Effects of botulinum toxin A on patient-specific keloid fibroblasts in vitro.

OBJECTIVES/HYPOTHESIS: To test whether therapeutic effects of botulinum toxin A on patient- specific keloid tissue can be reproduced on the cellular level. Specifically, effects on cell proliferation and expression of growth factors and cytokines relevant for wound healing were to be tested. STUDY DESIGN: Experimental study including patient specific cell cultures of keloids. METHODS: Patient-specific keloid tissue was tested in a cell culture model for effects of botulinum toxin incubation on cell proliferation and expression of the following cytokines and growth factors: IL-6 (interleukin-6), VEGF (vascular endothelial growth factor), TGF-ß (transforming growth factor-ß). RESULTS: None of the tested parameters of human keloid tissue were affected by botulinum toxin A incubation. CONCLUSION: The present study does not add evidence to suggest a significant therapeutic role of botulinum toxin injections for the treatment of keloids. LEVEL OF EVIDENCE: N/A.

Effects of external radiation in a co-culture model of endothelial cells and adipose-derived stem cells.

BACKGROUND: The inflammatory response clinically observed after radiation has been described to correlate with elevated expression of cytokines and adhesion molecules by endothelial cells. Therapeutic compensation for this microvascular compromise could be an important approach in the treatment of irradiated wounds. Clinical reports describe the potential of adipose-derived stem cells to enhance wound healing, but the underlying cellular mechanisms remain largely unclear. METHODS: Human dermal microvascular endothelial cells (HDMEC) and human adipose-derived stem cells (ASC) were cultured in a co-culture setting and irradiated with sequential doses of 2 to 12 Gy. Cell count was determined 48 h after radiation using a semi-automated cell counting system. Levels of interleukin-6 (IL-6), basic fibroblast growth factor (FGF), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were determined in the supernatants using enzyme-linked immunosorbent assay (ELISA). Irradiated HDMEC and ASC as well as non-irradiated co-cultures, HDMEC or ASC respectively were used as controls. RESULTS: Cell count was significantly reduced in irradiated co-cultures of HDMEC and ASC compared to non-irradiated controls. Levels of IL-6, FGF, ICAM-1 and VCAM-1 in the supernatants of the co-cultures were significantly less affected by external radiation in comparison to HDMEC. CONCLUSION: The increased expression of cytokines and adhesion molecules by HDMEC after external radiation is mitigated in the co-culture setting with ASC. These in vitro changes seem to support the clinical observation that ASC may have a stabilizing effect when injected into irradiated wounds.

Wound healing after radiation therapy: review of the literature.

Radiation therapy is an established modality in the treatment of head and neck cancer patients. Compromised wound healing in irradiated tissues is a common and challenging clinical problem. The pathophysiology and underlying cellular mechanisms including the complex interaction of cytokines and growth factors are still not understood completely. In this review, the current state of research regarding the pathomechanisms of compromised wound healing in irradiated tissues is presented. Current and possible future treatment strategies are critically reviewed.

Effects of botulinum toxin a on cytokine synthesis in a cell culture model of cutaneous scarring.

OBJECTIVE: To evaluate possible botulinum toxin A effects in a cell culture model. METHODS: In a cell culture model with dermal fibroblasts and microvascular endothelial cells, possible botulinum toxin A effects were evaluated. Cell proliferation and cytokine expression were analyzed using viability assays and enzyme-linked immunosorbent assay techniques. RESULTS: Neither cell proliferation nor cytokines and growth factors (interleukin 6, monocyte chemoattractant protein 2, fibroblast growth factor, macrophage colony-stimulating factor, and vascular endothelial growth factor) were affected by botulinum toxin A incubation. CONCLUSIONS: The present data do not add evidence to suggest a significant therapeutic role of botulinum toxin A injections for cutaneous wound healing beyond chemoimmobilization. Further studies that include patient-specific cells of hypertrophic scars are required to better understand what role botulinum toxin A can play in the treatment of mature scar tissue.

Altered lipid metabolism in a Drosophila model of Friedreich's ataxia.

Friedreich's ataxia (FRDA) is the most common form of autosomal recessive ataxia caused by a deficit in the mitochondrial protein frataxin. Although demyelination is a common symptom in FRDA patients, no multicellular model has yet been developed to study the involvement of glial cells in FRDA. Using the recently established RNAi lines for targeted suppression of frataxin in Drosophila, we were able to study the effects of general versus glial-specific frataxin downregulation. In particular, we wanted to study the interplay between lowered frataxin content, lipid accumulation and peroxidation and the consequences of these effects on the sensitivity to oxidative stress and fly fitness. Interestingly, ubiquitous frataxin reduction leads to an increase in fatty acids catalyzing an enhancement of lipid peroxidation levels, elevating the intracellular toxic potential. Specific loss of frataxin in glial cells triggers a similar phenotype which can be visualized by accumulating lipid droplets in glial cells. This phenotype is associated with a reduced lifespan, an increased sensitivity to oxidative insult, neurodegenerative effects and a serious impairment of locomotor activity. These symptoms fit very well with our observation of an increase in intracellular toxicity by lipid peroxides. Interestingly, co-expression of a Drosophila apolipoprotein D ortholog (glial lazarillo) has a strong protective effect in our frataxin models, mainly by controlling the level of lipid peroxidation. Our results clearly support a strong involvement of glial cells and lipid peroxidation in the generation of FRDA-like symptoms.