sentences:  Michael Rosen's group demonstrated that transplantation of HCN2-transfected human mesenchymal stem cells (hMSCs) leads to expression of functional HCN2 channels in vitro and in vivo, mimicking overexpression of HCN2 genes in cardiac myocytes.In 2010, Ruhparwar's group again demonstrated a type of biological pacemaker, this time showing that by injection of the "Adenylate Cyclase" gene into the heart muscle a biological cardiac pacemaker can be created.In 2014, a gene called TBX18 has been non-invasively applied to speed up heart rates caused by heart block.