Hans was born in Brunn, Czechoslovakia, in 1941 and grew up and went to school in Fulda, West Germany. After medical studies at the University of Freiburg and the University of Ulm in 1969, a love of science, relentless curiosity, and a spirit of adventure (and a serious failure to check out the climate in Canada) led him to pursue PhD studies at the Ontario Cancer Institute at the Princess Margaret Hospital in Toronto. Toronto in the 1960s was far from a sophisticated world city—it was not called ‘Toronto the Good’ for nothing. But what Hans knew very well was that Toronto was the home to the world-famous laboratories of James Till and Ernest McCulloch, which were at the epicenter of blood stem cell research at the time. What Hans could not, however, have known was that Toronto was also home to a young medical student named Sandy Shuve. The two met on Hans’ very first day in Toronto. Four years later they married. A short overseas gig in a famous lab in a faraway land best known for snow and polar bears had quickly turned into a most passionate professional and personal embrace lasting nearly five decades. And what decades they were, spanning two continents and the entire era of successful marrow transplantation to the present time.

Nearly 50 years later, in February 2017, Dr. Messner—scientist, clinician, husband, father, grandfather—stood before his colleagues in Tampa at the Tandem meetings. Having already failed at retiring a few times by then, Hans was presented with the lifetime achievement award of the American Society for Blood and Marrow Transplantation. For those who might not know why such an honor was bestowed, let us recount some of the many reasons.

The laboratories of Till and McCulloch attracted to Toronto some of the best and brightest to work on the problems of normal and leukemic hematopoiesis. As scientist, in their lab, and subsequently in his own lab, Dr Messner was the first to demonstrate in humans that marrow stem cells needed soluble factors to grow and differentiate (later these factors were identified as cytokines). He was the first to characterize human pluripotent stem cells (CFU-GEMM). He was the first to demonstrate that such stem cells could be found in cord blood. As clinician, he performed some of the first transplants in Canada, and co-founded and headed the first marrow transplant program in Canada, a program that now bears his name. He was co-founder of the Canadian Blood and Marrow Transplant Group and was its president for more than a decade. He was the driving force behind many of the CBMTG’s studies, but often let others take center stage. He was an early proponent of transplant standards and quality control at the national level, and supporter of the NMDP and the creator of the Canadian unrelated donor registry OneMatch.

While also an author of 200 papers and a mentor for scores of young transplant physicians, Hans always felt his career’s greatest mission—and ultimately its most rewarding—was to care for the thousands of patients with leukemia. His patients universally sensed this unwavering devotion. It was no surprise to be doing rounds on a Monday morning, when Hans walked across the bridge from an attached hospital, clearly diaphoretic with intravenous-running antibiotics, having been admitted the night before with a perforated appendix, hours post surgery. He was just checking to see that everything was okay and, by the way, do not tell Sandy.

Success of course has many colleagues in the laboratory, ward, and clinic. But beyond the lab and beyond the ward, and beyond the meetings, however, there was always and forever family. First there was Sandra, his wife and best friend. Then the four kids Anne, Andrew, Christine and Erika. Playtime when they were growing up was often in the early hours of the morning. Then there were the six grandchildren of an enthusiastic ‘Opa’, and fun weekends at the cottage.

At the end of these five decades and a month before his death, Hans and Sandra travelled to Ottawa to stand one last time in front of the Canadian transplant community and some of its guests from around the world (Mary Horowitz, Sergio Giralt, Mohammed Mohti among others). He was there to receive the lifetime achievement award from his Canadian colleagues. It was an unforgettable scene, one to test the soul and to lift the spirit. Initially disheartened by the frightening physical ravages of advanced cancer, his colleagues were astonished by a talk—on the outcome of the first 1000 patients transplanted in Canada all those years ago—astounding in its clarity and unmistakable in its messages to a new generation. In that unforgettable voice, with an unparalleled keenness of mind, he defied his illness and addressed his audience like he had done many times before. There can be no doubt there had to be just this one more talk, this one more conversation among colleagues, this one more idea to test, this one more old friend to greet, and this one more encouragement to give.

Less than 24 h later, back in Toronto, having been the official to see off the annual charity Bikeathon to raise money for his hospital, an event in which until the last year he would be a lead racer on one of his son’s custom bikes, Sandra said that Hans felt that he has gotten out of this life all that it had to offer and he in turn had given all that he could, and he had no regrets. He entered hospital that day. In his last few days, for his children at his bedside, he recounted and put to paper for family posterity all that he remembered of his own childhood those many years ago in the chaos and tragedies of war.

Surrounded by a series of ever-enlarging concentric circles of his loving family, the devoted staff of the hospital to which he had dedicated his career, his colleagues and friends, Hans Messner died on 24 July 2018. One would have to say that it was a life profoundly well-lived.

So to you Hans, from us— in Shakespeare’s words—“May Flights of Angels lead thee to thy Rest.”