Dexamethasone-induced healing of chronic leg ulcers in a patient with defective organization of the extracellular matrix of fibronectin

Use of topical corticosteroids on chronic leg ulcers

OBJECTIVE

Topical corticosteroids are widely used in the management of chronic wounds, yet there is little evidence to support this. This pilot study aimed to identify current practice by three specialist nurses and to assess the efficacy of topical corticosteroids.

METHOD

Data on healing, pain relief, exudate reduction and control of hypergranulation tissue were collected on 34 patients whose wounds were treated with topical corticosteroids prospectively in three centres over a three-month period.

RESULTS

Twenty-seven patients (79%) benefited from the application of topical corticosteroid either in terms of healing, pain relief, exudate reduction or the control of hypergranulation tissue. Two wounds deteriorated and treatment was immediately withdrawn.

CONCLUSION

Suppression of inflammation plays an important role in healing and pain relief. Applying topical corticosteroids to the wound can accelerate healing and reduce pain in certain cases. However, careful monitoring is essential as there is a risk of sensitisation with prolonged use as well as a potential increased risk of infection.

Simulations of cell-surface integrin binding to nanoscale-clustered adhesion ligands

Clustering of ligated integrins strongly influences integrin signaling and mechanical linkages between integrins and intracellular structures. Extracellular spatial organization of integrin ligands in clusters may facilitate clustering of bound integrins and thus potentially regulate cellular responses to a defined average amount of ligand in the extracellular environment. The possible role of such ligand clustering effects in controlling overall receptor occupancy is studied here using a simple mass-action equilibrium model as well as a two-dimensional Monte Carlo lattice description of the cell-substrate interface, where cell surface receptors are free to diffuse in the plane of the interface and interact with the substrate-immobilized ligand. Results from the analytical treatment and simulation data indicate that for a single-state model in which receptor-ligand binding equilibria are not influenced by neighboring complexes, clustering of ligand does not enhance total receptor binding. However, if receptor binding energy increases in the presence of neighboring ligated receptors, strong ligand spatial distribution effects arise. Nonlinear responses to increasing ligand density are also observed even in the case of random ligand placement due to stochastic juxtaposition of ligand molecules. These results describe how spatial distribution of ligand presented by the extracellular matrix or by synthetic biomimetic materials might control cell responses to external ligands, and suggest a feedback mechanism by which focal contact formation might be initiated.