Glioblastoma In Vitro Model That Recapitulates the Influence of the Hyaluronan Molecular Weight in Cancer Cell Motility and Permeability of the Blood-Brain Tumor Barrier

We report a glioblastoma (GBM) in vitro model that combines an extracellular matrix
(ECM)-mimicking hydrogel, hyaluronan (HA), GBM spheroids, and a blood-brain barrier (BBB)
component. The model was designed to study the impact of the HA’s chain size (i.e., molecular weight,
Mw) on cancer cell migration and on the permeability of the BBB. U-87 spheroids were encapsulated in
alginate (Alg) hydrogels previously loaded with HA of different Mw, i.e., 5 kDa, 700 kDa, and 1.5 MDa,
mimicking the tumor microenvironment (TME) of GBM. The results indicate that shorter HA
molecules (i.e., 5 kDa) enhance the invasion of U-87 cells, as observed by time-lapse microscopy.
Moreover, this increased cellular motility is accompanied by overexpression of cortactin by the U-87
cells confirming an increased cancer invasive character. In contrast, U-87 spheroids encapsulated in
hydrogels that presented HA of higher Mw, i.e., 700 kDa and 1.5 MDa, presented reduced motility,
being consistent with a limited cancer growth. Furthermore, dextran-based permeability measurements
showed that the presence of HA of low Mw (i.e., 5 kDa) led to increased permeability of the BBB
component, a feature that is characteristic of the blood-brain tumor barrier (BBTB). In summary, the
developed 3D in vitro GBM model effectively recapitulates key features of the TME, highlighting the impact of the HA size on cancer cell invasion and BBB/BBTB permeability.