Bioresorbable hydrogel microspheres for transcatheter embolization: preparation and in vitro evaluation

To develop and evaluate a bioresorbable spherical material for embolization.

New bioresorbable hydrogel microspheres were prepared from carboxymethyl cellulose and chitosan by using an inverse emulsion method. Size distribution of the microspheres was determined with a microscope, and the colorability was tested with Evans blue dye. The compressibility was examined with a texture analyzer. After sieving, the suspendability of the microspheres was tested in saline solution/contrast agent mixture in different ratios, and then the injectability was tested with microcatheters (lumen sizes of 0.0165, 0.019, and 0.027 inches). The in vitro degradability tests were performed in a lysozyme solution. Cell culture study of the microspheres was performed with human fibroblasts.

The microspheres exhibit diameters of 100-1,550 μm with a transparent appearance. Their fracture force can reach 0.58-0.88 N, and fracture deformation varies from approximately 70% to 95% of their original size. These microspheres can be colored by Evans blue dye, and uniform subgroups of microspheres can be readily obtained by sieving. Within 3 minutes, the microspheres form a stable suspension in a 4:6 contrast agent/saline solution mixture, which can be easily injected through microcatheters without aggregating or clogging. These microspheres are biodegradable, with degradation times varying from 2 weeks to 1 month, depending on their composition. Cell culture studies reveal no adverse effect on the growth of human fibroblasts in the presence of the microspheres.

A biodegradable and noncytotoxic microsphere was successfully prepared. It can be well suspended in the contrast solution and easily injected through a microcatheter.