Delivery of Cargo with a Bioelectronic Trigger

Biological systems exchange information often with chemical signals. Here, we demonstrate the chemical delivery of a fluorescent label using a bioelectronic trigger. Acid-sensitive microparticles release fluorescin diacetate upon low pH induced by a bioelectronic device. Cardiac fibroblast cells (CFs) uptake fluorescin diacetate, which transforms into fluorescein and emits a fluorescent signal. This proof-of-concept bioelectronic triggered delivery may be used in the future for real-time programming and control of cells and cell systems

Fabrication of micropatterned fish GelMA hydrogel and viability of cells on micropatterned gel surfaces.

<p>NIH3T3 cells readily adhered to fish GelMA surfaces irrespective of macromer concentration. (A-C) Pattern fidelity of fish GelMA using 5%, 10% and 15% macromer (scale bar = 800 μm). (D-F) LIVE/DEAD assay at 24 h after adhesion (scale bar = 200 μm). (G) Quantification of cell viability demonstrated high cell survival under all conditions and there was no significant difference between GelMA conditions. Error bars represent SDs of averages obtained from five images per condition.</p

Degradation characteristics of fish GelMA hydrogels.

<p>(A) Degradation profiles of fish GelMA hydrogels with various degrees of methacrylation (low, medium and high) and GelMA concentrations (5%, 10% and 15%) upon exposure to collagenase type II. (B) Comparison of fish and porcine GelMA hydrogels with high degree of methacrylation and 10% gel concentration. Error bars represent SDs of measurements performed on three samples. Representative cross-sectional SEM images of fish GelMA (C~F) and porcine GelMA (G~J) hydrogels reveal different gel morphologies after degradation with collagenase type II. (K) Pore size distribution of GelMA hydrogels (Pore size frequency obtained from 5 SEM images per condition).</p

Degree of methacrylation as determined by TNBS assay.

<p>(A) Various volume percentages of methacrylic anhydride (0.25%, 1.25% and 20%) were analyzed to investigate the degree of methacrylation of the synthesized fish GelMA. (B) Comparison of a high degree of methacrylation (20% MA) according to the origin of gelatin (fish GelMA vs. porcine GelMA); there was no significant difference. The percentage of incorporated substitution was calculated by comparing the amount of remaining amino groups (-NH₂) in GelMA to that in pristine gelatin. Error bars represent standard deviations (SDs) of measurements performed on six samples.</p

Analysis on scientific Articles from an Ethical Point of View involving Human Beings from 1990-1996

O presente estudo teve como objetivo analisar artigos científicos na área de saúde pública, que envolviam direta e indiretamente seres humanos, publicados anteriormente à Resolução 196/96. Analisamos artigos científicos da Revista de Saúde Pública e Cadernos de Saúde Pública de 1990 a 1996. Baseamos nossa análise em categorias retiradas da Resolução 196/96 previamente estabelecidas: consentimento do sujeito de Pesquisa, sujeitos com autonomia reduzida, proteção de sujeitos e grupos vulneráveis e legalmente incapazes, confidencialidade, privacidade, proteção da imagem, estigmatização, benefícios do retorno da pesquisa. A análise dos dados foi efetuada em dois momentos: caracterização das revistas analisadas e análise de conteúdo. Os resultados encontrados foram: 568 artigos levantados, 384 (67,6%) da Revista da Saúde Pública e 184 (32,4%) dos Cadernos de Saúde Pública. Destes, 296 (52,1%) envolviam direta ou indiretamente sujeitos humanos que foram objeto de nossa análise. Instituições mais utilizadas para o desenvolvimento de pesquisas: serviços de saúde 134 (23,6%), empresas, indústrias, escritórios e instituições públicas 52 (9,2%), residências 42 (7,4), lazer e assistência social somam 6 (10%). Tipos de pesquisa: epidemiológica 121 (21,3%), biológica 59 (10,4%), psicológica 10 (1,8%), nutricional 42 (7,4%), ambiental 9 (1,6%). Analisamos qualitativamente trechos de artigos baseando nossa análise na Resolução 196/96. Consideramos que antes da elaboração da resolução 196/95, talvez não existisse um interesseThe present study objective is analyse the scientific articles in the public health area, involving human beings directly and indirectly, published prior to the enforcement of Resolution 196/96. [It was researched all the published articles in the Revista de Saúde Pública and Cadernos de Saúde Pública Journals from 1990 to 1996]. The articles were analysed based on categories previously established by Resolution 196/96: subjects consent, subjects with little autonomy, protection of vulnerable and legally incapable groups, confidentiality, privacy, protection of the image, stigma, benefits, social return of the research. The analysis were divided in two moments: 1st moment: caractherization of the two periodicals and 2nd moment, qualitative analysis of the articles content analysis. The results were as follows: 568 scientific articles, 384 (67,6%) from Revista de Saúde Pública and 184 (32,4%) from Cadernos de Saúde Pública. Of these, 296 (52,1%) involved human beings direct or indirectly and that was the objective of the analysis. The institutions used for research: The health system 134 (23,6%); industries, offices and state institutions 52 (9,2%); residences 42 (7,4%), places of leisure and social services added 6 (10%). Type of research: Epidemiological 121 (21,3%), biological 59 (10,4%), psichological 10 (1,8%), nutritional 42 (7,4%), ambiental 21 (3,7%), social 20 (3,5%), services and programs evaluation 9 (1,6%). Extracts from articles were analysed qualitatively based on the Resolution 196/96. Bearing in mind that at the time of such publication 1990/1996 the concept of giving explanatory approach to the subject of research were not common practice, but with the enforcement of the Resolution this culture is being gradually changed

Behavior of cells encapsulated in fish GelMA hydrogels.

<p>(A-F) NIH3T3 cells embedded in medium and high degree of methacrylation fish GelMA containing 5% (w/v) GelMA were stained using calcein-AM/ethidium homodimer at 3 h and 24 h after encapsulation to evaluate the cell viability compared to high degree of methacrylation porcine GelMA. (G-I) After 2 days of culture, cells proliferated and elongated in fish and porcine GelMA hydrogel. (J-L) Representative images of the cells stained with phalloidin for the actin filaments (green) and nuclei counterstained with DAPI (blue) at 72 h. (P) Viability of the encapsulated cells. (Q) Quantification of cell proliferation in GelMA hydrogel until 5 days. Cell proliferation rate was not significantly different at all condition.</p

Synthesis of fish gelatin methacryloyl (GelMA) and fabrication of photocrosslinked GelMA hydrogel.

<p>(A) Gelatin was reacted with methacrylic anhydride (MA) to introduce a methacryloyl substitution group on the reactive amine and hydroxyl groups of the amino acid residues. (B) GelMA photocrosslinking to form A hydrogel matrix under UV irradiation. The free radicals generated by the photoinitiator initiated chain polymerization with methacryloyl substitution. (C) Schematic of formation of patterned hydrogels using photolithography.</p

Interconnectable Dynamic Compression Bioreactors for Combinatorial Screening of Cell Mechanobiology in Three Dimensions

Biophysical cues can potently direct a cell’s or tissue’s behavior. Cells interpret their biophysical surroundings, such as matrix stiffness or dynamic mechanical stimulation, through mechanotransduction. However, our understanding of the various aspects of mechanotransduction has been limited by the lack of proper analysis platforms capable of screening three-dimensional (3D) cellular behaviors in response to biophysical cues. Here, we developed a dynamic compression bioreactor to study the combinational effects of biomaterial composition and dynamic mechanical compression on cellular behavior in 3D hydrogels. The bioreactor contained multiple actuating posts that could apply cyclic compressive strains ranging from 0 to 42% to arrays of cell-encapsulated hydrogels. The bioreactor could be interconnected with other compressive bioreactors, which enabled the combinatorial screenings of 3D cellular behaviors simultaneously. As an application of the screening platform, cell spreading, and osteogenic differentiation of human mesenchymal stem cells (hMSCs) were characterized in 3D gelatin methacryloyl (GelMA) hydrogels. Increasing hydrogel concentration from 5 to 10% restricted the cell spreading, however, dynamic compressive strain increased cell spreading. Osteogenic differentiation of hMSCs was also affected by dynamic compressive strains. hMSCs in 5% GelMA hydrogel were more sensitive to strains, and the 42% strain group showed a significant increase in osteogenic differentiation compared to other groups. The interconnectable dynamic compression bioreactor provides an efficient way to study the interactions of cells and their physical microenvironments in three dimensions

Carbon Nanotube Reinforced Hybrid Microgels as Scaffold Materials for Cell Encapsulation

Hydrogels that mimic biological extracellular matrix (ECM) can provide cells with mechanical support and signaling cues to regulate their behavior. However, despite the ability of hydrogels to generate artificial ECM that can modulate cellular behavior, they often lack the mechanical strength needed for many tissue constructs. Here, we present reinforced CNT–gelatin methacrylate (GelMA) hybrid as a biocompatible, cell-responsive hydrogel platform for creating cell-laden three-dimensional (3D) constructs. The addition of carbon nanotubes (CNTs) successfully reinforced GelMA hydrogels without decreasing their porosity or inhibiting cell growth. The CNT–GelMA hybrids were also photopatternable allowing for easy fabrication of microscale structures without harsh processes. NIH-3T3 cells and human mesenchymal stem cells (hMSCs) readily spread and proliferated after encapsulation in CNT–GelMA hybrid microgels. By controlling the amount of CNTs incorporated into the GelMA hydrogel system, we demonstrated that the mechanical properties of the hybrid material can be tuned making it suitable for various tissue engineering applications. Furthermore, due to the high pattern fidelity and resolution of CNT incorporated GelMA, it can be used for <i>in vitro</i> cell studies or fabricating complex 3D biomimetic tissue-like structures

Carbon-Nanotube-Embedded Hydrogel Sheets for Engineering Cardiac Constructs and Bioactuators

We engineered functional cardiac patches by seeding neonatal rat cardiomyocytes onto carbon nanotube (CNT)-incorporated photo-cross-linkable gelatin methacrylate (GelMA) hydrogels. The resulting cardiac constructs showed excellent mechanical integrity and advanced electrophysiological functions. Specifically, myocardial tissues cultured on 50 μm thick CNT-GelMA showed 3 times higher spontaneous synchronous beating rates and 85% lower excitation threshold, compared to those cultured on pristine GelMA hydrogels. Our results indicate that the electrically conductive and nanofibrous networks formed by CNTs within a porous gelatin framework are the key characteristics of CNT-GelMA leading to improved cardiac cell adhesion, organization, and cell–cell coupling. Centimeter-scale patches were released from glass substrates to form 3D biohybrid actuators, which showed controllable linear cyclic contraction/extension, pumping, and swimming actuations. In addition, we demonstrate for the first time that cardiac tissues cultured on CNT-GelMA resist damage by a model cardiac inhibitor as well as a cytotoxic compound. Therefore, incorporation of CNTs into gelatin, and potentially other biomaterials, could be useful in creating multifunctional cardiac scaffolds for both therapeutic purposes and <i>in vitro</i> studies. These hybrid materials could also be used for neuron and other muscle cells to create tissue constructs with improved organization, electroactivity, and mechanical integrity