1 Department of Physiology and Pharmacology, Karolinska Institutet, Nanna Svartz väg 2, 171 77 Stockholm, Sweden; and at the Institute for Regenerative Medicine, Sechenov First Moscow State Medical University, Trubetskaya Street 8, Moscow 119048, Russia.
2 Institute for Regenerative Medicine, Sechenov First Moscow State Medical University, Trubetskaya Street 8, Moscow 119048, Russia.