Collagen-Heparin-FGF2-VEGF Scaffolds Induce a Regenerative Gene Expression Profile in a Fetal Sheep Wound Model.

Background: The developmental abnormality spina bifida is hallmarked by missing tissues (e.g. skin) and exposure of the spinal cord to the amniotic fluid, which can negatively impact neurological development.

Measuring steroids in hair opens up possibilities to identify congenital adrenal hyperplasia in developing countries.

Objective: Patients with congenital adrenal hyperplasia (CAH) in developing countries have limited access to appropriate laboratory facilities for diagnosis and follow-up. The aim of this study is to evaluate steroid measurement in hair as a diagnostic tool to identify and monitor CAH in these patients.

Design: A method was developed to measure steroids in hair, the stability of steroids in hair was assessed, and the concentration range in healthy volunteers was determined.

Sustained Postnatal Skin Regeneration Upon Prenatal Application of Functionalized Collagen Scaffolds.

Primary closure of fetal skin in spina bifida protects the spinal cord and improves clinical outcome, but is also associated with postnatal growth malformations and spinal cord tethering. In this study, we evaluated the postnatal effects of prenatally closed full-thickness skin defects in sheep applying collagen scaffolds with and without heparin/vascular endothelial growth factor/fibroblast growth factor 2, focusing on skin regeneration and growth. At 6 months, collagen scaffold functionalized with heparin, VEGF, and FGF2 (COL-HEP/GF) resulted in a 6.

The Impact of γ-Irradiation and EtO Degassing on Tissue Remodeling of Collagen-based Hybrid Tubular Templates.

Clinical implementation of novel products for tissue engineering and regenerative medicine requires a validated sterilization method. In this study, we investigated the effect of γ-irradiation and EtO degassing on material characteristics and the effect on template remodeling of hybrid tubular constructs in a large animal model. Hybrid tubular templates were prepared from type I collagen and Vicryl polymers and sterilized by 25 kGray of γ-irradiation or EtO degassing.

Ureteral Reconstruction in Goats Using Tissue-Engineered Templates and Subcutaneous Preimplantation.

Repair of long ureteral defects often requires long graft tissues and extensive surgery. This is associated with complications, including a lack of suitable tissue and graft site morbidity. Tissue engineering may provide an attractive alternative to the autologous graft tissues.

Clinical protocol levels are required in laboratory animal surgery when using medical devices: experiences with ureteral replacement surgery in goats.

It is common to test medical devices in large animal studies that are or could also be used in humans. In this short report we describe the use of a ureteral J-stent for the evaluation of biodegradable tubular constructs for tissue reconstruction, and the regeneration of ureters in Saanen goats. Similarly to a previous study in pigs, the ureteral J-stent was blindly inserted until some resistance was met.

Bladder Regeneration Using Multiple Acellular Scaffolds with Growth Factors in a Bladder.

Introduction: Tissue engineering may become an alternative to current bladder augmentation techniques. Large scaffolds are needed for clinically significant augmentation, but can result in fibrosis and graft shrinkage. The purpose of this study was to investigate the use of multiple scaffolds instead of one large scaffold, to enhance bladder tissue regeneration and bladder capacity.

The effect of a cyclic uniaxial strain on urinary bladder cells.

Purpose: Pre-conditioning of a cell seeded construct may improve the functional outcome of a tissue engineered construct for augmentation cystoplasty. The precise effects of mechanical stimulation on urinary bladder cells in vitro are not clear. In this study we investigate the effect of a cyclic uniaxial strain culture on urinary bladder cells which were seeded on a type I collagen scaffold.

Design of an elasticized collagen scaffold: A method to induce elasticity in a rigid protein.

Unlabelled: Type I collagen is widely applied as a biomaterial for tissue regeneration. In the extracellular matrix, collagen provides strength but not elasticity under large deformations, a characteristic crucial for dynamic organs and generally imparted by elastic fibers. In this study, a methodology is described to induce elastic-like characteristics in a scaffold consisting of solely type I collagen.

Functional Analysis of Vascularized Collagen/Fibrin Templates by MRI In Vivo.

Functional monitoring of the fate of implanted templates, which restore the function of lost tissues, is still a challenge. Whereas histology can give excellent insight into material and tissue remodeling, longitudinal studies are hampered by the invasive character. Noninvasive imaging techniques, which allow longitudinal studies in the same individual and provide functional information, might be beneficial.

Novel tubular constructs for urinary diversion: a biocompatibility study in pigs.

The use of bowel tissue for urinary diversion can be associated with severe complications, and regenerative medicine may circumvent this by providing an engineered conduit. In this study, a novel tubular construct was identified for this purpose. Three constructs (diameter 15 mm) were prepared from type I collagen and either (a) a semi-biodegradable Vypro II polymer (COL-Vypro), (b) a rapidly biodegradable Vicryl polymer (COL-Vicryl) or (c) an additional collagenous layer (COL-DUAL).

Bladder Regeneration Using a Smart Acellular Collagen Scaffold with Growth Factors VEGF, FGF2 and HB-EGF.

Tissue engineering may become an alternative to current bladder augmentation techniques. Large scaffolds are needed for clinically significant augmentation, but can result in fibrosis and graft shrinkage. The purpose of this study was to investigate whether smart acellular collagen-heparin scaffolds with growth factors (GFs) VEGF, FGF2, and HB-EGF enhance bladder tissue regeneration and bladder capacity in a large animal model of diseased bladder.

Recent advances in ureteral tissue engineering.

Reconstruction of long ureteral defects often warrants the use of graft tissue and extensive surgical procedures to maintain the safe transport of urine from the kidneys to the urinary bladder. Complication risks, graft failure-related morbidity, and the lack of suitable tissue are major concerns. Tissue engineering might offer an alternative treatment approach in these cases, but ureteral tissue engineering is still an underreported topic in current literature.

Tissue engineering of diseased bladder using a collagen scaffold in a bladder exstrophy model.

Objective: To compare the regenerative capacity of diseased bladder in a large animal model of bladder exstrophy with regeneration in healthy bladder using a highly porous collagen scaffold.

Materials And Methods: Highly porous bovine type I collagen scaffolds with a diameter of 32 mm were prepared. In 12 fetal sheep a bladder exstrophy was surgically created at 79 days' gestation.

Tissue engineering in animal models for urinary diversion: a systematic review.

Tissue engineering and regenerative medicine (TERM) approaches may provide alternatives for gastrointestinal tissue in urinary diversion. To continue to clinically translatable studies, TERM alternatives need to be evaluated in (large) controlled and standardized animal studies. Here, we investigated all evidence for the efficacy of tissue engineered constructs in animal models for urinary diversion.

Collagen-Vicryl scaffolds for reconstruction of the diaphragm in a large animal model.

Current methods for closure of congenital diaphragmatic hernia using patches are unsatisfactory, and novel collagen-based scaffolds have been developed, and successfully applied in a rat model. However, for translation to the human situation constructs must be evaluated in larger animal models. We developed collagen scaffolds enforced with Vicryl, loaded either with or without the muscle stimulatory growth factor insulin-like growth factor 1 (IGF1).

In vivo magnetic resonance imaging of type I collagen scaffold in rat: improving visualization of bladder and subcutaneous implants.

Noninvasive monitoring of implanted scaffolds is important to understand their behavior and role in tissue engineering, in particular to follow their degradation and interaction with host tissue. Magnetic resonance imaging (MRI) is well suited for this goal, but its application is often hampered by the low contrast of scaffolds that are prepared from biomaterials such as type I collagen. The aim of this study was to test iron oxide particles incorporation in improving their MRI contrasts, and to follow their degradation and tissue interactions.

Is there a need for smooth muscle cell transplantation in urethral reconstruction?

Background: Hypospadias and urethral strictures are conditions requiring additional tissue for reconstruction. Due to a limited source of tissue, autologous skin and oral mucosa are frequently used. However, long-term follow-up studies demonstrated significant complications and diminished quality of life.

Seamless vascularized large-diameter tubular collagen scaffolds reinforced with polymer knittings for esophageal regenerative medicine.

A clinical demand exists for alternatives to repair the esophagus in case of congenital defects, cancer, or trauma. A seamless biocompatible off-the-shelf large-diameter tubular scaffold, which is accessible for vascularization, could set the stage for regenerative medicine of the esophagus. The use of seamless scaffolds eliminates the error-prone tubularization step, which is necessary when emanating from flat scaffolds.

Ureteral tissue engineering: where are we and how to proceed?

In the field of regenerative medicine, various types of biodegradable and nonbiodegradable scaffolds have been developed for urinary tract tissue-engineering applications. Naturally derived or synthetic materials have been tested to determine their properties and their effectiveness. However, the majority of the current literature focuses on the reconstruction of the urethra, urinary diversion, and urinary bladder, while limited data have been published regarding the use of biomaterials in ureteral reconstruction.

Prenatal coverage of experimental gastroschisis with a collagen scaffold to protect the bowel.

Background/purpose: In fetuses with gastroschisis, toxic products in the amniotic fluid and constriction at the defect of the abdominal wall are considered causative of damage to the eviscerated bowel. The aim of this study was to cover the eviscerated bowel in gastroschisis with a collagen scaffold to protect the bowel and induce cell growth into the scaffold, which could lead to skin or abdominal wall formation replacing the scaffold.

Methods: In 12 fetal lambs gastroschisis was surgically created at 79 days gestation.

A new, straightforward ex vivo organoid bladder mucosal model for preclinical research.

Purpose: We developed an experimental ex vivo organoid bladder mucosal model that can be used for experimental research purposes to create alternatives to current animal models.

Materials And Methods: We developed an ex vivo organoid bladder mucosal model by immobilizing a type I collagen scaffold on the bottom of a Transwell® insert, creating a 2-compartment system. Mucosal biopsies from porcine bladders were placed on top of the scaffold and cultured in different mediums.