Biomaterials for Tissue Engineering – Bioabsorbability/Degradation in Marine Biotechnology

Biomaterials are most commonly recognized as scaffolds, potentially able to perform useful functions such as (i) promoting cell attachment, survival, proliferation and differentiation while possessing minimum toxicity in the original and biodegraded/bioabsorbed forms; (ii) allowing the transport or delivery of gases, nutrients and growth factors; and (iii) offering sufficient structural support while being degradable/absorbable at appropriate rates for tissue regeneration. Biodegradable/bioabsorbable materials intended to be used as implantable drug eluting scaffolds must fulfil several requirements in order to be considered for clinical integration. They must not elicit abnormal responses in local tissues and should neither produce local nor systemic toxic or carcinogenic side-effects. First and foremost, biodegradable/bioabsorbable platforms should serve their intended scaffolding and cell-signaling functions whilst degrading/absorbing into non-toxic metabolites. Breakdown of artificially manufactured scaffolds requires rigorous toxicological evaluation of each constituent component. Particularly when ambitious strategies involving the use of composite materials with integrated trophic factors are concerned, the importance of material biocompatibility evaluation rises significantly. The desired notion of effecting synergistic actions of GF (growth factor) and other incorporated component requires careful consideration of factor concentrations and release mechanisms in order to avoid potentially harmful overdosing. It therefore remains a priority to conduct systematic and rigorous toxicological studies – both in vitro and in vivo – to (1) eliminate grossly ineffective or toxic delivery platforms in order to (2) narrow down on potentially suitable candidate technologies as well as (3) ascertain any dose or time-dependencies which may influence the materials' suitabilities. Actually, the performance of many biomaterials depends largely on their degradation/absorbability behavior since the degradation/absorbability process may affect a range of events, such as cell growth, tissue regeneration, drug release, host response and material function. Biodegradable/bioabsorbable medical materials are those with the ability of functioning for a temporary period and to subsequently degrade/absorb in physiological conditions, under a controlled mechanism, into products easily eliminated in the body's metabolic pathways. The demands for biomaterials with the above-mentioned characteristics (controlled, predictable degradation/absorbability kinetics) included a wide range of biomedical applications (such as resorbable surgical sutures, matrices for the controlled release of drugs and scaffolds for tissue engineering) are becoming more and more crucial and urgent. Therefore, the aim to provide promising potentials of marine biotechnology for biomedical materials degradation/absorbability, and the relevant potential marine biotechnology related to enzymes are reviewed. It is indicated that strategies developed to obtain biomaterials with a controlled degradation/absorbability rate should be based on molecular design principles, such as the introduction of hydrolysable bonds into polymer backbones, copolymerization and blending techniques, crosslinking and surface modification methods, and inclusion of certain additives into polymeric matrices (e.g. excipients, drugs, salts, etc.). Meanwhile, controlled degradation/absorbability of biomedical materials by marine biotechnology-potential marine enzymes will have several advantages considering the high specificity of enzymes for their substrates and also because enzyme activity can be regulated by environmental conditions (e.g. pH, temperature, the presence of certain substances, like metal ions). In addition, the degradation/absorbability kinetics can be adjusted by the amount of encapsulated enzyme into the matrix.