Dendritic cell biocompatibility of ether-based urethane films.

The use of synthetic materials for biomedical applications is ever expanding. One of the major requirements for these materials is biocompatibility, which includes prevention of immune system responses. Due to the inherent complexity of their structural composition, the polyurethane (PU) family of polymers is being used in a variety of medical applications, from soft and hard tissue scaffolds to intricate coatings on implantable devices. Herein, we investigated whether two polymer materials, D3 and D7, induced an immune response, measured by their effects on a dendritic cell (DC) line, JAWS II. Using a lactate dehydrogenase cytotoxicity assay and Annexin V/PI staining, we found that the PU materials did not induce cytotoxicity in DC cells. Using confocal microscopy, we also showed that the materials did not induce activation or maturation, as compared to positive controls. This was confirmed by looking at various markers, CD80, CD86, MHC class I, and MHC class II, via flow cytometry. Overall, the results indicated that the investigated PU films are biocompatible in terms of immunotoxicology and immunogenicity and show great promise for use in regenerative medicine.

Exosome Traceability and Cell Source Dependence on Composition and Cell-Cell Cross Talk.

Exosomes are small vesicles with an average diameter of 100 nm that are produced by many, if not all, cell types. Exosome cargo includes lipids, proteins, and nucleic acids arranged specifically in the endosomes of donor cells. Exosomes can transfer the donor cell components to target cells and can affect cell signaling, proliferation, and differentiation. Important new information about exosomes' remote communication with other cells is rapidly being accumulated. Recent data indicates that the results of this communication depend on the donor cell type and the environment of the host cell. In the field of cancer research, major questions remain, such as whether tumor cell exosomes are equally taken up by cancer cells and normal cells and whether exosomes secreted by normal cells are specifically taken up by other normal cells or also tumor cells. Furthermore, we do not know how exosome uptake is made selective, how we can trace exosome uptake selectivity, or what the most appropriate methods are to study exosome uptake and selectivity. This review will explain the effect of exosome source and the impact of the donor cell growth environment on tumor and normal cell interaction and communication. The review will also summarize the methods that have been used to label and trace exosomes to date.

Influence of a novel scaffold composed of polyurethane, hydroxyapatite, and decellularized bone particles on the healing of fourth metacarpal defects in mares.

OBJECTIVE: To determine the effect of a novel scaffold, designed for use in bone regeneration, on healing of splint bone segmental defects in mares. STUDY DESIGN: In vivo experimental study. SAMPLE POPULATION: Five adult mares (4-10 years old; mean weight, 437.7 kg ± 29 kg). METHODS: Bilateral 2-cm full-thickness defects were created in the fourth metacarpal bones (MCIV) of each horse. Each defect was randomly assigned to either a novel scaffold treatment (n = 5) or an untreated control (n = 5). The scaffold was composed of polyurethane, hydroxyapatite, and decellularized bone particles. Bone healing was assessed for a period of 60 days by thermography, ultrasonography, radiography, and computed tomography (CT). Biopsies of each defect were performed 60 days after surgery for histological evaluation. RESULTS: On the basis of radiographic analysis, scaffold-treated defects had greater filling (67.42% ± 26.7%) compared with untreated defects (35.88% ± 32.7%; P = .006). After 60 days, CT revealed that the density of the defects treated with the scaffolds (807.80 ± 129.6 Hounsfield units [HU]) was greater than density of the untreated defects (464.80 ± 81.3 HU; P = .004). Evaluation of histology slides provided evidence of bone formation within an average of 9.43% ± 3.7% of the cross-sectional area of scaffolds in contrast to unfilled defects in which connective tissue was predominant throughout the biopsy specimens. CONCLUSION: The novel scaffold was biocompatible and supported bone formation within the MCIV segmental defects. CLINICAL SIGNIFICANCE: This novel scaffold offers an effective option for filling bone voids in horses when support of bone healing is indicated.

Plasmonic nano surface for neuronal differentiation and manipulation.

Neurodegenerative diseases and traumatic brain injuries can destroy neurons, resulting in sensory and motor function loss. Transplantation of differentiated neurons from stem cells could help restore such lost functions. Plasmonic gold nanorods (AuNR) were integrated in growth surfaces to stimulate and modulate neural cells in order to tune cell physiology. An AuNR nanocomposite system was fabricated, characterized, and then utilized to study the differentiation of embryonic rat neural stem cells (NSCs). Results demonstrated that this plasmonic surface 1) accelerated differentiation, yielding almost twice as many differentiated neural cells as a traditional NSC culture surface coated with poly-D-lysine and laminin for the same time period; and 2) promoted differentiation of NSCs into neurons and astrocytes in a 2:1 ratio, as evidenced by the expression of relevant marker proteins. These results indicate that the design and properties of this AuNR plasmonic surface would be advantageous for tissue engineering to address neural degeneration.

The role of surface chemistry in the cytotoxicity profile of graphene.

Graphene and its derivative, because of their unique physical, electrical and chemical properties, are an important class of nanomaterials being proposed as foundational materials in nanomedicine as well as for a variety of industrial applications. A major limitation for graphene, when used in biomedical applications, is its poor solubility due to its rather hydrophobic nature. Therefore, chemical functionalities are commonly introduced to alter both its surface chemistry and biochemical activity. Here, we show that surface chemistry plays a major role in the toxicological profile of the graphene structures. To demonstrate this, we chemically increased the oxidation level of the pristine graphene and compared the corresponding toxicological effects along with those for the graphene oxide. X-ray photoelectron spectroscopy revealed that pristine graphene had the lowest amount of surface oxygen, while graphene oxide had the highest at 2.5% and 31%, respectively. Low and high oxygen functionalized graphene samples were found to have 6.6% and 24% surface oxygen, respectively. Our results showed a dose-dependent trend in the cytotoxicity profile, where pristine graphene was the most cytotoxic, with decreasing toxicity observed with increasing oxygen content. Increased surface oxygen also played a role in nanomaterial dispersion in water or cell culture medium over longer periods. It is likely that higher dispersity might result in graphene entering into cells as individual flakes ~1 nm thick rather than as more cytotoxic aggregates. In conclusion, changes in graphene's surface chemistry resulted in altered solubility and toxicity, suggesting that a generalized toxicity profile would be rather misleading. Copyright © 2016 John Wiley & Sons, Ltd.

Bone-tissue engineering: complex tunable structural and biological responses to injury, drug delivery, and cell-based therapies.

Bone loss and failure of proper bone healing continues to be a significant medical condition in need of solutions that can be implemented successfully both in human and veterinary medicine. This is particularly true when large segmental defects are present, the bone has failed to return to normal form or function, or the healing process is extremely prolonged. Given the inherent complexity of bone tissue - its unique structural, mechanical, and compositional properties, as well as its ability to support various cells - it is difficult to find ideal candidate materials that could be used as the foundation for tissue regeneration from technological platforms. Recently, important developments have been made in the implementation of complex structures built both at the macro- and the nano-level that have been shown to positively impact bone formation and to have the ability to deliver active biological molecules (drugs, growth factors, proteins, cells) for controlled tissue regeneration and the prevention of infection. These materials are diverse, ranging from polymers to ceramics and various composites. This review presents developments in this area with a focus on the role of scaffold structure and chemistry on the biologic processes that influence bone physiology and regeneration.

Gold Nanorod Substrate for Rat Fetal Neural Stem Cell Differentiation into Oligodendrocytes.

Gold nanorods (AuNRs) have been proposed to promote stem cell differentiation in vitro and in vivo. In this study, we examined a particular type of AuNR in supporting the differentiation of rat fetal neural stem cells (NSCs) into oligodendrocytes (ODCs). AuNRs were synthesized according to the seed-mediated method resulting in nanorods with an aspect ratio of around 3 (~12 nm diameter, 36 nm length) and plasmon resonance at 520 and 780 nm, as confirmed by transmission electron microscopy (TEM) and UV-vis spectroscopy, respectively. A layer-by-layer approach was used to fabricate the AuNR substrate on the functionalized glass coverslips. NSCs were propagated for 10 days using fibroblast growth factor, platelet-derived growth-factor-supplemented culture media, and differentiated on an AuNR or poly-D-lysine (PDL)-coated surface using differentiation media containing triiodothyronine for three weeks. Results showed that NSCs survived better and differentiated faster on the AuNRs compared to the PDL surface. By week 1, almost all cells had differentiated on the AuNR substrate, whereas only ~60% differentiated on the PDL surface, with similar percentages of ODCs and astrocytes. This study indicates that functionalized AuNR substrate does promote NSC differentiation and could be a viable tool for tissue engineering to support the differentiation of stem cells.

Development of a polymeric biomedical device platform with controlled disassembly and in vivo testing in a swine intestinal model.

The aim of this study was to create a surgical guide platform that maintains its integrity while the surgeon performs an intestinal anastomosis or another similar procedure, which then breaks apart and is eliminated from the body in a controlled manner. The device contains mixed polymeric structures that give it a controlled rate of disassembly that could meet the requirements of a specific surgical purpose. The intraluminal anastomotic guide was manufactured as a hollow cylinder composed of layers of porous polyurethane/PCL with polyvinylpyrrolidone as the binding agent similar to a "brick-mortar" architecture. This combination of polymeric structures is a promising manufacturing method from which a variety of tunable devices can be fabricated for specific medical procedures and site-specific indications. The guide was designed to rapidly disassemble within the intestinal lumen after use, reliably degrading while maintaining sufficient mechanical rigidity and stability to support manipulation during complex surgical procedures. The nature of the device's disassembly makes it suitable for use in hollow structures that discharge their contents, resulting in their elimination from the body. A swine model of intestinal anastomosis was utilized to validate the use and function of the device.

Tracking Gold Nanorods' Interaction with Large 3D Pancreatic-Stromal Tumor Spheroids by Multimodal Imaging: Fluorescence, Photoacoustic, and Photothermal Microscopies.

Pancreatic cancer is one of the most complex types of cancers to detect, diagnose, and treat. However, the field of nanomedicine has strong potential to address such challenges. When evaluating the diffusion and penetration of theranostic nanoparticles, the extracellular matrix (ECM) is of crucial importance because it acts as a barrier to the tumor microenvironment. In the present study, the penetration of functionalized, fluorescent gold nanorods into large (>500 µm) multicellular 3D tissue spheroids was studied using a multimodal imaging approach. The spheroids were generated by co-culturing pancreatic cancer cells and pancreatic stellate cells in multiple ratios to mimic variable tumor-stromal compositions and to investigate nanoparticle penetration. Fluorescence live imaging, photothermal, and photoacoustic analysis were utilized to examine nanoparticle behavior in the spheroids. Uniquely, the nanorods are intrinsically photoacoustic and photothermal, enabling multi-imaging detection even when fluorescence tracking is not possible or ideal.

Development and in vivo Assessment of a Rapidly Collapsible Anastomotic Guide for Use in Anastomosis of the Small Intestine: A Pilot Study Using a Swine Model.

Various conditions in human and veterinary medicine require intestinal resection and anastomosis, and complications from these procedures are frequent. A rapidly collapsible anastomotic guide was developed for small intestinal end-to-end anastomosis and was investigated in order to assess its utility to improve the anastomotic process and to potentially reduce complication rates. A complex manufacturing method for building a polymeric device was established utilizing biocompatible and biodegradable polyvinylpyrrolidone and polyurethane. This combination of polymers would result in rapid collapse of the material. The guide was designed as a hollow cylinder composed of overlaying shingles that separate following exposure to moisture. An in vivo study was performed using commercial pigs, with each pig receiving one standard handsewn anastomosis and one guide-facilitated anastomosis. Pigs were sacrificed after 13 days, at which time burst pressure, maximum luminal diameter, and presence of adhesions were assessed. Burst pressures were not statistically different between treatment groups, but in vivo anastomoses performed with the guide withstood 10% greater luminal burst pressure and maintained 17% larger luminal diameter than those performed using the standard handsewn technique alone. Surgeons commented that the addition of a guide eased the performance of the anastomosis. Hence, a rapidly collapsible anastomotic guide may be beneficial to the performance of intestinal anastomosis.

Plasmonic Nanofactors as Switchable Devices to Promote or Inhibit Neuronal Activity and Function.

Gold nanosystems have been investigated extensively for a variety of applications, from specific cancer cell targeting to tissue regeneration. Specifically, a recent and exciting focus has been the gold nanosystems' interface with neuronal biology. Researchers are investigating the ability to use these systems neuronal applications ranging from the enhancement of stem cell differentiation and therapy to stimulation or inhibition of neuronal activity. Most of these new areas of research are based on the integration of the plasmonic properties of such nanosystems into complex synthetic extracellular matrices (ECM) that can interact and affect positively the activity of neuronal cells. Therefore, the ability to integrate the plasmonic properties of these nanoparticles into multidimensional and morphological structures to support cellular proliferation and activity is potentially of great interest, particularly to address medical conditions that are currently not fully treatable. This review discusses some of the promising developments and unique capabilities offered by the integration of plasmonic nanosystems into morphologically complex ECM devices, designed to control and study the activity of neuronal cells.

Simultaneous Electrochemical Deposition of Cobalt Complex and Poly(pyrrole) Thin Films for Supercapacitor Electrodes.

Supercapacitors are beneficial as energy storage devices and can obtain high capacitance values greater than conventional capacitors and high power densities compared to batteries. However, in order to improve upon the overall cost, energy density, and charge-discharge rates, the electrode material of supercapacitors needs to be fine-tuned with an inexpensive, high conducting source. We prepared a Co(III) complex and polypyrrole (PPy) composite thin films (CoN4-PPy) that was electrochemically deposited on the surface of a glassy carbon working electrode. Cyclic voltammetry studies indicate the superior performance of CoN4-PPy in charge storage in acidic electrolyte compared to alkaline and organic solutions. The CoN4-PPy material generated the highest amount of specific capacitance (up to 721.9 F/g) followed by Co salt and PPy (Co-PPy) material and PPy alone. Cyclic performance studies showed the excellent electrochemical stability of the CoN4-PPy film in the acidic medium. Simply electrochemically depositing an inexpensive Co(III) complex with a high electrically conducting polymer of PPy delivered a superior electrode material for supercapacitor applications. Therefore, the results indicate that novel thin films derived from Co(III) metal complex and PPy can store a large amount of energy and maintain high stability over many cycles, revealing its excellent potential in supercapacitor devices.

Quantification of cellular associated graphene and induced surface receptor responses.

The use of graphene for biomedical and other applications involving humans is growing and shows practical promise. However, quantifying the graphitic nanomaterials that interact with cells and assessing any corresponding cellular response is extremely challenging. Here, we report an effective approach to quantify graphene interacting with single cells that utilizes combined multimodal-Raman and photoacoustic spectroscopy. This approach correlates the spectroscopic signature of graphene with the measurement of its mass using a quartz crystal microbalance resonator. Using this technique, we demonstrate single cell noninvasive quantification and multidimensional mapping of graphene with a detection limit of as low as 200 femtograms. Our investigation also revealed previously unseen graphene-induced changes in surface receptor expression in dendritic cells of the immune system. This tool integrates high-sensitivity real-time detection and monitoring of nanoscale materials inside single cells with the measurement of induced simultaneous biological cell responses, providing a powerful method to study the impact of nanomaterials on living systems and as a result, the toxicology of nanoscale materials.

Functionalized gold nanorod nanocomposite system to modulate differentiation of human mesenchymal stem cells into neural-like progenitors.

A 2D multifunctional nanocomposite system of gold nanorods (AuNRs) was developed. Gold nanorods were functionalized via polyethylene glycol with a terminal amine, and, were characterized using transmission and scanning electron microscopy, ultra violet-visible and X-ray photoelectron spectroscopy, and Zeta-potential. The system was cytocompatible to and maintained the integrity of Schwann cells. The neurogenic potential of adipose tissue - derived human mesenchymal stem cells (hMSCs) was evaluated in vitro. The expression pattern and localization of Vimentin confirmed the mesenchymal origin of cells and tracked morphological changes during differentiation. The expression patterns of S100ß and glial fibrillary acidic protein (GFAP), were used as indicator for neural differentiation. Results suggested that this process was enhanced when the cells were seeded on the AuNRs compared to the tissue-culture surface. The present study indicates that the design and the surface properties of the AuNRs enhances neural differentiation of hMSCs and hence, would be beneficial for neural tissue engineering scaffolds.