Production of a double layer scaffold for the “on demand” release of fibroblast-like limbal stem cells

The production and characterization of a double layer scaffold, to be used as a system for the “on demand” release of corneal limbal stem cells are here reported. The devices used in the clinics and proposed so far in the scientific literature, for the release of corneal stem cells in the treatment of limbal stem cell deficiency, cannot control the in vivo space-time release of cells since the biomaterial of which they are composed is devoid of stimuli responsiveness features. Our approach was to produce a scaffold composed of two different polymeric layers that give the device the appropriate mechanical properties to be placed on the ocular surface and the possibility of releasing the stem cells following a non-invasive and cell-friendly treatment. This device consists of an electrospun micro fibrillar scaffold of poly-L-lactic acid coated by a polymeric film based on an amphiphilic derivative of hyaluronic acid sensitive to the ionic strength of the external medium and to the presence of a complexing agent. The latter represents the “sacrificial” cell containing layer of the scaffold that can be dissolved “on demand” by the treatment with a solution of cyclodextrins. The rapid removal of the external polymeric film from the device is exploited to control the space-time release of the cells. In vitro and ex vivo experiments showed that fibroblast-like limbal stem cells cultured on the scaffold without the use of the feeder layer maintained their characteristics of stem cells and can be released “on demand” on the culture well coated with Matrigel or on the decellularized bovine cornea, respectively.