Biomaterial characterization of off-the-shelf decellularized porcine pericardial tissue for use in prosthetic valvular applications

Abstract

Fixed pericardial tissue is commonly used for commercially available xenograft valve implants, and has proven durability, but lacks the capability to remodel and grow. Decellularized porcine pericardial tissue has the promise to outperform fixed tissue and remodel, but the decellularization process has been shown to damage the collagen structure and reduce mechanical integrity of the tissue. Therefore, a comparison of uniaxial tensile properties was performed on decellularized, decellularized‐sterilized, fixed, and native porcine pericardial tissue versus native valve leaflet cusps. The results of non‐parametric analysis showed statistically significant differences (p < .05) between the stiffness of decellularized versus native pericardium and native cusps as well as fixed tissue, respectively; however, decellularized tissue showed large increases in elastic properties. Porosity testing of the tissues showed no statistical difference between decellularized and decell‐sterilized tissue compared with native cusps (p > .05). Scanning electron microscopy confirmed that valvular endothelial and interstitial cells colonized the decellularized pericardial surface when seeded and grown for 30 days in static culture. Collagen assays and transmission electron microscopy analysis showed limited reductions in collagen with processing; yet glycosaminoglycan assays showed great reductions in the processed pericardium relative to native cusps. Decellularized pericardium had comparatively low mechanical properties among the groups studied; yet the stiffness was comparatively similar to the native cusps and demonstrated a lack of cytotoxicity. Suture retention, accelerated wear, and hydrodynamic testing of prototype decellularized and decell‐sterilized valves showed positive functionality. Sterilized tissue could mimic valvular mechanical environment in vitro, therefore making it a viable potential candidate for off‐the‐shelf tissue‐engineered valvular applications.

A Comprehensive Comparison of Bovine and Porcine Decellularized Pericardia: New Insights for Surgical Applications

“…In similar settings, this biomechanical property appeared to be strongly reduced by GA-treatment (e.g., elastic phase), by confirming previously revealed rigidity of these clinically applied biomaterials [34,55,66]. As generally documented [14,66,67], a similar ability of decellularized bovine pericardium to withstand tensile load as its native counterpart -differently from porcine one -is apparent [55][56][57]. These aptitudes seem to be intrinsically related to a species-specific biomechanical response of analyzed tissues, since they were observed also after the application of different extraction protocols.…”

“…The reduction of sGAGs has been described as being detrimental on the biomechanical behavior of connective tissues [64,65]; however, TRICOL decellularized scaffolds likely revealed only a tendency to an increased compliance under tensile load with respect to their original counterpart. In similar settings, this biomechanical property appeared to be strongly reduced by GA-treatment (e.g., elastic phase), by confirming previously revealed rigidity of these clinically applied biomaterials [34,55,66]. As generally documented [14,66,67], a similar ability of decellularized bovine pericardium to withstand tensile load as its native counterpart -differently from porcine one -is apparent [55][56][57].…”

“…Decellularization induces a decrease in the original amount of sulfated GAGs, as observed earlier by our and other groups [12,15,[55][56][57]. Although the loss of these weakly ECM-linked molecules might be supposed as beneficial to facilitate diffusion during decellularization and repopulation [56], its effects should be closely evaluated in a clinical application perspective.…”

“…In fact, pericardial tissues are characterized by an ECM scaffolding, which is able to guarantee pliability, conformability, and resistance to compression, but also to promote healing by repopulating cells. Moreover, they can be easily sutured by providing sufficient strength [55] and they are not immediately resorbable, thus constituting an efficient barrier. All of these features render them excellent biological membranes for guided tissue regeneration.…”

“…GA-treated pericardium, as applied in several reconstructive surgeries, is known to be poorly cytocompatible [69] and no comprehensive data are available with regard to ISO 10993-5 evaluations for commercial decellularized pericardia already used in the clinics, although declared biocompatible. In most cytocompatibility assays, murine immortalized lines, e.g., NIH/3T3 or L929, or other animals-derived cells are preferred [55,66,67]. In our investigation, we specifically selected human cytotypes to simulate the effects that are exerted by decellularized scaffolds in the in vivo human setting.…”