Examination of cell–host–biomaterial interactions via high-throughput technologies: A re-appraisal

Harnessing electromagnetic fields to assist bone tissue engineering

Bone tissue engineering (BTE) emerged as one of the exceptional means for bone defects owing to it providing mechanical supports to guide bone tissue regeneration. Great advances have been made to facilitate the success of BTE in regenerating bone within defects. The use of externally applied fields has been regarded as an alternative strategy for BTE. Electromagnetic fields (EMFs), known as a simple and non-invasive therapy, can remotely provide electric and magnetic stimulation to cells and biomaterials, thus applying EMFs to assist BTE would be a promising strategy for bone regeneration. When combined with BTE, EMFs improve cell adhesion to the material surface by promoting protein adsorption. Additionally, EMFs have positive effects on mesenchymal stem cells and show capabilities of pro-angiogenesis and macrophage polarization manipulation. These advantages of EMFs indicate that it is perfectly suitable for representing the adjuvant treatment of BTE. We also summarize studies concerning combinations of EMFs and diverse biomaterial types. The strategy of combining EMFs and BTE receives encouraging outcomes and holds a promising future for effectively treating bone defects.

Role of dendritic cells in the host response to biomaterials and their signaling pathways

Strategies to enhance, inhibit, or qualitatively modulate immune responses are important for diverse biomedical applications such as vaccine adjuvant, drug delivery, immunotherapy, cell transplant, tissue engineering, and regenerative medicine. However, the clinical efficiency of these biomaterial systems is affected by the limited understanding of their interaction with complex host microenvironments, for example, excessive foreign body reaction and immunotoxicity. Biomaterials and biomedical devices implanted in the body may induce a highly complicated and orchestrated series of host responses. As macrophages are among the first cells to infiltrate and respond to implanted biomaterials, the macrophage-mediated host response to biomaterials has been well studied. Dendritic cells (DCs) are the most potent antigen-presenting cells that activate naive T cells and bridge innate and adaptive immunity. The potential interaction of DCs with biomaterials appears to be critical for exerting the function of biomaterials and has become an important, developing area of investigation. Herein, we summarize the effects of the physicochemical properties of biomaterials on the immune function of DCs together with their receptors and signaling pathways. This review might provide a complete understanding of the interaction of DCs with biomaterials and serve as a reference for the design and selection of biomaterials with particular effects on targeted cells. STATEMENT OF SIGNIFICANCE: Biomaterials implanted in the body are increasingly applied in clinical practice. The performance of these implanted biomaterials is largely dependent on their interaction with the host immune system. As antigen-presenting cells, dendritic cells (DCs) directly interact with biomaterials through pattern recognition receptors (PRRs) recognizing "biomaterial-associated molecular patterns" and generate a battery of immune responses. In this review, the physicochemical properties of biomaterials that regulate the immune function of DCs together with their receptors and signaling pathways of biomaterial-DC interactions are summarized and discussed. We believe that knowledge of the interplay of DC and biomaterials may spur clinical translation by guiding the design and selection of biomaterials with particular effects on targeted cell for tissue engineering, vaccine delivery, and cancer therapy.

Understanding interactions between biomaterials and biological systems using proteomics

The role that biomaterials play in the clinical treatment of damaged organs and tissues is changing. While biomaterials used in permanent medical devices were required to passively take over the function of a damaged tissue in the long term, current biomaterials are expected to trigger and harness the self-regenerative potential of the body in situ and then to degrade, the foundation of regenerative medicine. To meet these different requirements, it is imperative to fully understand the interactions biomaterials have with biological systems, in space and in time. This knowledge will lead to a better understanding of the regenerative capabilities of biomaterials aiding their design with improved functionalities (e.g. biocompatibility, bioactivity). Proteins play a pivotal role in the interaction between biomaterials and cells or tissues. Protein adsorption on the material surface is the very first event of this interaction, which is determinant for the subsequent processes of cell growth, differentiation, and extracellular matrix formation. Against this background, the aim of the current review is to provide insight in the current knowledge of the role of proteins in cell-biomaterial and tissue-biomaterial interactions. In particular, the focus is on proteomics studies, mainly using mass spectrometry, and the knowledge they have generated on protein adsorption of biomaterials, protein production by cells cultured on materials, safety and efficacy of new materials based on nanoparticles and the analysis of extracellular matrices and extracellular matrix-derived products. In the outlook, the potential and limitations of this approach are discussed and mass spectrometry imaging is presented as a powerful technique that complements existing mass spectrometry techniques by providing spatial molecular information about the material-biological system interactions.

Differences in the expression of cell cycle genes in osteoblasts and endothelial cells cultured on the surfaces of Ti6Al4V and Ti6Al7Nb alloys

Three medically used alloys (Ti6Al4V, Ti6Al7Nb, and AISI 316 L) are compared due to proliferative potential and metabolic response of human cells (osteoblasts line Saos-2 and endothelial cells line EA.hy-926) seeded on the surfaces of these alloys. Although no statistically significant difference in the proliferative potential of the cells cultured on the surfaces of examined biomaterials was observed, it does not exclude relevant differences in metabolic response of these cells assessed as changes in genes' expression. As a result of our studies it was demonstrated that the changes in the expression of examined genes were very common. Our observation suggests the presence of the process of selective recognition of the contacted biomaterials by the cells seeded on their surfaces. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1607-1617, 2017.

The molecular mechanism for effects of TiN coating on NiTi alloy on endothelial cell function

The aim of this study is to systematically investigate the molecular mechanism of different effects of nickel titanium (NiTi) alloy surface and titanium nitride (TiN) coating on endothelial cell function. Release of nickel (Ni) ion from bare and TiN-coated NiTi alloys and proliferation of endothelial cells on the two materials were evaluated, and then influence of the two materials on cellular protein expression profiles was investigated by proteomic technology. Subsequently, proteomic data were analyzed with bioinformatics analyses and further validated using a series of biological experiments. Results showed that although the two materials did not affect cell proliferation, the Ni ions released from bare NiTi alloy generated inhibition on pathways associated with actin cytoskeleton, focal adhesion, energy metabolism, inflammation, and amino acid metabolism. In comparison, TiN coating not only effectively prevented release of Ni ions from NiTi alloy, but also promoted actin cytoskeleton and focal adhesion formation, increased energy metabolism, enhanced regulation of inflammation, and promoted amino acid metabolism. Furthermore, the two processes, "the initial mediation of adsorbed serum protein layer to endothelial cell adhesion and growth on the two materials" from our previous study, and "the following action of the two materials on cellular protein expression profile", were linked up and comprehensively analyzed. It was found that in stage of cell adhesion (within 4 h), release of Ni ions from bare NiTi alloy was very low, and the activation of adsorbed proteins to cell adhesion and growth related biological pathways (such as regulation of actin cytoskeleton, and focal adhesion pathways) was almost as same as TiN-coated NiTi alloy. This indicated that the released Ni ions did not affect the mediation of adsorbed proteins to endothelial cell adhesion. However, in stage of cell growth and proliferation, the release of Ni ions from bare NiTi alloy increased with time and reached a higher level, which inhibited endothelial cell function at molecular level, whereas TiN coating improved endothelial cell function.

Combinatorial on-chip study of miniaturized 3D porous scaffolds using a patterned superhydrophobic platform

One of the main challenges in tissue engineering (TE) is to obtain optimized products, combining biomaterials, cells and soluble factors able to stimulate tissue regeneration. Multiple combinations may be considered by changing the conditions among these three factors. The unpredictable response of each combination requires time-consuming tests. High-throughput methodologies have been proposed to master such complex analyses in TE. Usually, these tests are performed using cells cultured into 2D biomaterials or by dispensing arrays of cell-loaded hydrogels. For the first time an on-chip combinatorial study of 3D miniaturized porous scaffolds is proposed, using a patterned bioinspired superhydrophobic platform. Arrays of biomaterials are dispensed and processed in situ as porous scaffolds with distinct composition, surface characteristics, porosity/pore size, and mechanical properties. On-chip porosity, pore size, and mechanical properties of scaffolds based on chitosan and alginate are assessed by adapting microcomputed tomography equipment and a dynamic mechanical analyzer, as well as cell response after 24 hours. The interactions between cell types of two distinct origins-osteoblast-like and fibroblasts-and the scaffolds modified with fibronectin are studied and validated by comparison with conventional destructive methods (dsDNA quantification and MTS tests). Physical and biological on-chip analyses are coherent with the conventional measures, and conclusions about the most favorable conditions for each cell type are taken.

Biocompatibility of chitosan carriers with application in drug delivery

Chitosan is one of the most used polysaccharides in the design of drug delivery strategies for administration of either biomacromolecules or low molecular weight drugs. For these purposes, it is frequently used as matrix forming material in both nano and micron-sized particles. In addition to its interesting physicochemical and biopharmaceutical properties, which include high mucoadhesion and a great capacity to produce drug delivery systems, ensuring the biocompatibility of the drug delivery vehicles is a highly relevant issue. Nevertheless, this subject is not addressed as frequently as desired and even though the application of chitosan carriers has been widely explored, the demonstration of systems biocompatibility is still in its infancy. In this review, addressing the biocompatibility of chitosan carriers with application in drug delivery is discussed and the methods used in vitro and in vivo, exploring the effect of different variables, are described. We further provide a discussion on the pros and cons of used methodologies, as well as on the difficulties arising from the absence of standardization of procedures.

Nanobionics: the impact of nanotechnology on implantable medical bionic devices

The nexus of any bionic device can be found at the electrode-cellular interface. Overall efficiency is determined by our ability to transfer electronic information across that interface. The nanostructure imparted to electrodes plays a critical role in controlling the cascade of events that determines the composition and structure of that interface. With commonly used conductors: metals, carbon and organic conducting polymers, a number of approaches that promote control over structure in the nanodomain have emerged in recent years with subsequent studies revealing a critical dependency between nanostructure and cellular behaviour. As we continue to develop our understanding of how to create and characterise electromaterials in the nanodomain, this is expected to have a profound effect on the development of next generation bionic devices. In this review, we focus on advances in fabricating nanostructured electrodes that present new opportunities in the field of medical bionics. We also briefly evaluate the interactions of living cells with the nanostructured electromaterials, in addition to highlighting emerging tools used for nanofabrication and nanocharacterisation of the electrode-cellular interface.

Compatibility of different polymers for cord blood-derived hematopoietic progenitor cells

The low yield of hematopoietic progenitor cells (HPC) present in cord blood grafts limits their application in clinics. A reliable strategy for ex vivo expansion of functional HPC is a present goal in regenerative medicine. Here we evaluate the capacity of several two-dimensional polymers to support HPC proliferation. Basic compatibility was tested by measuring cell viability, cytotoxicity and apoptosis of CD34(+) progenitors that were short and long-term exposed to sixteen bio and synthetic polymers. Resomer(®) RG503, PCL and Fibrin might be good alternatives to tissue culture plastic for culture of CB-derived CD34(+) progenitors. Further, these polymers will be produced in three-dimensional structures and tested for their cytocompatibility.

Microarray-based bioinformatics analysis of osteoblasts on TiO2 nanotube layers

The TiO(2) nanotube layers fabricated by electrochemical anodization have received considerable attention in dentistry and orthopedic medicine due to their increased osseointegration compared with the unanodized titanium. The molecular mechanisms underlying the interactions between nanotubes and osteoblasts is unknown. To examine this, the mRNA expression profile of MG-63 osteoblast-like cells cultured on the TiO(2) nanotubes was explored by DNA microarray. The differentially expressed genes were identified by bioinformatics analysis. Gene ontology (GO) and Go-map network analysis indicated that the TiO(2) nanotubes enhanced osteoblast proliferation and differentiation and decreased osteoblast adhesion and immunization. The expressions of genes were mainly increased in pathways influencing cell proliferation and differentiation (Cell cycle, Terpenoid backbone biosynthesis, and TGF-beta signaling) and were decreased in pathways controlling cell immunization (Cell adhesion molecules (CAMs), Allograft rejection, and Graft-versus-host disease). Signal network analysis generated from differentially expressed genes suggested that CTNNB1 (beta-catenin) was the central gene for increasing osteoblast proliferation and differentiation, and IKBKG (inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase gamma) was the central gene for repressing osteoblast immunization on nanotube layers. These two genes were further confirmed by quantitative PCR. The identified signal pathways and central genes in the study are well correlated with osteoblast phenotype. Furthermore, microarray-based bioinformatics analysis is a powerful tool in efficiently understanding molecular mechanisms underlying the interactions between osteoblasts and the nanotube layers.

Standardization of Automated Cell-Based Protocols for Toxicity Testing of Biomaterials

Advances in high-throughput screening (HTS) instrumentation have led to enormous reduction of costs (e.g., of pipetting stations) and to the development of smaller instruments for automation of day-to-day routines in small research laboratories. In the biomaterials community, there has been an increasing interest for standardized screening protocols to identify cell type–specific cytocompatible biomaterials suitable for tissue engineering (TE) applications. In this study, the authors established a multiplexed assay protocol for toxicity screening of biomaterials using a low- to medium-throughput robotic liquid handling station (LHS). The protocol contains analysis of viability, cytotoxicity, and apoptosis combined in one assay. This study includes performance results of a side-by-side comparison of the EpMotion 5070 LHS and conventional pipetting/dispensing systems. Critical parameters were optimized each for a given platform. Higher accuracy and reproducibility were achieved for LHS compared to manually treated samples. The practicability and accuracy of the method in a typical small laboratory setting were tested by running daily routine tasks by trained and untrained laboratory staff. In addition, advantages and disadvantages as well as the step-by-step application protocol are reported. The approach described provides a potential utility in screening biomaterials toxicity, allowing researchers to meet the needs of low- and medium-throughput laboratories.