Speaker
Description
Introduction:
The low success rate of oncological drugs in clinical trials highlights the need for predictive preclinical models because the traditional 2D cultures and animal models fail to replicate human tumor microenvironments fully. The researchers have seen 3D bioprinting as a promising technology for the fabrication of more physiologically relevant tissue models. Bioinks for such applications must possess biocompatibility, biodegradability, non-toxicity, non-immunogenicity, and mechanical integrity. In this context, we investigate the development of alginate-gelatin hydrogels crosslinked with CaCl₂ and genipin as potential bioinks for fabricating 3D tissue models.
Methods:
The inks were synthesized using natural polymers such as sodium alginate and gelatin at different concentrations and proportions, crosslinked via ionic (CaCl₂) and natural (genipin) methods. The chemical structure was analyzed by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). The morphology of the structures was characterized using scanning electron microscopy (SEM). Cell viability studies were assessed through MTT assay using HUVEC and Caco-2 cell lines. Rheological properties, including viscosity and shear-thinning behavior, were preliminarily assessed by oscillatory and flow sweep tests to evaluate the printability and mechanical stability of the hydrogels under bioprinting conditions.
Results:
The ATR-FTIR spectra confirmed successful crosslinking between the alginate, gelatin, CaCl₂, and genipin. SEM imaging revealed a porous and interconnected structure favorable for cell proliferation. MTT assays demonstrated promising cell viability rates, with hydrogels crosslinked with CaCl₂ reaching 90% viability and those crosslinked with 0.25% w/v genipin reaching 75.07% for Caco-2 cells and for HUVEC cells after 48 hours of culture. Preliminary rheological analyses demonstrated that the g hydrogels with genipin significantly increased storage modulus (G'), indicating greater stiffness and mechanical stability than hydrogels crosslinked with CaCl₂ alone. Furthermore, the loss modulus (G'') also exhibited adequate behavior, indicating appropriate viscoelasticity for biofabrication, where fluidity and elasticity must be balanced.
Discussion:
The incorporation of another crosslinker, such as genipin, significantly improved the mechanical stability of the hydrogels. This facilitates better control during the 3D printing process and maintains structural integrity post-printing. The improved rheological properties made the bioinks more suitable for printing complex 3D structures. Compared to traditional 2D cultures, the hydrogels significantly improved the growth and adherence of Caco-2 and HUVEC cells, increasing cell survival and enabling a more accurate modeling of tumor tissue activity.
Acknowledgments:
This study was financed, in part, by the São Paulo Research Foundation (FAPESP), Brasil. Process Number 2024/17373-9 and 2018/22214-6. Also, the authors gratefully acknowledge the financial support provided by CNPq (grant No. 402816/2020-0).
References:
Gregory, T., Benhal, P., Scutte, A., Quashie Jr, D., Harrison, K., Cargill, C., ... & Ali, J. (2022). Rheological characterization of cell-laden alginate-gelatin hydrogels for 3D biofabrication. Journal of the mechanical behavior of biomedical materials, 136, 105474.
Ketabat, F., Maris, T., Duan, X., Yazdanpanah, Z., Kelly, M. E., Badea, I., & Chen, X. (2023). Optimization of 3D printing and in vitro characterization of alginate/gelatin lattice and angular scaffolds for potential cardiac tissue engineering. Frontiers in Bioengineering and Biotechnology, 11, 1161804.
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