The objectives of this study were to characterize fresh porcine menisci and develop a decellularization protocol with a view to the generation of a biocompatible and biomechanically functional scaffold for use in tissue engineering/regeneration of the meniscus. Menisci were decellularized by exposing the tissue to freeze-thaw cycles, incubation in hypotonic tris buffer, 0.1% (w/v) sodium dodecyl sulfate in hypotonic buffer plus protease inhibitors, nucleases, hypertonic buffer followed by disinfection using 0.1% (v/v) peracetic acid and final washing in phosphate-buffered saline. Histological, immunohistochemical, and biochemical analyses of the decellularized tissue confirmed the retention of the major structural proteins. There was, however, a 59.4% loss of glycosaminoglycans. The histoarchitecture was unchanged, and there was no evidence of the expression of the major xenogeneic epitope, galactose-alpha-1,3-galactose. Biocompatibility of the acellular scaffold was determined by using contact cytotoxicity and extract cytotoxicity tests. Decellularized tissue and extracts were not cytotoxic to cells. Biomechanical properties were determined by indentation and tensile tests, which confirmed the retention of biomechanical properties following decellularization. In conclusion, this study has generated data on the production of a biocompatible, biomechanically functional scaffold for use in meniscal repair.

This study aimed to produce an acellular human tissue scaffold with a view to recellularization with autologous cells to produce a tissue-engineered pericardium that can be used as a patch for cardiovascular repair. Human pericardia from cadaveric donors were treated sequentially with hypotonic buffer, SDS in hypotonic buffer, and a nuclease solution. Histological analysis of decellularized matrices showed that the human pericardial tissue retained its histioarchitecture and major structural proteins. There were no whole cells or cell fragments. There were no significant differences in the hydroxyproline (normal and denatured collagen) and glycosaminoglycan content of the tissue before and after decellularization (p > 0.05). There were no significant changes in the ultimate tensile strength after decellularization (p > 0.05). However, there was an increased extensibility when the tissue strips were cut parallel to the visualized collagen bundles (p = 0.005). No indication of contact or extract cytotoxicity was found when using human dermal fibroblasts and A549 cells. In summary, successful decellularization of the human pericardium was achieved producing a biocompatible matrix that retained the major structural components and strength of the native tissue.

Tissue engineering offers a promising solution to the replacement of anterior cruciate ligament. A decellularized porcine patella tendon scaffold was produced by immersing whole tissues sequentially in hypotonic buffer, 0.1% (w/v) sodium dodecyl sulfate (SDS) in hypotonic buffer, and nuclease solution prior to sterilization with 0.1% (w/v) peracetic acid. Initial studies revealed that primary human tenocytes would attach to, but failed to penetrate into, the decellularized scaffold. A novel use of ultrasonication was therefore developed to allow extrinsic cells to migrate into the acellular scaffold. Various intensities of ultrasonication were tested in order to produce a microscopically more open porous matrix without damaging the overall architecture of the scaffold. Ultrasonication treatment with the intensity of 360 W and a pulse time of 1 s for a total of 1 min was found to be the optimal treatment. This process did not have a significant effect upon the biochemical constituents (collagen, glycosaminoglycans), nor did it denature the collagen. Moreover, the acellular sonicated scaffold retained the essential biomechanical characteristics of the native tissue. Primary human tenocytes penetrated into the center of whole acellular sonicated scaffolds over a 3-week period in static culture. The viability of the cells in the center of the scaffold (depth of circa 2.5 mm) was, however, compromised. To circumvent the problem of nutrient limitation, acellular sonicated scaffolds were split into fascicular scaffolds (500 μm thick). Cells seeded onto the fascicular scaffolds penetrated throughout the scaffold and remained viable after 3 weeks of culture. This study has shown that an acellular biocompatible tendon scaffold can be produced using 0.1% (w/v) SDS and that ultrasonication can provide a novel method to enhance the recellularization of decellularized natural tissues.

A variety of conditions encountered in urology result in bladder dysfunction and the need for bioengineered tissue substitutes. Traditionally, a number of synthetic materials and natural matrices have been used in experimental and clinical settings. However, the production of functional bladder tissue replacements remains elusive. The urinary bladder sustains considerable structural deformation during its normal function and represents an ideal model tissue in which to study the effects of biomechanical simulation on tissue morphogenesis, differentiation, and function. However, the actual role of mechanical forces within the bladder has received little attention. A strategy in which in vitro-generated tissue constructs are conditioned by exposure to the same mechanical forces as they would encounter in vivo could potentially be used both in the development of functional tissue replacements and to further study the role of biomechanical signalling. The purpose of this review is to examine the role and structure-function relationship of the urinary bladder and, through consultation of the literature available on mechanotransduction and tissue engineering of alternative tissues, to determine the factors that need to be considered when biomechanically engineering a functional bladder.