Abstract: Topographical features, such as projections or recesses, having a maximum dimension which is less than 3 ?m, with the features being separated by a distance which is less than 10 ?m are transferred to polyetheretherketone, on an industrial scale, by injection moulding relatively low viscosity PEEK, using a mould in which is arranged a master structure which carries the desired topography. The topographical features increase the water contact angle of a surface which includes them and such a modified surface has been shown to influence cell attachment and differentiation. Parts which incorporate the topographical features may be used in medical devices such as implantable medical devices for cardiology or for neuromodulation.

Abstract: A method for promoting the retention of a stem cell phenotype in a population of stem cells. A biocompatible substrate is provided, e.g. in the form of cultureware. The substrate has an arrangement of topographical features arrayed in a pattern based on a notional symmetrical lattice in which the distance between nearest neighbour notional lattice points is between 10 nm and 10 ?m, and wherein the topographical features are either located in register with the respective notional lattice points or are locally misordered such that the centre of each topographical feature is at most 10% of the distance between nearest neighbour notional lattice points from its respective notional lattice point. A population of stem cells is provided in contact with said arrangement of topographical features. Culturing the population of stem cells under conditions that allow the stem cells to proliferate allows the retention of the stem cell phenotype in the population of stem cells.

Abstract: A biocompatible substrate for cell adhesion, differentiation, culture and/or growth, has an arrangement of topographical features arrayed in a pattern based on a notional symmetrical lattice in which the distance between nearest neighbor notional lattice points is C and is between 10 nm and 10 ?m. The topographical features are locally mis-ordered such that the centre of each topographical feature is a distance of up to one half of C from its respective notional lattice point.