Browsing by Subject "Heparin"

Now showing 1 - 10 of 10
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Heparinized Gelatin-Based Hydrogels for Differentiation of Induced Pluripotent Stem Cells
    (American Chemical Society, 2022) Arkenberg, Matthew R.; Koehler, Karl; Lin, Chien-Chi; Biomedical Engineering, School of Engineering and Technology
    Chemically defined hydrogels are increasingly utilized to define the effects of extracellular matrix (ECM) components on cellular fate determination of human embryonic and induced pluripotent stem cell (hESC and hiPSCs). In particular, hydrogels cross-linked by orthogonal click chemistry, including thiol-norbornene photopolymerization and inverse electron demand Diels-Alder (iEDDA) reactions, are explored for 3D culture of hESC/hiPSCs owing to the specificity, efficiency, cytocompatibility, and modularity of the cross-linking reactions. In this work, we exploited the modularity of thiol-norbornene photopolymerization to create a biomimetic hydrogel platform for 3D culture and differentiation of hiPSCs. A cell-adhesive, protease-labile, and cross-linkable gelatin derivative, gelatin-norbornene (GelNB), was used as the backbone polymer for constructing hiPSC-laden biomimetic hydrogels. GelNB was further heparinized via the iEDDA click reaction using tetrazine-modified heparin (HepTz), creating GelNB-Hep. GelNB or GelNB-Hep was modularly cross-linked with either inert macromer poly(ethylene glycol)-tetra-thiol (PEG4SH) or another bioactive macromer-thiolated hyaluronic acid (THA). The formulations of these hydrogels were modularly tuned to afford biomimetic matrices with similar elastic moduli but varying bioactive components, enabling the understanding of each bioactive component on supporting hiPSC growth and ectodermal, mesodermal, and endodermal fate commitment under identical soluble differentiation cues.
  • Thumbnail Image
    Item
    Improving the Patency of Jugular Vein Catheters in Sprague-Dawley Rats by Using an Antiseptic Nitrocellulose Coating
    (Ingenta, 2018-09-01) De Luca, Thomas; Szilágyi, Keely L; Hargreaves, Katherine A.; Collins, Kimberly S.; Benson, Eric A.; Department of Medicine, Indiana University School of Medicine
    Preclinical studies in animals often require frequent blood sampling over prolonged periods. A preferred method in rats is the implantation of a polyurethane catheter into the jugular vein, with heparinized glycerol as a lock solution. However, analysis of various biologic compounds (for example, microRNA) precludes the use of heparin. We used sodium citrate as an alternative to heparin but observed more frequent loss of catheter patency. We hypothesized that this effect was due to evaporation of lock solution at the exteriorized portion of the catheter, subsequent blood infiltration into the catheter, and ultimately clot formation within the catheter. We therefore tested evaporation and its variables in vitro by using 5 common catheter materials. We used the migration of dye into vertically anchored catheters as a measure of lock displacement due to evaporation. Exposure to dry room-temperature air was sufficient to cause dye migration against gravity, whereas a humid environment and adding glycerol to the lock solution mitigated this effect, thus confirming loss of the lock solution from the catheter by evaporation. We tested 4 catheter treatments for the ability to reduce lock evaporation. Results were validated in vivo by using male Sprague-Dawley rats (n = 12) implanted with polyurethane jugular vein catheters and randomized to receive a nitrocellulose-based coating on the exteriorized portion of the catheter. Coating the catheters significantly improved patency, as indicated by a Kaplan-Meier log-rank hazard ratio greater than 5 in untreated catheters. We here demonstrate that a simple nitrocellulose coating reduces evaporation from and thus prolongs the patency of polyurethane catheters in rats.
  • Thumbnail Image
    Item
    Incidence of Venous Thromboembolism and Hematoma Following Placement of Inflatable Penile Prosthetic: Safety of Perioperative Subcutaneous Heparin
    (2023-07-28) Good, Jacob; Bernie, Helen
    BACKGROUND/OBJECTIVE: Patients undergoing inflatable penile prosthetic (IPP) surgery are at an increased risk for cardiovascular complications such as venous thromboembolism (VTE) following surgery due to pre-existing comorbidities associated with erectile dysfunction. The use of perioperative subcutaneous heparin (SqH) along with a surgical drain has been shown to be effective in preventing VTE in IPP patients, without increasing hematoma formation. Not all prosthetic surgeons utilize surgical drains postoperatively. In this study we aim to assess the safety and efficacy of perioperative SqH in preventing VTE in IPP patients without the use of a surgical drain. METHODS: This was a retrospective review from January 2021-July 2023 of patients who underwent IPP placement or explant and replacement at a single institution. Patient demographics, comorbidities, Caprini risk factor scores, VTE risk factors, and 90-day post-operative complications, including hematoma formation, were reviewed. Statistical analyses were performed comparing these variables in men who received SqH and those who did not. RESULTS: We reviewed data for 240 patients; 53% (n=127) received perioperative SqH. The incidence of VTE was 0.9% (1/113) in the non-SqH group, and no VTE was recorded in the group receiving SqH. There was no statistical significance in hematoma formation between groups (SqH 5.5% vs. non-SqH 6.2% p=.898). Beyond hypertension prevalence (SqH 74.8% vs. non-SqH 62.8% p=.045), there was no difference between comorbidities or Caprini risk factor scores (SqH 6.79 vs. non-SqH 6.82 p=.474) between groups (Table 1). 94% of the patients in this study were considered high risk for VTE. CONCLUSIONS: Perioperative SqH use without placement of a surgical drain was found to be safe and effective in preventing VTE in patients undergoing IPP surgery. There was no increased risk of hematoma formation or post-operative complications between the groups. Perioperative SqH should be considered in all patients undergoing IPP surgery.
  • Thumbnail Image
    Item
    Modular crosslinking of gelatin based thiol-norbornene hydrogels for in vitro 3D culture of hepatic cells
    (ACS Biomaterials Science and Engineering, 2015-10-21) Greene, Tanja L.; Lin, Chien-Chi; Xie, Dong; Dai, Guoli; Yoshida, Ken
    As liver disease becomes more prevalent, the development of an in vitro culture system to study disease progression and its repair mechanisms is essential. Typically, 2D cultures are used to investigate liver cell (e.g., hepatocyte) function in vitro; however, hepatocytes lose function rapidly when they were isolated from the liver. This has promoted researchers to develop 3D scaffolds to recreate the natural microenvironment of hepatic cells. For example, gelatin-based hydrogels have been increasingly used to promote cell fate processes in 3D. Most gelatin-based systems require the use of physical gelation or non-specific chemical crosslinking. Both of these methods yield gelatin hydrogels with highly interdependent material properties (e.g., bioactivity and matrix stiffness). The purpose of this thesis research was to prepare modularly crosslinked gelatin-based hydrogels for studying the influence of independent matrix properties on hepatic cell fate in 3D. The first objective was to establish tunable gelatin-based thiol-norbornene hydrogels and to demonstrate that the mechanical and biological properties of gelatin hydrogels can be independently adjusted. Furthermore, norbornene and heparin dual-functionalized gelatin (i.e., GelNB-Hep) was prepared and used to sequester and slowly release hepatocyte growth factor (HGF). The second objective was to investigate the viability and functions of hepatocytes encapsulated in gelatin-based hydrogels. Hepatocellular carcinoma cells, Huh7, were used as a model cell type to demonstrate the cytocompatibility of the system. The properties of GelNB hydrogels were modularly tuned to systematically evaluate the effects of matrix properties on cell viability and functions, including CYP3A4 activity and urea secretion. The last objective was to examine the effect of heparin immobilization on hepatocyte viability and functions. The conjugation of heparin onto GelNB led to suppressed Huh7 cell metabolic activity and improved hepatocellular functions. This hybrid hydrogel system should provide a promising 3D cell culture platform for studying cell fate processes.
  • Thumbnail Image
    Item
    Modular Nanoparticles for Selective Cell Targeting
    (2019-05) Peuler, Kevin; Lin, Chien-Chi; Agarwal, Mangilal; Veronesi, Michael C.
    Nanoparticles (NPs) are an emerging technology in biomedical engineering with opportunities in diagnostics, imaging, and drug delivery. NPs can be prepared from a wide range of organic and/or inorganic materials. They can be fabricated to exhibit different characteristics for biomedical applications. The goal of this thesis was to develop NPs with tunable surface properties for selective cell targeting. Specifically, polyelectrolyte complexes composed of heparin (Hep, a growth factor binding glycosaminoglycan) and poly-L-lysine (PLL, a homopolymeric lysine) were prepared via a pulse sonication method. The Hep/PLL core NPs were further layered with additional Hep, tetrazine (Tz) modified Hep, or dextran sulfate (DS). The addition of Tz handle on Hep backbone permitted easy modification of NP surface with norbornene (NB) modified motifs/ligands, including inert poly(ethylene glycol) (PEG), cell adhesive peptides (e.g., RGD), and/or fluorescent marker. Both Hep and DS coated NPs could be readily internalized by J774A.1 monocytes/macrophages, whereas PEGylated NPs effectively reduced cellular uptake/recognition. The versatility of this NP system was further demonstrated by laying DS on the Hep/PLL NP surface. DS-coated NPs were recognized by J774A.1 cells more effectively. Furthermore, DS-layered NPs seemed to reduce IL-10 production on a per cell basis, suggesting that these NPs could be used to alter polarization of macrophages.
  • Thumbnail Image
    Item
    Soluble α-klotho and heparin modulate the pathologic cardiac actions of fibroblast growth factor 23 in chronic kidney disease
    (Elsevier, 2022) Yanucil, Christopher; Kentrup, Dominik; Campos, Isaac; Czaya, Brian; Heitman, Kylie; Westbrook, David; Osis, Gunars; Grabner, Alexander; Wende, Adam R.; Vallejo, Julian; Wacker, Michael J.; Navarro-Garcia, Jose Alberto; Ruiz-Hurtado, Gema; Zhang, Fuming; Song, Yuefan; Linhardt, Robert J.; White, Kenneth; Kapiloff, Michael S.; Faul, Christian; Medical and Molecular Genetics, School of Medicine
    Fibroblast growth factor (FGF) 23 is a phosphate-regulating hormone that is elevated in patients with chronic kidney disease and associated with cardiovascular mortality. Experimental studies showed that elevated FGF23 levels induce cardiac hypertrophy by targeting cardiac myocytes via FGF receptor isoform 4 (FGFR4). A recent structural analysis revealed that the complex of FGF23 and FGFR1, the physiologic FGF23 receptor in the kidney, includes soluble α-klotho (klotho) and heparin, which both act as co-factors for FGF23/FGFR1 signaling. Here, we investigated whether soluble klotho, a circulating protein with cardio-protective properties, and heparin, a factor that is routinely infused into patients with kidney failure during the hemodialysis procedure, regulate FGF23/FGFR4 signaling and effects in cardiac myocytes. We developed a plate-based binding assay to quantify affinities of specific FGF23/FGFR interactions, and found that soluble klotho and heparin mediate FGF23 binding to distinct FGFR isoforms. Heparin specifically mediated FGF23 binding to FGFR4, and increased FGF23 stimulatory effects on hypertrophic growth and contractility in isolated cardiac myocytes. When repetitively injected into two different mouse models with elevated serum FGF23 levels, heparin aggravated cardiac hypertrophy. We also developed a novel procedure for the synthesis and purification of recombinant soluble klotho, which showed anti-hypertrophic effects in FGF23-treated cardiac myocytes. Thus, soluble klotho and heparin act as independent FGF23 coreceptors with opposite effects on the pathologic actions of FGF23, with soluble klotho reducing and heparin increasing FGF23-induced cardiac hypertrophy. Hence, whether heparin injections during hemodialysis in patients with extremely high serum FGF23 levels contribute to their high rates of cardiovascular events and mortality remains to be studied.
  • Thumbnail Image
    Item
    Testing the renal signaling axis for FGF23
    (2015-11-13) Ni, Pu; White, Kenneth E.; Herbert, Brittney-Shea; Dlouhy, Stephen R.
    FGF23 is the central regulator for phosphate homeostasis. Both FGF23 and phosphate dysregulation are highly related with the progression of chronic kidney disease (CKD), which is a global health problem. In previous studies, FGF23 was found to be produced in bone and targeting the kidneys to regulate phosphate reabsorption and excretion. In the FGF23 signaling axis, it binds a receptor complex (αKlotho and FGFRs) in the distal convoluted tubules (DCT) and causes its biological effects in the proximal tubules (PT). The mechanism of how the signals passing on from DCT to PT is not clear. In my research, experiments were focused on the FGF23 signaling pathway within the kidney to study the communication steps between tubular cells. HBEGF treatment was given to FGF23 signaling impaired mouse models resulting in significant change of genes regulated by FGF23, indicating that HBEGF was important in the FGF23 signaling axis. Then high quality rabbit anti-mouse HBEGF antibodies were made to better study HBEGF activity in vivo and in vitro. A new cell model was characterized to test FGF23 effects on HBEGF signaling using Western blots and immunofluorescence. Lastly, the location of HBEGF activity was examined in the kidney in vivo. Immunostaining suggested that HBEGF activated the mitogen activated protein kinase (MAPK) pathway. This mapping may provide important information for the molecular relationships between FGF23 and HBEGF.
  • Thumbnail Image
    Item
    Thromboelastography-Guided Anticoagulant Therapy for the Double Hazard of Thrombohemorrhagic Events in COVID-19: A Report of 3 Cases
    (International Scientific Information, 2021) Bunch, Connor M.; Thomas, Anthony V.; Stillson, John E.; Gillespie, Laura; Lin, Kevin P.; Speybroeck, Jacob; Kwaan, Hau C.; Fulkerson, Daniel H.; Zamlut, Mahmud; Khan, Rashid; Walsh, Mark M.; Medicine, School of Medicine
    BACKGROUND: The novel coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), often manifests a coagulopathy in severely ill patients, which may cause hemorrhage and/or thrombosis of varying severity. This report comprises the cases of 3 patients with COVID-19-associated coagulopathy who were evaluated with thromboelastography (TEG) and activated partial thromboplastin time (aPTT) to enable personalized anticoagulant therapy. CASE REPORT: Three patients presented with COVID-19 pneumonia, confirmed by reverse transcription-polymerase chain reaction, who developed thrombohemorrhagic coagulopathy. Case 1: A 72-year-old woman on long-term warfarin therapy for a history of venous thromboembolism developed a right upper lobe pulmonary embolus, despite an international normalized ratio of 6.4 and aPTT of 120.7 s. TEG enabled successful anticoagulation with heparin, and her pulmonary infarct was no longer present 2 weeks later. Case 2: A 55-year-old woman developed a rectus sheath hematoma while on heparin, and TEG demonstrated increased fibrinolysis despite COVID-19 patients more commonly undergoing fibrinolytic shutdown. Case 3: A 43-year-old woman had significant thrombus burden while severely hypocoagulable according to laboratory testing. As the venous thrombi enlarged in a disseminated intravascular coagulopathic-like state, the heparin dose was escalated to achieve a target aPTT of 70 to 80 s, resulting in a flat line TEG tracing. CONCLUSIONS: These 3 cases of COVID-19 pneumonia with complex and varied clinical histories demonstrated the clinical value of TEG combined with the measurement of aPTT to facilitate personalized anticoagulation, resulting in good clinical outcomes.
  • Thumbnail Image
    Item
    Viscoelastic Hemostatic Assays: A Primer on Legacy and New Generation Devices
    (MDPI, 2022-02-07) Volod, Oksana; Bunch, Connor M.; Zackariya, Nuha; Moore, Ernest E.; Moore, Hunter B.; Kwaan, Hau C.; Neal, Matthew D.; Al-Fadhl, Mahmoud D.; Patel, Shivani S.; Wiarda, Grant; Al-Fadhl, Hamid D.; McCoy, Max L.; Thomas, Anthony V.; Thomas, Scott G.; Gillespie, Laura; Khan, Rashid Z.; Zamlut, Mahmud; Kamphues, Peter; Fries, Dietmar; Walsh, Mark M.; Medicine, School of Medicine
    Viscoelastic hemostatic assay (VHAs) are whole blood point-of-care tests that have become an essential method for assaying hemostatic competence in liver transplantation, cardiac surgery, and most recently, trauma surgery involving hemorrhagic shock. It has taken more than three-quarters of a century of research and clinical application for this technology to become mainstream in these three clinical areas. Within the last decade, the cup and pin legacy devices, such as thromboelastography (TEG® 5000) and rotational thromboelastometry (ROTEM® delta), have been supplanted not only by cartridge systems (TEG® 6S and ROTEM® sigma), but also by more portable point-of-care bedside testing iterations of these legacy devices (e.g., Sonoclot®, Quantra®, and ClotPro®). Here, the legacy and new generation VHAs are compared on the basis of their unique hemostatic parameters that define contributions of coagulation factors, fibrinogen/fibrin, platelets, and clot lysis as related to the lifespan of a clot. In conclusion, we offer a brief discussion on the meteoric adoption of VHAs across the medical and surgical specialties to address COVID-19-associated coagulopathy.