fabrication-inverted-colloidal-crystal-poly-ethylene-glycol-scaffold

Fabrication of Inverted Colloidal Crystal Poly(ethylene glycol) Scaffold: A Three-dimensional Cell Culture Platform for Liver Tissue Engineering

The ability to maintain hepatocyte function in vitro, for the purpose of testing xenobiotics&#39; cytotoxicity, studying virus infection and developing ...

Nanyang Technological University

In nature, pollen grains play a vital role for encapsulation. Many pollen species exist which are often used as human food supplements. Dynamic image particle analysis, scanning electron microscopy, and confocal microscopy analysis confirmed the size, structural uniformity, and macromolecular encapsulation in sunflower pollen, paving the way to explore natural pollen grains for the encapsulation of therapeutic molecules.

Natural Sunflower Pollen as a Drug Delivery Vehicle.

Development of artificial tissues providing the proper geometrical, mechanical, and environmental cues for cells is highly coveted in the field of tissue engineering. Recently, microfabrication strategies in combination with other chemistries have been utilized to capture the architectural complexity of intricate organs, such as the liver, in in vitro platforms. Here it is shown that a biofunctionalized poly (ethylene glycol) (PEG) hydrogel scaffold, fabricated using a sphere-template, facilitates hepatic sheet formation that follows the microscale patterns of the scaffold surface. The design takes advantage of the excellent diffusion properties of porous, uniform 3D hydrogel platforms, and the enhanced-cell-extracellular matrix interaction with the display of conjugated collagen type I, which in turn elicits favorable Huh-7.5 response. Collectively, the experimental findings and corresponding simulations demonstrate the importance of biofunctionalized porous scaffolds and indicate that the microscaffold shows promise in liver tissue engineering applications and provides distinct advantages over current cell sheet and hepatocyte spheroid technologies.

Biofunctionalized Hydrogel Microscaffolds Promote 3D Hepatic Sheet Morphology.

Loss of function is a major challenge for hepatocytes that are cultured on two-dimensional (2D) cell culture platforms. Biofunctionalized three-dimensional (3D) scaffolds produced by microfabrication strategies can overcome these limitations by presenting vital environmental cues, strong mechanical properties, and three-dimensional geometry to enable high-fidelity liver tissue engineering. Herein, we report the detailed investigation of hepatocarcinoma (Huh 7.5) cellular behavior in a collagen-functionalized microsphere-templated poly(ethylene glycol) (PEG) hydrogel scaffold which promotes 3D hepatic sheet morphology. Collagen conjugation led to improved liver-specific functions, including albumin production and cytochrome P450 (CYP450) activity. Importantly, the gene expression of numerous cell-adhesion markers was enhanced along with stimulated innate hepatocyte fibronectin production. Taken together, the findings reveal a close connection between hepatic cell morphology and gene expression, offering evidence that surface-coated collagen in the 3D hydrogel platform triggers the upregulation of hepatocyte-specific transcription factors and the secretion of liver metabolic markers.

Phenotypic regulation of liver cells in a biofunctionalized three-dimensional hydrogel platform.

Gelatin-methacryloyl (GelMA) is one of the most commonly used photopolymerizable biomaterials in bio-applications. However, GelMA synthesis remains suboptimal, as its reaction parameters have not been fully investigated. The goal of this study is to establish an optimal route for effective and controllable GelMA synthesis by systematically examining reaction parameters including carbonate-bicarbonate (CB) buffer molarity, initial pH adjustment, MAA concentration, gelatin concentration, reaction temperature, and reaction time. We employed several analytical techniques in order to determine the degree of substitution (DS) and conducted detailed structural analysis of the synthesized polymer. The results enabled us to optimize GelMA synthesis, showing the optimal conditions to balance the deprotonation of amino groups with minimizing MAA hydrolysis, which led to nearly complete substitution. The optimized conditions (low feed ratio of MAA to gelatin (0.1 mL/g), 0.25 M CB buffer at pH 9, and a gelatin concentration of 10-20%) enable a simplified reaction scheme that produces GelMA with high substitution with just one-step addition of MAA in one pot. Looking forward, these optimal conditions not only enable facile one-pot GelMA synthesis but can also guide researchers to explore the efficient, high methacrylation of other biomacromolecules.

Article	Year
Natural Sunflower Pollen as a Drug Delivery Vehicle. Small (Weinheim an der Bergstrasse, Germany)\| PubMed ID: 26516033	2015
Biofunctionalized Hydrogel Microscaffolds Promote 3D Hepatic Sheet Morphology. Macromolecular bioscience\| PubMed ID: 26612190	2015
Phenotypic regulation of liver cells in a biofunctionalized three-dimensional hydrogel platform. Integrative biology : quantitative biosciences from nano to macro\| PubMed ID: 26792030	2016
Precise Tuning of Facile One-Pot Gelatin Methacryloyl (GelMA) Synthesis. Scientific reports\| PubMed ID: 27503340	2016

Hitomi Shirahama

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