An Innovative Customized Biomimetic Hydrogel for Drug Screening Application Potential: Biocompatibility and Cell Invasion Ability.

The ability of Pluronic F127 (PF127) conjugated with tetrapeptide Gly-Arg-Gly-Asp (GRGD) as a sequence of Arg-Gly-Asp (RGD) peptide to form the investigated potential hydrogel (hereafter referred to as 3DG bioformer (3BE)) to produce spheroid, biocompatibility, and cell invasion ability, was assessed in this study. The fibroblast cell line (NIH 3T3), osteoblast cell line (MG-63), and human breast cancer cell line (MCF-7) were cultured in the 3BE hydrogel and commercial product (Matrigel) for comparison. The morphology of spheroid formation was evaluated via optical microscopy. The cell viability was observed through cell counting Kit-8 assay, and cell invasion was investigated via Boyden chamber assay. Analytical results indicated that 3BE exhibited lower spheroid formation than Matrigel. However, the 3BE appeared biocompatible to NIH 3T3, MG-63, and MCF-7 cells. Moreover, cell invasion ability and cell survival rate after invasion through the 3BE was displayed to be comparable to Matrigel. Thus, these findings demonstrate that the 3BE hydrogel has a great potential as an alternative to a three-dimensional cell culture for drug screening applications.

Fish-Scale Collagen Membrane Seeded with Corneal Endothelial Cells as Alternative Graft for Endothelial Keratoplasty Transplantation.

The human corneal endothelium has limited regeneration capacity. Several methods have been developed in an attempt to repair it. Descemet stripping automated endothelial keratoplasty (DSAEK) is commonly performed on patients with endothelial dysfunction. However, donor demand far exceeds donor supply. Here, we prepared fish-scale collagen membrane (FSCM) and seeded it with CECs in preparation for corneal endothelial transplantation. The fish scales were decellularized, decalcified, and curved. The FSCM was inspected by fluorescence microscopy, SEM, and TGA to validate decellularization, microstructure, and decalcification, respectively. The cytotoxicity of FSCM and the viability of the cells in contact with it were evaluated by LDH and WST-1, respectively. CEC tight junctions and ZO-1 structure were observed by SEM and confocal microscopy. FSCM seeded with CECs were implanted to rabbit anterior chambers to evaluate host tissue reactions to it. FSCM biocompatibility and durability were also assessed. The results showed that FSCM has excellent transparency, adequate water content, and good biocompatibility. The cultivated CECs mounted on the FSCM were similar to normal CECs in vivo. The FSCM plus CECs developed here have high potential efficacy for endothelial keratoplasty transplantation.

The Spatiotemporal Control of Osteoblast Cell Growth, Behavior, and Function Dictated by Nanostructured Stainless Steel Artificial Microenvironments.

The successful application of a nanostructured biomaterial as an implant is strongly determined by the nanotopography size triggering the ideal cell response. Here, nanoporous topography on 304L stainless steel substrates was engineered to identify the nanotopography size causing a transition in the cellular characteristics, and accordingly, the design of nanostructured stainless steel surface as orthopedic implants is proposed. A variety of nanopore diameters ranging from 100 to 220 nm were fabricated by one-step electrolysis process and collectively referred to as artificial microenvironments. Control over the nanopore diameter was achieved by varying bias voltage. MG63 osteoblasts were cultured on the nanoporous surfaces for different days. Immunofluorescence (IF) and scanning electron microscopy (SEM) were performed to compare the modulation in cell morphologies and characteristics. Osteoblasts displayed differential growth parameters and distinct transition in cell behavior after nanopore reached a certain diameter. Nanopores with 100-nm diameter promoted cell growth, focal adhesions, cell area, viability, vinculin-stained area, calcium mineralization, and alkaline phosphatase activity. The ability of these nanoporous substrates to differentially modulate the cell behavior and assist in identifying the transition step will be beneficial to biomedical engineers to develop superior implant geometries, triggering an ideal cell response at the cell-nanotopography interface.

Temporal Control of Osteoblast Cell Growth and Behavior Dictated by Nanotopography and Shear Stress.

Biomaterial design involves assessment of cellular response to nanotopography parameters such as shape, dimension of nanotopography features. Here, the effect of nanotopography alongside the in vivo factor, shear stress, on osteoblast cell behavior, is reported. Tantalum oxide nanodots of 50 or 100 nm diameter were engineered using anodized aluminum oxide as a template. Bare tantalum nitride coated silicon substrates were taken as control (flat). MG63 (osteoblast) cells were seeded for 72 hours on flat, 50 or 100 nm nanodots and modulation in cell morphology, cell viability and expression of integrins was studied. Cells displayed a well-extended morphology on 50 nm nanodots in contrast to an elongated morphology on 100 nm nanodots, as observed by scanning electron microscopy and immunofluorescence staining, thereby confirming the cellular response to different nanotopographies. Based on quantitative real-time polymerase chain reaction data, a greater fold change in the expression of α1 , α2 , α3 , α8 , α9 , [Formula: see text], ß1 , ß4 , ß5 , ß7 and ß8 integrins was observed in cells cultured on 100 nm than on 50 nm nanodots. Moreover, in the presence of a shear stress of 2 dyne/cm2, a 52% increase in the cell viability after culturing the cells for 72 hours was observed on 100 nm nanodots as compared to 50 nm nanodots, thereby validating the effect of shear stress on cell behavior. Duration-of-culture experiments revealed 100 nm nanodots to be an ideal nanotopography choice to engineer optimized implant geometries for an ideal cell response. This study highlights the in vivo factors which need to be considered while designing nanotopographies for in vivo applications, for an ideal response as the cell-nanomaterial interface. Applications in the field of Biomedical, tissue engineering and cancer research are expected.

Spatial Control of Cell-Nanosurface Interactions by Tantalum Oxide Nanodots for Improved Implant Geometry.

Nanotopological cues can be exploited to understand the nature of interactions between cells and their microenvironment to generate superior implant geometries. Nanosurface parameters which modulate the cell behavior and characteristics such as focal adhesions, cell morphology are not clearly understood. Here, we studied the role of different nanotopographic dimensions in modulating the cell behavior, characteristics and ultimately the cell fate and accordingly, a methodology to improve implant surface geometry is proposed. Tantalum oxide nanodots of 50, 100nm dot diameter with an inter-dot spacing of 20, 70nm and heights 40, 100nm respectively, were engineered on Silicon substrates. MG63 cells were cultured for 72 hours and the modulation in morphology, focal adhesions, cell extensible area, cell viability, transcription factors and genes responsible for bone protein secretion as a function of the nanodot diameter, inter-dot distance and nanodot height were evaluated. Nanodots of 50nm diameter with a 20nm inter-dot spacing and 40nm height enhanced cell spreading area by 40%, promoted cell viability by 70% and upregulated transcription factors and genes twice as much, as compared to the 100nm nanodots with 70nm inter-dot spacing and 100nm height. Favorable interactions between cells and all dimensions of 50nm nanodot diameter were observed, determined with Scanning electron microscopy and Immunofluorescence staining. Nanodot height played a vital role in controlling the cell fate. Dimensions of nanodot features which triggered a transition in cell characteristics or behavior was also defined through statistical analysis. The findings of this study provide insights in the parameters of nanotopographic features which can vitally control the cell fate and should therefore be taken into account when designing implant geometries.

DNA sequencing using electrical conductance measurements of a DNA polymerase.

The development of personalized medicine-in which medical treatment is customized to an individual on the basis of genetic information-requires techniques that can sequence DNA quickly and cheaply. Single-molecule sequencing technologies, such as nanopores, can potentially be used to sequence long strands of DNA without labels or amplification, but a viable technique has yet to be established. Here, we show that single DNA molecules can be sequenced by monitoring the electrical conductance of a phi29 DNA polymerase as it incorporates unlabelled nucleotides into a template strand of DNA. The conductance of the polymerase is measured by attaching it to a protein transistor that consists of an antibody molecule (immunoglobulin G) bound to two gold nanoparticles, which are in turn connected to source and drain electrodes. The electrical conductance of the DNA polymerase exhibits well-separated plateaux that are ~3 pA in height. Each plateau corresponds to an individual base and is formed at a rate of ~22 nucleotides per second. Additional spikes appear on top of the plateaux and can be used to discriminate between the four different nucleotides. We also show that the sequencing platform works with a variety of DNA polymerases and can sequence difficult templates such as homopolymers.

The spatial and temporal control of cell migration by nanoporous surfaces through the regulation of ERK and integrins in fibroblasts.

Nanotopography controls cell behaviours, such as cell adhesion and migration. However, the mechanisms responsible for topology-mediated cellular functions are not fully understood. A variety of nanopores was fabricated on 316L stainless steel to investigate the effects of spatial control on the growth and function of fibroblasts, the temporal regulation of integrins, and their effects on migration. The NIH-3T3 fibroblast cell line was cultured on the nanopore surfaces, whose pore diameters ranged from 40 to 210 nm. The 40 and 75 nm nanopores enhanced cell proliferation, focal adhesion formation and protein expression of vinculin and ß-tubulin after 24 h of incubation. Integrin expression was analysed by qPCR, which showed the extent of spatial and temporal regulation achieved by the nanopores. The protein expression of pERK1/2 was greatly attenuated in cells grown on 185 and 210 nm nanopore surfaces at 12 and 24 h. In summary, the 40 and 75 nm nanopore surfaces promoted cell adhesion and migration in fibroblasts by controlling the temporal expression of integrins and ERK1/2. The current study provides insight into the improvement of the design of stainless steel implants and parameters that affect biocompatibility. The ability to regulate the expression of integrin and ERK1/2 using nanopore surfaces could lead to further applications of surface modification in the fields of biomaterials science and tissue engineering.

Nanosurface design of dental implants for improved cell growth and function.

A strategy was proposed for the topological design of dental implants based on an in vitro survey of optimized nanodot structures. An in vitro survey was performed using nanodot arrays with dot diameters ranging from 10 to 200 nm. MG63 osteoblasts were seeded on nanodot arrays and cultured for 3 days. Cell number, percentage undergoing apoptotic-like cell death, cell adhesion and cytoskeletal organization were evaluated. Nanodots with a diameter of approximately 50 nm enhanced cell number by 44%, minimized apoptotic-like cell death to 2.7%, promoted a 30% increase in microfilament bundles and maximized cell adhesion with a 73% increase in focal adhesions. An enhancement of about 50% in mineralization was observed, determined by von Kossa staining and by Alizarin Red S staining. Therefore, we provide a complete range of nanosurfaces for growing osteoblasts to discriminate their nanoscale environment. Nanodot arrays present an opportunity to positively and negatively modulate cell behavior and maturation. Our results suggest a topological approach which is beneficial for the design of dental implants.

Control of growth and inflammatory response of macrophages and foam cells with nanotopography.

Macrophages play an important role in modulating the immune function of the human body, while foam cells differentiated from macrophages with subsequent fatty streak formation play a key role in atherosclerosis. We hypothesized that nanotopography modulates the behavior and function of macrophages and foam cells without bioactive agent. In the present study, nanodot arrays ranging from 10- to 200-nm were used to evaluate the growth and function of macrophages and foam cells. In the quantitative analysis, the cell adhesion area in macrophages increased with 10- to 50-nm nanodot arrays compared to the flat surface, while it decreased with 100- and 200-nm nanodot arrays. A similar trend of adhesion was observed in foam cells. Immunostaining, specific to vinculin and actin filaments, indicated that a 50-nm surface promoted cell adhesion and cytoskeleton organization. On the contrary, 200-nm surfaces hindered cell adhesion and cytoskeleton organization. Further, based on quantitative real-time polymerase chain reaction data, expression of inflammatory genes was upregulated for the 100- and 200-nm surfaces in macrophages and foam cells. This suggests that nanodots of 100- and 200-nm triggered immune inflammatory stress response. In summary, nanotopography controls cell morphology, adhesions, and proliferation. By adjusting the nanodot diameter, we could modulate the growth and expression of function-related genes in the macrophages and foam cell system. The nanotopography-mediated control of cell growth and morphology provides potential insight for designing cardiovascular implants.

Topographic control of the growth and function of cardiomyoblast H9c2 cells using nanodot arrays.

Cardiovascular stents require optimised control for the enhancement or inhibition epithelial and smooth muscle cell growth in close contact with the implant. Here we propose that the surface topology in contact with the living cells could be designed to control and optimise the growth and function of such cells. The cardiomyoblast H9c2 was cultured on nanodot arrays with dot diameters ranging between 10 and 200 nm. On the 50-nm nanodot arrays H9c2 showed maximum attachment and proliferation with largest cell area and extended lamellipodia. In contrast, 53.7% and 72.6% reductions of growth were observed on the 100- and 200-nm nanodot arrays after 3 days. Immunostaining indicated that nanodots smaller than 50-nm induced cell adhesion and cytoskeleton organization. Expression of genes associated with fibrosis and hypertrophy was up-regulated in cells grown on 100-nm nanodots. Western blot data showed high levels of expression for vinculin and plasminogen activator inhibitor-1 for cells cultured on 50-nm nanodots. Nanotopography controls cell adhesion, morphology and proliferation. By adjusting the diameter of the nanodots, we could modulate the growth and expression of function-related genes and proteins of H9c2 cardiomyoblasts. The current study provides insights for improved design of artificial implants and parameters that affect biocompatibility.

A nanodevice for rapid modulation of proliferation, apoptosis, invasive ability, and cytoskeletal reorganization in cultured cells.

We have fabricated a nanodevice composed of a matrix of nine nanodot arrays with various dot sizes, ranging from a flat surface to 10 nm, 50 nm, 100 nm, and 200 nm arrays. HELA, C33A, ES2, PA-1, TOV-112D, TOV-21G, MG63, and NIH-3T3 cells were seeded onto the device and cultured for three days. To evaluate the size-dependent effect of nanodot arrays on cell growth, indices corresponding to cell proliferation, apoptosis, cell adhesion, and cytoskeletal organization were defined. VD50 is defined as the diameter of nanodots on which 50% of the cell population remains viable. AD50 is defined as the diameter of nanodots on which 50% of the cell population appears to have an apoptosis-like morphology. FD50 is the diameter of nanodots that promotes the formation of 50% of the focal adhesions compared to cells grown on a flat surface. CD50 is defined as the diameter of nanodots on which cells have half the amount of microfilament bundles compared to cells grown on a flat surface. We were able to distinguish between the invasive ability of HELA versus later-staged C33A cells. Ovarian cancer cell lines (ES2, PA-1, TOV-112D, and TOV-21G) also exhibited differential growth parameters that are associated with cell type, grade, and stage. Modulation of the growth of MG63 cells was also achieved. More broadly, we have established a platform that can be used to assess basic parameters of cell growth. A simplified fabrication process ensures mass production and lowers cost. According to our results, the device is capable of distinguishing among cancer cell lines at various stages and also provides basic design parameters for artificial implants. Our device will serve as a convenient and fast tool for tissue engineering and cancer treatment.

A Nanodot Array Modulates Cell Adhesion and Induces an Apoptosis-Like Abnormality in NIH-3T3 Cells.

Micro-structures that mimic the extracellular substratum promote cell growth and differentiation, while the cellular reaction to a nanostructure is poorly defined. To evaluate the cellular response to a nanoscaled surface, NIH 3T3 cells were grown on nanodot arrays with dot diameters ranging from 10 to 200 nm. The nanodot arrays were fabricated by AAO processing on TaN-coated wafers. A thin layer of platinum, 5 nm in thickness, was sputtered onto the structure to improve biocompatibility. The cells grew normally on the 10-nm array and on flat surfaces. However, 50-nm, 100-nm, and 200-nm nanodot arrays induced apoptosis-like events. Abnormality was triggered after as few as 24 h of incubation on a 200-nm dot array. For cells grown on the 50-nm array, the abnormality started after 72 h of incubation. The number of filopodia extended from the cell bodies was lower for the abnormal cells. Immunostaining using antibodies against vinculin and actin filament was performed. Both the number of focal adhesions and the amount of cytoskeleton were decreased in cells grown on the 100-nm and 200-nm arrays. Pre-coatings of fibronectin (FN) or type I collagen promoted cellular anchorage and prevented the nanotopography-induced programed cell death. In summary, nanotopography, in the form of nanodot arrays, induced an apoptosis-like abnormality for cultured NIH 3T3 cells. The occurrence of the abnormality was mediated by the formation of focal adhesions.

Dual effect of adenovirus-mediated transfer of BMP7 in mixed neuron-glial cultures: neuroprotection and cellular differentiation.

Bone morphogenetic proteins (BMPs), members of the TGF-beta superfamily, have been implicated in nervous system development and in response to injury. Previous studies have shown that recombinant BMP7 can enhance dendritic growth and protect cultured neurons from oxidative stress. Because of the presence of extracellular BMP antagonists, BMP7 seems to act locally. Therefore, the present study uses BMP7 overexpression using adenovirus (Ad)-mediated gene transfer to examine its effect in mixed neuronal cultures. Enhanced BMP7 expression selectively induces neuronal CGRP expression in a time-dependent manner. BMP7 overexpression not only significantly protects cultures from H2O2 toxicity but reduces lipopolysaccharide (LPS) stimulation. Concurrently, it profoundly reduces microglial numbers, but increases oligodendroglial and endothelial cells. Together, low-dose and continuously expressed BMP7 is both neuroprotective and differentiation-inductive.