Browsing by Author "Sullivan, Millicent O."
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Item Area-based Image Analysis Algorithm for Quantification of Macrophage-fibroblast Cocultures(Journal of Visualized Experiments, 2022-02-15) Borjigin, Tohn; Boddupalli, Anuraag; Sullivan, Millicent O.Quantification of cells is necessary for a wide range of biological and biochemical studies. Conventional image analysis of cells typically employs either fluorescence detection approaches, such as immunofluorescent staining or transfection with fluorescent proteins or edge detection techniques, which are often error-prone due to noise and other non-idealities in the image background. We designed a new algorithm that could accurately count and distinguish macrophages and fibroblasts, cells of different phenotypes that often colocalize during tissue regeneration. MATLAB was used to implement the algorithm, which differentiated distinct cell types based on differences in height from the background. A primary algorithm was developed using an area-based method to account for variations in cell size/structure and high-density seeding conditions. Non-idealities in cell structures were accounted for with a secondary, iterative algorithm utilizing internal parameters such as cell coverage computed using experimental data for a given cell type. Finally, an analysis of coculture environments was carried out using an isolation algorithm in which various cell types were selectively excluded based on the evaluation of relative height differences within the image. This approach was found to accurately count cells within a 5% error margin for monocultured cells and within a 10% error margin for cocultured cells.Item Catch and release: photocleavable cationic diblock copolymers as a potential platform for nucleic acid delivery(Royal Society of Chemistry, 2014-06-05) Green, Matthew D.; Foster, Abbygail A.; Greco, Chad T.; Roy, Raghunath; Lehr, Rachel M.; Epps, Thomas H. III; Sullivan, Millicent O.; Matthew D. Green, Abbygail A. Foster, Chad T. Greco, Raghunath Roy, Rachel M. Lehr, Thomas H. Epps, III and Millicent O. Sullivan; Green, Matthew D.; Foster, Abbygail A.; Greco, Chad T.; Roy, Raghunath; Lehr, Rachel M.; Epps, Thomas H. III; Sullivan, Millicent O.Binding interactions between DNA and cationic nanocarriers must be sufficiently strong to prevent nuclease-mediated degradation, yet weak enough to permit transcription. We demonstrate cationic diblock copolymers containing PEG and o-nitrobenzyl moieties that facilitated tailorable DNA complexation and light-activated release. This design unlocks a new approach to improved non-viral gene packaging.Item Growth factors and growth factor gene therapies for treating chronic wounds(Bioengineering and Translational Medicine, 2023-12-28) Mullin, James A.; Rahmani, Erfan; Kiick, Kristi L.; Sullivan, Millicent O.Chronic wounds are an unmet clinical need affecting millions of patients globally, and current standards of care fail to consistently promote complete wound closure and prevent recurrence. Disruptions in growth factor signaling, a hallmark of chronic wounds, have led researchers to pursue growth factor therapies as potential supplements to standards of care. Initial studies delivering growth factors in protein form showed promise, with a few formulations reaching clinical trials and one obtaining clinical approval. However, protein-form growth factors are limited by instability and off-target effects. Gene therapy offers an alternative approach to deliver growth factors to the chronic wound environment, but safety concerns surrounding gene therapy as well as efficacy challenges in the gene delivery process have prevented clinical translation. Current growth factor delivery and gene therapy approaches have primarily used single growth factor formulations, but recent efforts have aimed to develop multi-growth factor approaches that are better suited to address growth factor insufficiencies in the chronic wound environment, and these strategies have demonstrated improved efficacy in preclinical studies. This review provides an overview of chronic wound healing, emphasizing the need and potential for growth factor therapies. It includes a summary of current standards of care, recent advances in growth factor, cell-based, and gene therapy approaches, and future perspectives for multi-growth factor therapeutics. Translational Impact Statement Chronic wounds persist as a healthcare challenge despite extensive research on various treatments, including growth factors and gene therapies. Progress in translating these therapeutics to clinical use has been slow, with many growth factor approaches demonstrating promise in preclinical studies but providing limited benefits in clinical trials or clinical application. This review presents recent advances in growth factor therapies and growth factor gene therapies, discusses obstacles to regulatory approval, and offers perspectives on potential innovations for successful clinical translation.Item Unlocking Chain Exchange in Highly Amphiphilic Block Polymer Micellar Systems: Influence of Agitation(American Chemical Society, 2014-10-14) Murphy, Ryan P.; Kelley, Elizabeth G.; Rogers, Simon A.; Sullivan, Millicent O.; Epps, Thomas H. III; Ryan P. Murphy, Elizabeth G. Kelley, Simon A. Rogers, Millicent O. Sullivan, and Thomas H. Epps, III; Murphy, Ryan P.; Kelley, Elizabeth G.; Rogers, Simon A.; Sullivan, Millicent O.; Epps, Thomas H. IIIChain exchange between block polymer micelles in highly selective solvents, such as water, is well-known to be arrested under quiescent conditions, yet this work demonstrates that simple agitation methods can induce rapid chain exchange in these solvents. Aqueous solutions containing either pure poly(butadiene-b-ethylene oxide) or pure poly(butadiene-b-ethylene oxide-d4) micelles were combined and then subjected to agitation by vortex mixing, concentric cylinder Couette flow, or nitrogen gas sparging. Subsequently, the extent of chain exchange between micelles was quantified using small angle neutron scattering. Rapid vortex mixing induced chain exchange within minutes, as evidenced by a monotonic decrease in scattered intensity, whereas Couette flow and sparging did not lead to measurable chain exchange over the examined time scale of hours. The linear kinetics with respect to agitation time suggested a surface-limited exchange process at the air–water interface. These findings demonstrate the strong influence of processing conditions on block polymer solution assemblies.