<p>Intravesical delivery of rapamycin via folate-modified liposomes dispersed in thermo-reversible hydrogel</p>

Abstract

Purpose To develop an intravesical instillation system for the treatment of bladder cancer, rapamycin (Rap) was encapsulated into liposomes and then homogeneously dispersed throughout a poloxamer 407 (P407)-based hydrogel. Methods Rap-loaded conventional liposomes (R-CL) and folate-modified liposomes (R-FL) were prepared using a film hydration method and pre-loading technique, and characterized by particle size, drug entrapment efficiency, and drug loading. The cellular uptake behavior in folate receptor-expressing bladder cancer cells was observed by flow cytometry and confocal laser scanning microscopy using a fluorescent probe. In vitro cytotoxic effects were evaluated using MTT assay, colony forming assay, and Western blot. For in vivo intravesical instillation, Rap-loaded liposomes were dispersed in P407-gel, generating R-CL/P407 and R-FL/P407. Gel-forming capacities and drug release were evaluated. Using the MBT2/Luc orthotopic bladder cancer mouse model, in vivo antitumor efficacy was evaluated according to regions of interest (ROI) measurement. Results R-CL and R-FL were successfully prepared, at approximately <160 nm, 42% entrapment efficiency, and 57 μg/mg drug loading. FL cellular uptake was enhanced over 2-fold than that of CL; folate receptor-mediated endocytosis was confirmed using a competitive assay with folic acid pretreatment. In vitro cytotoxic effects increased dose-dependently. Rap-loaded liposomes inhibited mTOR signaling and induced autophagy in urothelial carcinoma cells. With gelation time of <30 seconds and gel duration of >12 hrs, both R-CL/P407 and R-FL/P407 preparations transformed into gel immediately after instillation into the mouse bladder. Drug release from the liposomal gel was erosion controlled. In orthotopic bladder cancer mouse model, statistically significant differences in ROI values were found between R-CL/P407 and R-FL/P407 groups at day 11 ( P =0.0273) and day 14 ( P =0.0088), indicating the highest tumor growth inhibition by R-FL/P407. Conclusion Intravesical instillation of R-FL/P407 might represent a good candidate for bladder cancer treatment, owing to its enhanced retention and FR-targeting.

Enhanced Intracellular Delivery of BCG Cell Wall Skeleton into Bladder Cancer Cells Using Liposomes Functionalized with Folic Acid and Pep-1 Peptide

“…The colloidal stability of the liposomes in the PBS solution was maintained for 3 weeks; thereafter, no signs of aggregation were revealed. Based on ZP, CWS-FL had a higher negative charge than CWS-L, which might be attributed to the presence of negatively charged functional groups derived from the DP 5K F anchored on the liposome surface [19]. For CWS-PL, the ZP shifted toward a positive charge, which was clearly derived from the positively-charged Pep1.…”

“…The intracellular delivery of different liposomes was evaluated using the 5637 and MBT2 cell lines, which were well-known FR-expressing cancer cells that have been widely used to evaluate FR targeting [19]. As shown in the flow cytometry histogram (Figure 2A), in both cells, the fluorescence peak shifted to the right owing to liposomal treatment compared to no treatment (Isotype).…”

The Exploitation of Liposomes in the Inhibition of Autophagy to Defeat Drug Resistance

“…FL cell uptake was 2-fold higher than that of CL, and folate receptor-mediated endocytosis was proved by a competitive assay with folic acid pretreatment. In orthotopic bladder cancer mouse model, R-FL/P407-treated groups showed enhanced in vivo anti-tumor efficacy (Yoon et al, 2019).…”

Recent Advancements of Nanomedicine towards Antiangiogenic Therapy in Cancer

“…Many studies confirmed that these analogs inhibit the expression of VEGF in tumor cells. Recently, several studies elicited that rapamycin and its analogs, loaded as single and in combination with other drugs onto lipid-based NPs, could be used for effective antiangiogenic therapy [92][93][94][95]. There is a piece of evidence that somatostatin receptors (SSTRs), mainly subtype 2 (SSTR2), are significantly expressed in both glioma and glioma vasculature endothelial cells.…”