Association between gastroesophageal reflux disease and vocal fold polyps.

ABSTRACT: The aim of this study is to explore the relationship between gastroesophageal reflux disease (GERD) and vocal fold polyps (VFPs).This is a Case-Control study and was performed with the help of The Second Affiliated Hospital of Chongqing Medical University.Twenty-seven patients with VFP and 20 controls without VFP were recruited between May and October 2018. All the subjects underwent a saliva pepsin test, completed the GerdQ questionnaire and 24-hour multichannel intraluminal impedance with pH (24-h MII-pH) monitoring. Twenty-five resected VFP specimens were examined with immunohistochemical (IHC) and double immunofluorescence (IF) staining.The incidence of GERD in the VFP group was significantly higher than that in the control group (P = .003). Patients with VFP had significantly higher GerdQ scores, pepsin concentrations, and pepsin-positive rates (P < .05). Moreover, the number of proximal and upright reflux events was significantly higher in the VFP group (P < .05). The pepsin concentration in saliva showed a significant positive correlation with the pepsin levels in tissues (r2 = 0.50, P = .011). Pepsin and TGF-ß1-positive cells were colocalized with CD45RO-positive cells. IHC staining showed that the majority of VFP patients had a positive expression of pepsin (20/25, 80%) and pepsin-positive cells were found in both the squamous epithelium and mesenchymal tissues. IHC staining of TGF-ß1 in VFP revealed findings similar to those of pepsin staining.GERD is an important risk factor for VFP. Pepsin may promote the aggregation of immune cells, increase the local cytokines, and promote inflammatory reaction, suggesting a potential new pathogenesis for VFP. The saliva pepsin test is a reliable method for GERD diagnosis.

Electrogenerated alkaline hydrogen peroxide for rice straw pretreatment to enhance enzymatic hydrolysis.

In this work, alkaline hydrogen peroxide (AHP) solution with 1 wt% H2O2 was electrogenerated by oxygen reduction with a current efficiency of 75.2% in a home-made gas diffusion electrode-based electrochemical cell and used for rice straw pretreatment (0.1 g H2O2/g rice straw, 10% (w/v) biomass loading, 55 °C, 2 h). Results showed that the AHP pretreatment removed 97.56% of the initial lignin, 85.75% of the initial hemicellulose, and only 0.56% of the initial cellulose, and the specific surface area and porosity of the AHP pretreated rice straw (AHP-RS) were greatly increased. Saccharification results showed that after 48 h of enzymatic hydrolysis AHP-RS achieved a 3.2-fold increase in reducing sugar concentration compared to the untreated rice straw (5.81 and 1.81 g L-1), highlighting the potential use of this AHP solution for lignocellulose pretreatment.

Enhanced osteogenesis and angiogenesis by PCL/chitosan/Sr-doped calcium phosphate electrospun nanocomposite membrane for guided bone regeneration.

Membranes play pivotal role in guided bone regeneration (GBR) technique for reconstruction alveolar bone. GBR membrane that is able to stimulate both osteogenic and angiogenic differentiation of cells may be more effective in clinic practice. Herein, we fabricated the Sr-doped calcium phosphate/polycaprolactone/chitosan (Sr-CaP/PCL/CS) nanohybrid fibrous membrane by incorporating 20 wt% bioactive Sr-CaP nanoparticles into PCL/CS matrix via one-step electrospinning method, in order to endow the membrane with stimulation of osteogenesis and angiogenesis. The physicochemical properties, mechanical properties, Sr2+ release behavior, and the membrane stimulate bone mesenchymal stem cell (BMSCs) differentiation were evaluated in comparison with PCL/CS and CaP/PCL/CS membranes. The SEM images revealed that the nanocomposite membrane mimicked the extracellular matrix structure. The release curve presented a 28-day long continuous release of Sr2+ and concentration which was certified in an optimal range for positive biological effects at each timepoint. The in vitro cell culture experiments certified that the Sr-CaP/PCL/CS membrane enjoyed excellent biocompatibility and remarkably promoted rat bone mesenchymal stem cell (BMSCs) adhesion and proliferation. In terms of osteogenic differentiation, BMSCs seeded on the Sr-CaP/PCL/CS membrane showed a higher ALP activity level and a better matrix mineralization. What's more, the synergism of the Sr2+ and CaP from the Sr-CaP/PCL/CS membrane enhanced BMSCs angiogenic differentiation, herein resulting in the largest VEGF secretion amount. Consequently, the Sr-CaP/PCL/CS nanohybrid electrospun membrane has promising applications in GBR.

[In vitro tendon engineering using human dermal fibroblasts].

OBJECTIVE: To examine the feasibility of using human dermal fibroblasts (DFbs) and polyglycolic acids (PGA) to engineer tendon in vitro. METHODS: Human dermal fibroblasts (DFbs) were isolated from the foreskin tissues of children obtained during operation with collagenase and cultured in vitro. Human tendon was obtained from a patient undergoing amputation during operation to isolate tenocytes. The DFbs of second passage were seeded on PGA fibers to form cell-scaffold constructs in shape of tendons. Those constructs were divided into 4 groups: experimental group (n = 15) with the DFbs inoculated on PGA scaffold under constant tension generated by a U-shaped spring, control group 1 (n = 15) with the DFbs inoculated on PGA scaffold without tension, control group 2 (n = 3), i. e., cell-free pure PGA scaffolds under tension, and control group 3 (n = 5), i. e., tenocyte-scaffold constructs under tension that was harvested only at the ninth week. Samples were harvested 2, 5, 9, 14, and 18 weeks later to undergo histological examination and biomechanical test. RESULTS: Two weeks later histological examination showed that the constructs were mainly composed of PGA fibers in both the experimental group and the group without tension. Transmission electron microscopy showed fine cell attachment and stretching on the scaffold. By the 5th week, a neo-tendon was formed in all groups except for the cell-free group, and histology revealed the formation of collagen fibers. At the 9th week, the PGA fibers of the cell-free group were broken and partially degraded, the neo-tendon's diameter of the experimental group was (1.18 +/- 0.25) mm, significantly thinner than that of the group without tension[ (2.43 +/- 0.49) mm, P = 0.017]. The gross morphology of tendons of the experimental group and tenocyte group were similar to each other except for more cells in the experimental group. In experimental group, immunohistochemistry revealed the production of fibers of collagen type I & III that were aligned longitudinally along the force axis like the normal tendon pattern. An irregular collagen pattern was observed in the group without tension. The maximum tensile stress of the experimental group was (2.75 +/- 0.59) MPa, similar to that of the tenocyte group [(3.08 +/- 0.30) MPa, P = 0.439], and significantly greater than that of the group without tension [(0.82 +/- 0.21) MPa, P = 0.006]. At the 14th week the PGA fibers of the cell-free group were mostly degraded. In addition, more dead cells and tissue atrophy were observed in the experimental group, and the tensile stress was higher than that of the same group by the 9th week. In the 18th week the number of hollow fiber of the experimental group was more obvious, the number of dead cells increased, and the tensile stress was lower, however, there was no significant difference in other characteristics compared with those in the 14th week. CONCLUSIONS: DFbs can be used for in vitro tendon engineering as tenocytes. Mechanical stimulation by statistic strain is beneficial for tissue formation, but the effect may not be optimal if the tension is applied for too long.

Repair of tendon defect with dermal fibroblast engineered tendon in a porcine model.

Harvesting autologous tenocytes for tendon engineering may cause secondary tendon defect at the donor site. Dermal fibroblasts are an easily accessible cell source and do not cause major donor site defect. This study aims to explore the possibility of tendon engineering using dermal fibroblasts. A total of 45 hybrid pigs were randomly divided into three groups: experimental group (n = 15)--repair of tendon defect with a dermal fibroblast engineered tendon; control group 1 (n = 15)--repair of defect with a tenocyte engineered tendon; and control group 2 (n = 15)-repair of defect with a scaffold alone. Both autologous dermal fibroblasts and tenocytes were seeded on polyglycolic acid (PGA) unwoven fibers to form a cell-scaffold construct and cultured in vitro for 7 days before in vivo implantation to repair a defect of flexor digital superficial tendon. Specimens were harvested at weeks 6, 14, and 26 for gross, histological, and mechanical analyses. Microscopy revealed good attachment of both dermal fibroblasts and tenocytes on PGA fibers and matrix production. In vivo results showed that fibroblast and tenocyte engineered tendons were similar to each other in their gross view, histology, and tensile strength. At 6 weeks, parallel collagen alignment was observed at both ends, but not in the middle in histology, with more cellular components than natural tendons. At weeks 14 and 26, both engineered tendons exhibited histology similar to that of natural tendon. Collagens became parallel throughout the tendon structure, and PGA fibers were completely degraded. Interestingly, dermal fibroblast and tenocyte engineered tendons did not express type III collagen at 26 weeks, which remained observable in normal pig skin and control group 2 tissue using polarized microscopy, suggesting a possible phenotype change of implanted dermal fibroblasts. Furthermore, both fibroblast and tenocyte engineered tendons shared similar tensile strength, about 75% of natural tendon strength. At 6 weeks in control group 2, neo-tissue was formed only at the peripheral area by host cells. A cord-like tissue was formed at weeks 14 and 26. However, the formed tissue was histologically disorganized and mechanically weaker than both cell-engineered tendons (p < 0.05). These results suggest that dermal fibroblasts may have the potential as seed cells for tendon engineering.

Less is more: new biomimetic approach to control spatial and temporal cell loading for tissue engineering.

It is increasingly recognized that use of stiff biodegradable polymers in connective tissue engineering has an inherent flaw. Although polymer stiffness has early benefit for mechanical strength of implants, such pseudoprosthetic material function inevitably stress shields embedded cells, switching off their synthetic/remodeling functions. This core conundrum represents a tension between early mechanical benefits of polymer stiffness against blocking of cell load-dependent matrix production. In effect, an ideal system would produce a gradual, transfer of load onto resident cells and their matrix. Toward this target, our "less is more" (LiM) hypothesis proposes that less stress shielding (polymer stiffness) will lead to more cell-dependent tissue formation. To test this we have designed a hybrid segregation solution in which the cells are segregated into a native (but weak) collagen-gel matrix while the external mechanical loading is taken by temporary, reinforcing polyglycolic acid (PGA) fibers, with gradual, load transfer as the polymer µ-fibers fracture. Dermal fibroblasts grew predictably in the hybrid construct and the fine, parallel PGA fibers fractured and fragmented due to hydrolysis, giving a fall of construct stiffness to near collagen-only levels, over 14 days. The same fiber fracture and fall in stiffness occurred over 14 days in constructs implanted in vivo. In this case a cell dependent, net enhancement of connective tissue stiffness could be identified in hybrid constructs, supporting the LiM hypothesis for cytomechanical control of matrix. This is the first demonstration of spatiotemporal load transfer as a customizable tool for improved, biomimetic connective tissue engineering.

Repair of Achilles tendon defect with autologous ASCs engineered tendon in a rabbit model.

Adipose derived stem cells (ASCs) are an important cell source for tissue regeneration and have been demonstrated the potential of tenogenic differentiation in vitro. This study explored the feasibility of using ASCs for engineered tendon repair in vivo in a rabbit Achilles tendon model. Total 30 rabbits were involved in this study. A composite tendon scaffold composed of an inner part of polyglycolic acid (PGA) unwoven fibers and an outer part of a net knitted with PGA/PLA (polylactic acid) fibers was used to provide mechanical strength. Autologous ASCs were harvested from nuchal subcutaneous adipose tissues and in vitro expanded. The expanded ASCs were harvested and resuspended in culture medium and evenly seeded onto the scaffold in the experimental group, whereas cell-free scaffolds served as the control group. The constructs of both groups were cultured inside a bioreactor under dynamic stretch for 5 weeks. In each of 30 rabbits, a 2 cm defect was created on right side of Achilles tendon followed by the transplantation of a 3 cm cell-seeded scaffold in the experimental group of 15 rabbits, or by the transplantation of a 3 cm cell-free scaffold in the control group of 15 rabbits. Animals were sacrificed at 12, 21 and 45 weeks post-surgery for gross view, histology, and mechanical analysis. The results showed that short term in vitro culture enabled ASCs to produce matrix on the PGA fibers and the constructs showed tensile strength around 50 MPa in both groups (p > 0.05). With the increase of implantation time, cell-seeded constructs gradually form neo-tendon and became more mature at 45 weeks with histological structure similar to that of native tendon and with the presence of bipolar pattern and D-periodic structure of formed collagen fibrils. Additionally, both collagen fibril diameters and tensile strength increased continuously with significant difference among different time points (p < 0.05). In contrast, cell-free constructs failed to form good quality tendon tissue with fibril structure observable only at 45 weeks. There were significant differences in both collagen fibril diameter and tensile strength between two groups at all examined time points (p < 0.05). The results of this study support that ASCs are likely to be a potential cell source for in vivo tendon engineering and regeneration.