Autologous mesenchymal stem cells for the treatment of secondary progressive multiple sclerosis: an open-label phase 2a proof-of-concept study - Connick, P; Kolappan, M; Crawley, C; Webber, D J; Patani, R; Michell, A W; Du, M Q; Luan, S L; Altmann, D R; Thompson, A J; Compston, A; Scott, M A; Miller, D H; Chandran, S (Lancet Neurol, 2012)