4.      Initial characterisation of a new model of dermal papilla cell culture. 
Claire Higgins (1), Gavin Richardson (1), Gill Westgate (2), Martin Green (3), Desmond Tobin (4) Colin Jahoda (1), 1. Department of Biological Sciences, Durham University. 2. Westgate Consultancy, Stevington, Bedfordshire. 3. Unilever R&D Colworth, Sharnbrook, Bedford. 4. School of Life Sciences, University of Bradford

Human dermal papilla (DP) cells grown in culture have been studied extensively. However, some key differences between DP cell behaviour in vivo and in culture have been identified. Smooth muscle alpha actin (alphaSMA) is a sheath-cell specific marker in vivo, but once in culture both papilla and sheath cells express alphaSMA. Cells derived from anagen DP’s are highly proliferative whilst the same cells in vivo do not proliferate. Expression of extracellular matrix proteoglycans changes during the hair cycle. The chondroitin proteoglycan Bamacan is expressed in the anagen DP yet lost on entry to catagen and telogen whilst Syndecan-1 is absent in anagen but present in the telogen DP. In contrast, Perlecan expression remains constant throughout the hair cycle. We previously demonstrated that DP cells grown in suspension culture in tiny volumes form small spheroids which appear morphologically to be more akin to DP found in vivo. We have now investigated the differences between the two culture conditions using the expression profile of alphaSMA, proteoglycans and markers of proliferation. Human DP cells at P4/P5 were plated in 35mm dishes or placed in hanging drops. All cells were cultured in MEM containing 10% FBS. Cells were harvested when 80-90% confluent whilst spheres were harvested after 30 hours in culture. The two culture methods were compared using RT-PCR and immuno-cytochemistry. The integrity and viability of the spheres was confirmed using TEM and viability markers. Results show that dermal spheres have a different profile from normally cultured DP cells suggesting spheres may be an interesting new model for studying DP cells in vitro. Perlecan and Syndecan-1 expression is similar in both cells and dermal spheres in contrast to Bamacan which is reduced in dermal spheres. alphaSMA and Ki67 are expressed in DP cells but not in dermal spheres, even though the spheres remained viable.