Engineering bioprintable alginate/gelatin composite hydrogels with tunable mechanical and cell adhesive properties to modulate tumor spheroid growth kinetics

Abstract

Tunable bioprinting materials are capable of creating a broad spectrum of physiological mimicking 3D models enabling in vitro studies that more accurately resemble in vivo conditions. Tailoring the material properties of the bioink such that it achieves both bioprintability and biomimicry remains a key challenge. Here we report the development of engineered composite hydrogels consisting of gelatin and alginate components. The composite gels are demonstrated as a cell-laden bioink to build 3D bioprinted in vitro breast tumor models. The initial mechanical characteristics of each composite hydrogel are correlated to cell proliferation rates and cell spheroid morphology spanning month long culture conditions. MDA-MB-231 breast cancer cells show gel formulation-dependency on the rates and frequency of self-assembly into multicellular tumor spheroids (MCTS). Hydrogel compositions comprised of decreasing alginate concentrations, and increasing gelatin concentrations, result in gels that are mechanically soft and contain a greater number of cell-adhesion moieties driving the development of large MCTS; conversely gels containing increasing alginate, and decreasing gelatin concentrations are mechanically stiffer, with fewer cell-adhesion moieties present in the composite gels yielding smaller and less viable MCTS. These composite hydrogels can be used in the biofabrication of tunable in vitro systems that mimic both the mechanical and biochemical properties of the native tumor stroma.

Recent trends in protein and peptide-based biomaterials for advanced drug delivery

“…In vivo, inhibition of tumor growth was similar for hydrogels containing a low dose of cisplatin and conventional intraperitoneal administration of high doses of free cisplatin [ 306 ]. Kinsella and colleague fabricated various alginate-gelatin bio-printable composite hydrogels that resemble the microscopic architecture of native tumor stroma [ [307] , [308] , [309] ]. 3D-printed hydrogels embedded with breast cancer cells, and fibroblasts promoted the self-assembly of breast cancer cells into multicellular tumor spheroids (MCTS), which were viable for more than 30 days [ 307 ].…”

The Optimization of a Novel Hydrogel—Egg White-Alginate for 2.5D Tissue Engineering of Salivary Spheroid-Like Structure

“…One possible reason why EWA with 3.0% alginate showed lower cell proliferation and viability compared to the rest of the samples could also be attributed to the stiffness of the material [55]. Perhaps the stiffness of EWA containing 3% alginate is less favorable in that it does not reflect the stiffness of native SG tissue [57]; future tests should be performed comparing the stiffness of various EWA alginate percentages and the stiffness of native SG tissue. Furthermore, the formation of medium and larger spheroid-like structures in EWA 3% could also negatively impact the viability of the cell located in the core of the spheroid-like structure, resulting in a decrease of cell viability due to the self-assembly of the cell into a 3D structure [52].…”

Comparison of Hydrogels for the Development of Well-Defined 3D Cancer Models of Breast Cancer and Melanoma

“…However, mammalian cells cannot adhere to or degrade alginate. Material scientists modify the molecular structure by, for example, oxidizing alginate to alginate dialdehyde (ADA) or blending it with degradable proteins, like fibrin or gelatin, to optimize the material for 3D culture [21,22].…”

“…However, mammalian cells cannot adhere to or degrade alginate. Material scientists modify the molecular structure by, for example, oxidizing alginate to alginate dialdehyde (ADA) or blending it with degradable proteins, like fibrin or gelatin, to optimize the material for 3D culture [ 21 , 22 ]. Additionally, it is possible to bind free amino groups like from gelatin to the aldehyde groups of the polysaccharide through Schiff’s base formation (ADA–GEL) [ 23 ], leading to advantages in matrix remodeling for mammalian cells.…”