Human multilineage progenitor cell sensitivity to 4-hydroperoxycyclophosphamide.

Area of Science:

• Hematology
• Oncology
• Stem Cell Biology

Background:

• Autologous cryopreserved marrow cells are used for hematopoietic stem cell transplantation (HSCT) after purging with 4-hydroperoxycyclophosphamide (4-HC) to eliminate tumor cells.
• Patients treated with marrow-lethal chemoradiotherapy and rescued by reinfused purged marrow cells show consistent hematopoiesis reconstitution.

Purpose of the Study:

• To investigate the sensitivity of multilineage progenitor cells (CFU-GEMM) to 4-HC purging.
• To determine if CFU-GEMM assays can reliably predict marrow reconstitution ability after 4-HC treatment.

Main Methods:

• Assessing the frequency of committed progenitor cells (BFU-E, CFU-GM) and multilineage progenitor cells (CFU-GEMM) after in vitro incubation with 4-HC.
• Comparing the reduction in progenitor cell frequency with the observed marrow reconstituting ability in patients.

Main Results:

• 4-HC incubation significantly reduced the frequency of BFU-E, CFU-GM, and CFU-GEMM, often to undetectable levels.
• The reduction in these progenitor cells did not correlate with the loss of marrow reconstituting ability.
• CFU-GEMM showed similar dose-related sensitivity to 4-HC as BFU-E and CFU-GM.

Conclusions:

• Standard progenitor cell assays (BFU-E, CFU-GM, CFU-GEMM) are not reliable predictors of marrow reconstitution following 4-HC purging.
• The cells responsible for marrow reconstitution after 4-HC treatment are likely more resistant to purging or are not accurately represented by these assays.