Healing open wounds: The 'right' topical insulin can expedite closure

May 1, 2008

Researchers in the past have tried many different approaches to treating burn wounds and leg ulcers, including topical insulin, achieving mixed success. A recent study showed that the use of the right topical insulin could significantly speed up the wound healing process and wound closure.

Key Points

According to the results of a novel study, the treatment of such skin wounds with the right topical insulin can enhance the healing process of open wounds and significantly speed wound closure.

"The problem with burn wounds, as well as leg ulcers, is that these tissues are deplete of growth factors and nutrients that are so crucial to the normalcy and status quo of cell proliferation and wound healing.

Glucose is the essential source of energy required for mammalian cell proliferation, which reaches the wound via the blood supply. Dr. Kassem says the stress of a burn produces a hypermetabolic state that leads to peripheral insulin resistance and delays in healing.

"This is very much similar to the condition that occurs in diabetic chronic ulcers. Here, in addition to the diabetic relative deficiency of insulin, there is a local insulin resistance and a disturbed blood supply to the ulcerated tissue, all of which contribute to the characteristically difficult and protracted healing process of these wounds," Dr. Kassem tells Dermatology Times.

According to Dr. Kassem, the idea of adding growth factors to wounds, such as second-degree burns or leg ulcers, is not really new. However, the media in which these growth factors are delivered is special.

Insulin as a catalyst

Dr. Kassem says that insulin has been tried before in past experiments as a wound healing catalyst, but successes were limited due to the size of the molecules used.

"Topical treatment of these ulcers with topical recombinant regular insulin failed, probably due to the large molecule size of this insulin that makes it difficult for its penetration into and absorption by the wounded tissue," Dr. Kassem says.

Dr. Kassem and his co-workers from Rambam Medical Center took the insulin theory one step further and decided to research the effects of a topical cream that contained an analogous insulin (humalogue) on the healing of second-degree burns in guinea pigs.

"We believe that the past experiments with insulin failed because of the type of insulin that was used. Humalogue, on the other hand, has a very small molecular size, allowing this insulin to better penetrate and be absorbed by the target tissues," Dr. Kassem says.

In the study, 21 guinea pigs received either 10U or 30U of analogous insulin per gram or placebo on the healing of a second-degree burn. The wounds were treated every two days for two weeks, and clinical measurements of the size and contraction of the burn wounds were recorded.

Biopsies from the center of the wounds were also taken for histological proof of healing success under time.

Results demonstrate that the wounds treated with 10U of humalogue showed some increase in the speed of closure compared to placebo, but those that received 30U of humalogue cream showed a significant improvement of the burn wounds in terms of wound contraction and the amount of developed adnexa, compared to those burn wounds that received placebo.

Dr. Kassem also noticed in the 30U humalogue-treated group that there was a relatively significant improvement in the number of new epidermal layers, and that the epidermal architecture was more obvious, organized and complete compared to the placebo group.

"We believe that the topical insulin shows its positive wound-healing effects because of its effects on the myofibroblasts which are responsible for the wound contraction.

"Wound contraction is a critical stage in chronic ulcer healing, and our study proved that topical insulin is useful in this important process, promoting a faster wound closure," Dr. Kassem says.

No side effects were seen in guinea pigs, including decrease in blood glucose levels.

Dr. Kassem hopes this topical therapy may become a very useful tool in treating leg ulcers and burn patients in the future.