[1] Univ London Imperial Coll Sci Technol & Med, Dept Mat, London SW7 2BP, England
[2] Univ London Imperial Coll Sci Technol & Med, Fac Med, Tissue Engn & Regenerat Med Ctr, Chelsea & Westminster Hosp, London SW10 9NH, England
[3] St Marys Hosp, London W2, England
[4] Univ Manchester, Manchester Mat Sci Ctr, Manchester M1 7HS, Lancs, England
[5] Univ Manchester, Manchester M1 7HS, Lancs, England