The role of proteoglycans in bladder structure and function

Development of a mucoadhesive nanoparticulate drug delivery system for a targeted drug release in the bladder

PURPOSE

Purpose of the present study was the development of a mucoadhesive nanoparticulate drug delivery system for local use in intravesical therapy of interstitial cystitis, since only a small fraction of drug actually reaches the affected site by conventional treatment of bladder diseases via systemic administration.

METHODS

Chitosan-thioglycolic acid (chitosan-TGA) nanoparticles (NP) and unmodified chitosan NP were formed via ionic gelation with tripolyphosphate (TPP). Trimethoprim (TMP) was incorporated during the preparation process of NP. Thereafter, the mucoadhesive properties of NP were determined in porcine urinary bladders and the release of TMP among simulated conditions with artificial urine was evaluated.

RESULTS

The particles size ranged from 183nm to 266nm with a positive zeta potential of +7 to +13mV. Under optimized conditions the encapsulation efficiency of TMP was 37%. The adhesion of prehydrated chitosan-TGA NP on the urinary bladder mucosa under continuous urine voiding was 14-fold higher in comparison to unmodified chitosan NP. Release studies indicated a more sustained TMP release from covalently cross linked particles in comparison to unmodified chitosan-TPP NP over a period of 3h in artificial urine at 37°C.

CONCLUSION

Utilizing the method described here, chitosan-TGA NP might be a useful tool for local intravesical drug delivery in the urinary bladder.

Urinary glycosaminoglycans as biomarker for urothelial injury: is it possible to discriminate damage from recovery?

OBJECTIVES

The glycosaminoglycan (GAG) layer is referred to as a bladder protective factor. We reproduced an experimental model of urothelial damage to assess GAG metabolism in the process of injury and recovery of the urothelium.

METHODS

Wistar female rats were bladder catheterized and instilled with either protamine sulfate (PS groups) or sterile saline (control groups). At different days after the procedure, 24-hour urine samples were obtained. The urinary levels of hyaluronic acid (HA) and sulfated glycosaminoglycan were determined in all groups and in nonmanipulated rats (day 0). Additionally, sulfated-GAG synthesis was assessed by the incorporation of [(35)S]-inorganic sulfate. The bladders were analyzed by histochemical staining for HA and immunofluorescence for heparin sulfate and syndecan-4.

RESULTS

Urinary HA and sulfated-GAG were elevated after PS injection (P <0.05). A greater concentration of [(35)S]-labeled GAG in the PS group animals on the fifth day and, especially, on the seventh day represented increased GAG synthesis at these periods (P <0.05). Bladder sections from the PS group animals on day 1 showed a greater amount of HA in the urothelium. PS instillation damaged the urothelium layer of heparin sulfate and syndecan-4 seen in the control animals. On day 5, patchy areas of a restored layer were seen, and, on day 7, this layer had completely regenerated.

CONCLUSIONS

Urinary GAG cannot differentiate urothelial damage from recovery. Elevated levels of urinary GAG can result from either desquamation of the surface cell GAG layer or increased GAG synthesis to regenerate the damaged urothelium.