Abstract
Over 6.5 million individuals in the United States suffer from chronic wounds, resulting from interruption at a specific stage of the wound healing process. One of the most prevalent situations occurs when wound healing stops at the inflammatory stage; the wound becomes trapped in a prolonged state of inflammation and does not heal. Research shows that mesenchymal stem cells (MSCs) possess characteristics that can be utilized in improved chronic wound treatment. MSCs have the capability to accelerate wound closure by advancing angiogenesis and revascularization, two essential processes to wound healing. Existing treatment options incorporating MSCs currently lack adequate delivery mechanisms. One method being studied involves direct injection of MSCs into the wound area. While these studies provide evidence to support the use of MSCs for wound healing they also show low cell survival and engraftment in the wound area. The aim of the Maverakis lab is to develop a hydrogel delivery platform to maintain MSC viability at the wound bed as well as keep the cells localized, not allowing migration away from the wound site. Interactions between MSCs and the extracellular matrix (ECM) may be utilized as a mechanism for securing and maintaining viability of MSCs within a hydrogel delivery vehicle. Integrins are cell receptors found on MSCs that interact with the ECM via specific recognition sequences and initiate activation of cellular processes thought to be involved in wound healing. We hypothesized that stimulation of integrins on MSCs by ECM-like motifs would activate genes associated with the wound healing process supporting the use of a MSC laden delivery platform for wound healing therapies. The following study examines the interaction between integrins on MSCs and synthetically created peptides, thought to biomimic motifs naturally found in the ECM. Multiple synthetic peptides were first screened against K562 erythroleukemic cell lines to determine peptide interactions with specific integrins. Flow cytometry was then used to confirm MSC identity and evaluate expression level of integrins. Subsequently, an innovative method was developed to screen multiple peptides at one time to identify which peptide had the strongest interaction with MSCs. A co-culture method previously developed in the Maverakis lab was used as a platform to analyze the interaction between the selected peptide and MSCs. Gene expression analysis suggested maintenance of MSC multipotency and increased cell proliferation, two important aspects for utilizing this peptide in a hydrogel therapy. A concurrent study was conducted in mice to evaluate the degradation rates of varying hydrogel compositions. The results show that, by changing the ratios of the hydrogel components, the degradation rate of the hydrogel changes, demonstrating the tunable nature of the hydrogel. This study supports the continued development of a MSC based therapy consisting of a hydrogel seeded with synthetic peptide for chronic wound treatment.