Browsing by Author "Hartgerink, Jeffrey"

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    The Applications of Multidomain Peptide Hydrogels as Scaffolds for 3D Cell Culture
    (2023-12-01) Leyva Aranda, Claudia Viridiana; Hartgerink, Jeffrey
    3D cell culture constructs have emerged as indispensable tools in the field of cell biology and tissue engineering. These innovative scaffold-based platforms offer a more physiologically relevant environment for studying cell behavior, tissue development, disease modeling, and drug testing. In this work, we explore the importance of 3D cell culture scaffold-based constructs, the common biomaterials used for their creation, and prospective research routes that promise to further advance this field. In addition to that, we evaluate the use of multidomain peptides (MDPs) as platforms for 3D cell culture, and their applications for stem cell preservation, T cell-based therapies, and growth factor and nucleobase-modified MDP scaffolds. By providing a soft three-dimensional substrate, neutral MDP hydrogels proved to be successful at inducing stem cell quiescence and at maintaining stem cell phenotype and immunomodulatory properties. Additionally, MDP-based hydrogels demonstrated promising properties to be used as a 3D platform for T cell culture, enabling T cell in vitro activation, expansion, and maintenance of antigen specificity. Because of their chemical tunability, ongoing work explores the development of more complex chemistries by introducing growth factor peptide mimics, as well nucleobases for the generation of higher order supramolecular structures within the MDP hydrogels. This thesis describes the use of multidomain peptides as chemically tunable, biocompatible, versatile biomaterials for the generation of 3D culture scaffolds, with potential applications in the fields of cell therapy, drug delivery, stem cell preservation, and translational medicine.
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    Developing Supramolecular Peptide Hydrogels for Immunomodulation and Drug Delivery
    (2024-03-20) Pogostin, Brett Harris; McHugh, Kevin; Hartgerink, Jeffrey
    Supramolecular peptide hydrogels are promising materials for a wide variety of biomedical applications. Since they are composed of the same 20 natural amino acid building blocks that comprise all human proteins, they have the potential for enhanced biocompatibility and modular bioactivity. Their supramolecular nature endows them with shear-thinning and self-healing materials properties that enables their minimally invasive administration through small-bore needles. These viscoelastic materials can be over 99% water by mass. Their high-water content mimics the natural extracellular matrix and facilitates the facile loading of hydrophilic drugs and proteins while avoiding denaturation from organic solvents. Due to these promising properties, many groups have focused on developing these materials as tissue engineering scaffolds, drug delivery platforms, vaccine adjuvants, materials for cancer immunotherapy, hemostatic agents, antimicrobial wound dressings, etc. Multidomain peptide (MDP) hydrogels, developed in the Hartgerink lab, are a class of self-assembling peptides that form hydrogels under physiologically relevant conditions. These peptide sequences follow a general ABA structural pattern. The “A” motifs contain a charged amino acid selected from arginine, lysine, aspartic acid, and glutamic acid. The B domain is an amphiphilic region that promotes self-assembly into β-sheets. This region of the sequence typically contains repeating serine-leucine residues. For over a decade, these materials have been investigated for use in a plethora of different biomedical applications. In this thesis, I describe my investigations into using MDP hydrogels as vaccine adjuvants and drug delivery vehicles. I additionally explore designing novel peptide hydrogels with non-canonical motifs to improve their adjutancy and capacity to control the release of small and macromolecular payloads. Chapter 1 serves as an introduction to adjuvants and immunomodulatory materials. While each chapter relating to vaccine adjuvants contains a targeted introduction, this chapter particularly provides critical context for the importance of these materials in today’s world for pandemic preparedness. In Chapter 2, I investigate the use of differently charged MDPs to adjuvant the model antigen ovalbumin. I found that lysine containing MDPs are the best suited MDPs for vaccine adjuvant applications and that, interestingly, MDPs strongly bias a humoral immune response. I build on this work in Chapter 3 where, by modifying MDPs with a toll-like receptor 7 agonist, we further enhance the adjuvant potential of these peptide hydrogels. Further, we illicit a more balanced cellular and humoral immune response, which could be useful for a wide variety of infectious disease vaccines and cancer immunotherapies. Chapter 4 is a bridge chapter that links my work in immunomodulation to drug delivery leveraging dynamic covalent interactions. In this chapter, I aimed to control the release of the carbohydrate adjuvant mannan by forming dynamic imine bonds between the oxidized carbohydrate that the primary amines on a lysine containing MDP. I found that imine bonds can delay the release of oxidized mannan in vitro, but in vivo reduced and oxidized mannan is cleared much more rapidly than reduced mannan. The release of this oxidized carbohydrate can be reduced to the same rate as the reduced carbohydrate through imine bonding the MDP. The differences in reduced and oxidized mannan have been underappreciated in the literature, and I describe how MDPs may be useful for investigating the biological consequences of the different behaviors of these two materials in vivo. Chapter 5 focuses on peptide-based hydrogels that leverage boronic acid dynamic covalent chemistry for drug delivery. A thorough review of related drug delivery literature is included in the introduction of Chapter 5. In this part of my thesis, I describe my work developing new MDPs capable of forming dynamic covalent interactions with boronic acids (BAs). I found that these modified MDPs can significantly delay the release of BA-containing small molecules and BA-labeled proteins in vitro and in vivo. These materials can be used for both the local systemic delivery of therapeutics and improve the pharmacokinetic profiles of the drugs tested. I evaluate the potential application of this system by delivering basal insulin to diabetic mice. After a single injection of BA-modified insulin in this drug delivery platform, diabetic mice remain normoglycemic for 144 h. In comparison, a single injection of the maximum safe dose of insulin without hydrogel only maintained healthy blood glucose levels for 4 h. The work I present in this thesis aims to motivate the development of the next generation of peptide materials that leverage non-canonical modifications to improve upon the 20 amino acids nature provides. I show that including these modifications can alter both the immunological activity and drug delivery capabilities of MDPs and enhance their performance in in vivo models beyond what is possible with unmodified MDPs. This work shows the potential for next-generation MDPs that include non-canonical motifs to build on the past success of these materials and further their development towards clinical translation.
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    Fabrication of Macroscopic Nanofibrous Multidomain Peptide Hydrogels to Engineer Biological Tissues
    (2024-04-12) Farsheed, Adam Cyrus; Grande-Allen, K. Jane; Hartgerink, Jeffrey
    Fibrous extracellular matrix (ECM) proteins mechanically support cells and are hierarchically organized within macroscopic biological tissues. A longstanding goal of tissue engineering has been to fabricate scaffolds that mimic this organization, but it has been difficult to simultaneously mirror both micro and macroscale tissue complexity. Biomaterial design innovations have fostered the creation of synthetic ECM-mimetic hydrogels that recapitulate the mechanical and chemical properties of soft tissues. Still, the creation of large scaffolds at high fidelity has remained a bottleneck and is especially challenging when using soft biomaterials. Three- dimensional (3D) printing has emerged as a fabrication technology able to meet this goal due to its layer-by-layer working principal, but the number of hydrogels that have been adopted for 3D printing has remained limited. For over a decade, the Hartgerink lab has developed a synthetic class of biomaterials called multidomain peptides (MDPs), which form nanofibrous hydrogels that are useful for a variety of biomedical applications. My thesis presents the optimization of MDPs for 3D printing and the development of methods to create macroscopic MDP hydrogels with hierarchical order. In addition, I explore how biomaterial charge and fibrous alignment cues can be used to direct cellular spreading and engineer tissues from the bottom up. In the first chapter, I contextualize my work by reviewing the extracellular matrix, hydrogels, 3D printing of hydrogels, and MDPs. In the second chapter, I optimize MDPs for extrusion 3D printing and fabricate complex hydrogel structures and multi-material prints. In addition, I show how MDP charge can be used to control cell growth, which allows chemical functionality to provide an additional dimension to printing complexity. In the third chapter, I develop an extrusion-based fabrication strategy using MDPs to generate nanofibrous hydrogels that possess a spectrum of fibrillar alignments. In addition, I show how anisotropic MDP hydrogels can be used to directionally guide cellular growth, while differences in cell-matrix interactions determine a cell’s ability to understand nanofibrous alignment cues. In the fourth chapter, I present progress towards fabricating macroscopic MDP scaffolds with local anisotropy by optimizing support bath assisted 3D printing.
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    Synthetic multidomain peptide biomaterials that inhibit inducible nitric oxide synthase
    (2025-03-18) Hartgerink, Jeffrey; Sikora, Andrew G.; Leach, David; Newton, Jared M.; Young, Simon; Rice University; Baylor College of Medicine; The Board of Regents of the University of Texas System; United States Patent and Trademark Office
    Provided herein are compositions comprising multi domain peptide (MDP) hydrogels where the peptides that constitute the hydrogel have at least one N6-(1-iminoethyl)-lysine side chain. Also provided are hydrogels that further comprise a STING agonist, an immune checkpoint inhibitor, and/or an anti-cancer therapy. Also provided are methods of using such compositions in the treatment of cancer.