Long-term IgG response to porcine Neu5Gc antigens without transmission of PERV in burn patients treated with porcine skin xenografts.

Acellular materials of xenogenic origin are used worldwide as xenografts, and phase I trials of viable pig pancreatic islets are currently being performed. However, limited information is available on transmission of porcine endogenous retrovirus (PERV) after xenotransplantation and on the long-term immune response of recipients to xenoantigens. We analyzed the blood of burn patients who had received living pig-skin dressings for up to 8 wk for the presence of PERV as well as for the level and nature of their long term (maximum, 34 y) immune response against pig Ags. Although no evidence of PERV genomic material or anti-PERV Ab response was found, we observed a moderate increase in anti-αGal Abs and a high and sustained anti-non-αGal IgG response in those patients. Abs against the nonhuman sialic acid Neu5Gc constituted the anti-non-αGal response with the recognition pattern on a sialoglycan array differing from that of burn patients treated without pig skin. These data suggest that anti-Neu5Gc Abs represent a barrier for long-term acceptance of porcine xenografts. Because anti-Neu5Gc Abs can promote chronic inflammation, the long-term safety of living and acellular pig tissue implants in recipients warrants further evaluation.

Human allogeneic keratinocytes cultured on acellular xenodermis: the use in healing of burns and other skin defects.

The tissue engineered skin should be composed of both dermal and epidermal layers. We combined cultured human allogeneic keratinocytes with acellular xenodermis prepared from pig xenografts. The resulting composite skin was termed recombined human/pig skin (RHPS), and could be cultured in both, undifferentiated and differentiated phenotype. The undifferentiated RHPS was grown submerged and formed 1-2 layers of keratinocytes. The differentiated phenotype (D-RHPS) was grown at the air-liquid interface and formed 5-20 cell layers similar to the normal epidermis, including the granular and horny layers. Undifferentiated RHPS has skin-like consistency and has been successfully used for treatment of burns and skin defects using "upside-down" application. Donor sites and deep dermal burn wounds prepared by tangential excision or deep dermabrasion grafted with RHPS healed in the course of about one week after keratinocyte transplantation. Simple acellular xenodermis without keratinocytes can also be used as temporary cover for donor sites, small to medium leg ulcers and other skin defects. Xenodermis can be fully sterilized and stored at the room temperature.

Mannosides as crucial part of bioactive supports for cultivation of human epidermal keratinocytes without feeder cells.

Large-scale production of keratinocytes by cell culture is of interest for medical applications. Long-term cultivation of epidermal cells is presently possible with feeder cells, i.e. 3T3 fibroblasts with arrested mitosis, or with specially formulated culture medium. To define refinements for in vitro conditions, the analysis of the natural environment with growth-maintaining/stimulating factors can provide important clues. Cells with proliferative activity are located in the basal layer of the epidermis in close contact with a basement membrane. Employing lectin and reverse lectin histochemistry of skin, muscle fibers and feeder cells, we assumed that the interplay of mannose-binding sites of epidermal cells, detected by a labeled neoglycoprotein, with glycoligands in the feeder cell layer or basement membrane could trigger signaling with relevance for adhesion and growth regulation. Indeed, coating of polystyrene with mannose-containing neoglycoprotein mimicking a mannose-rich cell matrix enabled the cultivation of keratinocytes without feeder cells in a Ca(2+)-dependent manner in serum-containing culture medium. Following this experimental demonstration of specific binding of mannose residues as part of a neoglycoprotein controlled by testing sugar-free carrier protein and other substances, we next synthesized and tested biocompatible polymers. Attachment and proliferation of keratinocytes on the surface of these polymers compared favorably to control experiments using feeder cells. In conclusion, we suggest that these polymers are bioactive offering a perspective for keratinocyte cultivation without feeder cells.

Prevention of burn wound conversion by allogeneic keratinocytes cultured on acellular xenodermis.

Deep dermal burns frequently tend to convert into full-thickness skin loss. We found that this wound deepening may be prevented by recombined human/pig skin (RHPS), consisting of human allogeneic keratinocytes cultured on acellular pig dermis. RHPS has skin-like consistency and therefore optimal adhesiveness to the wound. It can be easily removed from the dish and transferred to the recipient. The wound bed has to be prepared by tangential excision or deep dermabrasion to the level of capillary bleeding. RHPS has to be applied 'upside-down', with the epidermal layer facing the wound, to avoid the dermal matrix forming a barrier to the nutrients for the keratinocytes. In our practice, more than 70% of early excised or deeply dermabraded wounds grafted with RHPS healed in the course of one week after keratinocyte transplantation.

Fluid therapy LiDCO controlled trial-optimization of volume resuscitation of extensively burned patients through noninvasive continuous real-time hemodynamic monitoring LiDCO.

This pilot trial aims at gaining support for the optimization of acute burn resuscitation through noninvasive continuous real-time hemodynamic monitoring using arterial pulse contour analysis. A group of 21 burned patients meeting preliminary criteria (age range 18-75 years with second- third- degree burns and TBSA ≥10-75%) was randomized during 2010. A hemodynamic monitoring through lithium dilution cardiac output was used in 10 randomized patients (LiDCO group), whereas those without LiDCO monitoring were defined as the control group. The modified Brooke/Parkland formula as a starting resuscitative formula, balanced crystalloids as the initial solutions, urine output of 0.5 ml/kg/hr as a crucial value of adequate intravascular filling were used in both groups. Additionally, the volume and vasopressor/inotropic support were based on dynamic preload parameters in the LiDCO group in the case of circulatory instability and oligouria. Statistical analysis was done using t-tests. Within the first 24 hours postburn, a significantly lower consumption of crystalloids was registered in LiDCO group (P = .04). The fluid balance under LiDCO control in combination with hourly diuresis contributed to reducing the cumulative fluid balance approximately by 10% compared with fluid management based on standard monitoring parameters. The amount of applied solutions in the LiDCO group got closer to Brooke formula whereas the urine output was at the same level in both groups (0.8 ml/kg/hr). The new finding in this study is that when a fluid resuscitation is based on the arterial waveform analysis, the initial fluid volume provided was significantly lower than that delivered on the basis of physician-directed fluid resuscitation (by urine output and mean arterial pressure).

Natriuretic peptide proANP (1-98), a biomarker of ALI/ARDS in burns.

INTRODUCTION: Plasma atrial natriuretic peptide levels (proANP (1-98)), a parameter of myocardial dysfunction, have been reported to be increased in critically ill patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS). The aim of the study was to examine if proANP is a biomarker of ALI/ARDS as assessed by the Sequential Organ Failure Assessment score (SOFA Lung ≥2) in burn patients, and how it compares to the corresponding values for age, total body surface area percent (TBSA%) and inhalation injury for mortality prediction. METHODS: A group of 22 burn patients with a mean TBSA of 30% (10-75%) and a mean age of 52 years (25-84 years) was investigated during 2010. Organ dysfunction/failure was classified according to the SOFA score. The criteria for ALI/ARDS were based on SOFA Lung ≥2. ProANP (1-98) concentrations (nmoll(-1)) were measured by commercially available enzyme linked immunosorbent assay (ELISA) immunoassays (Biomedica Austria) on post-burn days 2 and 7. RESULTS: ProANP levels on day 7 post-burn positively correlated with a SOFA score day 7 post-burn, c=0.91. The receiver operating curve (ROC) analysis proved a sensitivity of 75% and a specificity of 75% for ALI/ARDS at cut-off values >3.35 nmoll(-1). The ROC value of proANP for ALI/ARDS (SOFA Lung ≥2) was significantly larger than that of age, TBSA% and inhalation injury: 0.90, 0.71, 0.74, and 0.69 (p<0.001). CONCLUSIONS: ProANP levels, as a biomarker of ALI/ARDS, in critically burn patients correlated with SOFA scoring. The inhalation injury did not lead to increase in proANP values.

New biological temporary skin cover Xe-Derma(®) in the treatment of superficial scald burns in children.

BACKGROUND: Xe-Derma® is a new dry sterile biological cover derived from acellular pig dermis. Hydrated Xe-Derma® displays bio-mechanical features similar to the normal skin. The aim of the present study was to compare the efficacy of Xe-Derma® with hydrocolloid dressing Askina THINSite® for treatment of superficial burns in children in a prospective study. MATERIALS AND METHODS: In a prospective study, 86 patients (5 months to 7 years of age) with superficial scald burns on a surface area of 1-35% BSA were enrolled. In the course of the study, 43 patients were treated with Xe-Derma® and 43 patients with Askina THINSite®. We collected data including the percentage of BSA covered with biological or synthetic material, epithelization time, the number of complete conversions (deepening of 100% of covered area into deep dermal wound) under each cover, the number and extent of partial conversions (deepening of less then 100% of covered area into deep dermal wound), infectious complications, the number of reapplications of the temporary cover and the extent in square centimetres of dressing material needed for successful healing of 1% BSA. RESULTS: No significant difference in the epithelization time, percentage of conversion from superficial to deep dermal burns and percentage of infectious complication was detected between the two groups. However, patients in the Xe-Derma® group were burned on a more extensive burn surface area (p ≤ 0.028). Xe-Derma® showed adherence to the wound and therefore there has been no need to be changed The number of reapplications and therefore also the number of square centimetres needed for successful healing of 1% BSA were statistically higher in the Askina THINSite® group (p < 0.01) due to increased secretion and accumulation of fluid underneath this hydrocoloid cover. The minimal frequency of changes of this biological cover material brings a significant benefit to pediatric patients. CONCLUSION: Acellular pig dermis Xe-Derma® represents a reliable biological cover material. It is an advantageous alternative to synthetic temporary skin covers in the treatment of superficial scald burns in children.