Tissue Permeability Effects Associated with the Use of Mucoadhesive Cationic Nanoformulations of Docetaxel in the Bladder

Mucoadhesive Thiolated Hyaluronic Acid/Pluronic F127 Nanogel Formation via Thiol-Maleimide Click Reaction for Intravesical Drug Delivery

The development of nanocarriers to prolong the residence time and enhance the permeability of chemotherapeutic drugs on bladder mucosa is important in the postsurgery treatment of superficial bladder cancers (BCs). Here, the mucoadhesive HA-SH/PF127 nanogels composed of a temperature-sensitive Pluronic F127 (PF127) core and thiolated hyaluronic acid (HA-SH) shell were prepared by the emulsification/solvent evaporation method. The nanogels were constructed through the thiol-maleimide click reaction in the HA-SH aqueous side of the oil-water interface and self-oxidized cross-linking thiols between HA-SH. The HA-SH/PF127 nanogels prepared at different thiol-to-maleimide group molar ratios, water-to-oil volume ratios, and cross-linking reaction times were characterized regarding hydrodynamic diameter (Dh) and zeta potential (ζ), and the optimal formulation was obtained. The excellent mucoadhesive properties of the HA-SH/PF127 nanogels were evaluated by using the mucin particle method. Doxorubicin (DOX) was encapsulated in the PF127 core of DOX@HA-SH/PF127 nanogels with a high loading efficiency (87.5%) and sustained release from the nanogels in artificial urine. Ex vivo studies on porcine bladder mucosa showed that the DOX@HA-SH/PF127 nanogels enhanced the penetration of the DOX into the bladder mucosa without disrupting the mucus structure or the bladder tissue. A significant dose-dependent cytotoxic effect of DOX@HA-SH/PF127 nanogels on both T24 and MB49 cells was observed. The present study demonstrates that the mucoadhesive HA-SH/PF127 nanogels are a promising intravesical drug delivery system for superficial BC therapy.

Part 1. Evaluation of Epigallocatechin Gallate or Tannic Acid Formulations of Hydrophobic Drugs for Enhanced Dermal and Bladder Uptake or for Local Anesthesia Effects

Epigallocatechin gallate (EGCG) and tannic acid (TA) are known to increase the aqueous solubility and cellular uptake of the hydrophobic drugs docetaxel, paclitaxel, amphotericin B, and curcumin. In this study the practical application of gallate-based solubilization phenomena for the uptake of these drugs into dermal and bladder tissue and of lidocaine for wound healing application was studied. The penetration of all these drugs into pig skin or docetaxel into pig bladder using EGCG or TA formulations was measured. Overall, EGCG and TA particulate or propylene glycol paste formulations of drugs allowed for greatly increased levels of drug uptake into skin as compared to control formulations. EGCG/propylene glycol pastes allowed for rapid lidocaine uptake into skin. EGCG and TA formulations of docetaxel allowed for approximately 10 fold increases in bladder tissue uptake of docetaxel over tween based solutions. Morphologically, both EGCG and TA caused a mild, dose dependent exfoliation of the bladder wall. Both EGCG and TA formed injectable viscous pastes with propylene glycol which solidified in water and degraded and released lidocaine over 2-35 days. These data support the use of EGCG and TA based formulations of certain drugs for improved dermal, bladder and wound applications.

Enhanced taxane uptake into bladder tissues following co-administration with either mitomycin C, doxorubicin or gemcitabine: association to exfoliation processes

OBJECTIVE

To investigate the effect of three anticancer drugs (mitomycin c (MMC), doxorubicin or gemcitabine) on bladder wall morphology and the uptake of paclitaxel or docetaxel following coadministration. The primary objective of this study was to measure the uptake of MMC, doxorubicin or gemcitabine with or without exposure of the tissue to amine terminated cationic nanoparticles (CNPs) and to investigate any possible exfoliation effects of the three drugs on intact bladder tissue. The secondary objective was to investigate the uptake of taxane drugs (docetaxel, DTX) and paclitaxel, (PTX) from surfactant micelle formulations in the presence of MMC, doxorubicin or gemcitabine.

MATERIALS AND METHODS

Sections of fresh pig bladder tissue were incubated in Franz diffusion cells with the urothelial side exposed to solutions of doxorubicin, MMC and gemcitabine containing radioactive drug for 90 min. Some tissue samples were simultaneously exposed to each of the three drugs in combination with the surfactant micelle formulations of PTX (Taxol) or DTX (Taxotere). Tissue sections were then cryostat sectioned for drug quantitation by liquid scintillation counting or fixed for scanning electron microscopy and haematoxylin and eosin staining.

RESULTS

All three drugs caused exfoliation of the urothelial layer of bladder tissues. Drug uptake studies showed that all three drugs effectively penetrated the lamina propria through to the muscular layer over a 2-h incubation and these levels were unaffected by pre-treatment with CNPs. The uptake levels of the taxane drugs PTX and DTX were significantly enhanced following simultaneous treatment of bladders with MMC, doxorubicin or gemcitabine.

CONCLUSION

The exfoliation effects of MMC, doxorubicin and gemcitabine allow for good tissue penetration of these drugs with no additional effect from CNP treatment of bladders. The observed exfoliation effect of these amine-containing drugs probably arises from a cationic interaction with the mucus and urothelium cell layer in a manner similar to that previously reported for CNPs. These studies suggest that the lack of long-term clinical efficacy of these drugs may not arise from poor intravesical drug penetration but may result from a rapid diffusion of the drugs into the deeper vascularised muscular region with rapid drug clearance. The enhanced uptake of PTX or DTX following co-administration with MMC, doxorubicin or gemcitabine probably arises from the removal of the urothelial barrier by exfoliation allowing for improved taxane partitioning into superficial layers. These effects may allow for dual drug intravesical strategies offering greatly improved taxane uptake and potential additive drug effects for improved efficacy.

Mucoadhesive Cationic Polypeptide Nanogel with Enhanced Penetration for Efficient Intravesical Chemotherapy of Bladder Cancer

Initially, chemotherapy is effective for treatment of bladder cancer after transurethral resection of the bladder. However, certain patients progressively become unresponsive after multiple treatment cycles, which results from the rapid and almost complete excretion of clinically used formulations of antineoplastic agents with urinary voiding. Improving the mucoadhesiveness and penetrability of chemotherapeutic drugs are key factors in treatment of advanced bladder cancer. Here, a smart disulfide-crosslinked polypeptide nanogel of poly(l-lysine)-poly(l-phenylalanine-co-l-cystine) (PLL-P(LP-co-LC)) is developed to deliver 10-hydroxycamptothecin (HCPT) for treatment of orthotopic bladder cancer. The positively charged PLL-P(LP-co-LC) can significantly prolong the retention period and enhance the tissue permeability of HCPT within the bladder wall of rat. Moreover, the reduction-responsive polypeptide nanogel (i.e., NG/HCPT) possesses the capability to accurately and rapidly deliver HCPT in bladder cancer cells. NG/HCPT can significantly inhibit proliferation of human bladder cancer 5637 cells in vitro and enhance antitumor activity toward an orthotopic rat bladder cancer model in vivo. This work demonstrates that the smart polypeptide nanogel may function as a promising drug-delivery system for local chemotherapy of bladder cancer with unprecedented clinical benefits.