Measurement of Aldehyde Dehydrogenase Activity in Allogeneic or Autologous Peripheral Stemcell Grafts May Substitute Time Consuming Cells Cultures

Abstract

Autologous and allogeneic stem cell (PBSC) transplantations are a curative option in hematologic-oncologic diseases. In daily routine stem cell harvests are measured on CD34 antigen and vitality. The colony-forming ability (CFU) of the harvested stem cells is predictive for the hematological engraftment but results are not available until 14 days. The metabolic marker aldehyde dehydrogenase (ALDH) was found in hematological vital stem cells. Former investigations described a correlation between ALDH activity of harvested stem cells and CFU. Therefore this assay may be useful for characterizing PBSC graft quality, especially as the results are available simultaneously to the CD34 and vitality data. In a prospective analysis we investigated the ALDH activity in freshly collected PBSC and in frozen products and correlated the results with the number of CFUs In the allogeneic setting 16 PBSC harvests from 13 donors, 7 males and 6 females, median age of 45 years (24-60) and in the autologous setting 42 products of 25 patients, 15 males and 10 females, median age 52 years (21-67) were investigated. Stem cell harvests were measured on CD34+ cells and vitality with 7 AAD by flow cytometry according to the ISHAGE protocol. ALDH activity was also determined by FACS analysis using the Aldeflour®kit (Stemcell Technologies, France) according to the manufacture's instructions. Analyses were done in freshly collected PBSCs and in cryopreserved products before transplantation or after 6 months of storage, respectively. The allogeneic stem cell grafts had a CD34 purity of 0.74% (0.47-1.83), an ALDH activity of 0.7% (0.45-2.18) and a CFU content of 236 × 105 (28-480). The autologous grafts showed a CD34 purity of 0.6% (0.11-7.63), an ALDH activity of 0.59% (0.15-8.89) and CFUs of 139 × 105 (0-892). CFUs and ALDH activity showed a higher correlation than CFUs and CD34+ cells in the autologous grafts (R0.73 vs R0.40) No such difference was observed in the allogeneic grafts. Low initial ALDH activity (below 0.20%) was combined with low numbers and low recovery of CFUs after thawing frozen PBSC. No correlation was observed between vitality and CFUs in both settings. Measuring of ALDH activity in PBSCs may alleviate the PBSC harvest management in patients with CD34 yields near the threshold for a successful transplantation.