Study On Biodegradation Of PCLA Ureteral Stent In Vitro And In Vivo

Objective: To synthesize poly(DL-lactide- ε -caprolactone) (PCLA) stent with lactic acid and ε -caprolactone; To observe the degradation of the stent in vitro and in vivo ; To observe the ureteral histological change caused by the stent in vivo.Methods: 1. The synthesis and mould of PCLA stent: (1) Synthesis of PCLA: ring opening polymerization; (2) Mould of stent: molded artificially with syring. 2. Degradation test in vitro: (1) The stents were immersed in phosphate buffer solution (PBS); (2) The stent appearance change was observed weekly; (3) The structural degradation was checked weekly under electronic microscope; (4) The mass loss and the degradation of molecular weight (Mw) was measured by analytical balance and gel permeation chromatography (GPC) respectively each week. 3. Degradation test in vivo: (1) PCLA stents were placed in the left ureter of 19 goats, and polyurethane stents were placed in the right side; (2) The animals were sacrificed at the 2^nd, the 4^th, the 6^th and the 8^th week; (3) Observed whether there was obstruction of ureter and hydronephrosis; (4) The PCLA stents were checked for Mw degradation by GPC; (5) Specimens were obtained from the segments of ureteral proximal, middle and distal parts respectively. The specimens were fixed in 10% buffered formalin, sectioned and stained with hematoxylin...