Submucosal injection of poly(lactic-co-glycolic acid) microspheres in rabbit bladder as a potential treatment for urinary incontinence and vesicoureteral reflux: preliminary results

Combination of calcium hydroxyapatite and autologous blood for endoscopic treatment of vesicoureteral reflux in children

OBJECTIVE

To report the results of endoscopic correction of vesicoureteral reflux (VUR) with concomitant injection of pure calcium hydroxyapatite (CaHA) and autologous blood.

PATIENTS AND METHODS

Records of patients who underwent endoscopic correction of VUR using concomitant injection of CaHA and autologous blood from 2008 through 2010 were retrospectively reviewed. Data regarding patients' demographics, preoperative VUR grades, febrile urinary tract infections, complications of procedure, postoperative VUR grades and cure rates were collected. Voiding cystourethrography was performed 3 months postoperatively.

RESULTS

Total number of 23 children (9 girls and 14 boys) with 40 refluxing ureters were included. The mean age of children was 1.9 ± 0.97 (SD) years. Reflux grades were II to IV in 14, 11 and 15 renal refluxing units (RRUs), respectively. The mean follow-up period was 44 months. VUR was successfully treated in 87.5% of RRUs after three injections. Significant statistical difference was found between VUR grades before and after the first, second and third injections (p < 0.001, p = 0.001 and p = 0.011, respectively). Moreover, there was a significant difference between primary reflux grade and treatment success (p = 0.031). Febrile UTI was resolved in 85% of patients (17 of 20 patients with febrile UTI) after endoscopic treatment which shows significant improvement (p < 0.001). The procedure was uneventful in all patients, and no obstruction was reported during the follow-up period.

CONCLUSION

Concomitant injection of pure CaHA without any additives (hyaluronic acid, etc.) and autologous blood can be an effective, repeatable and cost-benefit approach for the management of children suffering VUR with a success rate of 87.5% after three injections.

Open macroporous poly(lactic-co-glycolic Acid) microspheres as an injectable scaffold for cartilage tissue engineering

Non-porous poly(lactic-co-glycolic acid) (PLGA) microspheres have been previously proposed as an injectable scaffold for in vivo cartilage tissue engineering. In this study, we tested whether using open macroporous PLGA microspheres as an injectable scaffold for in vivo cartilage tissue engineering provides a larger surface area for cell adhesion and a larger void space for cartilage tissue regeneration and, thus, regeneration of higher quality cartilage than non-porous PLGA microspheres. Rabbit chondrocytes were mixed with non-porous or macroporous PLGA microspheres and injected immediately through 18-gauge needles into subcutaneous sites in athymic mice. Six weeks after implantation, chondrocytes implanted using both types of PLGA microspheres formed solid, white cartilaginous tissues. Histological analysis of the implants with hematoxylin and eosin, safranin O and Masson's trichrome staining confirmed cartilaginous tissue formation. The portion of cartilage tissue area in the implant cross-sectional area was significantly higher in the macroporous PLGA microsphere group than in the non-porous PLGA microsphere group (88.9% versus 34.6%, P < 0.001). Importantly, the collagen (P < 0.01) and glycosaminoglycan (P < 0.01) contents of the implants were significantly higher in the macroporous PLGA microsphere group than in the non-porous PLGA microsphere group. We conclude that an open macroporous PLGA microsphere scaffold may be useful in cartilage regeneration through minimally-invasive surgical procedures in orthopedic applications.

The effect of microsphere degradation rate on the efficacy of polymeric microspheres as bulking agents: An 18-month follow-up study

The injection of bulking substances has been proposed as a new therapy to treat urinary incontinence and vesicoureteral reflux. Our previous study demonstrated that poly(lactic-co-glycolic acid) (PLGA) microspheres have the potential to serve as a bulking agent for urological injection therapies. Hybrid tissues exhibiting a bulking effect were formed in vivo by PLGA microsphere injection, but long-term volume stability was not proven. In this study, we hypothesized that the biodegradation rate of the bulking substance (polymer microspheres) would affect the duration of volume conservation of the induced hybrid tissue. To test this hypothesis, rapidly degrading 75:25 PLGA microspheres and slowly degrading poly(L-lactic acid) (PLLA) microspheres were used as injectable bulking agents for the injection therapy. In vitro degradation tests showed that the mass losses of PLLA and PLGA were 16 and 96% of the initial masses, respectively, at 30 weeks. PLLA and PLGA microspheres were injected into the subcutaneous dorsum of mice. Both types of microspheres were easily injectable through 24-gauge needles. Histological examinations at various time points indicated that host cells from the surrounding tissues migrated to the spaces between both types of injected microspheres and formed new hybrid tissue structures. Lymphocyte migration was noted around the implanted PLGA and PLLA microspheres, but the inflammatory reaction diminished with time. Importantly, the volume of the PLLA hybrid tissues slowly decreased to 52% of the initial volume at 12 months and maintained that volume until 18 months, whereas the volume of the PLGA hybrid tissues rapidly decreased to 22% at 6 months, and the PLGA hybrid tissues disappeared at 11 months. These results show that the biodegradation rate of the bulking substance may be useful for controlling the duration of volume conservation of the induced hybrid tissue.