Comparison of the Fresenius COM.TEC with the COBE Spectra for the Collection and Processing of Peripheral Blood Progenitor Cells for Autologous Transplantation

BACKGROUND: The Fresenius COM.TEC is a newer automated leukapheresis device with a software feature that predicts the CD34⁺ cell yield in peripheral blood progenitor cell (PBPC) collections. There is little published information comparing the collection efficacy of PBPC on the Fresenius COM.TEC with other apheresis machines, including the COBE Spectra.

AIM: To compare the collection and cell processing parameters of PBPC collected on the Fresenius COM.TEC with those collected on the COBE Spectra.

METHODS: A prospective, single institution study of patients undergoing PBPC collection following mobilisation with chemotherapy and G-CSF was performed. Patients were alternately assigned to have the 1^st day of PBPC collection performed on either the COBE Spectra (Version 6.0, MNC) or the Fresenius COM.TEC (Version 4.02, Auto MNC), dependent upon the availability of trained operators for the Fresenius COM.TEC. Patients were scheduled to have 3 blood volumes processed during leukapheresis.

RESULTS: Overall, 28 patients had PBPC collected on the COBE Spectra and 20 on the Fresenius COM.TEC. All collections except one were commenced when the peripheral blood CD34⁺ cell count was ≥10 × 10^6/L. Two patients on the COBE Spectra and 6 patients on the Fresenius COM.TEC had collections terminated after processing of only 2 blood volumes due to operational requirements. The median volume of PBPC collected on the Fresenius COM.TEC (328mL) was significantly higher than that collected on the COBE Spectra (257mL; p=0.015). This impacted upon the requirement for plasma reduction within the processing laboratory. There was no significant difference in the median number of total nucleated cells, total CD34⁺ cells or total platelets collected on the 2 machines. Collection efficiency of CD34⁺ cells was also similar on both machines. Regardless of apheresis machine used, there was a high degree of correlation between predicted and actual yield of total CD34⁺ cells. However an increased level of red cell contamination in PBPC collected on the Fresenius COM.TEC (median total red cells of 280.2 × 10⁹) compared with the COBE Spectra (median total red cells of 154.3 × 10⁹; p = 0.005) was observed. Also, there was significantly less overall recovery of viable CD34⁺ cells after laboratory processing of PBPC collected on the Fresenius COM.TEC (median of 73% recovery) compared with the COBE Spectra (median of 89% recovery; p= 0.0004). Of note, technical difficulty was experienced in the processing laboratory with plasma reduction of 7 PBPC products collected on the Fresenius COM.TEC, necessitating deviation from standard operating procedure and re-centrifugation at elevated g force (1000g) to ensure adequate sedimentation of nucleated and CD34⁺ cells. It is unclear whether the difficultly in plasma reduction in the Fresenius products may have contributed to the reduced recovery of progenitor cells post cryopreservation and thawing.

CONCLUSION: Although the Fresenius COM.TEC collects CD34⁺ cells with similar efficiency to that of the COBE Spectra, PBPC are collected in a larger volume with a higher level of red cell contamination. Furthermore, the recovery of CD34⁺ cells post cryopreservation and thawing is lower for PBPC collected on the Fresenius COM.TEC. Insufficient patients with collections performed on the COM.TEC have been infused to determine any effect on engraftment kinetics. This study underscores the importance of extending studies evaluating the collection of PBPC to investigate the entire production process including possible post processing effects.