Hypertrophic scar and keloid

Keloids in rural black South Africans. Part 1: general overview and essential fatty acid hypotheses for keloid formation and prevention

In the first part of this study a general overview on the hypertrophic scar and keloid phenomena regarding history, epidemiology, histopathology and aetiology, in general, together with an essential fatty acid approach as basis for hypotheses of keloid formation and prevention are given. Upon reviewing the literature in planning a strategy for prevention and treatment of keloids, one encounters an overwhelming amount of hypotheses on this topic. Based on a preliminary study on total fatty acid compositions in keloids, compared with normal skin of keloid prone and non-keloid prone patients, there can be argued as follows: an essential fatty acid deficiency of precursors and inflammatory competitors for arachidonic acid may be a factor in the multifactorial aetiology of keloid formations, and apart from a local essential fatty acid deficiency in the wound area, nutrition may also be a contributing factor in rural black South Africans. To confirm or refute the stated hypotheses of the role of essential fatty acids in keloid formation and prevention (outlined in this part of the study), dietary questionnaires and blood (plasma and red blood cell) phospholipid analyses for general information and true fatty acid intake and metabolism, respectively, in the diets of these patients (outlined in part II of this study), as well as a lipid model for keloid formations regarding phospholipids, triglycerides, cholesterol esters and free fatty acids (outlined in part III of this study), are given. The purpose of this comprehensive fatty acid study was an attempt to assess the enigma surrounding keloids and to end the nightmare of the plastic and reconstructive surgeon, since these dermal tumours are notoriously recurrent.

The effect of superpulsed carbon dioxide laser energy on keloid and normal dermal fibroblast secretion of growth factors: a serum-free study

An in vitro model was used to determine the effect of superpulsed CO2 laser energy on normal dermal and keloid-producing fibroblast proliferation and release of growth factors. Growth factors assayed included basic fibroblast growth factor (bFGF) and transforming growth factor beta1 (TGF-beta1). bFGF is mitogenic, inhibits collagen production, and stabilizes cellular phenotype. TGF-beta1 stimulates growth and collagen secretion and is thought to be integral to keloid formation. Growth in a serum-free medium allowed measurement of these growth factors without confounding variables. Keloid and normal dermal fibroblasts cell lines were established from facial skin samples using standard explant techniques. Samples consisted of three separate keloid and three separate normal dermal fibroblast cell lines. Cells were used at passage 4 to seed 24-well trays at a concentration of 6 x 10(4) cells per milliliter in serum-free medium. At 48 hours, 18.8 percent of each cell well was exposed to a fluence of 2.4, 4.7, and 7.3 J/cm2 using the superpulsed CO2 laser. Cell viability and counts were established at four time points: 0 (time of superpulsed CO2 laser treatment), 24, 72, and 120 hours. Supernatants were collected and assessed for bFGF and TGF-beta1 using a sandwich enzyme immunoassay. All cell lines demonstrated logarithmic growth through 120 hours (conclusion of experiment), with a statistically significant shorter population doubling time for keloid fibroblasts (p < 0.05). Use of the superpulsed CO2 laser shortened population doubling times relative to that of controls; the differences were statistically significant in keloid dermal fibroblasts when fluences of 2.4 and 4.7 J/cm2 were used (p < 0.05 and 0.01, respectively). bFGF was present in greater levels in normal dermal fibroblasts than in keloid dermal fibroblasts. Application of superpulsed CO2 demonstrated a trend toward increased bFGF secretion in both fibroblast types; the increase was significant in the keloid group at 4.7J/cm2. A consistent trend in suppression of TGF-beta1 was seen in both groups exposed to superpulsed CO2, with the maximal effect occurring at 4.7 J/cm2. Serum-free culture sustains logarithmic cell growth and allows growth factor measurement without confounding variables from serum-containing media. Superpulsed CO2 enhances fibroblast replication and seems to stimulate bFGF secretion and to inhibit TGF-beta1 secretion. Given the function of these growth factors, the application of superpulsed CO2 may support normalized wound healing. These findings may explain the beneficial effects of laser resurfacing on a cellular level and support the use of superpulsed CO2 in the management of keloid scar tissue.

Angiogenesis in pathological and surgical scars

We identified immunohistochemically vessels within cutaneous scars to test the hypothesis that they are qualitatively and quantitatively different in pathological and normally healing scars. The vascular density within and adjacent to 58 cutaneous scars was measured on histological sections stained for factor VIII-related antigen. Four scar types were studied; surgical scars (n = 25), hypertrophic scars (n = 10), keloid (n = 12), and periocular scars (n = 11). Statistical analyses were performed to test the hypothesis that vessel numbers were different in the varying types of scar. Results were also compared with mast cell counts previously derived from the same tissues. A significant reduction was found in the vascular density in keloids compared with surgical and hypertrophic scars (P < .05). No correlation was found between the vascular density and the number of mast cells in the lesions. We have shown quantitatively that keloids have a reduced vascular component compared with hypertrophic scars and normally healing surgical scars at periocular and systemic sites. The formation of keloid scars may be related to their reduced level of vascularization mediated through tissue hypoxia.

Hypertrophic or keloid scars?

Further attempts to achieve a clinical distinction between hypertrophic and keloid scars seem pointless. Research in recent years has shifted from the extracellular components towards the cells themselves. Much more work needs to be done to characterise the activities of the various cell lines and the mechanisms of their control. A key question is whether the cells are due to a different subpopulation of fibroblasts or whether they are normal wound-healing cells acting under some chemical or physical influence. Ultimately, most hypertrophic and keloid scars become flat and pale, although the time sequence is very variable and there is little understanding of the process of scar maturation. Meanwhile, the problem remains as a significant cause of human suffering deserving further investment of time and resources.