The effects of platelet apheresis in total hip replacement surgery on platelet activation.

BACKGROUND: Autologous platelet rich plasma (PRP) harvest with autotransfusion devices has been used for 10 years in cardiac surgery and recently in orthopedics as a blood saving method. The quality of the harvested platelets has not been adequately examined, in part because of methodological difficulties in studying platelet function during surgery. METHODS: Twenty patients undergoing primary total hip replacement (THR) were studied. Ten patients underwent an immediate preoperative platelet apheresis to obtain concentrated platelet rich plasma (c-PRP). The other 10 patients not undergoing apheresis were allocated to a control group. Platelet activation was evaluated as the population expressing P-selectin on the surface of platelets in the c-PRP and in blood samples collected pre-, per- and postoperatively. The method used was flow cytometry. RESULTS AND CONCLUSIONS: A minor population of activated platelets was found to be circulating in the patients' blood, with a highly significant difference between patients (P = 0.005), and with a range of 1-23% in peroperative activation. PRP harvest did not significantly alter platelet activity. The platelet apheresis procedure did not inhibit platelet function in the c-PRP, as judged by a high proportion of platelets that could be activated in ADP stimulation experiments (mean value +/- SD 86% +/- 7.5%).

Interactions between P-glycoprotein and drugs used in the supportive care of acute myeloid leukemia patients.

Multidrug resistance due to overexpression of P-glycoprotein (Pgp) leads to reduced intracellular drug accumulation and makes the cells resistant to chemotherapy. In this study we focused on how drugs used in the supportive care of acute myeloid leukemia (AML) patients interfere with Pgp. The effect on intracellular accumulation of the fluorescent dye Rhodamine 123 (Rh 123) was studied in the human promyelocytic leukemia cell line HL-60 and two anthracycline resistant, Pgp expressing, sublines. Each drug was used at two different concentrations: plasma peak concentration and half the plasma peak concentration. Drugs which increased the Rh 123 uptake by > 10% were included in the second part of the study where the cytotoxic effect was tested in combination with daunorubicin. In the Rhodamine assay none of the tested drugs had any significant effect on the Rh 123 efflux in the resistant cell lines. Amphotericin B, cefuroxime, erythromycin and dixyrazin had minor effects on Rh 123 uptake but showed a significant additive effect to the toxicity of daunorubicin suggesting other mechanisms of action than reversal of Pgp. In conclusion this in vitro model where Rh 123 uptake was studied in an anthracycline resistant leukemia cell line could not demonstrate any significant interactions with Pgp for the tested drugs.

Kinetics of peripheral blood stem cell harvests during a single apheresis.

BACKGROUND: The enumeration of CD34+ cells in the peripheral blood of patients before leukapheresis is commonly used to predict the outcome of stem cell harvests. The concept that an increased number of transplanted cells gives faster marrow reconstitution triggers an interest in investigating the kinetics of peripheral blood stem cells during leukapheresis. The aim of this study was to investigate the issue of recruitment of hematopoietic progenitor cells during a single leukapheresis. STUDY DESIGN AND METHODS: Nine leukapheresis procedures (in 8 patients) were investigated. In each case, 3 blood volumes were processed. Samples from peripheral blood, the collection line of apheresis equipment, and the collected component were obtained after each blood volume was processed. The enumeration of CD34+ cells was performed, and the total number of progenitors, as a sum of the number of cells in the peripheral blood and the number of cells in the collected component, was calculated. RESULTS: A mean of 13.3 L of blood was processed, and a component with a mean volume of 424 mL and a mean of 10.1 x 10(6) CD34+ cells per kg of body weight was collected. White cell and mononuclear cell counts in peripheral blood declined concomitantly during the procedures. The calculated total number of cells--that is, the sum of the number of cells in the collected component and the number of cells in the peripheral blood--showed a concomitant, but not equal, rise in polymorphonuclear cells, mononuclear cells, and CD34+ cells during the leukapheresis. This apparent mobilization of progenitors into the peripheral blood did not correlate with the slightly increased number of polymorphonuclear cells or with the more pronounced increase in mononuclear cells. CONCLUSION: There is a substantial recruitment of progenitor cells during a single leukapheresis.

Large-volume apheresis for the harvest of peripheral blood progenitor cells for autologous transplantation.

BACKGROUND: The mobilization and harvest of a sufficient number of peripheral blood stem and progenitor cells for autologous transplantation is an important aspect of treatment in patients with certain hematologic and solid tumor disease. The level of CD34+ cells in peripheral blood is often used as a predictor of successful harvest. STUDY DESIGN AND METHODS: A total of 129 apheresis procedures in 38 patients have been investigated retrospectively to evaluate the possibility to predict the outcome by other measures, such as total treated blood volume (TBV) during the apheresis. RESULTS: No significant correlation was observed between the level of CD34+ cells per kg of body weight in collected apheresis components and the TBV in all 129 apheresis procedures. However, analysis of results from 22 apheresis procedures with TBV > 16 L (large-volume apheresis) and with < 10 x 10(3) CD34+ cells per mL in the peripheral blood found a correlation between TBV and the number of CD34+ cells per kg of body weight in the collected component (R2 = 0.585, p = 0.005). In patients who underwent large-volume apheresis (> 16 L) and who had < 10 x 10(3) CD34+ cells per mL in their peripheral blood, the number of CD34+ cells in the apheresis component was not correlated with that in the peripheral blood prior to harvest (R2 = 0.262, p = 0.1569). In the patients who underwent apheresis procedures with TBV < 16 L and who had > 20 x 10(3) CD34+ cells per mL in their peripheral blood, there was a correlation between the number of CD34+ cells in the component and the number of CD34+ cells in the peripheral blood (R2 = 0.800, p = 0.0000). However, there was not a correlation in this group between the number of CD34+ cells in the component and the TBV. There were no significant differences in the content of CD34+/CD33+ and CD34+/ HLA-DR+ cells in the collected component in the two groups. CONCLUSION: TBV appears to be critical for the collection of a sufficient number of progenitor cells in patients with < 10 x 10(3) CD34+ cells per mL in peripheral blood.