Maurizio Stella

Epidemiology and Risk Factors for Pathologic Scarring After Burn Wounds

OBJECTIVE To describe the clinical characteristics of postburn scars and determine the independent risk factors specific to these patients. While burns may generate widespread and disfiguring scars and have a dramatic influence on patient quality of life, the prevalence of postburn pathologic scarring is not well documented, and the impact of certain risk factors is poorly understood. METHODS A retrospective analysis was conducted of the clinical records of 703 patients (2440 anatomic burn sites) treated at the Turin Burn Outpatient Clinic between January 1994 and May 15, 2006. Prevalence and evolution time of postburn pathologic scarring were analyzed with univariate and multivariate risk factor analysis by sex, age, burn surface and full-thickness area, cause of the burn, wound healing time, type of burn treatment, number of surgical procedures, type of surgery, type of skin graft, and excision and graft timing. RESULTS Pathologic scarring was diagnosed in 540 patients (77%): 310 had hypertrophic scars (44%); 34, contractures (5%); and 196, hypertrophic-contracted scars (28%). The hypertrophic induction was assessed at a median of 23 days after reepithelialization and lasted 15 months (median). A nomogram, based on the multivariate regression model, showed that female sex, young age, burn sites on the neck and/or upper limbs, multiple surgical procedures, and meshed skin grafts were independent risk factors for postburn pathologic scarring (Dxy 0.30). CONCLUSION The identification of the principal risk factors for postburn pathologic scarring not only would be a valuable aid in early risk stratification but also might help in assessing outcomes adjusted for patient risk.

Toxic Epidermal Necrolysis Treated with Intravenous High-Dose Immunoglobulins: Our Experience

Background: Toxic epidermal necrolysis (TEN) is a rare severe acute exfoliative drug-induced skin disorder which has recently been ascribed to alterations in the control of keratinocyte apoptosis, mediated by an interaction between the cell surface death receptor Fas and its respective ligand. A therapeutic approach with intravenous immunoglobulins (IVIG) associated with pulse methylprednisolone, based on the inhibition of Fas-mediated keratinocyte death by naturally occurring Fas-blocking antibodies included in human immunoglobulin preparations, has produced good preliminary results. Objective: To analyse the efficacy of IVIG in the treatment of TEN. Patients: Nine patients with erythematous body surface area ranging from 38 to 85% and dermo-epidermal detachment from 4 to 37% were treated. Results: Eight patients were healed and 1 died of septic shock and multiple organ failure. Interruption of further epidermal detachment occurred after an average of 4.8 days from the onset of IVIG therapy. Complete wound healing occurred after an average of 12 days. Concerning complications, 3 out of 8 surviving patients had acute respiratory failure requiring mechanical ventilation and 1 acute renal failure was treated with dialysis. Late sequelae were limited to dyschromia and nail dystrophies. No hypertrophic scars were observed. Conclusion: IVIG therapy represents a safe and valid approach for TEN.

In vitro mechanical compression induces apoptosis and regulates cytokines release in hypertrophic scars.

Hypertrophic scars resulting from severe burns are usually treated by continuous elastic compression. Although pressure therapy reaches success rates of 60–85% its mechanisms of action are still poorly understood. In this study, apoptosis induction and release of interleukin‐1β (IL‐1β) and tumor necrosis factor‐α (TNF‐α) were evaluated in normal (n = 3) and hypertrophic (=7) scars from burns after in vitro mechanical compression. In the absence of compression (basal condition) apoptotic cells, scored using terminal deoxyribonucleotidyl transferase assay, were present after 24 hours in the derma of both normal scar (23 ± 0.4% of total cell) and hypertrophic scar (11.3 ± 1.4%). Mechanical compression (constant pressure of 35 mmHg for 24 hours) increased apoptotic cell percentage both in normal scar (29.5 ± 0.4%) and hypertrophic scar (29 ± 1.7%). IL‐1β released in the medium was undetectable in normal scar under basal conditions while in hypertrophic scar the IL‐1β concentration was 3.48 ± 0.2 ng/g. Compression in hypertrophic scar‐induced secretion of IL‐1β twofold higher compared to basal condition. (7.72 ± 0.2 ng/g). TNF‐α basal concentration measured in normal scar medium was 8.52 ± 4.01 ng/g and compression did not altered TNF‐α release (12.86 ± 7.84 ng/g). TNF‐α basal release was significantly higher in hypertrophic scar (14.74 ± 1.42 ng/g) compared to normal scar samples and TNF‐α secretion was diminished (3.52 ± 0.97 ng/g) after compression. In conclusion, in our in vitro model, mechanical compression resembling the clinical use of elastocompression was able to strongly increase apoptosis in the hypertrophic scar derma as observed during granulation tissue regression in normal wound healing. Moreover, the observed modulation of IL‐1β and TNF‐α release by mechanical loading could play a key role in hypertrophy regression induced by elastocompression. (WOUND REP REG 2003;11:331–336)

Circulating plasma factors induce tubular and glomerular alterations in septic burns patients

BackgroundSevere burn is a systemic illness often complicated by sepsis. Kidney is one of the organs invariably affected, and proteinuria is a constant clinical finding. We studied the relationships between proteinuria and patient outcome, severity of renal dysfunction and systemic inflammatory state in burns patients who developed sepsis-associated acute renal failure (ARF). We then tested the hypothesis that plasma in these patients induces apoptosis and functional alterations that could account for proteinuria and severity of renal dysfunction in tubular cells and podocytes.MethodsWe studied the correlation between proteinuria and indexes of systemic inflammation or renal function prospectively in 19 severe burns patients with septic shock and ARF, and we evaluated the effect of plasma on apoptosis, polarity and functional alterations in cultured human tubular cells and podocytes. As controls, we collected plasma from 10 burns patients with septic shock but without ARF, 10 burns patients with septic shock and ARF, 10 non-burns patients with septic shock without ARF, 10 chronic uremic patients and 10 healthy volunteers.ResultsSeptic burns patients with ARF presented a severe proteinuria that correlated to outcome, glomerular (creatinine/urea clearance) and tubular (fractional excretion of sodium and potassium) functional impairment and systemic inflammation (white blood cell (WBC) and platelet counts). Plasma from these patients induced a pro-apoptotic effect in tubular cells and podocytes that correlated with the extent of proteinuria. Plasma-induced apoptosis was significantly higher in septic severe burns patients with ARF with respect to those without ARF or with septic shock without burns. Moreover, plasma from septic burns patients induced an alteration of polarity in tubular cells, as well as reduced expression of the tight junction protein ZO-1 and of the endocytic receptor megalin. In podocytes, plasma from septic burns patients increased permeability to albumin and decreased the expression of the slit diaphragm protein nephrin.ConclusionPlasma from burns patients with sepsis-associated ARF contains factors that affect the function and survival of tubular cells and podocytes. These factors are likely to be involved in the pathogenesis of acute tubular injury and proteinuria, which is a negative prognostic factor and an index of renal involvement in the systemic inflammatory reaction.

Characterization of T-cell subsets infiltrating post-burn hypertrophic scar tissues

In this study, skin-infiltrating cells were characterized in both the active and remission phases of post-burn hypertrophic scar biopsies. Immunohistochemistry examination of active phase samples showed an abundant presence of Langerhans cells, T cells, macrophages, a low presence of natural killer cells and the lack of B lymphocytes. In active hypertrophic scars T lymphocytes infiltrate deep into the superficial dermis and are also observed in the epidermis: CD3+ cells were present at about 222 +/- 107 per 0.25 mm2. In particular the analysis of lymphocyte subpopulations showed that CD4+ T cells predominate in the dermis as well as in the epidermis of active hypertrophic scars whereas CD8+ cells were less well represented (CD4/CD8 ratio is 2.06). This distribution was also shown in remission phase samples and in normotrophic scar specimens, although the lymphocyte number was significantly lower. Approximately 70 per cent of T lymphocytes present in the tissue involved in active phase hypertrophic scar samples were activated (positive with anti-HLA-DR and IL-2 receptor antibodies) which is significantly higher than remission phase hypertrophic and normotrophic scars, in which positivity was 40 and 38 per cent, respectively. Upon activation, the lesional lymphocytes release several cytokines, locally and transiently, that interact with specific receptors in response to different stimulation. Central to the immune hypothesis of hypertrophic scars is that some of the T-cell lymphokines act on keratinocytes, fibroblasts and other cell types to induce changes characteristic of these scars. The presence and close proximity of activated T lymphocytes and antigen-presenting cells of various phenotypes in both the epidermis and dermis of hypertrophic tissues provides strong circumstantial evidence of a local immune response. However, the manner in which T cells achieve and maintain their activated state in hypertrophic tissues is not yet known, and both antigen-dependent and independent mechanisms may contribute.

Acute complex traumas of the lower limbs : a modern reconstructive approach with negative pressure therapy

Acute traumas of the lower limbs cause complex functional damage for the association of skin loss with exposed tendons, bones, and/or vessels, requiring a multidisciplinary approach. Once bone fixation and vascular repair have been carried out, the surgical treatment for skin damage is usually based on early coverage with conventional or microsurgical flaps. Negative pressure therapy can play a primary role in the management of the elderly or intensive care patients, where wounds are secondary to life‐threatening problems. A total of 35 patients with 37 acute traumatic wounds of the lower limbs were treated with vacuum‐assisted closure (VAC®) therapy for an average of 22 days (range 3–46 days). The sponge was applied the day after bone fixation, vascular repair, and surgical debridement of nonviable tissues, so as to obtain a better control of bleeding. After VAC® treatment, all patients quickly developed healthy granulation tissue and a significant reduction in both extent and depth of wounds. Split‐thickness skin grafts were used to cover granulation tissue in most of the cases (66%—24 cases), and then local flaps (13%—five cases) or direct sutures (8%—three cases). The wounds healed spontaneously without surgical management in four patients. One patient died during the treatment period for concomitant diseases. No relevant complications directly related to VAC® therapy were observed other than one case of severe pain in an amputated stump. The average follow‐up duration was 265 days (range 33–874 days). No further tegumentary reconstruction was required. VAC® therapy may represent a valid alternative to immediate reconstruction in selected cases of acute complex traumas of the lower limb and allows for a stable functional result, using a minimally invasive approach.

Preparation and Characterization of a Novel Skin Substitute

Autologous epidermal cell cultures (CEA) represent a possibility to treat extensive burn lesions, since they allow a significative surface expansion which cannot be achieved with other surgical techniques based on autologous grafting. Moreover currently available CEA preparations are difficult to handle and their take rate is unpredictable. This study aimed at producing and evaluating a new cutaneous biosubstitute made up of alloplastic acellular glycerolized dermis (AAGD) and CEA to overcome these difficulties. A procedure that maintained an intact basement membrane was developed, so as to promote adhesion and growth of CEA on AAGD. Keratinocytes were seeded onto AAGD and cultured up to 21 days. Viability tests and immunohistochemical analysis with specific markers were carried out at 7, 14, and 21 days, to evaluate keratinocyte adhesion, growth, and maturation. Our results support the hypothesis that this newly formed skin substitute could allow its permanent engraftment in clinical application.

Anomalous expression of HLA class II molecules on keratinocytes and fibroblasts in hypertrophic scars consequent to thermal injury.

Immunoperoxidase staining of skin sections obtained from 11 hypertrophic scars, six normotrophic scars and three samples of normal skin were performed using anti‐HLA monoclonal antibodies (HLA‐DR, ‐DQ, class I), anti‐interleukin‐2 receptor (IL‐2R) and anti‐CD1. Sections from all hypertrophic scars showed an anomalous expression of HLA‐DR molecules on keratinocytes and fibroblasts. Moreover hypertrophic scars were characterized by dense infiltrates of IL‐2R‐positive cells and by the presence of abundant Langerhans (CD1+) cells in the epidermis and dermis. These results support the hypothesis that immunologic mechanisms play an important role in hypertrophic scarring and point to an involvement of cell‐mediated immune phenomena.

Imbalance between activin A and follistatin drives postburn hypertrophic scar formation in human skin

Abstract:  Hypertrophic scarring is a skin disorder characterized by persistent inflammation and fibrosis that may occur after wounding or thermal injury. Altered production of cytokines and growth factors, such as TGF‐β, play an important role in this process. Activin A, a member of the TGF‐β family, shares the same intra‐cellular Smad signalling pathway with TGF‐β, but binds to its own specific transmembrane receptors and to follistatin, a secreted protein that inhibits activin by sequestration. Recent studies provide evidences of a novel role of activin A in inflammatory and repair processes. The aim of this study was to evaluate the importance of activin A and follistatin expression in the different phases of scar evolution. Immunostaining of sections obtained from active phase hypertrophic scars (AHS) revealed the presence of a high number of α‐SMA+ myofibroblasts and DC‐SIGN+ dendritic cells coexpressing activin A. Ex‐vivo AHS fibroblasts produced more activin and less follistatin than normal skin or remission phase hypertrophic scar (HS) fibroblasts, both in basal conditions and upon TGF‐βs stimulation. We demonstrate that fibroblasts do express activin receptors, and that this expression is not affected by TGF‐βs. Treatment of HS fibroblasts with activin A induced Akt phosphorylation, promoted cell proliferation, and enhanced α‐SMA and type I collagen expression. Follistatin reduced proliferation and suppressed activin‐induced collagen expression. These results indicate that the activin/follistatin interplay has a role in HS formation and evolution. The impact of these observations on the understanding of wound healing and on the identification of new therapeutic targets is discussed.

Low triiodothyronine serum levels as a predictor of poor prognosis in burn patients.

OBJECTIVE Euthyroid sick syndrome is a common finding in critically ill patients with nonthyroidal illness, characterized by low serum levels of free triiodothyronine (fT3) with a peculiar increase in reverse T3 (rT3) and normal-to-low free thyroxine (fT4) as well as thyroid-stimulating hormone (TSH) levels. This condition has been proposed as a prognostic factor of worse outcome in critically ill patients, while no conclusive data are available in burns. METHODS Since thyroid function testing is contained in our baseline laboratory tests at admission, we retrospectively evaluated fT3, fT4 and TSH in 295 consecutive burn patients admitted to the Burn Center of Turin from January 2002 to December 2006, comparing hormone levels in survivors and non-survivors. RESULTS fT3 and TSH levels were significantly lower (p<or=0.0002) in non-survivors compared to survivors, while no significant difference between the two populations was found in fT4 concentrations. Excluding from the study 20 patients who received dopamine administration for more than 21h, serum fT3 levels fell further still (p=0.0003). In addition, fT3 concentrations showed a significant correlation with burn severity expressed by the Roi score (Spearmans correlation coefficient -0.37 with p<0.00001). CONCLUSION Low fT3 levels are associated with poor outcome in burn patients. Hence, fT3 measurement could be proposed as a strong and cost-effective tool of poor prognosis.