Intrabone cord blood hematopoietic stem cell transplantation in a subset of very high-risk pediatric patients: a safety and feasibility pilot study

The main limit of umbilical cord blood hematopoietic stem cell transplantation is a more difficult engraftment related to the number of cells infused per kilogram of recipient body weight. This limit makes the cord blood a suboptimal source of hematopoietic stem cells for transplantation in case of difficult engraftment situations. Direct intrabone cord blood (CB) injection has been recently investigated as a solution to cell dose problem in the adults population, but there is a lack of data concerning this approach in pediatric patients. Here, we describe 5 pediatric patients undergoing intrabone cord blood transplantation (IBCBT) for different diseases characterized by a high risk of posttransplant graft failure. The conditioning regimen differed according to the disease, whereas the GvHD prophylaxis consisted of cyclosporine, mycophenolate, and ATG. The median numbers of total nucleated cells infused and CD34(+) cells were 3.3 × 10(7)/kg, 2 × 10(5)/kg. All the patients showed complete hematological recovery and complete donor engraftment. No patient had secondary graft failure, whereas 1 patient relapsed 6 months after IBCBT. No patient died of transplant-related complications. Our results show that IBCBT is safe and feasible in pediatrics as well, and suggest that IBCBT might be an attractive option to overcome some limits of umbilical cord blood hematopoietic stem cell transplantation.