Regenerative Bandage Enhances Dermal Wound Healing

A new study describes how a novel antioxidant bandage heals wounds four times faster by delivering stromal cell derived factor-1 (SDF-1), a protein that promotes cell repair.

Developed by researchers at Northwestern University (NU, Chicago, IL, USA), the regenerative bandage was created using a Poly polyethylene glycol citrate-co-N-isopropylacrylamide (PPCN) thermoresponsive polymer with intrinsic antioxidant properties to counter inflammation, with SDF-1 entrapped into it via gelation. The PPCN polymer is applied to the wound bed in liquid form, solidifying into a gel when exposed to body temperature. It then slowly releases SDF-1 into the wound, hastening the body's ability to repair itself.

SDF-1 works by recruiting stem cells to the wound and creating new blood vessels that increase blood circulation. When the researcher compared wound repair timelines of SDF-1 in diabetic mice, they found that wounds treated with sustained release PPCN + SDF-1 had the shortest time for complete healing (24 days) and exhibited accelerated granulation tissue production, epithelial maturation, and the highest density of perfused blood vessels, as demonstrated by CXCR-4 activity, a receptor specific to SDF-1. The study was published on July 26, 2016, in the Journal of Controlled Release.

“We incorporated a protein that our body naturally uses to attract repair cells to an injury site. When the protein is secreted, progenitor cells or stem cells come to the wound and make blood vessels, which are part of the repair process,” said senior author professor of biomedical engineering Guillermo Ameer, ScD. “The repair process is impaired in people with diabetes. By mimicking the repair process that happens in a healthy body, we have demonstrated a promising new way to treat diabetic wounds.”

“Patients have to change the wound dressing often, which can rip off healing tissue and re-injure the site. The ability of the material to reversibly go from liquid to solid with temperature changes protects the wound,” added Professor Ameer. “Our material conforms to the shape and dimensions of the wound and can be rinsed off with cooled saline, if needed. This material characteristic can protect the regenerating tissue during dressing changes.”

Diabetes patients often suffer from nerve and circulation problems in the feet, which reduce their perception of pain. The nerve pathways that ensure that weight is automatically transferred from one foot to the other during prolonged standing are disrupted, and as a result, diabetics do not notice that their toes, heels, or the balls of their feet are too heavily loaded. The foot receives no relief, and pressure sores, ulcers, and infections may go unnoticed. Serious cases may even lead to amputation.

SDF1 is a chemokine that activates leukocytes and is strongly chemotactic for lymphocytes. During embryogenesis it directs the migration of hematopoietic cells from fetal liver to bone marrow and the formation of large blood vessels. In adulthood, it plays an important role in angiogenesis by recruiting endothelial progenitor cells (EPCs) from the bone marrow. It is this function that also makes it a very important factor in carcinogenesis and neovascularization linked to tumor progression and metastasis.

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