A comparative study evaluating the in vivo incorporation of biological sling materials.

OBJECTIVES: To comparatively investigate biological tissues that are clinical products currently used for implantation in urological reconstruction. Specifically, we examined biological materials in vivo and evidence regarding the tissue response observed. Biological tissues are widely used in urological surgeries to treat conditions such as pelvic organ prolapse and stress urinary incontinence. METHODS: Histologic data from 4 biological sling materials, that is, small intestinal submucosa (SIS), cadaveric fascia lata, cadaveric dermis, and porcine dermis, implanted within mice (n = 64) were evaluated at 2, 4, 8, and 12 weeks. Recovered tissue was assessed by several biocompatibility parameters such as capsule formation (collagen deposition), cellular number, cell morphology, and angiogenesis. RESULTS: Data provide a scientific depiction of the cellular response to these biomaterials through a 12-week evaluation. SIS had a significantly higher level of angiogenesis and cell infiltrate as compared with all other material tested. Collectively, the data suggest that SIS has improved biocompatibility over other tested materials. CONCLUSIONS: This study compared SIS with other biological tissues in an animal model and was found to have superior biocompatibility as seen in humans. This may be helpful for clinicians while selecting a particular biological material. The study provides evidence of the varying stages of remodeling each implant, with hopes to better understand the material response in vivo.

Alginate-matrigel microencapsulated schwann cells for inducible secretion of glial cell line derived neurotrophic factor.

Controlled expression of glial cell line derived neurotrophic factor (Gdnf) can be integrated in the development of a system for repair of injured peripheral nerves. This delivery strategy was demonstrated via inducible Gdnf from microencapsulated cells in barium alginate. The Schwann cell line RT4-D6P2T was initially modified utilizing an ecdysone-based stable transfection system to produce RT4-Gdnf cells. During construct preparation, it was found that C6 cells (where Gdnf cDNA was isolated) make three Gdnf transcript variants. Additionally, the importance of 5' untranslated region to drive biologically-functional Gdnf synthesis was shown. Encapsulation of RT4-Gdnf in 1% alginate was then performed. It was determined that cells were able to survive at least 1 month in vitro using starting densities of 20, 200 and 2000 cells/capsule and barium ion concentrations of 10, 50, 100 and 200 mM. Most importantly, encapsulated cells secreted exogenous Gdnf upon ponasterone A induction. Mixture of basement membrane extract Matrigel to alginate promoted increased proliferation, cell spreading and Gdnf release. Finally, compression tests showed that cell-loaded microcapsules fractured at 75% diameter compression with 38 kPa of stress. Regulated Gdnf release from these microcapsules in vivo may potentially aid in the regeneration of damaged nerves.