Application of hydrogel wound dressings in cell therapy-approaches to assessment in vitro

Cell therapy is actively used to treat skin defects, particularly burn lesions. The effectiveness of its application may depend on the appropriate choice of wound dressings used together with any cellular material. The aim of the study was to investigate the interaction of 4 hydrogel dressings used in clinical practice with human cells in an in vitro model to determine if their use in combination with cell therapy is possible. The effect of the dressings on the growth medium was assessed by considering the changes caused in the medium's acid-base equilibrium (pH) and viscosity. Cytotoxicity was determined by applying an MTT-assay and by direct contact methods. Cell adhesion and viability on the dressing surfaces were analyzed using fluorescence microscopy. Proliferative and secretory cell activity were determined concurrently. Characterized human dermal fibroblast cultures were used as the test cultures. Results: The tested dressings interacted differently with the growth medium and the test cultures. 1-day extracts of all dressings had almost no effect on the acid-base balance, but, after 7 days, the pH of the dressing Type 2 extract had sharply acidified. The viscosity of the media under the influence of dressings of Types 2 and 3 had also markedly increased. MTT-assays showed nontoxicity of all the 1-day-incubated dressing extracts, while incubation for 7-days resulted in extracts with evident cytotoxicity, which was reduced upon dilution. Cell adhesion to the surfaces of the dressings differed, being observed occurring on dressings 2 and 3, and to a limited extent on dressing 4. Cells under dressing 1 showed evident proliferative and secretory activity whereas the other dressings impaired either proliferation or secretion processes. These effects indicate that, in general, comprehensive studies including a variety of methodological approaches at the in vitro stage are needed to allow the selection of appropriate dressings if they are to be used in combination with cell therapy to act as cell carriers. Of those investigated, the Type 1 dressing can be recommended as a protective dressing for use after transplantation of cells into a wound defect area by some other method.