Cigarette smoke impedes wound healing

May 1, 2005

Riverside, Calif. — Fifty years after the negative effects of cigarette smoke first became broadly known, doctors are still discovering the magnitude of and mechanisms behind its toxic assault on the body. Dermatologists are particularly interested in discoveries over recent years that cigarette smoke results in premature aging of the skin and decreases blood flow to wound sites, resulting in retarded granulation tissue development and remodeling during wound healing and greater scarring.

The research of Manuela Martins-Green, M.D., University of California, Riverside, focuses on the effects of environmental chemicals on basic cellular and molecular mechanisms of healing.

Second-hand smoke She says indoor second-hand smoke is not appreciated fully as an environmental toxin because it is so ubiquitous. She adds that smoke lingers everywhere, long after that last drag.

Those chemicals constantly aerosolize and contaminate the indoor air supply.

"Nicotine, tar, nitric oxide and carbon monoxide levels are at least two times more abundant in second-hand smoke, while carcinogenic aromatics are preferentially formed in second-hand smoke," Dr. Martins-Green says.

Research findings Working with cell cultures and animal models exposed to levels of second-hand smoke commonly found in an indoor environment, she has discovered that moderate levels of smoke stimulate cellular proteins that enhance fibroblast survival even while altering their cytoskeletal structure to increase cell adhesion.

"This inhibits fibroblast migration from the periphery into the wound site. Fibroblasts accumulate at the edges; this prevents normal contraction and closure of the wound," she says.

Not only does the wound heal more slowly, this altered process also results in greater scarring.

Dr. Martins-Green says that while her work has focused on surface wounds, the exposure and the effect appear to be systemic rather than topical in nature. Thus, her findings are likely to apply to internal healing and possibly to broader immune system responses as well.

Dr. Martins-Green minimizes the significance of anecdotal and limited exposure to the toxins of second-hand smoke; a few hours spent in a smoky bar will not have much effect on wound healing, she says. But long-term or chronic exposure should be avoided. She is particularly concerned with the impact on the development of children, an area of research where even less is known.

The body does have an ability to recover from exposure to the toxins of smoking, though the pace and extent of that recovery has not been well documented.

Next phase of work The next phase of Dr. Martins-Green's work is to fractionate components of second-hand smoke to identify the ones that individually or synergistically produce these cellular effects. The goal is not a "safer" cigarette but to identify, isolate and harness mechanisms, such as enhanced cell survival and inhibition of cell migration that might be used beneficially in another setting, such as in cancer treatment.

Initial work has already demonstrated that those cellular functions are not a package caused by the same chemicals, but rather are individual functions stimulated by separate fractionated components of the smoke. She hopes to publish this work in about a year.