Tapping basement membrane motifs: Oral junctional epithelium for surface-mediated soft tissue attachment to prevent failure of percutaneous devices.

Teeth, long-lasting percutaneous organs, feature soft tissue attachment through adhesive structures, hemidesmosomes, in the junctional epithelium basement membrane adjacent to teeth. This soft tissue attachment prevents bacterial infection of the tooth despite the rich - and harsh - microbial composition of the oral cavity. Conversely, millions of percutaneous devices (catheters, dental, and orthopedic implants) fail from infection yearly. Standard of care antibiotic usage fuels antimicrobial resistance and is frequently ineffective. Infection prevention strategies, like for dental implants, have failed in generating durable soft tissue adhesion - like that seen with the tooth - to prevent bacterial colonization at the tissue-device interface. Here, inspired by the impervious natural attachment of the junctional epithelium to teeth, we synthesized four cell adhesion peptide (CAPs) nanocoatings, derived from basement membranes, to promote percutaneous device soft tissue attachment. The two leading nanocoatings upregulated integrin-mediated hemidesmosomes, selectively increased keratinocyte proliferation compared to fibroblasts, which cannot form hemidesmosomes, and expression of junctional epithelium adhesive markers. CAP nanocoatings displayed marked durability under simulated clinical conditions and the top performer CAP nanocoating was validated in a percutaneous implant murine model. Basement membrane CAP nanocoatings, inspired by the tooth and junctional epithelium, may provide an alternative anti-infective strategy for percutaneous devices to mitigate the worldwide threat of antimicrobial resistance. STATEMENT OF SIGNIFICANCE: Prevention and management of medical device infection is a significant healthcare challenge. Overzealous antibiotic use has motivated alternative material innovations to prevent infection. Here, we report implant cell adhesion peptide nanocoatings that mimic a long-lasting, natural "medical device," the tooth, through formation of cell adhesive structures called hemidesmosomes. Such nanocoatings sidestep the use of antimicrobial or antibiotic elements to form a soft-tissue seal around implants. The top performing nanocoatings prompted expression of hemidesmosomes and defensive factors to mimic the tooth and was validated in an animal model. Application of cell adhesion peptide nanocoatings may provide an alternative to preventing, rather that necessarily treating, medical device infection across a range of device indications, like dental implants.

Unraveling dominant surface physicochemistry to build antimicrobial peptide coatings with supramolecular amphiphiles.

With the increasing threat from antibiotic-resistant bacteria, surface modification with antimicrobial peptides (AMP) has been promisingly explored for preventing bacterial infections. Little is known about the critical factors that govern AMP-surface interactions to obtain stable and active coatings. Here, we systematically monitored the adsorption of a designer amphipathic AMP, GL13K, on model surfaces. Self-assembly of the GL13K peptides formed supramolecular amphiphiles that highly adsorbed on negatively charged, polar hydroxyapatite-coated sensors. We further tuned surface charge and/or surface polarity with self-assembled monolayers (SAMs) on Au sensors and studied their interactions with adsorbed GL13K. We determined that the surface polarity of the SAM-coated sensors instead of their surface charge was the dominant factor governing AMP/substrate interactions via hydrogen bonding. Our findings will instruct the universal design of efficient self-assembled AMP coatings on biomaterials, biomedical devices and/or natural tissues.

Cellular-Based Selections Aid Yeast-Display Discovery of Genuine Cell-Binding Ligands: Targeting Oncology Vascular Biomarker CD276.

Yeast surface display is a proven tool for the selection and evolution of ligands with novel binding activity. Selections from yeast surface display libraries against transmembrane targets are generally carried out using recombinant soluble extracellular domains. Unfortunately, these molecules may not be good models of their true, membrane-bound form for a variety of reasons. Such selection campaigns often yield ligands that bind a recombinant target but not target-expressing cells or tissues. Advances in cell-based selections with yeast surface display may aid the frequency of evolving ligands that do bind true, membrane-bound antigens. This study aims to evaluate ligand selection strategies using both soluble target-driven and cellular selection techniques to determine which methods yield translatable ligands most efficiently and generate novel binders against CD276 (B7-H3) and Thy1, two promising tumor vasculature targets. Out of four ligand selection campaigns carried out using only soluble extracellular domains, only an affibody library sorted against CD276 yielded translatable binders. In contrast, fibronectin domains against CD276 and affibodies against CD276 were discovered in campaigns that either combined soluble target and cellular selection methods or used cellular selection methods alone. A high frequency of non target-specific ligands discovered from the use of cellular selection methods alone motivated the development of a depletion scheme using disadhered, antigen-negative mammalian cells as a blocking agent. Affinity maturation of CD276-binding affibodies by error-prone PCR and helix walking resulted in strong, specific cellular CD276 affinity ( Kd = 0.9 ± 0.6 nM). Collectively, these results motivate the use of cellular selections in tandem with recombinant selections and introduce promising affibody molecules specific to CD276 for further applications.