Urinary Bladder Matrix Scaffolds Research Articles

Human Bronchial Epithelial Cell Growth on Homologous Versus Heterologous Tissue Extracellular Matrix

BackgroundExtracellular matrix (ECM) bioscaffolds produced by decellularization of source tissue have been effectively used for numerous clinical applications. However, decellularized tracheal constructs have been unsuccessful due to the immediate requirement of a functional airway epithelium on surgical implantation. ECM can be solubilized to form hydrogels that have been shown to support growth of many different cell types. The purpose of the present study is to compare the ability of airway epithelial cells to attach, form a confluent monolayer, and differentiate on homologous (trachea) and heterologous (urinary bladder) ECM substrates for potential application in full tracheal replacement. Materials and methodsPorcine tracheas and urinary bladders were decellularized. Human bronchial epithelial cells (HBECs) were cultured under differentiation conditions on acellular tracheal ECM and urinary bladder matrix (UBM) bioscaffolds and hydrogels and were assessed by histology and immunolabeling for markers of ciliation, goblet cell formation, and basement membrane deposition. ResultsBoth trachea and urinary bladder tissues were successfully decellularized. HBEC formed a confluent layer on both trachea and UBM scaffolds and on hydrogels created from these bioscaffolds. Cells grown on tracheal and UBM hydrogels, but not on bioscaffolds, showed positive-acetylated tubulin staining and the presence of mucus-producing goblet cells. Collagen IV immunolabeling showed basement membrane deposition by these cells on the surface of the hydrogels. ConclusionsECM hydrogels supported growth and differentiation of HBEC better than decellularized ECM bioscaffolds and show potential utility as substrates for promotion of a mature respiratory epithelium for regenerative medicine applications in the trachea.

Influence of porcine urinary bladder matrix and porcine acellular dermal matrix on wound healing of full-thickness skin defect in diabetic mice

Influence of porcine urinary bladder matrix and porcine acellular dermal matrix on wound healing of full-thickness skin defect in diabetic mice

Urinary Bladder Matrix Scaffolds Promote Pericardium Repair in a Porcine Model

Pericardium closure after cardiac surgery is recommended to prevent postoperative adhesions to the sternum. Synthetic materials have been used as substitutes, with limited results because of impaired remodeling and fibrotic tissue formation. Urinary bladder matrix (UBM) scaffolds promote constructive remodeling that more closely resemble the native tissue. The aim of the study is to evaluate the host response to UBM scaffolds in a porcine model of partial pericardial resection. Twelve Landrace pigs were subjected to a median sternotomy. A 5 × 7 cm pericardial defect was created and then closed with a 5 × 7 cm multilayer UBM patch (UBM group) or left as an open defect (control group). Animals were survived for 8 wk. End points included gross morphology, biomechanical testing, histology with semiquantitative score, and cardiac function. The UBM group showed mild adhesions, whereas the control group showed fibrosis at the repair site, with robust adhesions and injury to the coronary bed. Load at failure (gr) and stiffness (gr/mm) were lower in the UBM group compared with the native pericardium (199.9 ± 59.2 versus 405.3 ± 99.89 g, P = 0.0536 and 44.23 ± 15.01 versus 146.5 ± 24.38 g/mm, P = 0.0025, respectively). In the UBM group, the histology resembled native pericardial tissue, with neovascularization, neofibroblasts, and little inflammatory signs. In contrast, control group showed fibrotic tissue with mononuclear infiltrates and a lack of organized collagen fibers validated with a histologic score. Both groups had normal ultrasonography results without cardiac motility disorders. In this setting, UBM scaffolds showed appropriate features for pericardial repair, restoring tissue properties that could help reduce postsurgical adhesions and prevent its associated complications.

Urinary bladder matrix scaffolds improve endometrial regeneration in a rat model of intrauterine adhesions.

Intrauterine adhesions caused by damage to the basal layer of the endometrium have a serious impact on women's fertility. Currently, there is no effective treatment to promote the regeneration of the endometrium. Urinary bladder matrix (UBM) is a derivative extracellular matrix biomaterial that has a complete basement membrane and provides a basis for the body to achieve complete self-functional repair. In this study, UBM was transplanted into the uterine horns of intrauterine adhesions in Sprague-Dawley rats to test whether UBM could improve endometrial regeneration in rats with intrauterine adhesions. Thicker endometria, increased numbers of glands, fewer fibrotic areas and increased proliferation of cells and blood vessels were found in the UBM group compared to the injury group. Transplantation of UBM reduced the mRNA levels of proinflammatory cytokines (tumor necrosis factor α) and increased those of anti-inflammatory cytokines (basic fibroblast growth factor) compared to the injury group. In the UBM group, the mRNA expression of endometrial receptivity factors (leukemia inhibitory factor and integrin αVβ3) was higher than that in the injury group, but it was lower than that in the normal group and the sham-operated group. More embryos were seen in the UBM group than in the injury group, although the UBM group had fewer embryos than the normal and sham-operated groups. Therefore, UBM may contribute to endometrial regeneration and may improve endometrial receptivity and fertility.

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.

Urinary bladder matrix scaffolds strengthen esophageal hiatus repair

BackgroundLaparoscopic repair of the hiatal hernia is associated with a recurrence rate between 12% and 42% depending on the defect size. Although the impact of hiatal reinforcement on long-term recurrence remains controversial, the main limitation of this approach has been the risk of adverse events related with the use of synthetic materials in the vicinity of the esophagus. MethodsA total of 14 female domestic pigs underwent laparoscopic primary hiatal hernia repair of a simulated defect in the esophageal hiatus. Seven of the hiatal repairs were reinforced with an extracellular matrix (ECM) scaffold, whereas the remaining seven served as primary repair controls. Animals were survived for 8 wk. At necropsy, after gross morphologic evaluation, samples were sent for mechanical testing and histology. ResultsThe repaired defect site reinforced with ECM scaffolds showed a robust closure of the crura in all cases with a smooth peritoneal-like structure covering the entire repair. Average load at failure of the treated group was found to be significantly stronger than that of the controls (185.8 ± 149.7 g versus 57.5 ± 57.5 g, P < 0.05). Similarly, the stiffness was significantly higher in the treated animals (57.5 ± 26.9 g/mm versus 19.1 ± 17.5 g/mm; P < 0.01). Interestingly, there was no difference in elongation at failure (7.62 ± 2.02 mm versus 7.87 ± 3.28 mm; P = 0.44). ConclusionsIn our animal survival model, we have provided evidence that the addition of an ECM to augment a primary hiatal repair leads to tissue characteristics that may decrease the possibility of early failure of the repair. This may translate to decreased recurrence rates. Further study is necessary.

Porcine urinary bladder matrix does not generate appreciable de novo muscle tissue in rat models of volumetric muscle loss injury

Event Abstract Back to Event Porcine urinary bladder matrix does not generate appreciable de novo muscle tissue in rat models of volumetric muscle loss injury Amit Aurora1, Janet L. Roe1, Benjamin T. Corona1 and Thomas J. Walters1 1 US Army Institute of Surgical Research, Extremity Trauma Research and Regenerative Medicine, United States Background: The high prevalence of volumetric muscle loss (VML) among battlefield injuries has stimulated research efforts aimed at regenerating muscle de novo using tissue engineering approaches. Extracellular matrix (ECM) scaffolds, in particular, have been extensively used based on their ability to provide a bio-inductive platform that supports endogenous cell recruitment, proliferation, and differentiation, ultimately improving healing of the tissue[1][2]. Recently, surgeons have used commercially available porcine derived urinary bladder matrix (UBM) to repair lower extremity VML in a small cohort of patients[3][4]. The porcine UBM scaffold has clinically been used for surgical reinforcement of soft tissue where weakness exits and general wound management-indications for which it has been approved by the U.S. Food and Drug Administration. However, there is need to establish evidence that will support further clinical use of the scaffold for the repair of traumatic muscle injuries. The overarching objective of this study is to investigate the efficacy of the porcine UBM scaffold as a tissue engineered strategy for the repair of traumatic muscle injuries. Methods: A musculotendinous junction (MTJ) or volumetric muscle loss (VML) injury was created in Lewis rats. For the MTJ injury, the defect created either received no repair or was repaired with a 6-layer MatriStem Surgical Matrix PSMX (time points: 2, 4, or 8 weeks). For the VML injury, the defect created received no repair, repaired with autograft tissue or with a 3-layer MatriStem Surgical Matrix PSM (time points: 2, 8, or 16 weeks). The m-ECM was only investigated at 2 weeks. Upon finding that the porcine UBM scaffold partially restored the muscle function in VML injury at eight weeks; a second study was performed to determine if physical rehabilitation during an eight week period would further improve function. The porcine UBM repaired rats were given free access to running wheels beginning at one week or four weeks post - injury. In vivo function testing was done (MTJ injury: 4 weeks post-injury; VML injury: 8 and 16 weeks post-injury) followed by tissue harvest for histological analysis. Results and Discussion: The porcine UBM scaffold did not promote appreciable muscle tissue regeneration as demonstrated in two distinct models of extremity VML. The porcine UBM scaffold completely resorbed when used as an interpositional graft for MTJ repair. When used to augment a VML defect surrounded by muscle and fascia, the porcine UBM scaffold improves the contractile properties of the injured limb by 17%, but does so without significant muscle fiber regeneration compared to autograft that showed robust regeneration (A-C). Finally, inclusion of physical rehabilitation (i.e., voluntary wheel running) did not improve tissue remodeling or functional improvements observed with scaffold implantation alone. Conclusions: The scaffold may not be suitable for clinical repair of MTJ injuries. The porcine UBM scaffold when used for VML repair may hasten functional recovery not due to significant muscle regeneration, but through force transmission via scaffold mediated fibrosis. The study suggests that if appreciable muscle generation is to be realized, combinatorial approaches that incorporate myogenic cells, a myoconductive scaffold, and a vasculogenic accelerant need to be developed.

The use of urinary bladder matrix in the treatment of trauma and combat casualty wound care.

Treatment of combat injuries and resulting wounds can be difficult to treat due to compromised and evolving tissue necrosis, environmental contaminants, multidrug resistant microbacterial and/or fungal infections, coupled with microvascular damage and/or hypovascularized exposed vital structures. Our group has developed surgical care algorithms with identifiable salvage techniques to achieve stable, definitive wound coverage often with the aid of certain regenerative medicine biologic scaffold materials and advanced wound care to facilitate tissue coverage and healing. This case series reports on the role of urinary bladder matrix scaffolds in the wound care and reconstruction of traumatic and combat wounds. Urinary bladder matrix was found to facilitate definitive soft tissue reconstruction by establishing a neovascularized soft tissue base acceptable for second stage wound and skin coverage options within traumatic and combat-related wounds.

An acellular biologic scaffold does not regenerate appreciable de novo muscle tissue in rat models of volumetric muscle loss injury

Extracellular matrix (ECM) derived scaffolds continue to be investigated for the treatment of volumetric muscle loss (VML) injuries. Clinically, ECM scaffolds have been used for lower extremity VML repair; in particular, MatriStem™, a porcine urinary bladder matrix (UBM), has shown improved functional outcomes and vascularization, but limited myogenesis. However, efficacy of the scaffold for the repair of traumatic muscle injuries has not been examined systematically. In this study, we demonstrate that the porcine UBM scaffold when used to repair a rodent gastrocnemius musculotendinous junction (MTJ) and tibialis anterior (TA) VML injury does not support muscle tissue regeneration. In the MTJ model, the scaffold was completely resorbed without tissue remodeling, suggesting that the scaffold may not be suitable for the clinical repair of muscle-tendon injuries. In the TA VML injury, the scaffold remodeled into a fibrotic tissue and showed functional improvement, but not due to muscle fiber regeneration. The inclusion of physical rehabilitation also did not improve functional response or tissue remodeling. We conclude that the porcine UBM scaffold when used to treat VML injuries may hasten the functional recovery through the mechanism of scaffold mediated functional fibrosis. Thus for appreciable muscle regeneration, repair strategies that incorporate myogenic cells, vasculogenic accelerant and a myoconductive scaffold need to be developed.

Esophageal reinforcement with an extracellular scaffold during total gastrectomy for gastric cancer.

Esophagojejunal (EJ) anastomotic leaks after total gastrectomy (TG) for malignancy lead to significant morbidity and mortality, thus affecting long-term survival. Preclinical and clinical trials have shown promise in utilizing degradable extracellular matrix (ECM) scaffolds in buttressing anastomoses. We describe our experience buttressing the EJ anastomosis after TG with a ECM scaffold. From February 2012 to January 2014, a total of 37 consecutive patients underwent TG buttressing of the EJ anastomosis with the degradable ECM scaffold composed of a porcine urinary bladder called MatriStem (ACell Inc.). The scaffold was circumferentially wrapped around the EJ anastomosis. The primary end point was the EJ leak rate, while the secondary end point was the EJ stricture rate. The mean ± SD age and body mass index were 59 ± 16 years and 28.1 ± 4.9 kg/m(2), respectively. Most patients were male (51 %), white (78 %), and former smokers (51 %). Over half (59 %) underwent neoadjuvant chemotherapy. A minimally invasive TG was performed in 70 % of patients. Signet ring was the most common tumor type (48 %), and most patients had midstage disease (59 %). The mean number of lymph nodes procured was 36 ± 16. Eighteen patients (49 %) experienced a complication, mostly minor. One patient (2.7 %) developed an EJ leak, while three patients (8 %) developed an EJ stricture. Median follow-up was 7 months (range 2-12 months). There was no operative or in-hospital mortality. The use of urinary bladder matrix scaffolds may be helpful in decreasing the incidence of EJ anastomotic leak and/or stricture. A prospective phase II trial at our institution is currently under way.

Mechanical characterisation of unidirectional and cross-directional multilayered urinary bladder matrix (UBM) scaffolds

Multilayered biological scaffolds derived from mammalian extracellular matrix (ECM) have shown promising long-term clinical results when reconstructing damaged tissues and organs. Despite their established clinical applicability, experimental studies that describe the effects of alternate manufacturing protocols on an ECM's mechanical properties are lacking. In the present study the mechanical properties of multilayered ‘unidirectional’ porcine urinary bladder matrix (UBM) scaffolds were determined in favour of its longitudinal and circumferential axes. The scaffold's unidirectional mechanical properties were then compared with ‘cross-directional’ UBM scaffolds. The results showed significant variations when alternate manufacturing protocols for multilayered UBM were applied. Unidirectional longitudinal UBM remained the strongest biomaterial on a consistent basis. Its failure strength occurred at 4.79±0.85MPa compared to 3.36±0.53MPa for unidirectional circumferential and 2.91±1.05MPa for cross-directional UBM respectively (p<0.0001). Distensibility was greatest in unidirectional circumferential UBM with failure extension occurring at 14.77±1.66mm. In comparison, failure extension occurred at 12.88±0.94mm and 13.04±4.35mm for unidirectional longitudinal and cross-directional UBM respectively (p=0.0024). The present study demonstrates that predefined manufacturing protocols for UBM should be considered when reconstructing anatomical structures with specific mechanical requirements.

Cultured Keratinocytes on Urinary Bladder Matrix Scaffolds Increase Angiogenesis and Help in Rapid Healing of Wounds

Urinary Bladder Matrix (UBM) is an extracellular matrix (ECM) scaffold. It is now used in wound care management of partial and full-thickness wounds where conventional methods for wound care usually fail to give satisfactory results. In this study, the authors are comparing the healing of full-thickness excisional wounds in New Zealand rabbits using either UBM scaffolds alone or in combination with cultured keratinocytes. The wounds were compared grossly and histologically. It is a comparative controlled study including 40 full-thickness wounds in 2 groups. Group (A) wounds: treated with UBM scaffolds, Group (B) wounds: treated with UBM scaffolds with cultured keratinocytes. The wounds were examined grossly after 1, 2, and 3 weeks, and were examined histologically at the end of the 3rd week using ordinary hematoxylin-eosin staining techniques. All the wounds healed completely by the end of the 3rd week. Early wound contraction was significantly less in group B. More angiogenic response was evident in all specimens of group B. This study shows that adding cultured keratinocytes to the rough surface of the UBM scaffold may be beneficial in reducing early wound contraction and improving wound vascularity in treatment of full-thickness wounds.

Porcine extracellular matrix scaffolds in reconstructive urology: An ex vivo comparative study of their biomechanical properties

Functional reconstruction of the human urinary bladder has been attempted by replacing defective bladder tissue with tissue-engineered xenogenic extracellular matrix (ECM) scaffolds. However, experimental studies that demonstrate the effects of implanted ECMs on important biomechanical properties such as total bladder capacity (TBC) and compliance ( C ) are lacking. In the current study, the effects of ECM scaffold surface area (SA) on TBC and C was assessed, ex vivo, in an ovine model ( n = 5 ). TBC and C were measured at pressures ( P ) of 5, 10, 15 and 20 mm Hg prior to performing a 3×3 cm (9 cm 2) partial cystectomy defect. Equal-sized 3×3 cm (9 cm 2) and larger 6×6 cm (36 cm 2) urinary bladder matrix (UBM) scaffolds of porcine origin replaced the 3×3 cm cystectomy defect, and TBC and C were re-recorded for comparative analysis. The results showed that TBC decreased by 39.6%±0.005% (122.9 ml±15 ml, p < 0.05 ) and C by 38.9%±0.51%, ( Δ P = 0 – 5 mm Hg , p < 0.05 ) in ovine bladders reconstructed with 3×3 cm UBM scaffolds compared to their native values. It was also found that TBC increased by 25.6±0.64% (64.2 ml ± 8.8 ml, p > 0.05 ) and C by 24.5±0.43% ( Δ P = 0 – 5 mm Hg , p > 0.05 ) in the 6×6 cm UBM scaffold group compared to the 3×3 cm UBM scaffold group; however, these values were not statistically significant. The present work demonstrates that a fourfold increase in ECM scaffold SA relative to its intended defect does not lead to a significant improvement in TBC and C values.

Repair of the Thoracic Wall With an Extracellular Matrix Scaffold in a Canine Model

Naturally derived extracellular matrix (ECM) scaffolds have been successfully used to promote constructive remodeling of injured or missing tissue in a variety of anatomical locations, including abdominal wall repair. Furthermore, ECM scaffolds have shown the ability to resist infection and adhesion formation. The present study investigated the utility of an ECM scaffold, specifically, porcine urinary bladder matrix (UBM), for repair of a 5 x 5 cm full-thickness lateral thoracic wall defect in a canine model (n = 6) including 5-cm segments of the 6th and 7th rib. The resected portion of the 7th rib was replaced as an interpositional graft along with the UBM scaffold. As a control, a Gore-Tex patch was used to repair the same defect (n = 2). The control animals healed by encapsulation of the Gore-Tex patch by dense collagenous tissue. The remodeled UBM grafts showed the presence of site-specific tissue, including organized fibrous connective tissue, muscle tissue, adipose tissue, and bone. Upon fluoroscopic examination, it was shown that both bony defects were replaced with new calcified bone. In the 6th rib space, new bone bridged the entire span. In the 7th rib space, there was evidence of bone formation between the interpositional graft and the existing bone, as well as de novo formation of organized bone in the shape of the missing rib segment parallel to the interpositional graft. This study shows that a naturally occurring ECM scaffold promotes site-specific constructive remodeling in a large thoracic wall defect.

Uniaxial and biaxial properties of terminally sterilized porcine urinary bladder matrix scaffolds

Scaffolds composed of extracellular matrix have been successfully used to support the reconstruction of a variety of tissues in preclinical studies and in clinical applications. As an off-the-shelf product, extracellular matrix (ECM) scaffolds must be subjected to terminal sterilization before use. The choice of sterilization method may alter the integrity of the ECM's composition and structure such that the mechanical and material properties are adversely affected. The present study evaluated selected structural properties of an ECM scaffold derived from the urinary bladder termed urinary bladder matrix after being sterilized by three different methods: ethylene oxide (ETO) (750 mg/h for 16 h), gamma irradiation (2.0 Mrads), or electron beam irradiation (e-beam) (2.2 Mrads). The structural properties that were evaluated include maximum force, maximum elongation, maximum tangential stiffness, energy dissipation, and ball-burst strength. All sterilization methods affected at least two of the measured properties. ETO was shown to have the least detrimental effect upon the measured properties. Gamma and e-beam irradiation were shown to decrease the uniaxial and biaxial strength, maximum tangential stiffness, and the energy dissipation of the ECM scaffolds. The present study showed that the choice of terminal sterilization method affects the structural properties of scaffolds composed of extracellular matrix.