A hepatocellular carcinoma–bone metastasis-on-a-chip model for studying thymoquinone-loaded anticancer nanoparticles

We report the development of a metastasis-on-a-chip platform to model and track hepatocellular carcinoma(HCC)-bone metastasis and to analyze the inhibitory effect of an herb-based compound,thymoquinone(TQ),in hindering the migration of liver cancer cells into the bone compartment.The bioreactor consisted of two chambers,one accommodating encapsulated HepG2 cells and one bone-mimetic niche containing hydroxyapatite(HAp).Above these chambers,amicroporous membrane was placed to resemble the vascular barrier,where medium was circulated over the membrane.It was observed that the liver cancer cells proliferated inside the tumor microtissue and disseminated from the HCC chamber to the circulatory flow and eventually entered the bone chamber.The number of metastatic HepG2 cells to the bone compartment was remarkably higher in the presence of HAp in the hydrogel.TQ was then used as ametastasis-controlling agent in both free form and encapsulated nanoparticles,to analyze its suppressing effect on HCC metastasis.Results indicated that the nanoparticle-encapsulated TQ provided a longer period of inhibitory effect.In summary,HCC-bone metastasis-on-a-chip platform was demonstrated to model certain key aspects of the cancer metastasis process,hence corroborating the potential of enabling investigations on metastasis-associated biology as well as improved anti-metastatic drug screening.

A 3D in vitro co-culture model for evaluating biomaterial-mediated modulation of foreign-body responses

The immune response after implantation of a biomaterial may shorten the functional life of the implant,depending on the degree of the response.In this study,we used a polyacrylamide-alginate(PAAm-Alg)hydrogel,which has been previously characterized as a biocompatible material and shown to enhance regeneration of cartilage in vivo,along with a graphiteenhanced hydrogel(PAAm-Alg-G)as a non-biocompatible counterpart,to evaluate macrophage attachment and polarization to pro-or anti-inflammatory phenotypes.The performance of each biomaterial in the presence of fibroblasts and chondrocytes was validated by an in vitro model which demonstrated modulation of the foreign-body response.A blend of 5%gelatin methacryloyl and 0.1%methacrylated hyaluronic acid was optimized to mimic the extracellular matrix(ECM)and support cell viability,proliferation,migration,and functionality at an initial concentration of 3.25×10^(5) cells/mL.The PAAm-Alg-G hydrogel localized in the simulated ECM showed cytotoxic and genotoxic effects for both fibroblasts and chondrocytes,while exhibiting a proliferative effect on macrophages with elevated immune response.The M1/M2 ratio was 0.73 for PAAm-Alg hydrogel but 2.64 for PAAm-Alg-G,leading to significant M1 dominance(p<0.0001),as expected,on day 13.Moreover,loading PAAm-Alg hydrogel with transforming growth factor beta-3(TGF-β3)resulted in a slightly more balanced M1/M2 ratio of 0.87(p>0.05).The interleukin-6(IL-6)concentration secreted in the presence of PAAm-Alg hydrogel(4.58 pg/mL)significantly decreased(p<0.0001)on day 13,while the increase(p<0.0001)in interleukin-10(IL-10)concentration(120.73 pg/mL)confirmed the switch from a pro-inflammatory to an anti-inflammatory response.Predicting immune responses by developing a simplistic yet powerful three-dimensional in vitro model provides advantages in preparing for clinical use of biomaterials.