CD34+ selection of hematopoietic blood cell collections and autotransplantation in lymphoma: overnight storage of cells at 4 degrees C does not affect outcome

Liquid Storage of Peripheral Blood Stem Cell Products: Effects of Time and Temperature on Product Quality

Unrelated donor peripheral blood stem cell (PBSC) products often require transport to distant locations, which may take up to 72 hours. Temperature is an important variable that can be controlled during PBSC storage or transport; therefore, we studied the impact of temperature on prolonged storage of clinical-grade, mobilized PBSC products. PBSC products were collected by apheresis from 3 granulocyte colony-stimulating factor-mobilized donors, split into 2 PVC blood bags of equal volume, and stored at room temperature (RT) (18°C to 25 ºC) or 4 °C (2°C to 8 ºC) for 96 hours. Samples were obtained at 24-hour intervals for pH, cell counts, flow cytometry phenotyping and viability (7AAD), and hematopoietic colony-forming units (CFU). Starting PBSC products contained 52, 65, and 38 × 109 total nucleated cells (TNCs), with cell concentrations of 125, 263, and 94.6 × 106 TNCs/mL, respectively. Product pH dropped during storage, with significantly lower values for RT stored products than for 4 ºC stored products, and was greatest in the product with the highest TNC count. The percent recovery of viable CD34+ progenitor cells, CD3+ T cells, CD4+ T helper cells, CD8+ cytotoxic T cells, CD19+ B cells, CD15+ granulocytes, CD14+ monocytes, and CD16+/56+ natural killer (NK) cells all decreased over 96 hours but decreased more dramatically in the RT group. Cell recovery differences were statistically significant at most time points for all cell populations except CD15+ granulocytes. For CD34+ cells stored at 4 °C, mean recovery from prestorage values were 97 ± 3% at 24 hours, 87 ± 4% at 48 hours, 88 ± 10% at 72 hours, and 78 ± 1% at 96 hours, compared to RT product values of 45 ± 11%, 19 ± 19%, 2 ± 2%, and 0 ± 0%, respectively. CFUs were well preserved through 96 hours at 4 ºC but not at RT. During PBSC storage, pH and content of viable CD34+ cells, T cells, B cells, monocytes, NK cells, and CFU all declined. However, at 4 ºC, viable cell recoveries are relatively well preserved, even at 72 hours, whereas RT storage resulted in rapid product deterioration. PBSC products requiring prolonged liquid storage or transport before cryopreservation or infusion should be maintained at 4 ºC.

Liquid Storage of Hematopoietic Stem Cells Versus Proliferative Potential Colony-Forming Unit Granulocyte-Monocytes: Validation of Cell Processing

BACKGROUND

The material for transplantation must be of the highest quality. As far as we know, short-term storage is one of the crucial points of stem cell banking. According to the quality assurance system in a stem cell bank, each step of cell processing must be validated. The aim of this study was to assess the influence of short-term storage conditions into a clonogenic assay.

METHODS

Material was collected from mobilized peripheral blood by means of leukapheresis from 15 patients. Samples were stored at 4°C and 20°C; samples were evaluated on the day of leukapheresis and after 24 hours and after 48 hours of storage. The number of colony-forming unit granulocyte-monocyte (CFU-GM) precursors was analyzed with the use of in vitro culture. The material was evaluated before freezing and after thawing.

RESULTS

The average number of CFU-GM precursors in the material stored at 4°C before freezing on the day of collection was 84/10(5) nuclear cells (nc) and after 24 hours and 48 hours of storage was, respectively, 62/10(5) nc (P = .011719) and 36/10(5) nc (P = .02088). The average of the CFU-GM precursors in material stored at 20°C after 24 hours and 48 hours of storage amounted to 33/10(5) nc (P = .004439) and 2/10(5) nc (P = .00346), respectively.

CONCLUSIONS

In our study, the number of colonies of CFU-GM after 24 hours and 48 hours of storage, both at 4°C and 20°C, was significantly reduced compared with the number of colonies on the day of collection. Significantly greater numbers of CFU-GM precursors were observed in the material stored before freezing at 4°C in comparison with the material stored at 20°C.

Autologous Hematopoietic Stem Cell Transplantation for Multiple Myeloma without Cryopreservation

High-dose chemotherapy followed by autologous hematopoietic stem cell transplantation is considered the standard of care for multiple myeloma patients who are eligible for transplantation. The process of autografting comprises the following steps: control of the primary disease by using a certain induction therapeutic protocol, mobilization of stem cells, collection of mobilized stem cells by apheresis, cryopreservation of the apheresis product, administration of high-dose pretransplant conditioning therapy, and finally infusion of the cryopreserved stem cells after thawing. However, in cancer centers that treat patients with multiple myeloma and have transplantation capabilities but lack or are in the process of acquiring cryopreservation facilities, alternatively noncryopreserved autologous stem cell therapy has been performed with remarkable success as the pretransplant conditioning therapy is usually brief.

Evaluation of overnight storage conditions for autologous peripheral blood stem cell products: comparison of three different conditions

BACKGROUND

Overnight (ON) storage of peripheral blood stem cell (PBSC) occurs frequently in clinical settings. However, there are no standard guidelines for optimal storage conditions of freshly harvested PBSC. The aim of this study was to investigate the influence of storage temperatures on the quality of autologous PBSC and establish optimal storage conditions before cryopreservation.

METHODS

A retrospective analysis was performed on 260 PBSC harvests according to pre-cryopreservation conditions: immediate processing or ON storage at room temperature (RT). For direct comparison, 30 autologous PBSC products were collected prospectively and prepared under three different pre-cryopreservation conditions: immediate processing, ON storage at 4°C and ON storage at RT. The recovery of CD34(+) cells, post-thaw CFU-GM count and viability were analysed.

RESULTS

Retrospective analysis revealed that post-thaw CFU-GM count was significantly lower when PBSC were stored ON at RT compared to when immediately processed (136·4 vs. 409·6/μl). Prospective analysis showed a mean recovery of CD34(+) cells of 65·5 ± 25·1%, 70·5 ± 27·4% and 35·9 ± 25·1% for immediate processing, ON storage at 4°C and ON storage at RT, respectively. Similarly, mean viability and CFU-GM counts were significantly reduced when stored ON at RT compared to when immediately processed or stored ON at 4°C (60·4 ± 25·6 vs. 84·1 ± 12·9 vs. 82·7 ± 12·6%, 15·7 ± 25·7 vs. 398·5 ± 906·2 vs. 350·0 ± 847·9/μl, respectively).

CONCLUSIONS

ON storage of autologous PBSC at RT significantly decreased the quality of HPCs. These data indicate that ON storage of autologous PBSC at 4°C would be the most reasonable approach for maintaining the quality of HPCs when immediate processing is not possible.

Storage of hemopoietic stem cells

BACKGROUND

Autologous, and in some cases allogeneic, hemopoietic stem cells (HSC) are stored for varying periods of time prior to infusion. For periods of greater than 48 h, storage requires cryopreservation. It is essential to optimize cell storage and ensure the quality of the product for subsequent reinfusion.

METHODS

A number of important variables may affect the subsequent quality of infused HSC and therapeutic cells (TC). This review discusses these and also reviews the regulatory framework that now aims to ensure the quality of stem cells and TC for transplantation.

RESULTS

Important variables included cell concentration, temperature, interval from collection to cryopreservation, manipulations performed. They also included rate of freezing and whether controlled-rate freezing was employed. Parameters studied were type of cryoprotectant utilized [dimethyl sulphoxide (DMSO) is most commonly used, sometimes in combination with hydroxyethyl starch (HES)]; and storage conditions. It is also important to assess the quality of stored stem cells. Measurements employed included the total cell count (TNC), mononuclear cell count (MNC), CD34+ cells and colony-forming units - granulocyte macrophage (CFU-GM). Of these, TNC and CD34+ are the most useful. However, the best measure of the quality of stored stem cells is their subsequent engraftment. The quality systems used in stem cell laboratories are described in the guidance of the Joint Accreditation Committee of ISCT (Europe) and the EBMT (JACIE) and the EU Directive on Tissues and Cells plus its supporting commission directives. Inspections of facilities are carried out by the appropriate national agencies and JACIE.

CONCLUSION

For high-quality storage of HSC and TC, processing facilities should use validated procedures that take into account critical variables. The quality of all products must be assessed before and after storage.

Validation of short-term handling and storage conditions for marrow and peripheral blood stem cell products

BACKGROUND

Allogeneic hematopoietic stem cell transplants from unrelated donors are routinely used in the treatment of patients with hematologic malignancies. These cellular products are often collected off-site and require transport from the collection site to transplantation centers. However, the effects of transport conditions and media on stem cell graft composition during short-term storage have not been well described.

STUDY DESIGN AND METHODS

Five bone marrow (BM), four filgrastim-mobilized peripheral blood stem cell (PBSC), and four nonmobilized peripheral blood mononuclear cell (PBMNC) products were collected from healthy volunteer donors and stored at 4 or 20°C for up to 72 hours in 10% PlasmaLyte A plus anticoagulants such as 10% acid citrate dextran-A (ACD-A) and/or 10 IU/mL heparin. Products were evaluated at 0, 24, 48, and 72 hours for cellular content, viability, and metabolic activities.

RESULTS

BM products maintained equivalent cell viability when stored at either 4 or 20°C over 72 hours, but cell viability was better maintained for PBSC products stored at 4°C. The mean viable CD34+ cell recovery for PBSC and BM products stored over 72 hours at 4°C was higher than 75%. Significantly lower CD34+ cell and colony-forming unit recoveries were seen in PBSC products but not BM products stored at room temperature. Faster lactic acid accumulation was observed in PBMNC and PBSC products stored without ACD-A.

CONCLUSIONS

Seventy-two-hour storage of BM, PBSC, and PBMNC products at refrigerated temperature maintains optimal cell viability and recovery. Anticoagulation with ACD-A is preferred over heparin to reduce lactic acid accumulation in the product media.

Transportation of cellular therapy products: report of a survey by the cellular therapies team of the Biomedical Excellence for Safer Transfusion (BEST) collaborative

BACKGROUND AND OBJECTIVES

Most cell therapy products (CTP) are infused or processed shortly after collection but in some cases this may be delayed for up to 48 h. A number of variables such as temperature and cell concentration are of critical importance for the integrity of CTP during this time.

MATERIALS AND METHODS

We conducted a survey of cellular therapy laboratories to ascertain current practices for CTP transportation.

RESULTS

There were 194 respondents of whom 90% shipped or received CTP--84% allogeneic, 71% autologous and 62% therapeutic cells. Processing facilities shipped or received the following products--hematopoietic progenitor cells (HPC), Marrow 73%; HPC, Apheresis 90%; HPC, Cord Blood 54% and others 14%. Other CTP included donor lymphocytes, mesenchymal stem cells (MSC), natural killer cells, buffy coat neutrophils and virus-specific cytotoxic T lymphocytes (CTL). More than 70% of respondents believed that it was acceptable for CTP to be held for up to 2 h without checking the temperature or cell density and a similar proportion agreed that putting products in containers to control parameters such as temperature within this time period was unnecessary. The majority of centres shipped or received between 1 and 10 CTP annually and 66% received products taking more than 2 h to ship. Of these, 82% specified the conditions for temperature in transit whilst 57% monitored temperature in transit and 74% of these used a data logger. The temperature range most commonly specified was 18-24 degrees C. The majority of processing facilities did not request an adjustment to the cell density even for products taking more than 2 h to reach their facility. More than 90% of respondents tested HPC for CD34(+) cells, viability and sterility; 40-48% performed colony-forming unit-granulocyte macrophage (CFU-GM) analysis. Only viability was thought by > 50% of respondents to be impacted by temperature, cell density and other parameters.

CONCLUSION

Understanding current practice will help in the design of future studies for CTP storage and transportation.

Rapid transport and infusion of hematopoietic cells is associated with improved outcome after myeloablative therapy and unrelated donor transplant

We evaluated effects of graft transport time on outcomes after transplantation of 938 unrelated donor bone marrow (BM) or 507 peripheral blood progenitor cells (PBPC) in patients with acute or chronic leukemia and myelodysplastic syndrome (MDS). BM grafts were collected at 107 centers and PBPC, 89 centers. Median time from end of collection to infusion was 14 hours for BM and 15 hours for PBPC. Platelet recovery was less likely in BM recipients when the interval from end of collection to receipt at transplant center was >or=20 hours (odds ratio 0.47, P = .010) and when the interval from receipt to infusion was >or=6 hours (odds ratio 0.57, P = .001). Mortality rates were higher in recipients of HLA-matched BM when the interval from end of collection to receipt at transplant center was >or=20 hours (relative risk 2.67, P < .001) after adjustment for other significant prognostic factors. Mortality after HLA-mismatched BM transplants was not associated with transport time. Transport times had no demonstrable effect on outcomes after PBPC transplants. These data support a general review of current transport procedures, especially for BM grafts requiring longer transport time and every effort made to minimize time from collection to infusion.

Overnight refrigerator storage of autologous peripheral progenitor stem cells without cryopreservation

We compared cryopreservation of peripheral blood progenitor cell (PBPC) products immediately and after overnight storage. There was no statistically significant difference in the groups regarding median CD(34)+ cell count of the product, storage duration at -80 degrees C, viability rates, neutrophil and platelet engraftment days. Overnight storage of products with leukocyte count >300x10(9)/l has longer leukocyte (P=0.03) and platelet (P=0.01) engraftment days compared to other groups. Overnight storage without adding any medium or plasma for the apheresis product with leukocyte count of less than 300x10(9)/l in a commercially available refrigerator can easily and safely be used in transplantation centers.

Overnight storage of autologous stem cell apheresis products before cryopreservation does not adversely impact early or long-term engraftment following transplantation

To reduce costs and avoid inconvenient overtime work, our institution changed policy in September 2000 so that autologous stem cell apheresis products were stored overnight before cryopreservation rather than immediately processed. This retrospective review was conducted to evaluate the possible impact of this policy change on hematopoietic engraftment following autologous stem cell transplantation (ASCT). In total, 229 consecutive lymphoma patients who underwent a single, unpurged ASCT in Calgary between January 1995 and November 2003 were evaluated. Of these patients, 131 patients' autografts underwent immediate processing and cryopreservation before September 2000, and 98 patients' autografts underwent next-day cryopreservation after overnight storage following this date. Results of univariate and multivariate analyses demonstrated no adverse effect of overnight storage before cryopreservation on the number of days to initial engraftment of platelets or neutrophils, on the proportion of patients with low blood counts 6 months post-ASCT, or on lymphoma relapse rates or overall survival post-ASCT. These data suggest that overnight storage of the autograft before cryopreservation does not adversely affect graft viability or influence long-term disease status, and support the continued use of overnight storage of stem cells before cryopreservation as a convenient, cost reduction measure.

Cyclophosphamide, etoposide and carboplatine plus non-cryopreserved autologous peripheral blood stem cell transplantation rescue for patients with refractory or relapsed non-Hodgkin's lymphomas

A simplified schedule of high-dose chemotherapy consisting of cyclophosphamide (60 mg/kg/day for 2 days), etoposide (15 mg/kg/day for 2 days) and carboplatine (400 mg/m(2)/day for 2 days), together with autologous non-cryopreserved peripheral blood stem cells was used for treatment of relapsed (29 patients) and refractory (three patients) patients with non-Hodgkin's lymphoma (NHL). The use of such granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSC) after high-dose myeloablative therapy resulted in a rapid, complete and sustained hematopoietic recovery. The median time to achieve an absolute neutrophil count greater than 0.5 x 10(9)/l was 12 days (range 8-17 days). The median time to self-sustained platelet count greater than 20 x 10(9)/l was 14 days (range 7-19 days). Fifteen of the 32 patients (49%) were alive and disease free at a median follow-up of 18 months (range 10-96 months) for all surviving patients. The estimated 2-year overall survival (OS) and disease free survival (DFS) for all patients were 50 and 43%, respectively. Twelve patients died of relapse or progressive disease, two patients died of infection and one patient died of cardiac cause. The median time to relapse was 12 months (5-27) from PBSC infusion. High-dose chemotherapy with short-duration chemotherapy and non-cryopreserved bone marrow (BM) is an effective and safe treatment modality for patients with relapsed or resistant NHL.

Fresh PBSC harvests, but not BM, show temperature-related loss of CD34 viability during storage and transport

BACKGROUND

The optimum conditions for storage and transport of freshly harvested HPC in the liquid state are uncertain. It is not specified in commonly applied standards for stem cell transplantation. We used a viable CD34 assay to determine the optimum temperature for maintaining progenitor cell viability in freshly harvested BM and PBSC. Our aim was to identify standardized conditions for storage and transport of marrow or peripheral blood products that would optimize CD34 recovery, leading to better transplant outcomes.

METHODS

Samples were aseptically removed from 46 fresh HPC harvests (34 PBSC and 12 BM) and stored at refrigerated temperature (2-8 degrees C), room temperature (18-24 degrees C) and 37 degrees C for up to 72 h. Samples were analyzed for viable CD34+ cells/microL at 0, 24, 48 and 72 h.

RESULTS

The mean viable CD34+ yield prior to storage was 7.7 x 10(6)/kg (range 0.7-30.3). The mean loss of viable CD34+ cells in HPC products at refrigerated temperature was 9.4%, 19.4% and 28% at 24, 48 and 72 h, respectively. In contrast, the mean loss of viable CD34+ cells at room temperature was 21.9%, 30.7% and 43.3% at 24, 48 and 72 h, respectively. No viable CD34+ cells remained after storage at 37 degrees C for 24 h. Only PBSC products and not BM showed temperature-related loss of CD34 viability. Greater loss of viable CD34+ cells was observed for allogeneic PBSC compared with autologous PBSC.

DISCUSSION

These results demonstrate that the optimum temperature for maintaining the viability of CD34+ cells, during overnight storage and transport of freshly harvested HPC, is 2-8 degrees C. These findings will allow the development of standard guidelines for HPC storage and transport.

High-dose carmustine, etoposide, and cisplatin for autologous stem cell transplantation with or without involved-field radiation for relapsed/refractory lymphoma: An effective regimen with low morbidity and mortality

Over a 10-year period (January 1993 to October 2002), 101 relapsed or refractory non-Hodgkin lymphoma patients were treated at our center with high-dose chemotherapy and autologous transplantation. The median patient age was 54 years (range, 25-70 years). Thirty-two patients had indolent (low-grade), 42 had aggressive (intermediate-grade), and 27 had very aggressive (high-grade) non-Hodgkin lymphoma. Thirty-six patients had primary refractory disease, 20 had a chemoresistant relapse, 35 patients had a chemosensitive relapse, and 10 patients were "initial high risk" patients. The median number of prior chemotherapy regimens was 2 (range, 1-5). The preparative regimen (BEP) was bischloroethylnitrosourea (BCNU) 600 mg/m 2 , etoposide 2400 mg/m 2 , and Platinol (cisplatin) 200 mg/m 2 given intravenously over 5 days. Within 3 weeks before transplantation, 70 patients received involved-field radiotherapy (IFR) 20 Gy to sites of currently active (>2 cm) or prior bulky (>5 cm) disease. Most patients (n = 93) received mobilized peripheral blood stem cells (median CD34 + cell dose, 6.7 x 10 6 /kg). Median neutrophil (>500/microL) and platelet (>20 000/microL, untransfused) recoveries were 11 days (range, 7-19 days) and 14 days (range, 7-36 days), respectively. At a median follow-up of 41 months (range, 4 to 118 months) for survivors, Kaplan-Meier 5-year probabilities of overall survival (OS) and disease-free survival (DFS) were 58.6% and 51.1%, respectively. Four patients (4%) died within 30 days of stem cell infusion (1 pulmonary embolism, 2 septicemias with multiorgan failure, and 1 progressive lymphoma). Two patients (2%) developed interstitial pneumonitis most likely secondary to high-dose BCNU. Three cases (3%) of secondary acute myelogenous leukemia occurred. On multivariate analysis, age (<60 or > or =60 years), histologic grade (low versus intermediate or high), the use of IFR, and chemotherapy response at baseline did not affect OS or DFS. Of 70 patients given IFR, 27 relapsed: 10 (37%) within and 17 (63%) outside the radiation field. The use of IFR did not affect either OS or DFS, probably because IFR was offered to patients with bulky or chemoresistant disease. BEP with or without IFR is a highly effective and well-tolerated regimen in the relapsed/refractory lymphoma setting. It has low morbidity and transplant-related mortality and a low incidence (3%) of posttransplantation malignancy.

Retention of cellular properties of PBPCs following liquid storage and cryopreservation

BACKGROUND

G-CSF-mobilized PBPCs are routinely cryopreserved within 24 hours of collection. The ability to hold PBPCs for extended time would offer increased flexibility for patients and hospitals. Retention of PBPC properties following overnight shipping, extended liquid storage at 1 to 6 degrees C, and cryopreservation was evaluated.

STUDY DESIGN AND METHODS

PBPCs were stored in liquid at 1 to 6 degrees C up to 3 days, with and without shipping, and then cryopreserved in HES (6%), DMSO (5%), and HSA (4%). Thawed samples were assayed after two procedures, on dilution and after dilution and washing. Nucleated cells, viability, CD34+ cell number, committed progenitor colonies, and long-term culture-initiating cells were measured.

RESULTS

CD34+ cell number, committed colony-forming cells, and long-term culture-initiating cells were essentially maintained when samples were stored in liquid for 1, 2, or 3 days before cryopreservation or after thawing and dilution. Nevertheless, significant (p < 0.05, paired t test) losses in total nucleated cell numbers were observed if thawed PBPC samples were washed before assay.

CONCLUSION

PBPCs can be maintained at 1 to 6 degrees C for up to 3 days and can be cryopreserved after extended storage with properties minimally altered. Dilution alone, without centrifugation and washing, of thawed PBPC samples is a satisfactory procedure for preparing samples for in vitro assays.

Storage of blood for in vitro generation of dendritic cells

BACKGROUND

Since the development of techniques to cultivate DC from peripheral blood, there has been a great deal of interest in the use of these cells in immunotherapeutic strategies. In a clinical setting, delays often occur between when blood is drawn and when it is processed. We therefore investigated the effect of overnight storage on the yield, morphology and phenotype of DC cultured from the peripheral blood of healthy volunteers.

METHOD

Blood was processed either immediately, or after storage for 24 h in the fridge (4 degrees C) or at room temperature (RT, 20 degrees C). Samples were compared for starting cell number, DC yield and characteristics (morphology and phenotype).

RESULTS

The number of PBMC that could be obtained was significantly lower from the refrigerated samples compared with both the freshly processed sample and that stored at RT. Samples processed after overnight storage at RT yielded cells morphologically identical to DC cultured from freshly processed samples. Only when samples were both stored and processed cold did the cultured cells not have typical DC morphology. DC cultured from the refrigerated samples showed a significant reduction in MHC II expression compared with samples processed fresh or stored at RT. This expression increased slightly when the sample was first warmed. Total DC yield and the percentage yield of cultured DC was not significantly different for any of the groups.

DISCUSSION

We conclude that, if immediate processing of blood for in vitro generation of DC is not possible, samples should be stored at room temperature (approximately 20 degrees C).

Positive selection of CD34+ cells by immunoadsorption: factors affecting the final yield and hematopoietic recovery in patients with hematological malignancies and solid tumors

There is a progressive increase in the use of selected hematopoietic progenitor cells after myeloablative therapy in patients affected by malignancies. Our goal was to determine which blood parameters, in the starting cell population, influence the concentration of CD34+ progenitors and the removal of unwanted cells in the final product. Also, we evaluated the hematopoietic recovery and toxicity associated with peripheral blood stem cell infusion. We retrospectively reviewed 53 procedures of positive selection of CD34+ cells, performed with the Ceprate SC immunoadsorption system, in 47 paticnts affected by various hematologic malignancies and solid tumors. An increased percentage of CD34+ cells in the starting fraction was associated both with the final purity and enrichment of CD34+ cells and with a decreased percentage of CD3+ and CD19+ cells in the final product. A low platelet count before selection had a borderlinc influence on the recovery of CD34+ cells. Forty patients received a median of 5 x 10(6) CD34+ cells per kg; the absolute neutrophil count (ANC) reached 0.5 x 10(9)/l in a median of 10 days whereas a PLT count above 20 x 10(9)/l was observed in 14 days. The reinfusion of selected CD34+ cells, containing a very low amount of dymethylsulfoxide. was well tolerated and no adverse reactions were observed. Autologous transplantation with selected CD34+ cells is a safe and well-tolerated procedure in patients affected by hematologic malignancies and solid tumors. Positive selection of CD34+ cells seems to be related to the quality of the apheresis products, particularly to the initial CD34+ cell and PLT content.

Extensive early apoptosis in frozen-thawed CD34-positive stem cells decreases threshold doses for haematological recovery after autologous peripheral blood progenitor cell transplantation

Stem cell doses necessary for engraftment after myelo-ablative therapy as defined for fresh transplants vary largely. Loss of CD34+ cell quality after cryopreservation might contribute to this variation. With a new early apoptosis assay including the vital stain Syto16, together with the permeability marker 7-AAD, CD34+ cell viability in leucapheresis samples of 49 lymphoma patients receiving a BEAM regimen was analysed. After freeze-thawing large numbers of non-viable, early apoptotic cells appeared, leading to only 42% viability compared to 72% using 7-AAD only. Based on this Syto16 staining in the frozen-thawed grafts, threshold numbers for adequate haematological recovery of 2.8-3.0 x 10(6) CD34+ cells/kg body weight determined for fresh grafts, now decreased to 1.2-1.3 x 10(6) CD34+ cells/kg. In whole blood transplantation of lymphoma patients (n = 45) receiving a BEAM-like regimen, low doses of CD34+ cells were sufficient for recovery (0.3-0.4 x 10(6)CD34+ cells/kg). In contrast to freeze-thawing of leucapheresis material, a high viability of CD34+ cells was preserved during storage for 3 days at 4 degrees C, leaving threshold doses for recovery unchanged. In conclusion, the Syto16 assay reveals the presence of many more non-functional stem cells in frozen-thawed transplants than presumed thus far. This led to a factor 2.3-fold adjustment downward of viable CD34+ threshold doses for haematological recovery.

Autologous CD34+ enriched peripheral blood progenitor cell (PBPC) transplantation is associated with higher morbidity in patients with lymphoma when compared to unmanipulated PBPC transplantation

High-dose chemotherapy followed by CD34+ enriched peripheral blood progenitor cell (PBPC) transplantation is used for the treatment of primary refractory or relapsed Hodgkin's and non-Hodgkin's lymphomas. The CD34+ enrichment procedure, while reducing tumor burden, may compromise immunological reconstitution in the transplanted patient and result in increased rates of post-transplant infection. We compared infectious complications in patients with lymphoma who were treated with high-dose chemotherapy and supported either with CD34+ enriched PBPC (n = 19) or unmanipulated PBPCs (n = 24). Analysis was limited to patients discharged from initial hospitalization for transplantation with a minimum of 1 year followup and free of lymphoma recurrence. We found a statistically significant increase in the number of patients with one or more infectious events in the CD34+ transplant group (14/19) compared with the unmanipulated PBPC group (9/24, P < 0.01). Greater numbers of patients with two or more infectious events were observed in the CD34+ group (7/19 vs 2/24, P < 0.03) and an increased incidence of bacterial infections was observed in the CD34+ group (10/19 vs 5/24, P < 0.05). Two deaths due to infectious complications were observed in the CD34+ group. There was no significant difference in blood lymphocyte or monocyte recovery between the groups. These data demonstrate a significant increase in the long-term incidence of infectious events in lymphoma patients transplanted with autologous CD34+ enriched PBPCs compared to unmanipulated PBPCs. Thus, patients who undergo CD34+ enriched PBPC transplantation should be followed closely for infectious complications and prolonged infectious prophylaxis should be considered.