The objective of this Phase I study is to develop elastic, biodegradable ureteral stents that will degrade in the body within 2 weeks after a procedure. Current ureteral stents are made of non-degradable polymers and, unless they are permanent, have to be removed by second procedure, which requires further intervention on the patients. Biodegradable ureteral stents will not require a second surgical removal procedure. There are many surgical procedures that require the emplacement of a ureteral stent. The ureter is a tube that allows urine to flow from the kidney to the bladder. Ureteral stent emplacement is utilized in surgical procedures for ailments, such as kidney infections, or kidney stones. Commonly, the stent is used to provide temporary support for the ureter and to allow urine flow until the ureter heals sufficiently to maintain its own integrity and flow or to bypass ureteral obstruction. This process takes approximately 2 weeks, after which non-degradable stents must be removed by a second procedure. The proposed stent will degrade in 2 weeks eliminating the need for a second procedure. The two main properties to be optimized in this study are elasticity and degradation.
Specific Aim 1 is to synthesize biodegradable polymers with good elasticity and degradation kinetics matching the applications of ureteral stents. These polymers will be formulated from macromonomers containing biodegradable portions and water-soluble portions in controlled amounts so as to maximize elasticity and have degradation occur with approximately 2 weeks.
Specific Aim 2 is to design ureteral stent configuration to ensure degradation into small pieces, e.g., less than 2 mm, for easy removal from the ureter. This stent will be manufactured layer-by-layer by either electrospraying or spraying through an ultrasonic nozzle polymer solution onto a rotating mandrel. The innermost layer will be a rapidly degrading formulation, the middle layer will be a mixture of biological polymers, such as chitosan or alginate formulated in microbeads, and the outermost layer will be a slow degrading formulation capable of providing mechanical support during degradation. Pigtail coils will be formed on each end to ensure the stent remains in place. Successful completion of this Phase I study will demonstrate the feasibility of novel, elastic, biodegradable stents capable of degrading after 2 weeks eliminating the need for a second removal procedure. These stents will remain until sufficient healing has occurred and they are no longer necessary. The stent will be designed to have the same size and properties as currently existing stents so that currently existing catheter guide wires and techniques may be used for their emplacement. Phase II development will focus on creating a marketable prototype and animal studies.
The objective of this research is to generate elastic, biodegradable polymer-based ureteral stents for use in ureteral surgery. These stents will overcome problems associated with current technology by eliminating the need for a second surgery to remove the stent. This technology will improve patient convenience, reduce complications associated with a second removal procedure, and eliminate the cost for the stent removal procedure.
