Development of a porcine renal extracellular matrix scaffold as a platform for kidney regeneration.

Acellular scaffolds, possessing an intact three-dimensional extracellular matrix (ECM) architecture and biochemical components, are promising for regeneration of complex organs, such as the kidney. We have successfully developed a porcine renal acellular scaffold and analyzed its physical/biochemical characteristics, biocompatibility, and kidney reconstructive potential. Segmented porcine kidney cortexes were treated with either 1% (v/v) Triton X-100 (Triton) or sodium dodecyl sulfate (SDS). Scanning electron microscopy showed both treatments preserved native tissue architecture, including porosity and composition. Swelling behavior was higher in the Triton-treated compared with the SDS-treated scaffold. Maximum compressive strength was lower in the Triton-treated compared with the SDS-treated scaffold. Attenuated total reflective-infrared spectroscopy showed the presence of amide II (-NH) in both scaffolds. Furthermore, richer ECM protein and growth factor contents were observed in the Triton-treated compared with SDS-treated scaffold. Primary human kidney cell adherence, viability, and proliferation were enhanced on the Triton-treated scaffold compared with SDS-treated scaffold. Following murine in vivo implantation, tumorigenecity was absent for both scaffolds after 8 weeks and in the Triton-treated scaffold only, glomeruli-like structure formation and neovascularity were observed. We identified 1% Triton X-100 as a more suitable decellularizing agent for porcine renal ECM scaffolds prior to kidney regeneration.

Characterization of a novel composite scaffold consisting of acellular bladder submucosa matrix, polycaprolactone and Pluronic F127 as a substance for bladder reconstruction.

The bladder is an organ susceptible to a variety of congenital anomalies, injuries and disorders. To address the clinical limitations of existing scaffolds, we fabricated a novel scaffold that can be applied to morphological and functional bladder reconstruction. As a first step to prove the benefit of the scaffold, intensive in vitro and in vivo analyses were conducted. The novel composite scaffold was fabricated using polycaprolactone/Pluronic F127 (PCL/F127) and variable proportions (1, 3, 5 and 10wt.%) of porcine acellular bladder submucosa matrix (BSM). Physicochemical properties and biocompatibilities of the scaffolds were characterized. For cell-mediated analysis, upper-urinary-tract-derived urine stem cells were used. Observations of tensile strength, modulus, porosity, cell adhesion, viability and proliferation characteristics of scaffolds indicated that the optimum proportion of BSM in the composite scaffolds was 3 or 5 wt.%. Based on comparison of 3 and 5 wt.% BSM/PCL/F127 scaffolds with respect to degradability, hydrophilicity, surface properties and functional group presence, the 3 wt.% BSM was chosen for in vivo studies. 8 weeks after kidney-subcapsular implantation of the 3 wt.% BSM/PCL/F127 scaffold, cells remained attached to the surface and there was no evidence of teratomas. A BSM content of 3 wt.% was the optimum proportion for fabrication of the neo scaffold. We predict that the 3 wt.% BSM/PCL/F127 composite scaffold could act as an ideal matrix after cystectomy based on its favorable physicochemical properties and biocompatibilities.

Tracheal reconstruction with asymmetrically porous polycaprolactone/pluronic F127 membranes.

BACKGROUND: Congenital and acquired tracheal stenosis continues to be challenging problems. The purpose of this study was to evaluate the efficacy of an asymmetrically porous membrane (APM) to induce tracheal reconstruction by inhibition of granulation tissue growth into the tracheal lumen whereas minimizing graft failure. METHODS: The APM was fabricated with polycaprolactone (PCL) and pluronic F127 to have nano-size pores at top side, whereas the bottom side had micro-size pores. Fifteen rabbits underwent tracheal defect, which was then reconstructed with the APM. Rabbits were euthanized 1, 4, and 12 weeks postoperatively, and endoscopic, histologic, and radiologic evaluations were conducted. RESULTS: Endoscopy did not reveal granulation ingrowth into tracheal lumen. APM was well incorporated into the surrounding tissue on histologic evaluation. CT scans showed well maintained airways. CONCLUSION: Off-the-shelf use of APM for tracheal reconstruction seems to be a promising strategy in the treatment of tracheal defects.

Acceleration of peripheral nerve regeneration through asymmetrically porous nerve guide conduit applied with biological/physical stimulation.

Sufficient functional restoration of damaged peripheral nerves is a big clinical challenge. In this study, a nerve guide conduit (NGC) with selective permeability was prepared by rolling an asymmetrically porous polycaprolactone/Pluronic F127 membrane fabricated using a novel immersion precipitation method. Dual stimulation (nerve growth factor [NGF] as a biological stimulus and low-intensity pulse ultrasound [US] as a physical stimulus) was adapted to enhance nerve regeneration through an NGC. The animal study revealed that each stimulation (NGF or US) has a positive effect to promote the peripheral nerve regeneration through the NGC, however, the US-stimulated NGC group allowed more accelerated nerve regeneration compared with the NGF-stimulated group. The NGC group that received dual stimulation (NGF and US) showed more effective nerve regeneration behavior than the groups that received a single stimulation (NGF or US). The asymmetrically porous NGC with dual NGF and US stimulation may be a promising strategy for the clinical treatment of delayed and insufficient functional recovery of a peripheral nerve.

Effect of surface pore structure of nerve guide conduit on peripheral nerve regeneration.

Polycaprolactone (PCL)/Pluronic F127 nerve guide conduits (NGCs) with different surface pore structures (nano-porous inner surface vs. micro-porous inner surface) but similar physical and chemical properties were fabricated by rolling the opposite side of asymmetrically porous PCL/F127 membranes. The effect of the pore structure on peripheral nerve regeneration through the NGCs was investigated using a sciatic nerve defect model of rats. The nerve fibers and tissues were shown to have regenerated along the longitudinal direction through the NGC with a nano-porous inner surface (Nanopore NGC), while they grew toward the porous wall of the NGC with a micro-porous inner surface (Micropore NGC) and, thus, their growth was restricted when compared with the Nanopore NGC, as investigated by immunohistochemical evaluations (by fluorescence microscopy with anti-neurofilament staining and Hoechst staining for growth pattern of nerve fibers), histological evaluations (by light microscopy with Meyer's modified trichrome staining and Toluidine blue staining and transmission electron microscopy for the regeneration of axon and myelin sheath), and FluoroGold retrograde tracing (for reconnection between proximal and distal stumps). The effect of nerve growth factor (NGF) immobilized on the pore surfaces of the NGCs on nerve regeneration was not so significant when compared with NGCs not containing immobilized NGF. The NGC system with different surface pore structures but the same chemical/physical properties seems to be a good tool that is used for elucidating the surface pore effect of NGCs on nerve regeneration.