Synthetic polymers engineered constructs

Abstract Synthetic polymers and biopolymers are extensively used within the field of tissue engineering. Some common examples of these materials include polylactic acid, polyglycolic acid, collagen, elastin, and various forms of polysaccharides. In terms of application, these materials are primarily used in the construction of scaffolds that aid in the local delivery of cells and growth factors, and in many cases fulfill a mechanical role in supporting physiologic loads that would otherwise be supported by a healthy tissue. In this review we will examine the development of scaffolds derived from biopolymers and their use with various cell types in the context of tissue engineering the nucleus pulposus of the intervertebral disc. 

The combination of sohd phase peptide synthesis with polymer chemistry has proven to be a versatile method for the preparation of polymer-peptide hybrids. Introduction of native ligation methods even allows the synthesis of polymer modified polypeptides and proteins via an entire organic chemistry approach. In the field of polymer chemistry—besides the advances in NCA polymerization, which will be discussed by others and is therefore not part of the scope of this review—controlled radical polymerization has been shown to be a robust technique, capable of creating well-defined biofunctional polymer architectures. Through protein engineering, methods have been estabhshed that enable the construction of tailor-made proteins, which can be functionalized with synthetic polymer chains in a highly defined manner. 

In this review the different synthetic strategies for constructing polymer-peptide hybrids will be discussed, as well as some of the characteristic features of the materials. The complexity of the hybrid structures prepared will increase as this review progresses, starting with the controlled polymerization of peptide-containing monomers and later covering the creation of block copolymer structures via a protein engineering approach. 

Natural polymers such as collagen, elastin, and fibrin make up much of the body s native extracellular matrix (ECM), and they were explored as platforms for tissue engineered constructs [34,47 9]. Polysaccharides such as chitosan, starch, alginate, and dextran were also studied for these purposes. Simultaneously, silk fibroin was widely explored for vascular applications due to its higher mechanical properties in comparison to other natural polymers, such as fibrin [48]. The utilization of natural polymers to create tissue-engineered scaffolds has yielded promising results, both in vitro and in vivo, due in part to the enhanced bioactivity provided by materials normally found within the human body [50]. However, their mechanical response is usually below the required values therefore, synthetic polymers have been explored to achieve the desired properties. 

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