Quality of thawed hematopoietic progenitor cell grafts

Abstract

Background : The appropriate dose of compatible and viable hematopoietic progenitor cells (HPC) is crucial for successful engraftment of transplanted cells within patients. In the study we therefore checked the viability of HPC in thawed HPC grafts which were transplanted into haematology patients in one year. Methods: We acquired HPC by apheresis and froze them in a programmable freezer in autologous plasma with 10 % DMSO and stored them in liquid nitrogen vapour . We thawed the bags with HPC in a water bath at the patient's bedside and in the eluate residues from the bags after the addition of saline solution we determined the viability ( 7 - AAD) of HPC ( CD34 + ) and lymphocytes by flow cytometry. Results: After the transplantation of HPC, the viability of HPC was 79.9 ± 12.4 % and of leukocytes 62.2 ± 12.2 % (paired t-test, P 0.5). Rinsing of HPC bags and storing cells after thawing in saline solution significantly ( n = 7 ; paired t - test, P < 0.01) increased the mortality of HPC , since the viability immediately after thawing was 84.1 ± 4.5 % and in samples diluted with saline solution 60.1 ± 15.7 % . Conclusions: In our laboratory, cca 20 % of HPC are lost during freezing and thawing of HPC grafts. Freezing HPC grafts 18 hours after cell collection does not affect the viability of thawed cells in comparison with grafts which are frozen immediately. Saline solution is not suitable for rinsing bags and storing HPC residuals after thawing HPC products.