Tohoku J. Exp. Med., 2005, 205(1)

Evaluation of Hematological Reconstitution Potential of Autologous Peripheral Blood Progenitor Cells Cryopreserved by a Simple Controlled-Rate Freezing Method

YOSHINORI KUDO,¹ MASAYOSHI MINEGISHI,¹ TSUNEO ITOH,¹ JUNKO MIURA,¹ NAOKO SAITO,¹ HIROYUKI TAKAHASHI,¹ AKIRA SUZUKI,¹ AYUKO NARITA,¹ YUKO SATO,¹ JUN-ICHI KAMEOKA,² MASUE IMAIZUMI,³ MAKOTO SATO,⁴ YASUKO MURAKAWA⁵ and SHIGERU TSUCHIYA^1,6

¹Division of Blood Transfusion, Tohoku University Hospital, ²Department of Rheumatology and Hematology, ³Department of Pediatrics, ⁴Department of Urology, ⁵Department of Clinical Oncology, and ⁶Department of Pediatric Oncology, Tohoku University School of Medicine, Sendai, Japan

A novel and simple procedure for the controlled-rate cryopreservation of peripheral blood progenitor cells (PBPCs) was introduced. A freezing bag housed in a protective aluminum canister was placed on top of a styrene foam box in the −85C electric freezer. A second set of samples was kept in cryotubes placed in a double styrene foam box in the same electric freezer. Measurement of the freezing rate in the PB bags and cryotubes demonstrated that this simple method for PBPC cryopreservation provided optimal conditions for both large-scale and small-scale cryopreservation. Within several days after autologous peripheral blood stem cell transplantation, we thawed the cells in the small sample tubes and evaluated the cell viability, the cell recovery, and the recovery rates of hematopoietic progenitor cells (HPCs), such as CD34⁺ cells and colony-forming unit-granulocyte/macrophage (CFU-GM) colonies. The median duration of cryopreservation was 59 days (range, 14 - 365 days). According to our analysis, infusions of more than 2 × 10⁶ CD34⁺ cells/kg body weight and 0.5 × 10⁶ CFU-GM colonies/kg body weight after thawing had favorable influences on the neutrophil engraftment. We have therefore established a simple freezing method for cryopreservation of human PBPCs, which ensures the transplantability of hematopoietic progenitors even after thawing. In vitro HPC assay after thawing is important to evaluate the quality of cryopreservation procedures.

keywords —— peripheral blood progenitor cell; CD34⁺ cell; CFU-GM colony; cryopreservation

© 2005 Tohoku University Medical Press

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Address for reprints: Masayoshi Minegishi, M.D., Division of Blood Transfusion, Tohoku University Hospital, 1-1 Seiryomachi, Aoba-ku, Sendai 980-8574, Japan.

e-mail: minegisi@idac.tohoku.ac.jp