Pre infusion, post thaw CD34+ peripheral blood stem cell enumeration as a predictor of haematopoietic engraftment in autologous haematopoietic cell transplantation.

INTRODUCTION

By convention, peripheral blood stem cell products for autologous transplantation are evaluated for quality by CD34(+) cell dose at the time of harvesting. A CD34(+) cell dose in excess of 2.0 × 10(6)/kg of recipient body weight is considered adequate for haematopoietic engraftment. Viable CD34(+) cell numbers are enumerated in most laboratories using the ISHAGE single platform flow cytometric method which utilizes monoclonal antibodies to CD45, CD34 and 7 amino actinomycin D (7AAD) dye exclusion.

METHODS

One hundred and six consecutive autologous transplantation procedures underwent viable CD34(+) cell enumeration at the time of harvesting and post thaw prior to re-infusion. Neutrophil and platelet engraftment and markers of haematopoietic support were analyzed.

RESULTS

Mean pre-cryopreservation viable CD34(+) numbers were 4.882 × 10(6)/kg. Mean post thaw viable CD34(+) numbers were 3.234 × 10(6)/kg. Mean loss of viable CD34(+) cells with processing and cryo-preservation was 1.648 × 10(6)/kg (33%). For neutrophil engraftment, there was no significant difference between high (⩾ 3.0 × 10(6)/kg) and low (<1.5 × 10(6)/kg) post thaw viable CD34(+) cell counts (p=0.545). For platelet engraftment, there was however a significant difference observed between the high and low pre infusion viable CD34(+) groups (p<0.001). Additionally, significant differences were seen between the post thaw viable CD34(+) cell count and the associated length of hospital admission, days of use of G-CSF post transplantation, use of antibiotics in the post transplantation period and transfusion support in the post transplantation period.

CONCLUSION

A significant loss of viable CD34(+) cells occurs during processing, cryopreservation and thawing. Low numbers of viable CD34(+) cells infused post thaw will still result in adequate neutrophil engraftment however may delay platelet engraftment. Low viable CD34(+) cell numbers have significant effects on admission duration and use of haematopoietic supportive measures with consequent effects on healthcare resources.