Effect of collagenase and hyaluronidase on free and anomalous diffusion in multicellular spheroids and xenografts.

BACKGROUND: A critical step in the delivery of nanomedicines to tumour cells is transporting these particles through the extracellular matrix. Tumour-specific anticancer agents, such as encapsulated drugs, proteins, and genes, show low uptake in tumour tissue. It is not clear whether the collagen network or the glycosaminoglycan gel plays the most important role in limiting the interstitial transport of macromolecules. Therefore, we measured the effect of the collagen- and hyaluronan-degrading enzymes, collagenase and hyaluronidase, on interstitial diffusion.
MATERIALS AND METHODS: Human osteosarcomas were grown as multicellular spheroids and xenografts in dorsal skinfold window chambers. Diffusion of fluorescein isothiocyanate (FITC)-dextran molecules was measured by fluorescence recovery after photobleaching based on two-photon scanning laser excitation.
RESULTS: Collagenase, hyaluronidase, and relaxin increased the diffusion coefficient of the 2-MDa FITC-dextrans in the spheroids, but 150-kDa FITC-dextran diffusion was not affected by the enzymatic treatment. In tumour tissue in vivo, collagenase and hyaluronidase increased the diffusion of the 150-kDa FITC-dextrans. In xenografts, anomalous diffusion occurred, whereas only free diffusion was seen in spheroids.
CONCLUSION: The results indicate that the collagen network has a greater impact on the interstitial diffusion of macromolecules in tumour tissue than the hyaluronan gel.