Biomaterials Day 2018

Student Presentations

Oral Presentations

Shreedevi Kumar

Graduate Student | University of Florida | J. Crayton Pruitt Family Dept. of Biomedical Engineering

Manganese dioxide nanoparticles protect cytokine-challenged cartilage from oxidative stress

Shreedevi Kumar; Isaac M. Adjei, Ph.D.; Blanka Sharma, Ph.D.

Osteoarthritis (OA) is associated with chronic low-grade inflammation whereby oxidative stress leads to chondrocyte death, extracellular matrix degradation, and pain. The overall goal of this research is to develop strategies to scavenge reactive oxygen species (ROS) in cartilage in order to modulate joint inflammation. We hypothesized that MnO2 nanoparticles (MnO2-NP) which degrade hydrogen peroxide (H2O2) will protect cartilage from inflammation-induced oxidative stress. The synthesized polyethylene glycol-stabilized MnO2-NPs were 10nm in size and positively charged. The NPs effectively scavenged H2O2, with 5ug/mL MnO2-NPs neutralizing 55% of 100uM H2O2. Chondrocytes in monolayer showed uptake of MnO2-NPs without cytotoxicity. In ex vivo cartilage explants, the MnO2-NPs penetrated through the depth of the biopsies and were retained within the tissue matrix. In cytokine-challenged cartilage explants, supplementation with MnO2-NPs decreased nitric oxide production by 80% (p < 0.0001) and reduced glycosaminoglycan loss by 55% (p<0.01) compared to controls. After in vivo injection in rat articular joints, Alexa 750 labelled MnO2-NPs displayed a linear decline (R2 = 0.95) in fluorescent signal with time with 63% of the initial amount of NPs remaining in joints 11 days post-injection. Given their joint retention time and ROS scavenging capacity, these NPs could target oxidative stress mechanisms to treat or prevent OA.

Jiapu Liang

Graduate Student | University of Florida | J. Crayton Pruitt Family Dept. of Biomedical Engineering

Localized Release of Steroids from Macroporous Organosilicone Beads Scaffolds

Jiapu Liang1, Kaiyuan Jiang1, Cherie Stabler, Ph.D.1,2.

1Department of Biomedical Engineering, 2Diabetes Institute, University of Florida, Gainesville, FL USA

The local delivery of drugs provides a promising approach to improve the efficacy of islets transplantation for treatment of Type 1 Diabetes. In our previous study, anti-inflammatory Dexamethasone (Dex) was loaded within PDMS directly to fabricate homogeneous scaffolds to accelerate islet transplant engraftment. To achieve more controlled and extended release, beads scaffolds were fabricated. Dex and pro-angiogenic estradiol (E2) were loaded within PDMS for fabricating microbeads by emulsion method. Drug-beads were then mixed within PDMS and NaCl to obtain 85% macroporous scaffolds by particulate leaching and solvent casting method. The resulting microbeads exhibited a bead diameter of 75 ± 51μm. The in vitro kinetic release of Dex from PDMS beads scaffolds loaded with 0.5% (w/v) drug was found to be stable for over 30 days within the range from 50ng/mL to 150ng/mL, while E2 was released from the 0.01% (w/v) scaffolds within the range from 0.135ng/ml to 32.5ng/ml. The in vivo results confirmed the in vitro stable release profile of Dex, since the beads scaffolds groups had reduced infiltration when compared to the homogeneous scaffolds groups on day 14. Compared to the homogeneous scaffolds, PDMS beads scaffolds system presented greater potential for stable release of multiple drugs within desired ranges.

Zhiting Chen

Graduate Student | University of Florida | Dept. of Chemical Engineering

Demonstration of SiO2/SiC based protective coating for ceramic prostheses

Chen Z (presenter), Yang J, Ahn S, Ren F, Abdulhameed N, Kim M, Clark AE, Esquivel-Upshaw JF

As protective coating for ceramic prostheses, silicon dioxide/silicon carbide (SiO2/SiC) thin films deposited by plasma-enhanced chemical vapor deposition (PECVD) were studied. Depended on different deposition conditions such as deposition time, deposition pressure and gas flow ratio (SiH4/CH4), the optical constants (refractive index n and extinction coefficient k) and film stresses were varied. Therefore, the effects of different deposition parameters were investigated in this study. By adjusting and optimizing the deposition conditions, SiO2/SiC thin films with low extinction coefficient were developed to achieve a wide range of color shades, A2-A4, B2-B4, C1, C2 and D2-D4. Results of film stress showed that SiO2/SiC thin films exhibited low compressive stress to ensure good coating adhesion. Chewing simulator proved that no peeling of SiO2/SiC composited film was observed after 15,000 cycles of chewing. In this study, a novel composited SiO2/SiC coating technique was demonstrated to protect ceramic prostheses and achieve a wide color range.

 

Pei-Ying Wu

Graduate Student | University of Florida | Dept. of Biomedical Engineering

Selective laser melting (SLM) is a powder-based additive manufacturing process. Components manufactured using SLM have applications in a wide variety of areas including biomedical, automobile, and aerospace engineering. Post-processes are important to the high-level surface requirement for many applications using SLM-manufactured components, especially in medical industry. Magnetic field assisted finishing (MAF) has shown its versatility to process complicated geometries such as knee prosthesis by altering the magnetic tools. This research describes the effects of tool configuration, by changing the size of magnetic particles mixed with abrasive, and abrasive type on the material removal mechanism using MAF and resulting surface profiles of biocompatible 316L stainless steel components made by SLM process.

 

 

Mozghan Shojaee, Ph.D.

Post-doc | Florida Institute of Technology | Dept. of Biomedical Engineering

A novel pouch design to minimize peritoneal adhesions with in vivo bioreactor-based vascular graft strategies

Mozhgan Shojaee1, Kranthi Vuppuluri1, Mahyar Sameti1, Matthew Ziff2, Alessandra Carriero2, and Chris A Bashur1
1Department of Biomedical Engineering, Florida Institute of Technology, Melbourne, FL
2 Department of Biomedical Engineering, City College of New York, New York City, NY

Strategies are required for tissue engineered vascular grafts to avoid concerns with stenosis and loss of graft mechanics. We have previously shown that pre-implantation in the peritoneal cavity for electrospun vascular conduits enclosed within a porous pouch had a beneficial effect by reducing intimal hyperplasia and expression of macrophage markers. In this study, the goal was to overcome the potential side-effect of peritoneal adhesion formation by designing a new pouch composed of poly(ethylene glycol) diacrylate (PEGDA) to replace poly(tetrafluoroethylene) (PTFE) pouches.  Compressive testing of hydrogels with different PEGDA concentrations (15%, 20%, and 25% (w/v)) demonstrated a systematic increase in ultimate compressive strength and modulus with increasing PEGDA concentration. Importantly, 25% hydrogels provided a 65.6% increase in toughness over 20% hydrogels.  These material properties for cylindrical hydrogels were used to generate FEM models of pouches to predict the best design to withstand the forces within the peritoneal cavity.  PEGDA pouches demonstrated negligible peritoneal adhesions after implantation in rats, unlike PTFE pouches. After intra-aortal grafting of conduits, immunofluorescence images showed similar expression of endothelial cell and contractile markers as samples from PTFE pouches. Overall, the porous pouch system allows cell recruitment within while simultaneously preventing adhesions, overcoming a potential barrier for translation.

Adam Grippin

Graduate Student | University of Florida | J. Crayton Pruitt Family Dept. of Biomedical Engineering

mRNA-loaded magnetoliposomes enhance antitumor responses to dendritic cell vaccines and enable MRI-based detection of cell migration

Adam J. Grippin1,2, Elias J. Sayour1, Brandon Wummer1, Adam Monsalve2, Tyler Wildes1, Kyle Dyson1, Jon Dobson2,3 and Duane A. Mitchell1

1 Preston A. Wells, Jr. Center for Brain Tumor Therapy, Department of Neurosurgery, University of Florida, Gainesville, Florida

2 J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida.

3 Department of Materials Science & Engineering, University of Florida, Gainesville, Florida.

Despite aggressive chemotherapy, surgical resection, and radiation therapy, glioblastoma (GBM) remains almost universally fatal. We recently showed in a randomized and blinded clinical trial that RNA-loaded dendritic cell (DC) vaccines were associated with significantly improved progression-free and overall survival in patients with glioblastoma (Mitchell et al, Nature 2015). We also demonstrated that tracking DC migration to vaccine-site draining lymph nodes (LNs) with 111-Indium may be an important prognostic indicator of DC vaccination efficacy, but the complexity and regulatory requirements associated with nuclear labelling to track DCs limits widespread application of this technique. We therefore developed magnetic liposomes to enhance DC migration to LNs and track that migration with MRI. Cationic liposomes were loaded with iron oxide nanoparticles with or without cholesterol. The resulting nanoparticles were complexed with RNA and used to transfect DCs. We found that iron oxide and cholesterol both enhance magnetoliposome-mediated transfection of DCs and subsequent stimulation of CD8 T cells. Magnetoliposome-loaded DsRed+ DCs were then injected intradermally into mice. Migration to LNs was tracked noninvasively with T2-weighted 11T MRI before LNs were excised and analyzed with flow cytometry. Treatment with magnetoliposomes enhanced DC migration to lymph nodes and reduced intensity of T2-weighted MRI. We are now evaluating the correlation between MRI-detected DC migration and tumor rejection in murine models of glioblastoma.

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