′Ome is where the Wound is: Biomarkers of Healing in Chronic Diabetic Foot Ulcers

Of the approximate 30 million Americans that suffer from Type 2 diabetes, 25% will develop a foot ulcer during their lifetime that often exhibit impaired healing with a cost of diagnosis and treatment exceeding $250 billion per year. These chronic wounds require continuous care and treatment to promote healing and prevent infection. To provide insight into the biochemical and molecular mechanisms underlying diabetic foot ulceration that are currently unclear, we sought to define biomarkers as an objective biologic measurement and evaluation of the normal versus pathological biological processes leading to wound healing. The objective is to discover and validate proteins that may predict what patient will heal or not. These biomarkers can thus be used for diagnosis, prognosis and for targeted therapies. Our approach was to obtain patient plasma samples from current diabetic and non‐diabetic patients with foot ulcers and utilize both genomic and proteomic approaches to discover lead molecules. Debridement of the wound yielded the sample, blood collected (aliquot of whole blood or serum was for RNA analysis), centrifugation and protease inhibitors added, aliquoted and frozen. One aliquot was used for Luminex 18 flow cytometry‐based cytokine analyses. Another aliquot was immunodepleted of the 12 most abundant proteins comprising 95% of total plasma protein content and separated and identified by electrospray ionization mass spectrometry. Bioinformatics was then used for protein identification and quantification of samples. Patients returned bimonthly for medical assessment: wound size, cardiovascular, diabetes, and physical data with follow‐up samples obtained and processed accordingly. The proteomics and genomics discovery phases yielded an increase in RANTES (CCL5), CXCL2 (GRO2), and Leucine Rich Alpha‐2‐ glycoprotein in non‐healing patients whereas there was an increase in interleukin IL‐8, granulocyte colony stimulating factor (G‐CSF), colony stimulating factor‐2, matrix metalloprotease 7, Alpha‐2‐HS‐glycoprotein, and Kininogen 1 in healing patients. We are currently validating these results in archived patient samples and assaying more patients to yield a further understanding of the factors for prediction of wound healing in diabetic foot ulcers. Identification of biomarkers of wound healing in DFU will allow for better clinical diagnosis, treatments and new targets, to prevent complications and non‐traumatic amputations to improve patient quality of life and reduce financial burdens. Support or Funding Information Supported by a Pilot Grant from RFUMS/DePaul University and NIH OD010662 (MJG).