Modular Self-Assembled Coatings for Biomaterials

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DESCRIPTION (provided by applicant): Many implanted biomaterials, including vascular grafts, corneal prostheses, urological prostheses, and cultured skin substitutes, function at tissue interfaces that would normally be lined with epithelia or endothelia. However, in most cases these devices do not adequately support the formation of epithelia or endothelia on their surfaces, making them prone to a host of complications including thrombogenesis, immunoreactivity, disregulation of cell growth around them, or poor barrier function. The long-term goal of this research is to develop coatings for implanted biomaterials capable of supporting the formation of functional epithelia and endothelia by mimicking the construction of their native substrates, basement membranes (BMs). BMs are exquisitely tailored protein architectures, and many signaling domains, peptide sequences, mechanical factors, and spatial patterns of ligands have been identified in them that influence the behavior of the epithelia and endothelia they support. However, integrating and tuning this complexity of multiple factors reliably in synthetic biomaterials coatings is currently challenging. The objective of this research is to design biomaterials coatings based on modular peptide co-assembly allowing the incorporation, adjustment, and optimization of many of these factors so as to elicit rapid and functional epithelialization or endothelialization. In addition, steps will be taken to avoid any potentially immunogenic combinations of peptides. The work is divided into four aims: Aim 1) Design a modular system of self-assembling peptides and protein domains where ligand identity, ligand clustering, and viscoelasticity can be independently and precisely adjusted; Aim 2) Identify any peptides or combinations of peptides that significantly raise the immunogenicity of the synthetic BMs; Aim 3) Using factorial experimentation, identify combinations of ligands, viscoelastic moduli, and spatial arrangements of ligands that lead to functional epithelialization and endothelialization; Aim 4) Apply synthetic BMs to existing biomaterials and re-evaluate epithelialization and endothelialization in vitro. This work will be accomplished by a collaborative team of engineers, immunologists, cell biologists, biophysicists, and surgeons by designing and investigating a series of peptides and protein domains capable of co-assembling into precisely defined hydrogels with independent control over ligand identity, ligand clustering on the nanoscale and micron-scale, and matrix viscoelasticity. Experimentally optimized coatings will be applied to commonly used ePTFE and collagen implant materials. The outcomes of this research will include coated prostheses that can be evaluated in large animal models in future investigations, as well as a self-assembling set of peptides that may additionally be useful for a variety of other biomedical applications, including 3-D cell culture or controlled therapeutic release. PUBLIC HEALTH RELEVANCE: This research will positively affect public health by introducing optimally tuned biomaterials coatings capable of supporting the rapid regeneration of epithelia and endothelia on synthetic surfaces, which in turn will result in the enhanced performance of implanted devices such as vascular prostheses, corneal implants, cultured skin substitutes, and other tissue engineered constructs.