Instructive biomaterials for controlling cellular response and second harmonic generation imaging for quantitative characterization of collagen

Abstract

<p>Biomaterial - biological system interaction triggers complex response to the implanted materials. The response includes series of overlapping processes as coagulation, inflammation and wound healing. Immune cells interaction with the material interface during these processed play crucial role in successful outcome of the implanted biomaterials in tissue engineering, wound healing, and artificial organs. Biomaterial type and microenvironment influence host response. Here, we show ability to reprogram immune cell as macrophages towards either pro-inflammatory or anti-inflammatory response through polystyrene latex beads bearing different functional groups. Although there is a plethora of evidence illustrating how biomaterials influence functions of macrophages, there is a paucity of studies investigating the effects of polymer materials on both polarizations and phenotype differentiation. During the wound healing stage polymer can also influence healing quality and time through affecting formation of proteins as collagen. The quality of the healed wound depends on collagen organization. Achieving random collagen deposition that more closely resembles young, healthy skin would be a vast improvement upon the imperfections of the natural wound healing process and the integration of tissue engineered scaffolds. Collagen secreted around implant can play crucial role in the successful outcome of the implanted devices such as sensors or delivery devices. Our goal is to affect cells responsible for formation of collagen and its orientation during the wound healing process through polymer substrates. The library of materials used here is based on the basic amino acid arginine. Our results demonstrate the ability to exert a level of control over cellular responses through biomaterials and the potential to attain the desired outcome with exposure to these materials in wound healing and tissue engineering.</p> <p>Second harmonic generation imaging was used for quantitative characterization of collagen fiber deposited by cells. Non-centrosymmetric helical structure of collagen fibers allow us to image without any labels and minimum damage. One of the main applications of SHG microscopy has been imaging collagen fibers and determining fiber organization and parameters related to the second-order nonlinear susceptibility. We have used SHG microscopy to assess the quality of deposited collagen through quantitative analysis of collagen orientation and structure.</p>