No abstract

Lubrication is key for the efficient function of devices and tissues with moving surfaces, such as articulating joints, ocular surfaces and the lungs. Indeed, lubrication dysfunction leads to increased friction and degeneration of these systems. Here, we present a polymer-peptide surface coating platform to non-covalently bind hyaluronic acid (HA), a natural lubricant in the body. Tissue surfaces treated with the HA-binding system exhibited higher lubricity values, and in vivo were able to retain HA in the articular joint and to bind ocular tissue surfaces. Biomaterials-mediated strategies that locally bind and concentrate HA could provide physical and biological benefits when used to treat tissue-lubricating dysfunction and to coat medical devices.

Metastasis begins with the escape, or dissemination, of cancer cells from the primary tumor. We recently demonstrated that tumors preferentially disseminate into collagen I and not into basement membrane protein gels (Matrigel). In this study, we used synthetic polymer systems to define material properties that could induce dissemination into Matrigel. We first specifically varied rigidity by varying the crosslinking density of poly(ethylene glycol) (PEG) networks within Matrigel scaffolds. Increased microenvironmental rigidity limited epithelial growth but did not promote dissemination. We next incorporated adhesive signals into the PEG network using peptide-conjugated cyclodextrin (α-CDYRGDS) rings. The α-CDYRGDS rings threaded along the PEG polymers, enabling independent control of matrix mechanics, adhesive peptide composition, and adhesive density. Adhesive PEG networks induced dissemination of normal and malignant mammary epithelial cells at intermediate values of adhesion and rigidity. Our data reveal that microenvironmental signals can induce dissemination of normal and malignant epithelial cells without requiring the fibrillar structure of collagen I or containing collagen I-specific adhesion sequences. Finally, the nanobiomaterials and assays developed in this study are generally useful both in 3D culture of primary mammalian tissues and in the systematic evaluation of the specific role of mechanical and adhesive inputs on 3D tumor growth, invasion, and dissemination.

Poly(ethylene glycol) (PEG)-based hydrogels are extensively used in a variety of biomedical applications due to ease of synthesis and tissue-like properties. Recently, there have been varied reports regarding PEG hydrogel’s degradation kinetics and in vivo host response. In particular, these studies suggest that the surrounding tissue environment could play a critical role in defining the inflammatory response and degradation kinetics of PEG implants. In the present study we demonstrated a potential mechanism of PEG hydrogel degradation, and in addition we show potential evidence of the role of the surrounding tissue environment on producing variable inflammatory responses.