Temperature-responsive gels are showing promise for tissue regeneration therapy, according to researchers in the UK.

Stephen Rimmer of the University of Sheffield and colleagues have modified a water-swollen polymer gel with a cell-adhesive peptide. The gel can be used to pick up skin cells and move them to a new substrate, where they can then be gently detached. Rimmer explains that a motivation for the team was the gel's potential applications in would healing, as the second substrate could potentially be a damaged tissue. 'Cell therapy for regenerating tissues requires transporting the cells to the desired wound bed,' he says.

Rimmer's gel works by binding to surface proteins on cells grown in a normal culture, thus removing them from the substrate. In the next step, cooling the swollen gel from the 37°C cell culture temperature to below 34°C causes it to swell even further, which has the effect of reducing cell adhesion. This releases the bound cells and can be used to deposit them at a new location.

In current methods, the protein-hydrolysing enzyme trypsin can be used to detach cells from their culture dish but this can result in damage. Using temperature-responsive polymers to transport cells avoids this problem and these have been used in the past. However, in these cases it is usually necessary to grow the cells on the polymer itself, which can be challenging say the researchers. Rimmer's approach avoids this requirement and can be used with commercially available culture substrates.

Fred Grinnell, a cell biologist at the University of Texas, Dallas, US, is impressed. 'I would have said this work was impossible if someone had asked me in advance,' he says. 'The Rimmer group has added a competitive cell adhesion functionality to temperature sensitive polymers and use a physiologically normal mechanism to transfer cells. A very surprising outcome!'

'We believe that this will be a key tool,' says Rimmer, outlining how he expects the gel to be used in the future. 'One of our goals is to find a partner for commercialisation of the materials for transferring delicate cell types,' he adds.

Michael Spencelayh

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