A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item Overcoming the Extracellular Matrix Barrier to Nanoparticle Transport(2024) Cahn, Devorah; Duncan, Gregg A; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The extracellular matrix (ECM) is a major component of the tumor microenvironment which poses a significant barrier to nanoparticle (NP) transport, preventing delivery of therapeutic cargo. Studies have shown that PEGylation offers an effective strategy for improving NP transport in ECM. However, these studies have generally used ECM models that are not wholly representative of the native matrix. Furthermore, while ECM characteristics and composition varies across organs, it is unclear to what extent these tissue-specific characteristics affect NP transport through the ECM and how NP surface chemistry impacts ECM penetration in distinct tissues. The overall objective of this dissertation is to identify key factors of NP transport through the tumor microenvironment, facilitating the development of strategies to improve NP distribution throughout the tumor microenvironment. We hypothesized that PEG branching will enhance stability and mobility of NPs in ECM and that ECM source impacts NP transport. We further hypothesized that PEG architecture significantly affects NP mobility in ECM as well as biodistribution and tumor accumulation in vivo. Our first aim was to determine the effects of PEG branching on NP stability and transport through in vitro basement membrane model. We found that branched PEG significantly increased both the stability and mobility of NPs in Matrigel, a basement membrane model. We then assessed the impact of tissue source on NP transport through an in vitro ECM model. We decellularized porcine lung, liver, and small intestine submucosa to form tissue specific hydrogels and found NP mobility was significantly impacted by tissue source where low molecular weight linear PEG generally provided the greatest benefit to NP mobility within the different matrices. Finally, we evaluated how PEG branching affects biodistribution, immune cell infiltration, and NP uptake in tumors in vivo. We found that NPs coated with branched PEG increased NP accumulation within tumors and PEGylation significantly impacted immune cell infiltration within these tumors. This work provides additional insight into the transport mechanisms of NPs throughout the tumor microenvironment as well as additional considerations for the design of efficient NP delivery systems.Item ENGINEERING NANOPARTICLES FOR IMPROVED LYMPHATIC DELIVERY AND ELUCIDATING MECHANISMS REGULATING NANOPARTICLE TRANSPORT INTO LYMPHATICS(2023) McCright, Jacob Connor; Maisel, Katharina; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Immune modulatory therapies usually need to be effectively delivered to lymph nodes to enhance therapeutic effectiveness. Lymphatic vessels exist throughout the body and can transport 10 – 250 nm therapeutic nanoparticles to lymph nodes, however, nanoparticle formulations required to maximize this transport, and the mechanisms governing this transport are poorly understood. Here, we probed the effect of surface charge, surface poly(ethylene glycol) (PEG) density, shape, and size on nanoparticle transport across LECs (LECs) and lymph node delivery. Using an established in-vitro lymphatic transport model, we found PEGylation improved the transport of 100 and 40 nm nanoparticles across LECs 50-fold compared to non-PEGylated nanoparticles and that transport is maximized when the PEG is in a dense brush conformation corresponding to a high grafting density (Rf/D = 4.9). PEGylating 40 nm nanoparticles improved transport efficiency across LECs 68-fold compared to unmodified nanoparticles, demonstrating that the addition of PEG improves transport in a size-independent manner. We injected these nanoparticle formulations intradermally into C57Bl/6J mice and found that PEGylated 100 nm and 40 nm nanoparticles accumulate in lymph nodes within 4 hours, while unmodified nanoparticles accumulated minimally. Densely PEGylated nanoparticles also traveled furthest from the injection site. In this thesis, we also determined that nanoparticles are transported via both paracellular and transcellular mechanisms, and that both PEG conformation and nanoparticle size and shape modulates the cellular transport mechanisms. We also expanded our in-vitro lymphatic transport model to model important physiological conditions including transmural flow and found that the presence of this flow increased transport across lymphatic barriers in a shape and mechanism-dependent manner. To further investigate the mechanisms regulating nanoparticle transport, we generated a computational kinetic transport model that was able to quantify the contributions of both paracellular and transcellular transport mechanisms, as well as predict transport efficiency as a function of nanoparticle characteristics including size and surface chemistry. Using transport inhibitors, we can expand our system of equations to describe precise uptake and transport mechanisms, and the relation between nanoparticle formulation and mechanism. This computational model is one of the first to describe transport across lymphatic vessels, and offers some of the first definitions for coefficients used to quantitatively describe nanoparticles transport across LECs (i.e., permeability). Our computational, in-vitro, and in-vivo results indicate that nanoparticle surface charge, PEG conformation, and size are key criteria for nanoparticle design for effective lymphatic delivery with a dense, neutrally charged coating of PEG maximizing transport across LEC barriers and transport to lymph nodes. Optimizing nanoparticle formulation and surface characteristics, including PEG density, has the potential to enhance immunotherapeutic and vaccine outcomes.Item Leveraging Biomaterial Properties to Reprogram Immune Function in Autoimmunity(2020) Gosselin, Emily A; Jewell, Christopher M; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Autoimmune diseases occur when immune cells incorrectly identify and attack the body’s tissues as foreign. In Multiple Sclerosis (MS), the immune system targets myelin, the protective layer that insulates nerves. Current MS therapies reduce disease severity without treating the cause, requiring frequent treatments to slow disease progression. Further, existing therapies cannot differentiate between dysfunctional myelin-reactive inflammatory cells and normal lymphocytes, leaving patients vulnerable to infection. To overcome these limitations, this dissertation investigated biodegradable polymeric microparticles (MPs) co-loaded with myelin peptides and rapamycin, an immunomodulatory signal. Directly injecting these tolerogenic MPs into key immune tissues (e.g. lymph nodes, LNs), induces myelin-specific regulatory immune cells that selectively control myelin-specific inflammation. This work aimed to advance pre-clinical studies and motivate clinical research in two ways: investigating the systemic impact of intra-LN tolerogenic MPs in two MS models, and enhancing MP stability using Chemistry, Manufacturing, and Controls (CMC) considerations. This work showed that across both progressive and relapsing-remitting disease, one tolerogenic intra-LN treatment promoted long-lasting improvements in disease-induced paralysis. Tolerogenic MPs delivered prior to symptom onset promoted tolerance and protected against disease. Treatment at peak disease reversed paralysis and prevented relapse, while treatment during relapse limited disease progression. Strikingly, mice vaccinated against a foreign protein on the same day as intra-LN treatment generated protein-specific T cells and antibodies at similar levels to healthy vaccinated mice, while simultaneously exhibiting significantly reduced paralysis – highlighting the myelin-specific nature of this therapy. While the low dosage requirements of these studies allowed for on-demand preparation, clinical translation requires investigation into manufacturing, preservation, storage, and stability of this immunotherapy. Thus, this dissertation also tested the impact of lyophilization (freeze-drying) and excipients (stabilizing molecules) on MP stability after storage. Lyophilization with low concentrations of excipients significantly improved MP stability and formulation recovery after reconstitution. Storage for 5 months at room temperature did not negatively impact cargo loading, MP size, or biofunctionality. MP formulations with excipients could deactivate inflammatory signaling and restrict myelin-specific immune cell proliferation as well as formulations without excipients. Together, these studies motivate the development of intra-LN delivery of tolerogenic MPs as a potential MS immunotherapy for clinical translation.Item ACTUATION OF MULTIFUNCTIONAL HARD NANOPARTICLES FOR ACTIVELY CONTROLLED DRUG RELEASE(2019) Sangtani, Ajmeeta; Delehanty, James B; Stroka, Kimberly M; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Systemic drug delivery relies on repeated dosing of large concentrations of poorly targeted drug leading to off-target toxicity. Recently, nanoparticle (NP)-mediated drug delivery (NMDD) has been developed as an approach to overcome the limitations of traditional drug delivery. The unique size-dependent properties of NPs and their ability to augment the activity of attached/loaded cargos makes them attractive drug delivery vectors. NPs are classified into two categories (soft or hard depending on their material composition) and our understanding of how to load and control soft NP materials currently surpasses that of hard NPs. In this dissertation we seek to further our fundamental knowledge of hard NP-based drug delivery systems. In Aim 1 we utilize a quantum dot (QD)-cell uptake peptide complex as a central scaffold to append various responsive peptide-drug constructs in order to modulate the toxicity of one of the most widely used chemotherapeutics, doxorubicin. By doing a comparative study of four chemical linkages, we determine the role played by attachment chemistry in controlling drug release. In Aim 2, we utilize the knowledge gained from Aim 1 to develop a system capable of overcoming multidrug resistance in cancer cells, which is known to severely limit the efficacy of chemotherapeutics. Our hard NP conjugate system is unique as it is one of the few systems reported in the literature to bypass multidrug resistance pumps without the need for exogenous drugs. Finally, in Aim 3 we append a peptide for membrane targeting and a photosensitizing drug capable of generating reactive oxygen species to the QD. This multifunctional system displays augmented therapeutic efficacy of the appended photosensitizer by delivering it to the membrane of cells and controlling its actuation using energy transfer. The work described here details basic concepts for the design of “smart” hard NP materials for internally and externally-triggered, active release of surface-appended drug cargos. Additionally, we hope to elucidate the important design considerations that must be taken into account when designing hard NP systems for controlled drug delivery.