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    Evaluating the physicochemical effects of conjugating peptides into thermogelling hydrogels for regenerative biomaterials applications
    (Oxford University Press, 2021) Pearce, Hannah A.; Jiang, Emily Y.; Swain, Joseph W.R.; Navara, Adam M.; Guo, Jason L.; Kim, Yu Seon; Woehr, Andrew; Hartgerink, Jeffrey D.; Mikos, Antonios G.; Bioengineering; Chemistry
    Thermogelling hydrogels, such as poly(N-isopropylacrylamide) [P(NiPAAm)], provide tunable constructs leveraged in many regenerative biomaterial applications. Recently, our lab developed the crosslinker poly(glycolic acid)-poly(ethylene glycol)-poly(glycolic acid)-di(but-2-yne-1,4-dithiol), which crosslinks P(NiPAAm-co-glycidyl methacrylate) via thiol-epoxy reaction and can be functionalized with azide-terminated peptides via alkyne-azide click chemistry. This study’s aim was to evaluate the impact of peptides on the physicochemical properties of the hydrogels. The physicochemical properties of the hydrogels including the lower critical solution temperature, crosslinking times, swelling, degradation, peptide release and cytocompatibility were evaluated. The gels bearing peptides increased equilibrium swelling indicating hydrophilicity of the hydrogel components. Comparable sol fractions were found for all groups, indicating that inclusion of peptides does not impact crosslinking. Moreover, the inclusion of a matrix metalloproteinase-sensitive peptide allowed elucidation of whether release of peptides from the network was driven by hydrolysis or enzymatic cleavage. The hydrophilicity of the network determined by the swelling behavior was demonstrated to be the most important factor in dictating hydrogel behavior over time. This study demonstrates the importance of characterizing the impact of additives on the physicochemical properties of hydrogels. These characteristics are key in determining design considerations for future in vitro and in vivo studies for tissue regeneration.
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    Machine Learning and Medical Devices: The Next Step for Tissue Engineering
    (Elsevier, 2021) Pearce, Hannah A.; Mikos, Antonios G.; Bioengineering
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    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.; Bioengineering
    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.