Numbers of circulating endothelial cells during the course of hematopoietic stem cell transplantation. (A) Maximal numbers of circulating endothelial cells according to different conditioning regimens until day 21 and cell numbers in healthy controls. Shaded boxes are interquartile ranges and horizontal lines indicate the median. Dashed lines indicate the mean. TBI denotes total body irradiation, Bu/Cy denotes busulfan/cyclophosphamide. (B) Cell numbers (median) during the course of hematopoietic stem cell transplantation.