Physical and chemical factors affecting the loading and release of bromelain from DC beads

Doxorubicin loaded DC beads (microspheres) has been used for treating un-resectable tumours by transarterial chemoembolization (TACE). We have shown that bromelain, an enzyme from the pineapple plant, enhances the cytotoxic effect of a number of chemotherapeutic drugs and in an earlier study we have demonstrated that it can be loaded into DC beads. Therefore, in the current study we have investigated how certain physical and chemical parameters affect its loading and release for future development of DC beads in cancer therapy. Aliquots of 40-60 µL of DC beads (100-300 µm) were treated to bromelain in distilled water and various parameters such as pH of solution, bromelain concentration, temperature, loading period, presence/absence of agitation and the cytotoxic effect of bromelain loaded beads were investigated. Further release kinetics was also studied with additional investigation of pH effect on the proteolytic activity of bromelain. Results indicate that higher loading of bromelin was achieved in the beads at lower pH, higher concentration of bromelain, with agitation, 24 hours loading and ambient room temperature. Proteolytic activity of bromelain was maximal at pH 4.5 whilst cytotoxicity was at par if not better in the bromelain loaded DC beads. Release kinetics indicated that bromelain can be delivered over several hours. Hence, we conclude that bromelain can be loaded more efficiently with manipulation of certain parameters with noticeable cytotoxicity in tumour cells.