Printability and Cell Viability in Bioprinting Alginate Dialdehyde-Gelatin Scaffolds

Abstract

bioprinting is a promising technique used to fabricate scaffolds from hydrogels with living cells. However, the printability of hydrogels in bioprinting has not been adequately studied. The aim of this study was to quantitatively characterize the printability and cell viability of alginate dialdehyde (ADA)-gelatin (Gel) hydrogels for bioprinting. ADA-Gel hydrogels of various concentrations were synthesized and characterized using Fourier transform infrared spectroscopy, along with rheological tests for measuring storage and loss moduli. Scaffolds (with an area of 11 × 11 mm) of 1, 2, and 13 layers were fabricated from ADA-Gel hydrogels using a 3D-bioplotter under printing conditions with and without the use of cross-linker, respectively, at room temperature and at 4 °C. Scaffolds were then quantitatively assessed in terms of the minimum printing pressure, quality of strands and pores, and structural integrity, which were combined together for the characterization of ADA-Gel printability. For the assessment of cell viability, scaffolds were bioprinted from ADA-Gel hydrogels with human umbilical vein endothelial cells (HUVECs) and rat Schwann cells and were then examined at day 7 with live/dead assay. HUVECs and Schwann cells were used as models to demonstrate biocompatibility for potential angiogenesis and nerve repair applications, respectively. Our results illustrated that ADA-Gel hydrogels with a loss tangent (ratio of loss modulus over storage modulus) between 0.24 and 0.28 could be printed in cross-linker with the best printability featured by uniform strands, square pores, and good structural integrity. Additionally, our results revealed that ADA-Gel hydrogels with an appropriate printability could maintain cell viability over 7 days. Combined together, this study presents a novel method to characterize the printability of hydrogels in bioprinting and illustrates that ADA-Gel hydrogels can be synthesized and bioprinted with good printability and cell viability, thus demonstrating their suitability for bioprinting scaffolds in tissue engineering applications.

3D Bioprinted Vascularized Tumour for Drug Testing

“…It remained above 80% even on day seven. The viability is comparable or superior to that of HUVECs and fibroblasts cultured on other hydrogels, such as the poly(ethylene glycol)-polycaprolactone hydrogel or alginate dialdehyde-gelatine [30,31]. The results suggest that the GAF hydrogel is suitable for bioprinting as well as for growing HUVECs and LFs.…”

Encapsulation of Human Natural and Induced Regulatory T‐Cells in IL‐2 and CCL1 Supplemented Alginate‐GelMA Hydrogel for 3D Bioprinting

“…Over‐“gelled” bioink is not optimal in extrusion‐based bioprinting due to nonuniformity in fiber deposition leading to undesirable scaffold morphology and stability. [ 35 ] High cell density has been shown to decrease the viscosity of the bioink; [ 36 ] thus, 2|7.5|3.5% w/v alginate‐GelMA‐gelatin bioink with slight over‐gelation was further characterized by rheology measurements. Upon oscillation temperature sweep, alginate‐GelMA‐gelatin bioink showed higher storage moduli (G′) than alginate‐GelMA bioink across the temperature range.…”

Engineered 3D Polymer and Hydrogel Microenvironments for Cell Culture Applications

“…Approaches include tuning the degree of crosslinking of the bioink and formation of composites or mixtures such as with NiCu NPs [237], e-polylysine [238], carrageenan [239], gelatin [240][241][242], and nanocellulose [243,244]. Rheological studies show composition ratio, printing temperature, extrusion pressure, and crosslinking concentration affect fidelity and resolution [239,240,242,245]. In comparison to other materials, there has been little work on light assisted 3D printing of alginate.…”

“…For example, gelatin-alginate [240,[319][320][321], Laponite [322], nanoclays [323], and synthetic polymers such as Pluronic F-127 [208] and PCL [324], have all been studied. Alginate dialdehyde-gelatin scaffolds were printed in the presence of a cross-linker for reaching feature sizes of~500 µm [245], while alginate-GelMA interpenetrating networks via UV crosslinking of GelMA followed by Ca crosslinking of alginate was reported [321]. Embedded bioprinting of gelatin into a support material of agarose slurry was optimized to allow freestanding 3D structures [325].…”

“…Inclusion of alginate [240,[319][320][321], Laponite [322], nanoclays [323], Pluronic F-127 [208], PCL [324]; Feature size 500 µm [245] [ [313][314][315][316]; Feature size 300 µm (SLA), Compressive E: 0.5-18 MPa [328] Mouse planta dermis [319]; dental pulp stem cells [320]; hMSCs and amniotic epithelial cells [240]; chondrocytes [214,327] Silk ( Mouse articular chondrocytes [342]; human fibroblasts [338]; porcine chondrocytes [340]; hMSCs [344,345]; human mesenchymal progenitor cells [346]…”