Tissue Engineering and Regenerative Medicine

Consequential to its essential role as a mechanical support and affinity regulator in extracellular matrices, collagen constitutes a highly sought after scaffolding material for regeneration and healing applications. However, substantiated concerns have been raised with regard to quality and safety of animal tissue-extracted collagen, particularly in relation to its immunogenicity, risk of disease transmission and overall quality and consistency. In parallel, contamination with undesirable cellular factors can significantly impair its bioactivity, vis-a-vis its impact on cell recruitment, proliferation and differentiation.Large scale production of recombinant human collagen type-I (rhCOL1) in the tobacco plant provides a source of a homogenic, heterotrimeric, thermally stable “virgin” collagen which self assembles to fine homogenous fibrils displaying intact binding sites and has been applied to form numerous functional scaffolds for tissue engineering and regenerative medicine which have already reached the clinic. In addition we have shown that rhCOL1 can form liquid crystal structures, yielding well-organized and mechanically strong fibers 6 times tougher than human achiles tendon, two properties indispensable to extracellular matrix (ECM) mimicry. Combining resiline, an elastic protein derived from insects, further increased collagen fiber toughness and strain at break. Injections of fibrillated rhCOL1 combined with PRP (platlet rich plasma) to patients suffer from tendinopathy (in tennis elbow) forms in situ matrix composed of collagen and fibrin. The rhCOL1/PRP matrix reduces inflammation and promotes cell proliferation and tissue healing, promotes in situ growth factors generation and release while gradually degrading. Both in vivo and in vitro studies showed superior performance of rhCOL1/PRP compared to PRP alone.