The storage and re-infusion of autologous blood and BM as back-up following failed primary hematopoietic stem-cell transplantation: A survey of European practice

Traditionally, autologous BM or PBSC have been stored as a secondary source (‘back-up’) of hematopoietic stem cells (HSC) prior to allogeneic and autologous HSC transplantation. We conducted an audit of a single transplant center practice for providing back-up HSC and compared this practice with other European centers. Laboratory records relating to the collection and re-infusion of consecutive HSC harvests were reviewed for 515 transplants (300 autologous and 215 allogeneic HSC transplants). In our experience, 2.3% (five of 215) of allogeneic HSC transplants required secondary HSC rescue for failure to engraft or graft failure (MUD, n=2; un-manipulated sibling BMT, n=1; T-cell depleted sibling BMT, n=2). For autologous transplants, 4.7% (14 of 300) required rescue due to failure to engraft or late graft failure (ABMT for AML, n=8; CD34+ cell selection/ex vivo expanded, n=4; ABMT/PBSCT, n=2). Among the European centers, 69.7% replied to a postal questionnaire, demonstrating that 81.4% and 45.6% of centers stored a secondary HSC source for manipulated and unmanipulated MUD BMT, respectively; 50% and 11.6% of centers stored a secondary source of HSC for manipulated and unmanipulated matched sibling BMT, respectively; 36.4% and 12.7% of centers stored HSC for manipulated and unmanipulated matched sibling PBSCT, respectively. In the autologous setting, 15.2% and 62.1% of centers stored back-up for unmanipulated and manipulated BMT, respectively and 19.5% and 68.5% stored back-up for unmanipulated and manipulated PBSCT, respectively, when myeloablative conditioning regimens were used. These data suggest that a small minority of patients require a secondary source of HSC rescue, most commonly in transplants with higher risk of graft failure. This is reflected in the practice across Europe of storing ‘back-up’ HSC. Guidelines should accommodate the need for storage of a secondary source of HSC only in those transplants associated with a higher risk of graft failure, especially in relation to graft engineering.