Hyaluronic acid hydrogel stiffness and oxygen tension affect cancer cell fate and endothelial sprouting

Abstract

Three-dimensional (3D) tissue culture models may recapitulate aspects of the tumorigenic microenvironment in vivo, enabling the study of cancer progression in vitro. Both hypoxia and matrix stiffness are known to regulate tumor growth. Using a modular culture system employing an acrylated hyaluronic acid (AHA) hydrogel, three hydrogel matrices with distinctive degrees of viscoelasticity — soft (78±16 Pa), medium (309± 57 Pa), and stiff (596± 73 Pa) — were generated using the same concentration of adhesion ligands. Oxygen levels within the hydrogel in atmospheric (21 %), hypoxic (5 %), and severely hypoxic (1 %) conditions were assessed with a mathematical model. HT1080 fibrosarcoma cells, encapsulated within the AHA hydrogels in high densities, generated nonuniform oxygen distributions, while lower cell densities resulted in more uniform oxygen distributions in the atmospheric and hypoxic environments. When we examined how varying viscoelasticity in atmospheric and hypoxic environments affects cell cycles and the expression of BNIP3 and BNIP3L (autophagy and apoptosis genes), and GLUT-1 (a glucose transport gene), we observed that HT1080 cells in 3D hydrogel adapted better to hypoxic conditions than those in a Petri dish, with no obvious correlation to matrix viscoelasticity, by recovering rapidly from possible autophagy/apoptotic events and alternating metabolism mechanisms. Further, we examined how HT1080 cells cultured in varying viscoelasticity and oxygen tension conditions affected endothelial sprouting and invasion. We observed that increased matrix stiffness reduced endothelial sprouting and invasion in atmospheric conditions; however, we observed increased endothelial sprouting and invasion under hypoxia at all levels of matrix stiffness with the upregulation of vascular endothelial growth factor (VEGF) and angiopoeitin-1 (ANG-1). Overall, HT1080 cells encapsulated in the AHA hydrogels under hypoxic stress recovered better from apoptosis and demonstrated greater angiogenic induction. Thus, we propose that oxygen tension more profoundly influences cell fate and the angiogenic potential of 3D cultured HT1080 fibrosarcoma cells than does matrix stiffness.

Engineering fibrin hydrogels to promote the wound healing potential of mesenchymal stem cell spheroids

“…However, the entrapment of MSC spheroids in hydrogels likely reduces diffusion-mediated transport from that observed with free spheroids, altering the oxygen microenvironment and potentially upregulating hypoxia-adaptive signals even further. While we did not study the oxygen gradient for entrapped MSC spheroids within these materials, others have modeled the extent of oxygen diffusion and cellular consumption in engineered hydrogels [36–38]. In fibrin hydrogels, gel thickness has the most pronounced influence on the distribution of oxygen within the system [39].…”

Polymeric hydrogels as artificial extracellular microenvironments for cancer research

“…Recently, our group has developed a tumor angiogenesis model using HA hydrogels through a co-culture system of ECs and human fibrosarcoma cells (HT1080) [8]. We investigated the effects of matrix stiffness and oxygen tension on the vascular cell invasion in order to recapitulate the tumor-associated vascular invasion process common in tumor growth.…”

“…In order to create 3D tumor microenvironments in vitro, polymeric hydrogel materials have been widely used due to their tunable properties and structural similarity to native ECMs [7][8][9]. Various kinds of hydrogel materials, derived from natural, synthetic, and semi-synthetic polymers, have been utilized to generate preclinical models for studying basic cancer biology and screening newly developed drugs and carriers for cancer research.…”

For whom the cells pull: Hydrogel and micropost devices for measuring traction forces

“…Hyaluronic acid-based hydrogels can harbor cell adhesive ligands [173–175], be mechanically modified [171, 173, 175], release soluble factors [174] and be patterned [173, 175]. Polyethylene glycol-based hydrogels have been developed for mechanical tunability [176], microenvironmental modifications [177], biocompatibility and harboring of cell ligands and soluble factors [178].…”