A new freezing and storage procedure improves safety and viability of haematopoietic stem cells and neutrophil engraftment: a single institution experience.

BACKGROUND AND OBJECTIVES: Autologous peripheral blood stem cell transplantation has recently become a standard therapeutic approach to virus-related or infected haematological malignancies. Collection, manipulation, storage and thawing of leukapheresis products in this subset of patients require strict monitoring to prevent infection risk for operators and risk of contamination for other stored bags. MATERIALS AND METHODS: This is a non-randomized retrospective observational study. In the 2000-2002 period, a single bag freezing procedure was used for autologous peripheral blood stem cell transplantation. Bags were stored in tanks containing liquid and gas phase nitrogen. In 2002, the processing procedure was revised, and a second additional safety bag and a new storage tank containing jacketed liquid nitrogen have been used. RESULTS: A total of 524 bags were thawed, of which 121 processed with the single bag method and 403 with the double bag method. Forty-nine and 109 patients were infused respectively. The observed rupture rate with the single bag in liquid and gas phase nitrogen was 17 and 2.5%, respectively, against a rupture rate as little as 0.24% with the new methodology. Viability revealed levels of 84.4% +/- 6.1% and 96.9% +/- 2.4% for the single and double-bag respectively. This statistically significant (P < 0.0001) difference correlated with better neutrophil engraftment. CONCLUSIONS: The new proposed method, based on a double bag and storage freezer without liquid or gas phase nitrogen into a cryogenic chamber, significantly reduces bag rupture and bio-hazard and improves stem cell viability and neutrophil engraftment remarkably.

Preclinical ex vivo expansion of peripheral blood CD34+ selected cells from cancer patients mobilized with combination chemotherapy and granulocyte colony-stimulating factor.

BACKGROUND AND OBJECTIVES: Ex vivo peripheral blood progenitor cell (PBPC) expansion has been proposed as a strategy to increase the number of haematopoietic progenitors available for cell transplantation. We have expanded CD34+ cells from PBPCs obtained from four patients with haematological malignancies and one patient with an Ewing's sarcoma. MATERIALS AND METHODS: Cells were expanded in the Dideco 'Pluricell system'. After 12 days in culture, we evaluated cell phenotype, total nucleated cells, CD34+ fold increase, cell apoptosis and colony assay of expanded cells. Cell engraftment has been evaluated by transplanting two groups of irradiated non-obese diabetic/severe combined immunodeficient (NOD-SCID) mice with expanded and non-expanded cell populations. RESULTS: Total nucleated cells and CD34+ cells increased 59.5 and 4.0 times, respectively. The expanded cells were mainly constituted of myeloid and megakaryocytic cells. A significant increase in the number of colony-forming unit-granulocyte macrophage (CFU-GM) was observed in the CFU assay. Ten mice transplanted with expanded cells showed a best overall survival (80%) compared to 10 mice transplanted with non-expanded cells (20%). Human CD45+ cells were detected by flow cytometry and polymerase chain reaction in bone marrow and spleen of transplanted animals. The relative low engraftment level obtained with the expanded cells suggests a loss of SCID repopulating cells maybe due to cell differentiation during expansion. CONCLUSIONS: We have demonstrated the feasibility of the ex vivo expansion of mobilized PBPCs from cancer patients, evidencing a clonal expansion of CFUs and the ability of the expanded cells to engraft the bone marrow and spleen of immunosuppressed mice. The differentiation of the CD34+ stem cell compartment could be further minimized by ameliorating the expansion conditions.

Esophageal dischalasia: serendipity during 99mTc thyroid scan.

It is rare for a large amount of pooled radioactive saliva to be observed in the neck during a thyroid scan. Such a finding would imply abnormal salivation and/or esophageal kinesis. The case of esophageal dischalasia reported here suggests that a complete study of the esophagus is advisable when a large area or amount of radioactive saliva is observed in the neck during a thyroid scan.