Tissue engineering mechanical properties

Key Words Bioscaffold, Tissue Engineering, Mechanical Properties, Gas Foaming, Salt Leaching. 

In all types of PHAs, P4HB is of the most interest because it was used in the degradable scaffold that resulted in the first successful demonstration of a tissue-engineered tri-leaflet heart valve in a sheep animal model. Its copolymers with PHB and polyhydroxyoctanoate (PHO) are also promising in tissue engineering because of their nontoxic degradation products, stability in tissue culmre media, and the potential to tailor the mechanical and degradation properties to match soft tissue. 

Another example was done by Opitz et al. They utilized P4HB scaffolds to produce viable ovine blood vessels, and then implanted the blood vessels in the systemic circulation of sheep. Enzymatically derived vascular smooth muscle cells (vSMC) were seeded on the scaffolds both under pulsatile flow and static conditions. Mechanical properties of bioreactor-cultured blood vessels which were obtained from tissue engineering approached those of native aorta. 

Multiple applications for resilin-like polypeptides have garnered renewed research interest since the report of the first recombinant resilin in 2005. The excellent mechanical properties of the resilin-like polypeptides has directed investigation toward their use as high-performance materials and in tissue engineering applications. It is widely acknowledged that cells interact and take cues from their microenvironment and, therefore, the development of polymeric scaffolds to mimic the extracellular matrix and drive desired cell or tissue responses has been of wide interest. To this end, our laboratories have developed a modular resilin-like polypeptide (RLP12) (see Fig. 20) that contains not only twelve repeats of the... 

Chondrocytes respond biologically to mechanical stimuli, and this is called mechanotransduction. Understanding cellular responses to mechanical stimuli and how they can be related to tissue level characteristics has many applications in biology, tissue engineering and medical science. Information about the mechanical properties of chondrocytes is fundamental to such research. Micropipette aspiration has been applied to investigate the deformation of single chondrocytes (Jones et al., 1999). It was found that human chondrocytes behave like viscoelastic solids. The Young s modulus of normal chondrocytes appeared to be very variable, but was of the order of 0.65 + 0.63 kPa. However, the viscoelastic behaviour was not quantified. 

In Nature, there are many examples of protein and peptide molecular self-assembly. Of the genetically engineered fibrous proteins, collagen, spider silks, and elastin have received attention due to their mechanical and biological properties which can be used for biomaterials and tissue engineering. 

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