In Vivo assessment of a tissue-engineered vascular graft combining a biodegradable elastomeric scaffold and muscle-derived stem cells in a rat model

Limited autologous vascular graft availability and poor patency rates of synthetic grafts for bypass or replacement of small-diameter arteries remain a concern in the surgical community. These limitations could potentially be improved by a tissue engineering approach. We report here our progress in the development and in vivo testing of a stem-cell-based tissue-engineered vascular graft for arterial applications. Poly(ester urethane)urea scaffolds (length=10mm; inner diameter=1.2mm) were created by thermally induced phase separation (TIPS). Compound scaffolds were generated by reinforcing TIPS scaffolds with an outer electrospun layer of the same biomaterial (ES-TIPS). Both TIPS and ES-TIPS scaffolds were bulk-seeded with 10×106 allogeneic, LacZ-transfected, muscle-derived stem cells (MDSCs), and then placed in spinner flask culture for 48h. Constructs were implanted as interposition grafts in the abdominal aorta of rats for 8 weeks. Angiograms and histological assessment were performed at the time of explant. Cell-seeded constructs showed a higher patency rate than the unseeded controls: 65% (ES-TIPS) and 53% (TIPS) versus 10% (acellular TIPS). TIPS scaffolds had a 50% mechanical failure rate with aneurysmal formation, whereas no dilation was observed in the hybrid scaffolds. A smooth-muscle-like layer of cells was observed near the luminal surface of the constructs that stained positive for smooth muscle α-actin and calponin. LacZ+ cells were shown to be engrafted in the remodeled construct. A confluent layer of von Willebrand Factor-positive cells was observed in the lumen of MDSC-seeded constructs, whereas acellular controls showed platelet and fibrin deposition. This is the first evidence that MDSCs improve patency and contribute to the remodeling of a tissue-engineered vascular graft for arterial applications. © 2010 Mary Ann Liebert, Inc

Peptide hydrogels — a tissue engineering strategy for the prevention of oesophageal strictures

Endoscopic treatment of Barrett’s oesophagus often leads to further damage of healthy tissue causing fibrotic tissue formation termed as strictures. This study shows that synthetic, self-assembling peptide hydrogels (PeptiGelDesign) support the activity and function of primary oesophageal cells, leading to epithelialisation and stratification during in vitro 3D co-culture. Following buffering in culture media, oesophageal stromal fibroblasts (rOSFs) were incorporated into a library of peptide hydrogels, whereas oesophageal epithelial cells (mOECs) were seeded on the surface. Optimal hydrogels (PGD-AlphaProC and PGD-CGD2) supported mOEC viability (>95 %), typical cell morphology (cobblestone-like), a migration rate of 17.4 μm/hr and a migration distance of 364 μm, at 48 hours. Positive expression of typical epithelial markers (ZO-1 and cytokeratins) was witnessed detected using immunocytochemistry at day 3 in culture. Furthermore, optimal hydrogels were identified which supported rOSF viability (> 95%) with homogenous distribution when incorporated into the hydrogels and also promoted the secretion of collagen type I detected using ELISA, at day 7. 3D co-culture model using optimal hydrogels for both cell types supported a stratified epithelial layer (expressing involucrin and AE1/AE3 markers). Findings from this study could lead to the use of peptide hydrogels as a minimally invasive endoscopic therapy to manage oesophageal strictures

The impact of detergents on the tissue decellularization process: a ToF-SIMS study

Biologic scaffolds are derived from mammalian tissues, which must be decellularized to remove cellular antigens that would otherwise incite an adverse immune response. Although widely used clinically, the optimum balance between cell removal and the disruption of matrix architecture and surface ligand landscape remains a considerable challenge. Here we describe the use of time of flight secondary ion mass spectroscopy (ToF-SIMS) to provide sensitive, molecular specific, localized analysis of detergent decellularized biologic scaffolds. We detected residual detergent fragments, specifically from Triton X-100, sodium deoxycholate and sodium dodecyl sulphate (SDS) in decellularized scaffolds; increased SDS concentrations from 0.1% to 1.0% increased both the intensity of SDS fragments and adverse cell outcomes. We also identified cellular remnants, by detecting phosphate and phosphocholine ions in PAA and CHAPS decellularized scaffolds. The present study demonstrates ToF-SIMS is not only a powerful tool for characterization of biologic scaffold surface molecular functionality, but also enables sensitive assessment of decellularization efficacy

Ablación por radiofrecuencia en esófago de Barrett. Experiencia Inicial

La radiofrecuencia endoscópica utiliza energía térmica para ablacionar la capa superficial del esófago donde se localiza el tejido característico del Esófago de Barrett (EB). Pacientes y métodos. Se incluyeron 50 pacientes adultos con diagnóstico de EB de acuerdo a la clasificación de Viena. Objetivos. Se evaluó la seguridad y la eficacia de la ablación por radio-frecuencia (ARF) en pacientes con EB. Resultados. Fueron tratados 50 pacientes con una mediana de seguimiento de 18 meses. La mediana de edad fue de 58 años. Hasta lograr la erradicación del EB se realizaron 1,4 sesiones de ARF por paciente. La morbilidad del procedimiento fue del 6% y la complicación más frecuente fue la estenosis esofágica (dos casos). No se observó recurrencia de la metaplasia intestinal durante el seguimiento. Conclusiones. En nuestra experiencia la ARF es un procedimiento seguro con baja morbilidad. Los resultados a mediano y largo plazo publicados son estimulantes y permiten comenzar a reevaluar los protocolos de seguimiento vigentes

Biomechanical Features of Reinforced Esophageal Hiatus Repair in a Porcine Model

Recurrence rates in the laparoscopic repair of the hiatal hernia range from 12% to 59%. Limitation of reinforcement has been principally the risk of adverse events caused by synthetic materials. Biologic and resorbable synthetic materials are valid alternatives. This study compares the host response to all these materials after hiatal hernia repair. A total of 20 Landrace pigs, underwent laparoscopic primary hiatal hernia repair and reinforced with a polypropylene mesh (PROLENE: polypropylene [PP]), an absorbable synthetic scaffold (GOREBIO-A: polyglycolic acid [PGA]), a urinary bladder matrix scaffold, (Gentrix: urinary bladder matrix [UBM]), or without reinforcement, control group (C). Animals were survived for 3 months. Endpoints included gross morphology, biomechanical testing, and histology. Pigs in PP and PGA groups showed fibrosis at the repair site, with robust adhesions. In UBM and C groups, only mild adhesions were found. Load at failure (gr) and stiffness (gr/mm) of PP were higher than C group (PP:2103 ± 548.3 versus C:951.1 ± 372.7, P = 0.02; PP:643.3 ± 301 versus C:152.6 ± 142.7, P = 0.01). PGA and UBM values for both parameters were in between PP and C samples. However, stiffness in UBM was tended to be lower than PP group, and approached a significant difference (643.3 ± 301 versus 243 ± 122.1, P = 0.0536). In UBM group, the histology resembled native tissue. By contrast, PP and PGA groups showed mononuclear infiltrates, fibroencapsulation, necrosis, remnants of mesh, and disorganized tissue that was validated with a histologic score. In this setting, UBM scaffolds showed the most appropriate features for hiatal hernia repair, recovering the tissue properties that can help reduce the possibility of early failure and prevent complications associated with the implanted material.Fil: Amigo, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Medicina Traslacional, Trasplante y Bioingeniería. Fundación Favaloro. Instituto de Medicina Traslacional, Trasplante y Bioingeniería; ArgentinaFil: Zubieta, Cecilia. Fundación Favaloro; ArgentinaFil: Riganti, Juan Martin. Fundación Favaloro; ArgentinaFil: Ramirez, Mauricio. Fundación Favaloro; ArgentinaFil: Renda, Pedro. Fundación Favaloro; ArgentinaFil: Lovera, Romina. Fundación Favaloro; ArgentinaFil: Pascaner, Ariel Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Medicina Traslacional, Trasplante y Bioingeniería. Fundación Favaloro. Instituto de Medicina Traslacional, Trasplante y Bioingeniería; ArgentinaFil: Vigliano, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Medicina Traslacional, Trasplante y Bioingeniería. Fundación Favaloro. Instituto de Medicina Traslacional, Trasplante y Bioingeniería; ArgentinaFil: Craiem, Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Medicina Traslacional, Trasplante y Bioingeniería. Fundación Favaloro. Instituto de Medicina Traslacional, Trasplante y Bioingeniería; ArgentinaFil: Young, D. Adam. No especifíca;Fil: Gilbert, Thomas W.. University of Pittsburgh; Estados UnidosFil: Nieponice, Alejandro. University of Pittsburgh; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Medicina Traslacional, Trasplante y Bioingeniería. Fundación Favaloro. Instituto de Medicina Traslacional, Trasplante y Bioingeniería; Argentin

Development of a tissue-engineered vascular graft combining a biodegradable scaffold, muscle-derived stem cells and a rotational vacuum seeding technique

There is a clinical need for a tissue-engineered vascular graft (TEVG), and combining stem cells with biodegradable tubular scaffolds appears to be a promising approach. The goal of this study was to characterize the incorporation of muscle-derived stem cells (MDSCs) within tubular poly(ester urethane) urea (PEUU) scaffolds in vitro to understand their interaction, and to evaluate the mechanical properties of the constructs for vascular applications. Porous PEUU scaffolds were seeded with MDSCs using our recently described rotational vacuum seeding device, and cultured inside a spinner flask for 3 or 7 days. Cell viability, number, distribution and phenotype were assessed along with the suture retention strength and uniaxial mechanical behavior of the TEVGs. The seeding device allowed rapid even distribution of cells within the scaffolds. After 3 days, the constructs appeared completely populated with cells that were spread within the polymer. Cells underwent a population doubling of 2.1-fold, with a population doubling time of 35 h. Stem cell antigen-1 (Sca-1) expression by the cells remained high after 7 days in culture (77±20% vs. 66±6% at day 0) while CD34 expression was reduced (19±12% vs. 61±10% at day 0) and myosin heavy chain expression was scarce (not quantified). The estimated burst strength of the TEVG constructs was 2127±900 mmHg and suture retention strength was 1.3±0.3 N. We conclude from this study that MDSCs can be rapidly seeded within porous biodegradable tubular scaffolds while maintaining cell viability and high proliferation rates and without losing stem cell phenotype for up to 7 days of in-vitro culture. The successful integration of these steps is thought necessary to provide rapid availability of TEVGs, which is essential for clinical translation. © 2007 Elsevier Ltd. All rights reserved