Evaluation of allylated gelatin as a bioink supporting spontaneous spheroid formation of HepG2 cells.

The spheroid culture system has gained significant attention as an effective in vitro model to mimic the in vivo microenvironment. Even though numerous studies were focused on developing spheroids, the structural organization of encapsulated cells within hydrogels remains a challenge. Allylated gelatin or GelAGE is used as a bioink due to its excellent physicochemical properties. In this study, GelAGE was evaluated for its capacity to induce spontaneous spheroid formation in encapsulated HepG2 cells. GelAGE was synthesized and characterized using 1HNMR spectroscopy and ninhydrin assay. Then the physicochemical and biological attributes of GelAGE hydrogel was examined. The results demonstrate that GelAGE has remarkable ability to induce the encapsulated cells to self-organize into spheroids.

In vitro Cytotoxicity Evaluation of Flowable Hyaluronic Acid-Acellular Stromal Vascular Fraction (HA-aSVF) Mixture for Tissue Engineering Applications.

Background: The stromal vascular fraction (SVF) is an aqueous fraction isolated from the adipose tissue that constitutes different kinds of cells and extracellular matrix components. Hyaluronic acid (HA) is a linear polysaccharide in vertebrate tissues and is considered a potential tissue engineering scaffold due to its biocompatible nature. In this study, we have evaluated the cytotoxicity of xenofree HA in combination with an acellular component of adipose SVF (HA-aSVF) to propose it as a candidate biomaterial for future applications. Materials and Methods: 3-(4,5-dimethyl thiazolyl-2)-2,5-diphenyltetrazolium bromide assay of L-929 cells treated with HA-aSVF was used in our study. Data were normalized to cell control (untreated) and extracts of copper and ultra-high molecular weight polyethylene were used as positive (PC) and negative controls (NC). Results: Fibroblast cells retained the morphology after 24 h of treatment with HA-aSVF mixture and exhibited a similar percentage of cell activity compared to NC. PC showed a positive cytotoxic response as expected. The cells incubated with HA-aSVF showed a linear increase in cell activity indicating proliferation. Conclusion: The mixture of HA and acellular SVF in its flowable form is non-cytotoxic and showed improved cell proliferation. Hence the mixture can be proposed as a biomaterial and can be further explored for specific tissue engineering applications.