Novel high-dense microelectrode array based multimodal bioelectronic monitoring system for cardiac arrhythmia re-entry analysis.

In recent decades, significant progress has been made in the treatment of heart diseases, particularly in the field of personalized medicine. Despite the development of genetic tests, phenotyping and risk stratification are performed based on clinical findings and invasive in vivo techniques, such as stimulation conduction mapping techniques and programmed ventricular pacing. Consequently, label-free non-invasive in vitro functional analysis systems are urgently needed for more accurate and effective in vitro risk stratification, model-based therapy planning, and clinical safety profile evaluation of drugs. To overcome these limitations, a novel multilayer high-density microelectrode array (HD-MEA), with an optimized configuration of 512 sensing and 4 pacing electrodes on a sensor area of 100 mm2, was developed for the bioelectronic detection of re-entry arrhythmia patterns. Together with a co-developed front-end, we monitored label-free and in parallel cardiac electrophysiology based on field potential monitoring and mechanical contraction using impedance spectroscopy at the same microelectrode. In proof of principle experiments, human induced pluripotent stem cell (hiPS)-derived cardiomyocytes were cultured on HD-MEAs and used to demonstrate the sensitive quantification of contraction strength modulation by cardioactive drugs such as blebbistatin (IC50 = 4.2 µM), omecamtiv and levosimendan. Strikingly, arrhythmia-typical rotor patterns (re-entry) can be induced by optimized electrical stimulation sequences and detected with high spatial resolution. Therefore, we provide a novel cardiac re-entry analysis system as a promising reference point for diagnostic approaches based on in vitro assays using patient-specific hiPS-derived cardiomyocytes.

Marine biomaterials: Biomimetic and pharmacological potential of cultivated Aplysina aerophoba marine demosponge.

Marine demosponges of the Verongiida order are considered a gold-mine for bioinspired materials science and marine pharmacology. The aim of this work was to simultaneously isolate selected bromotyrosines and unique chitinous structures from A. aerophoba and to propose these molecules and biomaterials for possible application as antibacterial and antitumor compounds and as ready-to-use scaffolds for cultivation of cardiomyocytes, respectively. Among the extracted bromotyrosines, the attention has been focused on aeroplysinin-1 that showed interesting unexpected growth inhibition properties for some Gram-negative clinical multi-resistant bacterial strains, such as A. baumannii and K. pneumoniae, and on aeroplysinin-1 and on isofistularin-3 for their anti-tumorigenic activity. For both compounds, the effects are cell line dependent, with significant growth inhibition activity on the neuroblastoma cell line SH-SY5Y by aeroplysinin-1 and on breast cancer cell line MCF-7 by isofistularin-3. In this study, we also compared the cultivation of human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) on the A. aerophoba chitinous scaffolds, in comparison to chitin structures that were pre-coated with Geltrex™, an extracellular matrix mimetic which is used to enhance iPSC-CM adhesion. The iPSC-CMs on uncoated and pure chitin structures started contracting 24 h after seeding, with comparable behaviour observed on Geltrex-coated cell culture plates, confirming the biocompatibility of the sponge biomaterial with this cell type. The advantage of A. aerophoba is that this source organism does not need to be collected in large quantities to supply the necessary amount for further pre-clinical studies before chemical synthesis of the active compounds will be available. A preliminary analysis of marine sponge bioeconomy as a perspective direction for application of biomaterials and secondary bioactive metabolites has been finally performed for the first time.

Enhanced structural maturation of human induced pluripotent stem cell-derived cardiomyocytes under a controlled microenvironment in a microfluidic system.

The lack of a fully developed human cardiac model in vitro hampers the progress of many biomedical research fields including pharmacology, developmental biology, and disease modeling. Currently, available methods may only differentiate human induced pluripotent stem cells (iPSCs) into immature cardiomyocytes. To achieve cardiomyocyte maturation, appropriate modulation of cellular microenvironment is needed. This study aims to optimize a microfluidic system that enhances maturation of human iPSC-derived cardiomyocytes (iPSC-CMs) through cyclic pulsatile hemodynamic forces. Human iPSC-CMs cultured in the microfluidic system show increased alignment and contractility and appear more rod-like shaped with increased cell size and increased sarcomere length when compared to static cultures. Increased complexity and density of the mitochondrial network in iPSC-CMs cultured in the microfluidic system are in line with expression of mitochondrial marker genes MT-CO1 and OPA1. Moreover, the optimized microfluidic system is capable of stably maintaining controlled oxygen levels and inducing hypoxia, revealed by increased expression of HIF1α and EGLN2 as well as changes in contraction parameters in iPSC-CMs. In summary, this microfluidic system boosts the structural maturation of iPSC-CM culture and could serve as an advanced in vitro cardiac model for biomedical research in the future. STATEMENT OF SIGNIFICANCE: The availability of in vitro human cardiomyocytes generated from induced pluripotent stem cells (iPSCs) opens the possibility to develop human in vitro heart models for disease modeling and drug testing. However, iPSC-derived cardiomyocytes remain structurally and functionally immature, which hinders their application. In this manuscript, we present an optimized and complete microfluidic system that enhances maturation of iPSC-derived cardiomyocytes through physiological cyclic pulsatile hemodynamic forces. Furthermore, we improved our microfluidic system by using a closed microfluidic recirculation and oxygen exchangers to achieve and maintain low oxygen in the culture chambers, which is suitable for mimicking the hypoxic condition and studying the pathophysiological mechanisms of human diseases in vitro. In the future, a variety of technologies including 3D tissue engineering could be integrated into our system, which may greatly extend the use of iPSC-derived cardiac models in drug development and disease modeling.

Spider Chitin. The biomimetic potential and applications of Caribena versicolor tubular chitin.

Diverse fields of modern technology and biomedicine can benefit from the application of ready-to-use chitin-based scaffolds. In this work we show for the first time the applicability of tubular and porous chitin from Caribena versicolor spiders as a scaffold for the development of an effective CuO/Cu(OH)2 catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AM), and as a scaffold for the tissue engineering of selected cells. The formation of CuO/Cu(OH)2 phases on and within the chitinous tubes leads to a hybrid material with excellent catalytic performance with respect to the reduction of p-nitrophenol. On the other hand, experimental results provide for the first time strong evidence for the biocompatibility of spider chitin with different cell types, a human progenitor cell line (hPheo1), as well as cardiomyocytes differentiated from induced pluripotent stem cells (iPSC-CMs) that were cultured on a tube-like scaffold.

Naturally Drug-Loaded Chitin: Isolation and Applications.

Naturally occurring three-dimensional (3D) biopolymer-based matrices that can be used in different biomedical applications are sustainable alternatives to various artificial 3D materials. For this purpose, chitin-based structures from marine sponges are very promising substitutes. Marine sponges from the order Verongiida (class Demospongiae) are typical examples of demosponges with well-developed chitinous skeletons. In particular, species belonging to the family Ianthellidae possess chitinous, flat, fan-like fibrous skeletons with a unique, microporous 3D architecture that makes them particularly interesting for applications. In this work, we focus our attention on the demosponge Ianthella flabelliformis (Linnaeus, 1759) for simultaneous extraction of both naturally occurring ("ready-to-use") chitin scaffolds, and biologically active bromotyrosines which are recognized as potential antibiotic, antitumor, and marine antifouling substances. We show that selected bromotyrosines are located within pigmental cells which, however, are localized within chitinous skeletal fibers of I. flabelliformis. A two-step reaction provides two products: treatment with methanol extracts the bromotyrosine compounds bastadin 25 and araplysillin-I N20 sulfamate, and a subsequent treatment with acetic acid and sodium hydroxide exposes the 3D chitinous scaffold. This scaffold is a mesh-like structure, which retains its capillary network, and its use as a potential drug delivery biomaterial was examined for the first time. The results demonstrate that sponge-derived chitin scaffolds, impregnated with decamethoxine, effectively inhibit growth of the human pathogen Staphylococcus aureus in an agar diffusion assay.

Naturally Prefabricated Marine Biomaterials: Isolation and Applications of Flat Chitinous 3D Scaffolds from Ianthella labyrinthus (Demospongiae: Verongiida).

Marine sponges remain representative of a unique source of renewable biological materials. The demosponges of the family Ianthellidae possess chitin-based skeletons with high biomimetic potential. These three-dimensional (3D) constructs can potentially be used in tissue engineering and regenerative medicine. In this study, we focus our attention, for the first time, on the marine sponge Ianthella labyrinthus Bergquist & Kelly-Borges, 1995 (Demospongiae: Verongida: Ianthellidae) as a novel potential source of naturally prestructured bandage-like 3D scaffolds which can be isolated simultaneously with biologically active bromotyrosines. Specifically, translucent and elastic flat chitinous scaffolds have been obtained after bromotyrosine extraction and chemical treatments of the sponge skeleton with alternate alkaline and acidic solutions. For the first time, cardiomyocytes differentiated from human induced pluripotent stem cells (iPSC-CMs) have been used to test the suitability of I. labyrinthus chitinous skeleton as ready-to-use scaffold for their cell culture. Results reveal a comparable attachment and growth on isolated chitin-skeleton, compared to scaffolds coated with extracellular matrix mimetic Geltrex®. Thus, the natural, unmodified I. labyrinthus cleaned sponge skeleton can be used to culture iPSC-CMs and 3D tissue engineering. In addition, I. labyrinthus chitin-based scaffolds demonstrate strong and efficient capability to absorb blood deep into the microtubes due to their excellent capillary effect. These findings are suggestive of the future development of new sponge chitin-based absorbable hemostats as alternatives to already well recognized cellulose-based fabrics.