Studies on the mechanism of action of salicylates. VI. Effect of topical application of retinoic acid on wound-healing retardation action of salicylic acid

Retinoids and Wound Healing

BACKGROUND

Retinoids are widely used in dermatology and may play a role in wound healing. The exact role of retinoids in wounds is confusing and controversial, however. Systemic retinoids are presumed to be detrimental to wound healing; however, this standard is based on isolated reports.

OBJECTIVE

The objective was to provide a critical review of the available literature regarding the role of both topical and systemic retinoids in various aspects of wound healing.

CONCLUSIONS

Pretreatment with retinoids likely promotes wound healing after facial resurfacing procedures and full- or partial-thickness wounds. While the evidence is mixed regarding the effects of retinoids applied to fresh and healing wounds, the majority of the evidence available shows favorable wound-healing properties in this setting. The medical-legal standard regarding the avoidance of facial resurfacing and surgical procedures in patients on or recently completing a course of systemic retinoids was likely prematurely established.

A double-blind, placebo-controlled trial of acitretin for the treatment of psoriasis

Acitretin, the active metabolite of etretinate, has the clinical advantage of a much shorter terminal elimination half-life. We report the results of a double-blind, placebo-controlled trial of acitretin (Soriatane) in 15 patients with moderate to severe psoriasis. Patients received 25 mg or 50 mg daily of acitretin or placebo in a double-blind fashion for 8 weeks and then were given 25 to 75 mg acitretin daily during an open study. Only two placebo patients completed the double-blind phase; one patient's psoriasis worsened, and one showed no significant change. All 15 patients then completed at least 8 weeks with 25 to 75 mg acitretin daily, with a moderate change in erythema, scaling, and induration (mean 28% to 37% improvement) but with minimal change in the percentage of body surface area involved. Prolonged treatment (greater than or equal to 20 weeks) with acitretin resulted in further significant improvement and a 44% reduction of involved surface area from baseline.

Effect of dietary supplementation with vitamin A on arterial healing in rats

The effect of dietary supplementation with vitamin A on the healing of rat aortas was studied. Rats were divided into two groups: rats fed a standard chow and rats fed the chow supplemented with 150 IU vitamin A palmitate/g diet. Seven rats from each group were fed with the above diets for 7 days, killed with ether, and the abdominal aorta excised and assayed for hydroxyproline content and collagenase activity. Ten rats from each group were fed for 7 days on the above diets and then underwent a longitudinal aortotomy which was sutured with prolene sutures under pentobarbital anesthesia. The rats were maintained on their respective diets for 7 days and then killed with ether, their abdominal aorta was excised and both the segment with the arteriotomy and the adjacent distal normal segment were analyzed for hydroxyproline content and collagenase activity. Seven rats from each group were fed with the above diets and then underwent transverse division of the abdominal aorta and reanastomosis using nylon sutures under pentobarbital anesthesia. Rats were maintained on their respective diets throughout the postoperative period. Seven days later, all rats were killed with ether and the bursting strength of the aortic anastomoses was measured. The results showed that vitamin A supplementation in non-operated animals had no significant effect on aortic hydroxyproline content or collagenase activity. In rats undergoing longitudinal aortotomy and suture, there was a significant increase in hydroxyproline content both at the healing arteriotomy and at the adjacent non-wounded aorta in the vitamin A-supplemented group. There was also a significant increase in bursting strength of the healing aortic anastomosis in the vitamin A-supplemented rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of supplemental vitamin A on the healing of colon anastomosis

The effect of dietary supplementation with vitamin A on the healing of colon anastomoses was studied. Fifty adult male Sprague-Dawley rats were divided into two groups: (1) rats fed a standard chow which contains the equivalent of about 15 IU vitamin A/g diet; (2) rats fed the chow supplemented with an additional 150 IU vitamin A/g diet. Rats were prefed for 5 days; on Day 6 under ether anesthesia the colon was divided 1-in. distal to the ileocecal junction and then reanastomosed. The rats were maintained on the above diets for 5 days and killed on the sixth postoperative day with ether and the segment of colon containing the anastomosis was resected. In 15 rats of each group, the breaking strength of the anastomosis was measured. In the remaining 10 rats of each group, the bursting strength of the anastomotic site and a segment of normal distal colon was measured. Samples of colon from the anastomotic site and the normal segment were analyzed for hydroxyproline. There was a significant decrease in hydroxyproline content at the anastomotic site when compared to the normal distal colon segment in each group of rats (P less than 0.01). The hydroxyproline content of both normal colon and the anastomotic site was significantly higher in the vitamin A-supplemented rats than in the control diet rats (P less than 0.01). There was also a significant increase in bursting strength in the vitamin A-supplemented rats both of the anastomotic site (P less than 0.01) and of the normal colon segment (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of vitamin A on wound healing in rats with femoral fracture

Groups of healthy wounded rats with and without comminuted femoral fractures, and maintained on nutritionally complete commercial rat chow with and without supplemental vitamin A, were studied. The test wounds were standard dorsal skin incisions and s.c. polyvinyl alcohol sponge implants. In some experiments the rats were pair-fed; the rats with femoral fracture not receiving supplemental vitamin A were the lead group for determining food allowanced. In other experiments, the rats were allowed food ad libitum. We found that wound healing of rats with femoral fracture was increased when supplemental vitamin A was given, but the supplemental vitamin A did not completely obviate the adverse effects of fracture. The ratio of the breaking strengths of the skin incisions after formalin fixation to the breaking strengths of the incisions in the fresh state was higher in the unsupplemented rats, supporting the results of our earlier experiments that vitamin A increases the rate of collagen cross-linking.