Transparent cranial window to the brain is highly desirable for brain therapies because such cranial implant would allow for continuous monitoring of brain disorders and long‐term delivery of photodynamic therapy into the brain without repeated surgeries for opening skull. Nanostructured yttria‐stabilized zirconia (YSZ) is a potential candidate for the window to the brain application because of its promising mechanical and optical properties. In this study, a new process using aerosol spray pyrolysis was established for synthesizing 6–7 nm YSZ nanopowders with precisely controlled compositions. YSZ nanopowders with 3 M ratios of yttria to zirconia, specifically 3, 6, and 8% yttria in zirconia (referred to as 3YSZ, 6YSZ, and 8YSZ, respectively) were synthesized and characterized. The size, structure, and composition of the produced YSZ nanoparticles are highly controllable and scalable. The in vitro cytocompatibility of the YSZ nanoparticles with bone marrow mesenchymal stem cells (BMSCs) was investigated using a direct exposure culture method for cranial implant applications. Nondoped ZrO2and commercially available 8YSZ (named as C_8YSZ) served as controls for the in vitro cell studies. BMSCs exhibited normal morphology when cultured with the YSZs of 3 M ratios in the concentrations of 10 mM, 30 mM, and 60 mM, as well as ZrO2and C_8YSZ controls. The BMSCs cultured with 3YSZ and 6YSZ showed no statistical differences in cell adhesion density when compared with the ZrO2and C_8YSZ controls at respective concentrations of 10–60 mM. The possible release of YSZ nanoparticles from cranial window implants should be carefully considered and further studied.
Magnesium (Mg)‐based materials have shown great potentials for bioresorbable implant applications. Previous studies showed that Mg with 10 and 20 vol % β‐tricalcium phosphate (β‐TCP) composites produced by spark plasma sintering, improved mechanical properties when compared with pure Mg. The objectives of this study were to evaluate the degradation behaviors of Mg/10% β‐TCP and Mg/20% β‐TCP composites in revised stimulated body fluid (rSBF), and to determine their cytocompatibility with bone marrow derived mesenchymal stem cells (BMSCs) using the direct culture method. During the 11 days of immersion in rSBF, Mg/β‐TCP composites showed different degradation behaviors at different immersion periods, that is, the initial stage (0–1 hr), the mid‐term stage (1 hr to 2 days), and the long‐term stage (2−11 days). The counter effects of mass loss due to microgalvanic corrosion and mass gain due to deposition of Ca‐P containing layers resulted in slower Mg2+ion release for Mg/20% β‐TCP than Mg/10% β‐TCP in the mid‐term, but eventually 16% mass loss for Mg/20% β‐TCP and 10% mass loss for Mg/10% β‐TCP after 11 days of immersion. The in vitro studies with BMSCs showed the highest cell adhesion density (i.e., 68% of seeding density) on the plate surrounding the Mg/10% β‐TCP sample, that is, under the indirect contact condition of direct culture. The β‐TCP showed a positive effect on direct adhesion of BMSCs on the surface of Mg/β‐TCP composites. This study elucidated the degradation behaviors and the cytocompatibility of Mg/β‐TCP composites in vitro; and, further studies on Mg/ceramic composites are needed to determine their potential for clinical applications. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2238–2253, 2019.
more » « less- NSF-PAR ID:
- 10460396
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Biomedical Materials Research Part B: Applied Biomaterials
- Volume:
- 107
- Issue:
- 7
- ISSN:
- 1552-4973
- Page Range / eLocation ID:
- p. 2238-2253
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
more » « less
Abstract For degradable magnesium (Mg) alloy‐based stents it would be desirable to delay early corrosion to maintain mechanical strength. Similarly, early after stent placement reduced thrombogenicity is an important feature, while chronically, endothelial cell adhesion and vessel integration are desirable. In this study, surface eroding polymers of amino‐grafted poly(1,3‐trimethylene carbonate) (PTMC‐NH2) and PTMC‐NH2combined with sulfobetaine bearing polymer PSB (PTMC‐NHCO‐PSB) are developed, and these polymers are covalently attached onto 6‐phosphonohexanoic acid (PHA)‐coated AZ31 Mg alloy surfaces in sequence. In vitro degradation testing in ovine plasma shows PTMC, PTMC‐NH2, and PTMC‐NHCO‐PSB cast films experience a gradual thickness and mass loss with maintenance of smooth surfaces, confirming surface erosion behavior. The PTMC‐NH2polymer is firmly bound to the PHA‐modified AZ31 surface and demonstrates a resistance to peeling. PTMC, PTMC‐NH2, and PTMC‐NHCO‐PSB coated AZ31 have a lower corrosion rate versus polylactide‐
co ‐glycolide coated and untreated AZ31. PTMC‐NHCO‐PSB coated AZ31 inhibits platelet deposition and smooth muscle cell adhesion and growth, but after 2‐week immersion in plasma, this surface supports endothelial cell adhesion and growth. These results suggest PTMC‐NHCO‐PSB surface eroding coating offers a means of controlling corrosion while providing a temporally varying bio‐functionality for biodegradable vascular stent applications. -
more » « less
Abstract The colloidal stability, cytotoxicity, and cellular uptake of hafnium oxide (HfO2) nanoparticles (NPs) were investigated
in vitro to assess safety and efficacy for use as a deliverable theranostic in nanomedicine. Monoclinic HfO2NPs, ~60–90 nm in diameter and ellipsoidal in shape, were directly prepared without calcination by a hydrothermal synthesis at 83% yield. The as‐prepared, bare HfO2NPs exhibited colloidal stability in cell culture media for at least 10 days without significant agglomeration or settling. The viability (live/dead assay) of human epithelial cells (HeLa) and monocyte‐derived macrophages (THP‐1) did not fall below 95% of untreated cells after up to 24 h exposure to HfO2NPs at concentrations up to 0.80 mg/ml. Similarly, the mitochondrial activity (MTT assay) of HeLa and THP‐1 cells did not fall below 80% of untreated cells after up to 24 h exposure to HfO2NPs at concentrations up to 0.40 mg/ml. Cellular uptake was confirmed and visualized in both HeLa and THP‐1 cells by fluorescence microscopy of HfO2NPs labeled with Cy5 and transmission electron microscopy (TEM) of bare HfO2NPs. TEM micrographs provided direct observation of macropinocytosis and endosomal compartmentalization within 4 h of exposure. Thus, the HfO2NPs in this study exhibited colloidal stability, cytocompatibility, and cellular uptake for potential use as a deliverable theranostic in nanomedicine. -
more » « less
Abstract Tracheal stenting currently using non‐degradable stents is commonplace for treatment of trauma, prolonged intubation related adult airway obstructions, and pediatric patients‐associated tracheal stenosis conditions. Degradable tracheal stent placement will avoid complications of stent removal and restenosis. Widespread reports exist on degradable magnesium alloys success for orthopedic and cardiovascular applications but none to date for intra tracheal use. This research explores the use of pure Mg, AZ31, and Mg‐3Y alloys for degradable tracheal stent assessment.
In vitro evaluation of magnesium, prototype stents in a bioreactor simulate the airway environment and corrosion. Micro‐CT imaging and biocompatibility evaluation helped assess the 24‐week degradation of intraluminal alloy stents following implantation in a rat trachealin vivo bypass model. Histological analysis indicate tissue response of the harvested stented trachea segments after each time point. Corrosion studies for each alloy indicate significant differences between the simulated and controlin vitro conditions. AZ31 exhibited the lowest volume loss of 6.8% in saline, while pure Mg displayed the lowest volume loss of 4.6% in simulated airway fluid (SAF), both at 1‐week time points. Significant differences in percentage of total volume lost after 6 months were determined between the alloys over time. MgY alloy displayed the slowest corrosion losing only 15.1% volume after 24 weeks of immersion. Additionally,in vitro magnesium alloy corrosion was not significantly different from the percentage of total volume lostin vivo at 1‐week time point. The study demonstrates promise of magnesium alloys for intraluminal tracheal stent application albeit viability of a clinically translatable model warrants further studies. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1844–1853, 2019. -
2938 Using a Human Liver Tissue Equivalent (hLTE) Platform to Define the Functional Impact of Liver-Directed AAV Gene Therapy 63rd ASH Annual Meeting and Exposition, December 11-14, 2021, Georgia World Congress Center, Atlanta, GA Program: Oral and Poster Abstracts Session: 801. Gene Therapies: Poster II Hematology Disease Topics & Pathways: Bleeding and Clotting, Biological, Translational Research, Hemophilia, Genetic Disorders, Clinically Relevant, Diseases, Gene Therapy, Therapies Sunday, December 12, 2021, 6:00 PM-8:00 PM Ritu M Ramamurthy1*, Wen Ting Zheng2*, Sunil George, PhD1*, Meimei Wan1*, Yu Zhou, PhD1*, Baisong Lu, PhD1*, Colin E Bishop, PhD1*, Anthony Atala, M.D.1*, Christopher D Porada, PhD1* and M. Graca Almeida-Porada, MD3 1Fetal Research and Therapy Program, Wake Forest Institute for Regenerative Medicine, Winston Salem, NC 2Massachusetts Institute of Technology, Cambridge, MA 3Fetal Research and Therapy Program, Wake Forest Institute For Regenerative Medicine, Winston-Salem, NC Clinical trials employing AAV vectors for hemophilia A have been hindered by unanticipated immunological and/or inflammatory responses in some of the patients. Also, these trials have often yielded lower levels of transgene expression than were expected based upon preclinical studies, highlighting the poor correlation between the transduction efficiency observed in traditional 2D cultures of primary cells in vitro, and that observed in those same cell types in vivo. It has been also recognized that there are marked species-specific differences in AAV-vector tropism, raising the critical question of the accuracy with which various animal models will likely predict tropism/vector transduction efficiency, and eventual treatment success in humans. Human liver tissue equivalents (hLTEs) are comprised of major cell types in the liver in physiologically relevant frequencies and possess the ability to recapitulate the biology and function of native human liver. Here, we hypothesize that hLTEs can be used as a better model to predict the efficacy and safety of AAV gene therapy in humans. We fabricated hLTEs using 75% hepatocytes, 10% stellate cells, 10% Kupffer cells, and 5% liver sinusoid-derived endothelial cells in 96-well Elplasia plates with 79 microwells per well. hLTEs were transduced at an MOI of 105vg/cell, on the day of fabrication, with the clinically relevant serotypes AAV5 (hLTE-5) or AAV3b (hLTE-3b), both encoding a GFP reporter. After 4 days of self-aggregation, live/dead assay was performed to confirm viability. Non-transduced hLTEs served as negative controls (hLTE(-)), and hLTEs exposed to 20 mM acetaminophen were used as positive controls for liver inflammation/damage. Incucyte® Live-Cell Imaging system was used to track the aggregation and GFP expression of hLTEs. Over the course of the next 5 days, media was collected to determine hepatic functionality, RNA was isolated to assess dysregulation of genes involved in inflammation and fibrosis, DNA was isolated to determine whether AAV vectors integrate into the genome of human hepatocytes and, if so, to define the frequency at which this occurs and the genomic loci of integration, and hLTEs were fixed and processed at appropriate times for histological analyses and transmission electron microscopy (TEM). TEM analysis revealed that all groups exhibited microvilli and bile-canaliculus-like structures, demonstrating the formation of a rudimentary biliary system and, more importantly, proving that hLTEs resemble native liver structure. Incucyte® imaging showed that AAV5 and AAV3b transduction impaired formation of hLTEs (57.57 ± 2.42 and 24.57 ± 4.01 spheroids/well, respectively) in comparison with hLTE(-) (74.86 ± 3.8 spheroids/well). Quantification of GFP expression demonstrated that AAV5 yielded the most efficient transduction of hLTEs (fold change in GFP expression compared to control: 2.73 ± 0.09 and 1.19 ± 0.03 for hLTE-5 and hLTE-3b, respectively). Chromogenic assays showed decreased urea production in cell culture supernatants of AAV transduced groups compared to the non-transduced hLTEs on days 6 and 10 of culture, demonstrating decreased hepatocyte functionality. However, ALT and AST levels were similar in all groups. On day 10, hLTEs were either used for RNA isolation or fixed in 4% PFA and processed for histology. Masson’s Trichrome and Alcian Blue/Sirius Red staining was performed to detect fibrosis, which was then quantified using ImageJ. These analyses showed no significant increase in fibrosis in either hLTE-5 or hLTE-3b compared to hLTE(-). Nevertheless, RT2 PCR Array for Human Fibrosis detected dysregulation of several genes involved in fibrosis/inflammation in both hLTE-5 and hLTE-3b (16/84 and 26/84, respectively). In conclusion, data collected thus far show successful recapitulation of native liver biology and demonstrate that AAV5 transduces hLTEs more efficiently than AAV3b. However, impaired self-aggregation and decreased hepatocyte functionality was observed in both AAV-transduced groups. Studies to address the incidence and location(s) of AAV integration are ongoing. We have thus shown that the hLTE system can provide critical new knowledge regarding the efficacy and safety of AAV gene therapy in the human liver. Disclosures: No relevant conflicts of interest to declare.more » « less
