Processing of hematopoietic stem cells from peripheral blood before cryopreservation: use of a closed automated system.

BACKGROUND: Hematopoietic stem cell transplantation is commonly used to treat several oncohematologic diseases. The autologous hematopoietic progenitor cells collected through apheresis (HPC-A) must be cryopreserved and stored before use in vivo. Cell processing that precedes cryopreservation of HPC-A includes volume reduction aimed at reducing the amount of dimethyl sulfoxide used, as well as storage space. STUDY DESIGN AND METHODS: The aim of our study was to assess the effectiveness of volume reduction performed with an automated closed system, namely, the Sepax S100 cell separation device (Biosafe SA). A total of 165 procedures were carried out on concentrates collected from 104 adult and pediatric patients. As a control group, 30 HPC-A units processed according to the standard method (i.e., centrifugation at a speed of 850 × g for 10 minutes, followed by manual plasma reduction) were evaluated. RESULTS: The volume reduction obtained was 59% (range, 20.54%-84.21%; standard deviation [SD], ± 12.19%), going from 236 mL (range, 100-443 mL; SD, ± 80.41 mL) to 97 mL (range, 33.00-263.00 mL; SD, ± 47.41 mL); recovery of nucleated cells was 90% (range, 64.84%-105.93%; SD, ± 8.76%), while that of CD34+ cells was 91% (range, 59.30%-119.37%; SD, ± 13.30%). These values did not differ from those obtained using the standard method. Automated processing required 20 minutes versus 40 minutes of manual processing. DISCUSSION: Our data demonstrate that volume reduction carried out with the Sepax S100 automated system was particularly effective; cell recovery was excellent and the time spent was short. Moreover, the closed system allows cell processing to be carried out in a contamination-controlled environment, in accordance with good manufacturing practice guidelines.

Induction of regulatory T cells after prophylactic treatment with photopheresis in renal transplant recipients.

Extracorporeal photopheresis (ECP), originally used to treat cutaneous T-cell lymphoma, also has been applied to the therapy of transplant rejection. Our aim was to investigate the biologic response in two children who underwent kidney transplantation with ECP as prophylactic treatment. They received conventional immunosuppressive therapy and ECP immediately after transplantation: six applications over the course of 3 weeks. During a 12-month follow-up, the clinical course was favorable in both patients; renal histology was normal 6 months after transplantation. When compared with four transplanted controls, the ECP-treated patients showed lower tumor necrosis factor-alpha serum levels in the short-term and a marked increase of Foxp3-positive T-regulatory cells. T-regulatory cells were still higher than in the controls 1 year after transplantation. These preliminary results suggest that the addition of ECP to standard immunosuppressive therapy induces a tolerogenic shift in the immune system of kidney transplanted patients and may pave the way to preventing chronic rejection.

The immunological effects of extracorporeal photopheresis unraveled: induction of tolerogenic dendritic cells in vitro and regulatory T cells in vivo.

Extracorporeal photopheresis (ECP) may represent an alternative to immunosuppression, as a means of reducing rejection after thoracic organ transplantation. The mechanism by which ECP exerts its protective effects has, until now, remained elusive. We analyzed peripheral blood mononuclear cells of four children with chronic heart and lung transplant rejection, who received ECP in addition to conventional immunosuppressive treatment. The effects of ECP were evaluated at each cycle, comparing blood samples from the same patient collected before and after treatment. In vitro, peripheral blood mononuclear cells treated with ECP undergo apoptosis and are phagocytosed by immature dendritic cells, which, in turn, acquire a tolerogenic phenotype. The frequency of T cells, with a regulatory phenotype and strong suppressive activity, was significantly increased in the blood of ECP-treated patients. The immunomodulatory effects of ECP may be explained by its ability to increase the frequency of regulatory T cells with inhibitory action on transplant immune rejection.