Heart failure (HF) remains a global public health burden and often results following myocardial infarction (MI). Following injury, cardiac fibrosis forms in the myocardium which greatly hinders cellular function, survival, and recruitment, thus severely limits tissue regeneration. Here, we leverage biophysical microstructural cues made of hyaluronic acid (HA) loaded with the anti-fibrotic proteoglycan decorin to more robustly attenuate cardiac fibrosis after acute myocardial injury. Microrods showed decorin incorporation throughout the entirety of the hydrogel structures and exhibited first-order release kinetics in vitro. Intramyocardial injections of saline ( n = 5), microrods ( n = 7), decorin microrods ( n = 10), and free decorin ( n = 4) were performed in male rat models of ischemia-reperfusion MI to evaluate therapeutic effects on cardiac remodeling and function. Echocardiographic analysis demonstrated that rats treated with decorin microrods (5.21% ± 4.29%) exhibited significantly increased change in ejection fraction (EF) at 8 weeks post-MI compared to rats treated with saline (−4.18% ± 2.78%, p < 0.001) and free decorin (−3.42% ± 1.86%, p < 0.01). Trends in reduced end diastolic volume were also identified in decorin microrod-treated groups compared to those treated with saline, microrods, and free decorin, indicating favorable ventricular remodeling. Quantitative analysis of histology and immunofluorescence staining showed that treatment with decorin microrods reduced cardiac fibrosis ( p < 0.05) and cardiomyocyte hypertrophy ( p < 0.05) at 8 weeks post-MI compared to saline control. Together, this work aims to contribute important knowledge to guide rationally designed biomaterial development that may be used to successfully treat cardiovascular diseases.

Introduction: Currently, there are no non-surgical FDA-approved biological approaches to accelerate fracture repair. Injectable therapies designed to stimulate bone healing represent an exciting alternative to surgically implanted biologics, however, the translation of effective osteoinductive therapies remains challenging due to the need for safe and effective drug delivery. Hydrogel-based microparticle platforms may be a clinically relevant solution to create controlled and localized drug delivery to treat bone fractures. Here, we describe poly (ethylene glycol) dimethacrylate (PEGDMA)-based microparticles, in the shape of microrods, loaded with beta nerve growth factor (β-NGF) for the purpose of promoting fracture repair.Methods: Herein, PEGDMA microrods were fabricated through photolithography. PEGDMA microrods were loaded with β-NGF and in vitro release was examined. Subsequently, bioactivity assays were evaluated in vitro using the TF-1 tyrosine receptor kinase A (Trk-A) expressing cell line. Finally, in vivo studies using our well-established murine tibia fracture model were performed and a single injection of the β-NGF loaded PEGDMA microrods, non-loaded PEGDMA microrods, or soluble β-NGF was administered to assess the extent of fracture healing using Micro-computed tomography (µCT) and histomorphometry.Results:In vitro release studies showed there is significant retention of protein within the polymer matrix over 168 hours through physiochemical interactions. Bioactivity of protein post-loading was confirmed with the TF-1 cell line. In vivo studies using our murine tibia fracture model show that PEGDMA microrods injected at the site of fracture remained adjacent to the callus for over 7 days. Importantly, a single injection of β-NGF loaded PEGDMA microrods resulted in improved fracture healing as indicated by a significant increase in the percent bone in the fracture callus, trabecular connective density, and bone mineral density relative to soluble β-NGF control indicating improved drug retention within the tissue. The concomitant decrease in cartilage fraction supports our prior work showing that β-NGF promotes endochondral conversion of cartilage to bone to accelerate healing.Discussion: We demonstrate a novel and translational method wherein β-NGF can be encapsulated within PEGDMA microrods for local delivery and that β-NGF bioactivity is maintained resulting in improved bone fracture repair.

The immune system plays a crucial role during tissue repair and wound healing processes. Biomaterials have been leveraged to assist in this in situ tissue regeneration process to dampen the foreign body response by evading or suppressing the immune system. An emerging paradigm within regenerative medicine is to use biomaterials to influence the immune system and create a pro-reparative microenvironment to instigate endogenously driven tissue repair. In this review, we discuss recent studies that focus on immunomodulation of innate and adaptive immune cells for tissue engineering applications through four biomaterial-based mechanisms of action: biophysical cues, chemical modifications, drug delivery, and sequestration. These materials enable augmented regeneration in various contexts, including vascularization, bone repair, wound healing, and autoimmune regulation. While further understanding of immune-material interactions is needed to design the next generation of immunomodulatory biomaterials, these materials have already demonstrated great promise for regenerative medicine. The immune system plays an important role in tissue repair. Many biomaterial strategies have been used to promote tissue repair, and recent work in this area has looked into the possibility of doing repair by tuning. Thus, we examined the literature for recent works showcasing the efficacy of these approaches in animal models of injuries. In these studies, we found that biomaterials successfully tuned the immune response and improved the repair of various tissues. This highlights the promise of immune-modulating material strategies to improve tissue repair.

Tissue engineering strategies, notably biomaterials, can be modularly designed and tuned to match specific patient needs. Although many challenges within tissue engineering remain, the incorporation of diagnostic strategies to create theranostic (combined therapy and diagnostic) biomaterials presents a unique platform to provide dual monitoring and treatment capabilities and advance the field toward personalized technologies. In this review, we summarize recent developments in this young field of regenerative theranostics and discuss the clinical potential and outlook of these systems from a tissue engineering perspective. As the need for precision and personalized medicines continues to increase to address diseases in all tissues in a patient-specific manner, we envision that such theranostic platforms can serve these needs.

Transthyretin (TTR) cardiac amyloidosis involves deposition of fibrils of misfolded TTR in the aging human heart, leading to cardiac dysfunction and heart failure. Our novel in vitro studies show that TTR fibrils alter primary cardiac fibroblast cytoskeletal and nuclear structure and focal adhesion formation. Furthermore, both fibrillar and tetrameric TTR significantly increased cellular migration velocity and caused upregulation of inflammatory genes determined by transcriptomic RNA and protein analysis. These findings may suggest new therapeutic approaches.

Formulations and devices for precision medicine applications must be tunable and multiresponsive to treat heterogeneous patient populations in a calibrated and individual manner. We engineered modular poly(acrylamideco-methacrylic acid) copolymers, cross-linked into multiresponsive nanogels with either a nondegradable or degradable disulfide cross-linker, that were customized via orthogonal chemistries to target biomarkers of an individual patient's disease or deliver multiple therapeutic modalities. Upon modification with functional small molecules, peptides, or proteins, these nanomaterials delivered methylene blue with environmental responsiveness, transduced visible light for photothermal therapy, acted as a functional enzyme, or promoted uptake by cells. In addition to quantifying the nanogels' composition, physicochemical characteristics, and cytotoxicity, we used a QCM-D method for characterizing nanomaterial degradation and a high-throughput assay for cellular uptake. In conclusion, we generated a tunable nanogel composition for precision medicine applications and new quantitative protocols for assessing the bioactivity of similar platforms.

Environmentally responsive biomaterials have played key roles in the design of biosensors and drug delivery vehicles. Their physical response to external stimuli, such as temperature or pH, can transduce a signal or trigger the release of a drug. In this work, we designed a robust, highly tunable, pH-responsive nanoscale hydrogel system. We present the design and characterization of poly(methacrylic acid-co-acrylamide) hydrogel nanoparticles, crosslinked with methylenebisacrylamide, through inverse emulsion polymerization. The effects of polymerization parameters (i.e., identities and concentrations of monomer and surfactant) and polymer composition (i.e., weight fraction of ionic and crosslinking monomers) on the nanoparticles' bulk and environmentally responsive properties were determined. We generated uniform, spherical nanoparticles which, through modulation of crosslinking, exhibit a volume swelling of 1.77-4.07, relative to the collapsed state in an acidic environment. We believe our system has potential as a base platform for the targeted, injectable delivery of hydrophilic therapeutics. With equal importance, however, we hope that our systematic analysis of the individual impacts of polymerization and purification conditions on nanoparticle composition, morphology, and performance can be used to expedite the development of alternate hydrophilic nanomaterials for a range of biomedical applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1677-1686, 2018.

Molecularly imprinted polymers (MIPs) with selective affinity for protein biomarkers could find extensive utility as environmentally robust, cost-efficient biomaterials for diagnostic and therapeutic applications. In order to develop recognitive, synthetic biomaterials for prohibitively expensive protein biomarkers, we have developed a molecular imprinting technique that utilizes structurally similar, analogue proteins. Hydrogel microparticles synthesized by molecular imprinting with trypsin, lysozyme, and cytochrome c possessed an increased affinity for alternate high isoelectric point biomarkers both in isolation and plasma-mimicking adsorption conditions. Imprinted and non-imprinted P(MAA-co-AAm-co-DEAEMA) microgels containing PMAO-PEGMA functionalized polycaprolactone nanoparticles were net-anionic, polydisperse, and irregularly shaped. MIPs and control non-imprinted polymers (NIPs) exhibited regions of Freundlich and BET isotherm adsorption behavior in a range of non-competitive protein solutions, where MIPs exhibited enhanced adsorption capacity in the Freundlich isotherm regions. In a competitive condition, imprinting with analogue templates (trypsin, lysozyme) increased the adsorption capacity of microgels for cytochrome c by 162% and 219%, respectively, as compared to a 122% increase provided by traditional bulk imprinting with cytochrome c. Our results suggest that molecular imprinting with analogue protein templates is a viable synthetic strategy for enhancing hydrogel-biomarker affinity and promoting specific protein adsorption behavior in biological fluids. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1565-1574, 2017.

Event Abstract Back to Event Molecularly imprinted polymers for protein capture, sequestration, and delivery John Clegg1, 2, Justin Zhong3, Heidi R. Culver1, 2 and Nicholas A. Peppas1, 2, 3, 4 1 University of Texas at Austin, Department of Biomedical Engineering, United States 2 University of Texas at Austin, Institute for Biomaterials, Drug Delivery, and Regenerative Medicine, United States 3 University of Texas at Austin, McKetta Department of Chemical Engineering, United States 4 University of Texas at Austin, College of Pharmacy, United States Introduction: Molecularly imprinted polymers (MIPs) for protein detection have been limited to a few model protein templates[1]. MIPs entrap protein within their pores during polymerization, requiring denaturing or even destructive purification techniques to purify and extract templates[2]. The cost of many therapeutic proteins is therefore prohibitive to their use as imprinting templates. Herein, we hypothesized that rationally-selected templates, possessing similar geometry, molecular weight and isoelectric point to disease-relevant biomarkers could be used as low-cost alternatives. We demonstrate a MIP system, using Trypsin as a low-cost template, to capture and sequester low molecular weight, positively charged biomolecules while excluding larger, negative proteins. The ability to displace and release a model therapeutic protein through template binding is also investigated. Materials and Methods: Trypsin was allowed to pre-assemble with methacrylate monomers possessing hydrophilic, positive, or negative moieties, as well as hydrophobic core nanoparticles and crosslinker in phosphate buffer under a nitrogen atmosphere. Following polymerization, entrapped trypsin and unreacted monomers were extracted with 10 washes in 10% acetic acid (Fig. 1). Non-imprinted control polymers (NIPs) were prepared in the same manner, excluding Trypsin. Hydrogel microparticles were subjected to binding assays, with proteins of varying charge and molecular weight (Fig. 2A). MIP sequestration and delivery of cytochrome c was demonstrated through loading cytochrome c within MIPs and NIPs, and monitoring payload release over 24 hours in the presence and absence of trypsin. Results and Discussion: MIPs bound more trypsin than NIPs (Fig. 2B) and similar quantities of cytochrome c and lysozyme, while binding small quantities of hemoglobin (Fig. 2C). Normalization of equilibrium rebinding for MIPs to NIPs (Imprinting Factor) revealed no difference in relative protein binding between trypsin, lysozyme, cytochrome c, which were all significantly greater than bovine hemoglobin (Fig 2D). All imprinting factors were significantly different from 1, (p< .05), demonstrating a measurable impact of molecular imprinting on protein binding. MIPs exhibited 84.9% loading efficiency of cytochrome c, as compared to 52.3% for NIPs. MIPs were capable of sequestering cytochrome c in 0.1x PBS, releasing only 5.7% of payload released in 24h, while subsequently releasing 41.5% during 24h incubation with trypsin. Conclusion: Trypsin imprinting impacts cytochrome c, lysozyme, trypsin, and hemoglobin binding through exclusion on the basis of size and electric potential. Cytochrome c and lysozyme bind in similar capacity to Trypsin, likely as their similar charge and smaller size permit entry and sequestration into trypsin-MIP pores. These proteins can be efficiently loaded, excluded, sequestered, and delivered. Future studies, using rationally-selected imprinting templates with structural similarity to clinical biomarkers will determine if this fully-synthetic, low cost system can be employed in medical diagnostics and drug delivery. NSF Graduate Research Fellowship; Pratt Foundation; UT-Portugal Collaborative Research ProgramReferences:[1] Kryscio, D. R., & Peppas, N. A. (2012). Critical review and perspective of macromolecularly imprinted polymers. Acta Biomaterialia, 8(2), 461-473.[2] Verheyen, E., Schillemans, J. P., van Wijk, M., Demeniex, M. A., Hennink, W. E., & van Nostrum, C. F. (2011). Challenges for the effective molecular imprinting of proteins. Biomaterials, 32(11), 3008-3020. Keywords: Drug delivery, Biomimetic, Smart material, Nano/micro particle Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: General Session Oral Topic: Protein interactions with biomaterials Citation: Clegg J, Zhong J, Culver HR and Peppas NA (2016). Molecularly imprinted polymers for protein capture, sequestration, and delivery. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.02358 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers John Clegg Justin Zhong Heidi R Culver Nicholas A Peppas Google John Clegg Justin Zhong Heidi R Culver Nicholas A Peppas Google Scholar John Clegg Justin Zhong Heidi R Culver Nicholas A Peppas PubMed John Clegg Justin Zhong Heidi R Culver Nicholas A Peppas Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.