Acute and chronic wound fluids inversely influence adipose-derived stem cell function: molecular insights into impaired wound healing.

Wound healing is a complex biological process that requires a well-orchestrated interaction of mediators as well as resident and infiltrating cells. In this context, mesenchymal stem cells play a crucial role as they are attracted to the wound site and influence tissue regeneration by various mechanisms. In chronic wounds, these processes are disturbed. In a comparative approach, adipose-derived stem cells (ASC) were treated with acute and chronic wound fluids (AWF and CWF, respectively). Proliferation and migration were investigated using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and transwell migration assay. Gene expression changes were analysed using quantitative real time-polymerase chain reaction. AWF had a significantly stronger chemotactic impact on ASC than CWF (77·5% versus 59·8% migrated cells). While proliferation was stimulated by AWF up to 136·3%, CWF had a negative effect on proliferation over time (80·3%). Expression of b-FGF, vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 was strongly induced by CWF compared with a mild induction by AWF. These results give an insight into impaired ASC function in chronic wounds. The detected effect of CWF on proliferation and migration of ASC might be one reason for an insufficient healing process in chronic wounds.

Acute and chronic wound fluids influence keratinocyte function differently.

Wound healing requires a proper functioning of keratinocytes that migrate, proliferate and lead to a competent wound closure. Impaired wound healing might be due to a disturbed keratinocyte function caused by the wound environment. Basically, chronic wound fluid (CWF) differs from acute wound fluid (AWF). The aim of this study was to analyse the effects of AWF and CWF on keratinocyte function. We therefore investigated keratinocyte migration and proliferation under the influence of AWF and CWF using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] test and scratch assay. We further measured the gene expression by qRT-PCR regarding growth factors and matrixmetalloproteinases (MMPs) involved in regeneration processes. AWF had a positive impact on keratinocyte proliferation over time, whereas CWF had an anti-proliferative effect. Keratinocyte migration was significantly impaired by CWF in contrast to an undisturbed wound closure under the influence of AWF. MMP-9 expression was strongly upregulated by CWF compared with AWF. Keratinocyte function was significantly impaired by CWF. An excessive induction of MMP-9 by CWF might lead to a permanent degradation of extracellular matrix and thereby prevent wounds from healing.

Staphylococcus aureus bacteremia after thermal injury: the clinical impact of methicillin resistance.

OBJECTIVE: To evaluate the impact of methicillin resistance in Staphylococcus aureus bacteremia (SAB) on mortality and length of stay in burn patients. DESIGN: Retrospective cohort study. SETTING: A 750-bed tertiary care university hospital in Cologne, Germany. PATIENTS: Patients registered in the database of the burn intensive care unit (BICU) between 1989 and 2009 with complete data sets (n=1688). RESULTS: Over the 21-year study period, 74 patients with SAB were identified; 33 patients had methicillin-resistant S. aureus (MRSA) and 41 methicillin-susceptible S. aureus (MSSA). Comparing the MRSA with the MSSA population the following parameters were significantly different in the univariate analysis: BMI (27.2 kg/m(2) vs. 23.6 kg/m(2); P=0.05), extent of deep partial thickness burns (17.8% vs. 9.0% of total body surface area; P=0.007), antibiotic requirement on admission (45.5% vs. 22.0%; P=0.046), median length of hospitalization prior SAB (24 days vs. 7 days; P<0.001), packed red blood cells administration (47.6 units vs. 26.1 units; P=0.003), intubation requirement (100% vs. 80.5%; P=0.007), intubation period (43.5 days vs. 26.8 days; P=0.008), catecholamine requirement (90.9% vs. 61.0%; P=0.004), sepsis (60.6% vs. 34.1%; P=0.035) and organ failures (81.8% vs. 39.0%; P<0.001). Regarding outcome parameters, methicillin resistance was not significantly related with mortality (adjusted OR 1.55, 95% CI 0.56-4.28; P=0.40) and length of BICU stay after SAB (Kaplan-Meier analysis log-rank test P=0.32; Cox's proportional hazards regression HR 1.22, 95% CI 0.65-2.27, P=0.535) in the univariate and multivariate analyses. CONCLUSION: Our data suggest that methicillin resistance is not associated with significant increases in mortality and length of BICU stay among burn patients with SAB.

Vascular endothelial growth factor (VEGF165) plus basic fibroblast growth factor (bFGF) producing cells induce a mature and stable vascular network--a future therapy for ischemically challenged tissue.

BACKGROUND: Vascular endothelial growth factor (VEGF)(165) induces formation of immature blood vessels with increased permeability. In this study, we used a cell-based gene-transfer model of fibroblasts to investigate the effects of a combined in vivo treatment consisting of the VEGF165 and basic fibroblast growth factor (bFGF) proteins on ischemic and non-ischemic tissues. MATERIALS AND METHODS: After controlled in vitro adenoviral transfection we transplanted fibroblasts into either healthy tissue, or into an ischemic skin flap model at different tissue locations and at different time points. Subsequent protein expression and angiogenic effects were measured using ELISA, PCR, immunohistology, planimetry, and microangiography. RESULTS: Transfected fibroblasts temporarily produced VEGF(165) and bFGF. After transdermal implantation we found an up-regulation of genes encoding for both factors in tissue samples. The combined transplantation of VEGF(165) and bFGF modified cells increased the number of sm-actin+/CD31+ blood vessels and reduced necrosis by 25%. The number of functional blood vessels increased over a period of 168 d even in healthy tissue. CONCLUSIONS: We achieved stable vessel growth in healthy tissue by inducing a temporary overexpression of VEGF(165) and bFGF and improved the survival of ischemic tissue. One possible mechanism for the latter observation is the stabilization of VEGF(165)-induced hyperpermeable vessels by a bFGF-mediated pericytial recruitment of smooth muscle cells.

Severe burn injuries: acute and long-term treatment.

BACKGROUND: The physician that initially sees a patient with an extensive and deep dermal burn injury must be able to provide initial acute treatment and to make a well-founded decision whether to have the patient transported to a burn care center (BCC). Physicians from a variety of specialities will be involved in the management of long-term sequelae. METHODS: This article provides an overview of the treatment of severe burns and their commonest complications. Special attention is paid to initial emergency treatment (first aid) and to late complications, because physicians from multiple specialties are often involved in these phases of treatment. The data and guidelines that are summarized here were obtained through a selective Medline search and supplemented by the authors' experience in their own burn care center. RESULTS: Analgesia, careful fluid balance, and early intubation are important elements of the initial emergency treatment. Long-term complications of burns, such as disfiguring scars on exposed areas of skin and functionally significant contractures, often require surgical treatment. Early measures for scar care may improve the outcome. CONCLUSIONS: The effective treatment of severe burns is interdisciplinary, involving general practitioners and emergency physicians as well as plastic surgeons and physicians of other specialties. Knowledge of the basic principles of treatment enables physicians to care for patients with burns appropriately both in the acute setting and in the long term.