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The present study investigates the potential use of non-catalyzed water-soluble blocked polyurethane prepolymer (PUP) as a bifunctional cross-linker for collagenous scaffolds. The effect of concentration (5, 10, 15 and 20%), time (4, 6, 12 and 24 h), medium volume (50, 100, 200 and 300%) and pH (7.4, 8.2, 9 and 10) over stability, microstructure and tensile mechanical behavior of acellular pericardial matrix was studied. The cross-linking index increased up to 81% while the denaturation temperature increased up to 12 °C after PUP crosslinking. PUP-treated scaffold resisted the collagenase degradation (0.167 ± 0.14 mmol/g of liberated amine groups vs. 598 ± 60 mmol/g for non-cross-linked matrix). The collagen fiber network was coated with PUP while viscoelastic properties were altered after cross-linking. The treatment of the pericardial scaffold with PUP allows (i) different densities of cross-linking depending of the process parameters and (ii) tensile properties similar to glutaraldehyde method.

Bovine pericardium is a collagenous tissue commonly used as a natural biomaterial in the fabrication of cardiovascular devices. For tissue engineering purposes, this xenogeneic biomaterial must be decellularized to remove cellular antigens. With this in mind, three decellularization protocols were compared in terms of their effectiveness to extract cellular materials, their effect on glycosaminoglycan (GAG) content and, finally, their effect on tensile biomechanical behavior. The tissue decellularization was achieved by treatment with t-octyl phenoxy polyethoxy ethanol (Triton X-100), tridecyl polyethoxy ethanol (ATE) and alkaline treatment and subsequent treatment with nucleases (DNase/RNase). The quantified residual DNA content (3.0 ± 0.4%, 4.4 ± 0.6% and 5.6 ± 0.7% for Triton X-100, ATE and alkaline treatment, respectively) and the absence of nuclear structures (hematoxylin and eosin staining) were indicators of effective cell removal. In the same way, it was found that the native tissue GAG content decreased to 61.6 ± 0.6%, 62.7 ± 1.1% and 88.6 ± 0.2% for Triton X-100, ATE and alkaline treatment, respectively. In addition, an alteration in the tissue stress relaxation characteristics was observed after alkaline treatment. We can conclude that the three decellularization agents preserved the collagen structural network, anisotropy and the tensile modulus, tensile strength and maximum strain at failure of native tissue.

Para mitigar la calcificación de las bioprótesis cardiacas fabricadas con pericardio de ternera o válvulas porcinas se aplican tratamientos químicos posteriores al entrecruzamiento con glutaraldehído. Uno de los tratamientos ensayados ha sido el surfactante dodecil sulfato sódico(DSS). Este detergente inhibe, en modelos experimentales,en pequeños animales, la calcificación del pericardio de ternera utilizado en la construcción de bioprótesis cardiacas. Estudiamos el comportamiento mecánico del pericardio tratado, con este detergente, comparándolo con un tratamiento control con glutaraldehído (GA) 0.625% durante 24 horas. Se ensayaron al esfuerzo de tracción muestras pareadas, es decir, cortadas de forma contigua y en la misma dirección del corte, tratadas respectivamente con glutaraldehído (grupo de control) y con dodecil sulfato sódico (DSS). El tejido tratado con DSS fue a su vez incubado con dos tiempos diferentes 2 o 24 horas respectivamente y posteriormente tratados con glutaraldehído (GA). En las muestras tratadas dos horas con DSS,se observó un estrés de rotura similar al de las parejas que recibieron el tratamiento de control.Los valores estuvieron comprendidos entre 8.42 y 15.81 MPa. Las muestras tratadas con DSS, 24 horas perdieron su resistencia mecánica. El estrés de rotura medio osciló entre 1.77 y 1.95 MPa, existiendo diferencias estadísticamente significativas (p<0.001), cuando se las comparaba con el grupo control tratado con GA. Por otra parte cuando se analizó la elasticidad, las series tratadas con DSS y dos horas de incubación presentaron en la región elástica, módulos de elasticidad menores, cuando se comparan con valores similares de las series de control, dejando patente la mayor elasticidad del biomaterial tratado con DSS. Desde el punto de vista de investigación aplicada la buena correlación obtenida, cuando se comparan mediante mínimos cuadrados las muestras pareadas, permite predecir el comportamiento mecánico de una muestra, conocido el c, Peer Reviewed