Tissue engineering degradability

Optimum chemical degradation behavior (often to a large extent a water-permeation problem) for surgical sutures, scaffold materials for tissue engineering, degradable screws in orthopaedic surgery and so on. 

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. 

Pego AP, Siebum SB, Luyn MJAV, et al. Preparation of degradable porous structures based on 1,3-trimethylene carbonate and D,L-lactide(co)polymers for heart tissue engineering. Tissue Eng, 2003, 9, 981 994. 

Concurrent with these investigations, polyphosphazene matrices, functionalized with aminoacid esters or with imidazole groups, became of importance because of their tissue engineering aspects in bone regeneration [655,656,679], treatment of periodontal diseases [657], and nerve reconstruction problems [680-682] in which the remarkable bio compatibility of POP matrices was coupled with their tuneable bio degradability. 

PGA was one of the very first degradable polymers ever investigated for biomedical use. PGA found favor as a degradable suture, and has been actively used since 1970 [45 -7]. Because PGA is poorly soluble in many common solvents, limited research has been conducted with PGA-based drug delivery devices. Instead, most recent research has focused on short-term tissue engineering scaffolds. PGA is often fabricated into a mesh network and has been used as a scaffold for bone [48-51], cartilage [52-54], tendon [55, 56], and tooth [57]. 

Chitosan has found many biomedical applications, including tissue engineering approaches. Enzymes such as chitosanase and lysozyme can degrade chitosan. However, chitosan is easily soluble in the presence of acid, and generally insoluble in neutral conditions as well as in most organic solvents due to the existence of amino groups and the high crystallinity. Therefore, many derivatives have been reported to enhance the solubility and processability of this polymer. 

Polymers from renewable sources have received great attention over many years, predominantly due to the environmental concerns. Potato starch is a promising biopol5mier for various food, pharmaceutical, and biomedical applications because of its higher water solubility that raises its degradability and speed of degradation non-toxicity, easy availability, and abundancy. The role of starch for tissue engineering of bone, bone fixation, carrier for the controlled release... 

Cima, L. G., Vacanti, J. P., Vacant, C., Ingber, D., Mooney, D., and Langer, R. (1991). Tissue engineering by cell transplantation using degradable polymer substrates. /. Biomech. Eng. 113,143-151. 

Tissue engineering is an interdisciplinary approach aiming at the generation of new functional living tissue. The new tissue should be fabricated using living cells associated with a degradable porous scaffold. The scaffold... 

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