We hypothesize that the fibroblast, or the myofibroblast, or both are the key cells responsible for keloid and hypertrophic scar formation. These cell types produce the bulk of extracellular matrix components during normal wound healing. In fact, experimental evidence suggests that hypertrophic scars and keloids result from excessive amounts of collagen and proteoglycan production or from lack of remodeling of these moieties.''-" We also hypothesize that wound tension is a major factor in the formation of both the hypertrophic scar and the keloid, which occurs secondary to direct biochemical changes induced by this mechanical factor. Most likely these changes are a direct result of the effect of wound tension on the metabolism of the fibroblast or myofibroblast. Fibroblasts have been shown to increase cell proliferation in response to mechanical tension in Mechanical stretch alone has been shown to raise the number of myofibroblasts in mouse dermis in Presumably, mechanical tension is also responsible for a positive balance in the collagen and proteoglycan production-degradation cycle in the wound healing under excessive tension. We are currently studying the effects of mechanical tension on wound healing at the biochemical level. The cause-effect relationship between hypertrophic scar and keloid formation as well as other etiologic factors, such as the age and race of the patient, remain more highly speculative and are not discussed here.
Oral cyclosporine was effective in the DEBR model for alopecia areata. All rats had a full pelage by 5 weeks of treatment with 10 mg/kg/d, 5 d/wk for 7 weeks. Studies in humans also have proven efficacy with doses of 6 mg/kg/d for 3 months in 6 patients. All patients experienced regrowth, and cosmetically acceptable regrowth was seen in 3 of 6 patients. Unfortunately, all patients relapsed within 3 months of discontinuation of cyclosporine. No evidence indicates that CsA can prevent hair loss during an active episode because reports have described patients taking CsA who developed alopecia areata while they were under treatment for unrelated conditions.