INTRODUCTION:Hyaluronan (HA) molecular weight (Mw) present an important role in tumor invasiveness and metastasis[1, 2]. The reported trends are contradicting: in some cases, lower Mw species are associated with more invasive tumors [3], while other reports suggest that higher HA Mw are the culprit for the invasion. A possible reason for this contradiction can be due to the use of different models. Herein, we evaluated the impact of HA Mw in cancer invasiveness using core-shell hydrogels – a physiological relevant 3D model. We encapsulated MKN45 gastric cancer cells in the core of the hydrogel, composed by alginate and HA of different Mws, and evaluated the formation of cancer spheroids under a 3D environment.

METHODS:The core of the hydrogels (spheres) was made by a combination of alginate (Pronova VLVG, 20 mg/mL) and HA (of different Mws, i.e. 6.4, 752 and 1500 kDa, c=1mg/mL) and crosslinked with CaCl₂(100mM). We encapsulated MKN45 cells (at 5x10⁶cells/mL) during the processing of the core spheres, that were further embedded in an alginate disc (shell). Cell viability was accessed by live/dead staining using calcein (1.2 mL/mL) and propidium iodide (0.6 mL/min), respectively. 

 RESULTS:Cell viability analysis clearly shows a higher cell density in all mixed systems (combination of alginate and HA) as compared with the controls (only alginate). The increase of HA Mws induces a higher cell proliferation and formation of bigger cell clusters (spheroids).

 DISCUSSION & CONCLUSIONS:

We were able to correlate high Mw of HA with an increment on cancer cell viability and spheroid sizes (up to 150 μm for the HA of 1500kDa -measured in the Z axis). The presented data clearly illustrate the influence of HA Mw on tumor growth and in the formation of cancer spheroids.