Chronic wounds, including diabetic ulcers, represent a tremendous burden on the US health care system. Some of the current treatment methods include skin substitutes, vacuum assisted closure and topical adjuvants. However in a significant number of cases, chronic wounds do not respond to treatment. The major difference between acute and chronic wounds is that the latter fails to progress to the proliferative phase from the inflammatory phase of healing, which also makes chronic wounds more susceptible to infection. Topical application of chemokines to assist with the transition to proliferative phase demonstrates limited success, as these are rapidly degraded in the highly proteolytic wound environment. Another difference is that a large number of antimicrobial peptides, including LL-37, have been shown to be absent/repressed in chronic wounds. Hyperglycemic chronic wound environment is also associated with accumulation of advanced glycation endproducts (AGEs), which greatly contributes to persistent inflammation in diabetic wounds and interferes with growth factor signaling pathways. It has been shown that the receptor of AGEs (RAGE) can be blocked by the soluble form of RAGE (sRAGE). In this study, it is proposed to use elastin like polypeptides (ELP) as the vehicle to deliver two important peptides: sRAGE, to target the chronic inflammation, and the antimicrobial peptide LL-37, to serve as an anti-infection agent, which also promotes angiogenesis and re- epithelisation. In order to assess the chemokine activity recovery properties of sRAGE, this therapeutic will be tested together with a dermal growth factor (SDF-1?). The therapeutic proteins will be genetically fused to micelle forming ELP nanoparticles (NPs), which will allow for their protection from surroundings and their sustained release. In addition, these particles self-assemble in response to temperature changes, can be expressed and purified inexpensively and are suitable to be incorporated into other treatment modalities currently in use, such as skin substitutes.
The specific aims of the proposed study are: 1) Construct and characterize sRAGE/SDF-1? micelle NPs in vitro; 2) Construct and characterize LL-37 micelle NPs in vitro; 3) Evaluate the stability and efficacy of therapeutic NPs targeting several aspects of chronic wounds in vivo. The results of this study will constitute a major step towards synergistically targeting the chronic inflammation and infection within the wound environment, which play a major role in the arrest of healing process in chronic wounds. In addition, due to their wide biological activities, the developed therapeutic NPs can be potentially used in the treatment of a variety of tissues and biomedical problems.
Chronic wounds are susceptible to infection and constitute a major health problem with the rise of diabetes and obesity worldwide. In the proposed project, the extended inflammation and infection state of chronic wounds will be targeted via an antimicrobial peptide and an anti-inflammatory protein, which will be delivered via protein-based nanoparticles. This will lead to a new generation of therapies targeting the bottleneck in chronic wounds, which can be easily incorporated into clinical wound applications currently in use.
