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.

Multilineage engraftment of refrozen cord blood hematopoietic progenitors in NOD/SCID mice.

Seven cord blood (CB) units were tested for their capacity to repopulate irradiated NOD/SCID mice after one or two successive cryopreservation procedures. In primary transplants with frozen or refrozen CB cells we observed equivalent human colonies and percentages of human CD45+ cells, with multilineage engraftment. In secondary transplants flow cytometry and polymerase chain reaction for the a satellite region of chromosome 17 showed equivalent levels of human engraftment. Since CB units have, to date, mainly been stored in individual bags, our results suggest new options for optimizing the timing of infusions of expanded and non-expanded progenitors in transplants.

Recovery of cord blood hematopoietic progenitors after successive freezing and thawing procedures.

BACKGROUND AND OBJECTIVES: Cord blood (CB) is a valuable source of stem cells. Most CB units are still cryopreserved in single bags in the world's CB banks. Thawing a single CB unit, dividing it into two parts, expanding the smaller one and refreezing the other would optimize ex vivo expansion of CB progenitors prior to transplantation: expanded and unexpanded cells could be infused together to accelerate early engraftment. DESIGN AND METHODS: The feasibility of refreezing CB samples was investigated by evaluating the effect of 3 successive cryopreservation procedures in 9 CB units. The number and viability of WBC, BFU-E, CFU-GM, CFU-MIX, LTC-IC, and the absolute CD34+ cell count were assessed at time 0 and after each thawing. The percentage of CD34 cells expressing CD38, L-selectin, VLA-4, VLA-5, H-CAM, LFA-1 and CXCR4 was also evaluated. RESULTS: After three freezing and thawing procedures, WBC counts decreased, while lymphocytes were unchanged. Viability was 90% of basal values after the first thawing and did not change. BFU-E decreased significantly only after the third thawing. CFU-GM and CFU-MIX did not change significantly, nor did LTC-IC, CD34+ cell counts and CAM and CXCR4 expression on CD34+/ CD38-- cells. INTERPRETATION AND CONCLUSIONS: These data show that two successive freeze-thaw procedures do not significantly affect the clonogenic potential and CAM expression of cord blood progenitors. This information could be exploited to devise new options in ex vivo expansion procedures and quality controls prior to transplantation.