Bladder Regeneration Using a Polycaprolactone Scaffold with a Gradient Structure and Growth Factors in a Partially Cystectomized Rat Model

Background@#Tissue engineering can be used for bladder augmentation. However, conventional scaffolds result in fibrosis and graft shrinkage. This study applied an alternative polycaprolactone (PCL)-based scaffold (diameter = 5 mm) with a noble gradient structure and growth factors (GFs) (epidermal growth factor, vascular endothelial growth factor, and basic fibroblast growth factor) to enhance bladder tissue regeneration in a rat model. @*Methods@#Partially excised urinary bladders of 5-week-old male Slc:SD rats were reconstructed with the scaffold (scaffold group) or the scaffold combined with GFs (GF group) and compared with sham-operated (control group) and untreated rats (partial cystectomy group). Evaluations of bladder volume, histology, immunohistochemistry (IHC), and molecular markers were performed at 4, 8, and 12 weeks after operation. @*Results@#The bladder volumes of the scaffold and GF group recovered to the normal range, and those of the GF group showed more enhanced augmentation. Histological evaluations revealed that the GF group showed more organized urothelial lining, dense extracellular matrix, frequent angiogenesis, and enhanced smooth muscle bundle regeneration than the scaffold group. IHC for α-smooth muscle actin, pan-cytokeratin, α-bungarotoxin, and CD8 revealed that the GF group showed high formation of smooth muscle, blood vessel, urothelium, neuromuscular junction and low immunogenicity. Concordantly, real-time polymerase chain reaction experiments revealed that the GF group showed a higher expression of transcripts associated with smooth muscle and urothelial differentiation. In a 6-month in vivo safety analysis, the GF group showed normal histology. @*Conclusion@#This study showed that a PCL scaffold with a gradient structure incorporating GFs improved bladder regeneration functionally and histologically.

Hyaluronic Acid/Alginate Hydrogel Containing Hepatocyte Growth Factor and Promotion of Vocal Fold Wound Healing

BACKGROUND@#Hepatocyte growth factor (HGF) has been shown to facilitate vocal fold (VF) wound healing. This study was undertaken to determine whether the therapeutic efficacy of HGF could be enhanced by applying it in hyaluronic acid and alginate (HA/ALG) composite hydrogels into VFs after injury in a rabbit model. @*METHODS@#HGF was loaded into HA/ALG composite hydrogel (HGF–HA/ALG) and its in vitro release profile was evaluated. In addition, HGF–HA/ALG was injected into the VFs of rabbits immediately after direct injury and HGF or PBS was injected in the same manner into control groups. Macroscopic features were observed by endoscopy at 3 months postinjury. Functional analyses including mucosal waves of VFs and viscoelastic properties were performed by kymography following high-speed digital imaging and rheometer. Histopathological and immunohistochemical evaluations were also conducted on VFs. @*RESULTS@#HGF release from HGF–HA/ALG was sustained for up to 3 weeks. Rabbits treated with HGF–HA/ALG showed improved mucosal vibrations and VF viscoelastic properties as compared with the PBS and HGF controls.Histopathological staining revealed HGF–HA/ALG treated VFs showed less fibrosis than PBS and HGF controls, and immunohistochemical analysis demonstrated amounts of type I collagen and fibronectin were lower in HGF–HA/ALG treated animals than in PBS and HGF controls at 3 months post-injury. @*CONCLUSION@#HGF containing HA/ALG hydrogel enhanced healing in our rabbit model of VF injury.

Hyaluronic Acid/Alginate Hydrogel Containing Hepatocyte Growth Factor and Promotion of Vocal Fold Wound Healing

BACKGROUND@#Hepatocyte growth factor (HGF) has been shown to facilitate vocal fold (VF) wound healing. This study was undertaken to determine whether the therapeutic efficacy of HGF could be enhanced by applying it in hyaluronic acid and alginate (HA/ALG) composite hydrogels into VFs after injury in a rabbit model. @*METHODS@#HGF was loaded into HA/ALG composite hydrogel (HGF–HA/ALG) and its in vitro release profile was evaluated. In addition, HGF–HA/ALG was injected into the VFs of rabbits immediately after direct injury and HGF or PBS was injected in the same manner into control groups. Macroscopic features were observed by endoscopy at 3 months postinjury. Functional analyses including mucosal waves of VFs and viscoelastic properties were performed by kymography following high-speed digital imaging and rheometer. Histopathological and immunohistochemical evaluations were also conducted on VFs. @*RESULTS@#HGF release from HGF–HA/ALG was sustained for up to 3 weeks. Rabbits treated with HGF–HA/ALG showed improved mucosal vibrations and VF viscoelastic properties as compared with the PBS and HGF controls.Histopathological staining revealed HGF–HA/ALG treated VFs showed less fibrosis than PBS and HGF controls, and immunohistochemical analysis demonstrated amounts of type I collagen and fibronectin were lower in HGF–HA/ALG treated animals than in PBS and HGF controls at 3 months post-injury. @*CONCLUSION@#HGF containing HA/ALG hydrogel enhanced healing in our rabbit model of VF injury.

In Situ Gelling Hydrogel with Anti-Bacterial Activity and Bone Healing Property for Treatment of Osteomyelitis

BACKGROUND: Despite the development of progressive surgical techniques and antibiotics, osteomyelitis is a big challenge for orthopedic surgeons. The main aim of this study is to fabricate an in situ gelling hydrogel that permits sustained release of antibiotic (for control of infection) and growth factor (for induction of new bone formation) for effective treatment of osteomyelitis. METHODS: An in situ gelling alginate (ALG)/hyaluronic acid (HA) hydrogel containing vancomycin (antibiotic) and bone morphogenetic protein-2 (BMP-2; growth factor) was prepared by simple mixing of ALG/HA/Na₂HPO₄ solution and CaSO₄/vancomycin/BMP-2 solution. The release behaviors of vancomycin and BMP-2, anti-bacterial effect (in vitro); and therapeutic efficiency for osteomyelitis and bone regeneration (in vivo, osteomyelitis rat model) of the vancomycin and BMP-2-incorporated ALG/HA hydrogel were investigated. RESULTS: The gelation time of the ALG/HA hydrogel was controlled into approximately 4 min, which is sufficient time for handling and injection into osteomyelitis lesion. Both vancomycin and BMP-2 were continuously released from the hydrogel for 6 weeks. From the in vitro studies, the ALG/HA hydrogel showed an effective anti-bacterial activity without significant cytotoxicity for 6 weeks. From an in vivo animal study using Sprague-Dawley rats with osteomyelitis in femur as a model animal, it was demonstrated that the ALG/HA hydrogel was effective for suppressing bacteria (Staphylococcus aureus) proliferation at the osteomyelitis lesion and enhancing bone regeneration without additional bone grafts. CONCLUSIONS: From the results, we suggest that the in situ gelling ALG/HA hydrogel containing vancomycin and BMP-2 can be a feasible therapeutic tool to treat osteomyelitis.

Thermoresponsive and Biodegradable Amphiphilic Block Copolymers with Pendant Functional Groups

BACKGROUND: To develop the biodegradability and thermoresponsive hydrogel, in this work we designed a pendant-functionalized, thermoresponsive, amphiphilic block copolymer. METHODS: Methoxy poly(ethylene glycol) (MPEG)-b-[poly(ε-caprolactone)-ran-poly(ε-caprolactone-3-one)-ran-polylactic acid] (MCL) and (MPEG-b-[PCL-ran-POD-ran-PLA]) [MCL-(CO)] block copolymers were prepared by ringopening polymerization of ε-caprolactone, OD and lactide monomers. The subsequent derivatization of MCL-(CO) provided MPEG-b-[PCL-ran-poly(ε-caprolactone-3-COOH)-ran-PLA] [MCL-(COOH)] with COOH pendant groups and MPEG-b-[PCL-ran-poly(ε-caprolactone-3-NH2)-ran-PLA] [MCL-(NH2)] with NH2 pendant groups. RESULTS: The measured segment ratios of MCL-(CO), MCL-(COOH), and MCL-(NH2) agreed well with the target ratios. The abundances of the COOH and NH2 groups in the MCL-(COOH) and MCL-(NH2) copolymers were determined by 1H- and 13C-nuclear magnetic resonance spectroscopy, and agreed well with the target abundances. MCL-(CO), MCL-(COOH), and MCL-(NH2) formed homogeneous, white, opaque emulsions at room temperature. Rheological analysis of the block copolymer suspensions indicated a solution-to-hydrogel phase transition as a function of temperature. The solution-to-hydrogel phase transitions and the biodegradation of MCL-(CO), MCL-(COOH), and MCL-(NH2) were affected by varying the type (ketone, COOH, or NH2) and abundance of the pendant groups. CONCLUSION: MCL-(CO), MCL-(COOH), and MCL-(NH2) with ketone, COOH, and NH2 pendant groups showed solution-to-hydrogel phase transitions and biodegradation behaviors that depended on both the type and number of pendant groups.

Platelet-Derived Growth Factor-BB-Immobilized Asymmetrically Porous Membrane for Enhanced Rotator Cuff Tendon Healing

Rotator cuff tear is a common musculoskeletal disease that often requires surgical repair. Despite of recent advances in surgical techniques, the re-tear rate of the rotator cuff tendon is very high. In this study, a platelet-derived growth factor-BB (PDGF-BB)-immobilized asymmetrically porous membrane was fabricated to investigate the feasibility for enhancing rotator cuff tendon regeneration through the membrane. PDGF-BB is recognized to promote tendon regeneration. The asymmetrically porous membrane was fabricated by polycaprolactone and Pluronic F127 using an immersion precipitation technique, which can allow selective permeability (preventing scar tissue invasion into defect region but allowing permeation of oxygen/nutrients) and incorporation of bioactive molecules (e.g., PDGF-BB) via heparin binding. The PDGF-BB immobilized on the membrane was released in a sustained manner over 42 days. In an animal study using Sprague-Dawley rats, the PDGF-BB-immobilized membrane group showed significantly greater regeneration of rotator cuff tendon in histological and biomechanical analyses compared with the groups of control (suturing) and membrane without PDGF-BB immobilization. The enhancing regeneration of rotator cuff tendon of the PDGF-BB-immobilized membrane may be caused from the synergistic effect of the asymmetrically porous membrane with unique properties (selective permeability and hydrophilicity) as a scaffold for guided tendon regeneration and PDGF-BB sustainedly released from the membrane.

Human Urine-derived Stem Cells Seeded Surface Modified Composite Scaffold Grafts for Bladder Reconstruction in a Rat Model

We conducted this study to investigate the synergistic effect of human urine-derived stem cells (USCs) and surface modified composite scaffold for bladder reconstruction in a rat model. The composite scaffold (Polycaprolactone/Pluronic F127/3 wt% bladder submucosa matrix) was fabricated using an immersion precipitation method, and heparin was immobilized on the surface via covalent conjugation. Basic fibroblast growth factor (bFGF) was loaded onto the heparin-immobilized scaffold by a simple dipping method. In maximal bladder capacity and compliance analysis at 8 weeks post operation, the USCs-scaffold(heparin-bFGF) group showed significant functional improvement (2.34 ± 0.25 mL and 55.09 ± 11.81 microL/cm H2O) compared to the other groups (2.60 ± 0.23 mL and 56.14 ± 9.00 microL/cm H2O for the control group, 1.46 ± 0.18 mL and 34.27 ± 4.42 microL/cm H2O for the partial cystectomy group, 1.76 ± 0.22 mL and 35.62 ± 6.69 microL/cm H2O for the scaffold group, and 1.92 ± 0.29 mL and 40.74 ± 7.88 microL/cm H2O for the scaffold(heparin-bFGF) group, respectively). In histological and immunohistochemical analysis, the USC-scaffold(heparin-bFGF) group showed pronounced, well-differentiated, and organized smooth muscle bundle formation, a multi-layered and pan-cytokeratin-positive urothelium, and high condensation of submucosal area. The USCs seeded scaffold(heparin-bFGF) exhibits significantly increased bladder capacity, compliance, regeneration of smooth muscle tissue, multi-layered urothelium, and condensed submucosa layers at the in vivo study.

Injection of porous polycaprolactone beads containing autologous myoblasts in a dog model of fecal incontinence / 대한외과학회지

PURPOSE: Few studies have examined whether bioengineering can improve fecal incontinence. This study designed to determine whether injection of porous polycaprolactone beads containing autologous myoblasts improves sphincter function in a dog model of fecal incontinence. METHODS: The anal sphincter of dogs was injured and the dogs were observed without and with (n = 5) the injection of porous polycaprolactone beads containing autologous myoblasts into the site of injury. Autologous myoblasts purified from the gastrocnemius muscles were transferred to the beads. Compound muscle action potentials (CMAP) of the pudendal nerve, anal sphincter pressure, and histopathology were determined 3 months after treatment. RESULTS: The amplitudes of the CMAP in the injured sphincter were significantly lower than those measured before injury (1.22 mV vs. 3.00 mV, P = 0.04). The amplitudes were not different between dogs with and without the injection of autologous myoblast beads (P = 0.49). Resting and squeezing pressures were higher in dogs treated with autologous myoblast beads (2.00 mmHg vs. 1.80 mmHg; 6.13 mmHg vs. 4.02 mmHg), although these differences were not significant in analyses of covariance adjusted for baseline values. The injection site was stained for smooth muscle actin, but showed evidence of foreign body inflammatory reactions. CONCLUSION: This was the first study to examine whether bioengineering could improve fecal incontinence. Although the results did not show definite evidence that injection of autologous myoblast beads improves sphincter function, we found that the dog model was suitable and reliable for studying the effects of a potential treatment modality for fecal incontinence.

In vivo Osteogenesis of Cultured Human Periosteal-derived Cells and Polydioxanone/Pluronic F127 Scaffold

Osteogenic Activity of Cultured Human Periosteal-Derived Cells in a Three Dimensional Polydioxanone/pluronic F127 Scaffold