The impact of the CD34+ cell dose on engraftment in allogeneic peripheral blood stem cell transplantation

Total nucleated cell dose in graft is a better prognostic factor for survival in pediatric patients transplanted with bone marrow compared to CD34+, CD3+, or total mononuclear cell count

BACKGROUND

Most studies investigating the impact of graft composition on transplant-related outcomes have focused on the effect of CD34+ cell dose and reported equivocal results. The aim of this study is to investigate the impact of doses of total nucleated cells (TNCs), total mononuclear cells (TMCs), CD3+, and CD34+ cells on the outcome of children receiving allogeneic hematopoietic stem cell transplantation (HSCT).

METHODS

Children and adolescents who underwent allogeneic HSCT for malignant hemato-oncological diseases or nonmalignant diseases in Cukurova University Faculty of Medicine, Pediatric Bone Marrow Transplantation Center between 2010 and 2020 were enrolled in the study.

RESULTS

A total of 212 patients receiving allogeneic HSCT (154 bone marrow transplantation; 58 peripheral blood stem cell transplantation) from matched related or unrelated donors were included in the study. Higher TNC doses associated with a superior 5-year event-free survival (EFS; 67.7% vs 44.7%) in the whole group (log-rank P = .027). Overall survival (OS) and EFS of bone marrow-transplanted patients differed significantly according to TNC doses (log-rank P = .041 and .027, respectively). Multivariant analysis for OS revealed a P value of .038 for TNC, Exp(B) = 1.939 (95% CI: [1.038, 3.621]). That for EFS revealed a P value of .025 for TNC, Exp(B) = 1.992 (95% CI: [1.088, 3.647]). There was no relationship between doses of CD34+ cells, CD3+ cells, TMC, TNC, and neutrophil or platelet engraftment.

CONCLUSION

Our data suggest that TNC dose is a better prognostic factor for pediatric allogeneic HSCT outcomes than doses of CD34+ cells, CD3+ cells, or TMC in patients transplanted with bone marrow. Future studies analyzing cell subsets and other components in TNC could elaborate the factor(s) accompanying this observed survival advantage.

A CD34+ Cell Enrichment Protocol of Hematopoietic Stem Cells in a Well-Established Quality Management System

Allogeneic stem cell transplantation applications have improved tremendously over the past quarter of a century. The use of new immunosuppressive protocols and elimination of T cells by CD34+ cell enrichment or T cell depletion on apheresis products increases the chance of using partially matched or haploidentical grafts. This is without increasing the risk of graft-versus-host disease, which is observed as a major complication of hematopoietic stem cell transplantation. The aim of this protocol is to evaluate the results obtained from 6 different process cycles performed on 6 different days. We used the CliniMACS Plus system located in our Cell and Tissue Manufacturing Center Quality Control Unit which is already calibrated as a class D room and includes a class A microbiological safety cabinet inside. The average purity of the end products was 95.66%, excluding only one end product which was 70%; this was higher than the values in current studies in the field. Superior to the reported studies, the CD3 quantity in each end product was below the dedicated thresholds. BactecTM FX40 blood culture system test results were detected as negative for each end product. Endotoxin testing suggested the absence of endotoxin within the products. The consistent outcomes obtained from these 6 different process cycles confirmed that the CliniMACS® Plus process cycles performed in accordance with our well-defined quality management system procedure is sufficient for the routine application of high-quality and safe CD34+ enrichment processes within our clean room area.

Factors affecting the CD34+ cell yields from the second donations of healthy donors: The steady-state lymphocyte count is a good predictive factor

BACKGROUND

A second allogeneic hematopoietic stem-cell transplantation and donor lymphocyte infusion using cells from the same donor is a therapeutic option in the case of stem-cell graft failure or disease relapse, but little is known about the factors associated with the CD34⁺ cell yields from second donations.

METHODS

One-hundred healthy donors who underwent a second mobilization treatment and peripheral blood stem-cell (PBSC) collection were studied. For both mobilization processes, 5 µg of granulocyte colony-stimulating factor per kg per day was administered. The blood counts of the donors were monitored during the processes.

RESULTS

The second donations from the same donors provided lower apheresis yields than did the initial collections. The number of CD34⁺ cells collected from normal donors after a second cycle of PBSC mobilization was associated with their steady-state lymphocyte counts and the intertransplantation interval. Female sex negatively affected the CD34⁺ cell yields. The cutoff value for the steady-state absolute lymphocyte count was 2.055 × 10⁹/L.

CONCLUSION

To harvest greater numbers of CD34⁺ cells from second collections, male donors and those with intervals of longer than 9 months between donations should be selected. The lymphocyte counts prior to the first donations may predict the content of CD34⁺ cells in the allografts prepared using the second donations.

Immunology of hematopoietic stem cell transplant

Hematopoietic stem cell transplantation (HSCT) is a procedure in which infusion of hematopoietic stem cells is used to reestablish hematopoietic function in patients with damaged or defective bone marrow or immune systems. Early and late complications following allogeneic HSCT include acute and chronic graft-versus-host disease (GVHD), donor rejection, graft failure, relapse of primary malignancy, conditioning-related toxicity, immunodeficiency and infections. Immunology has a central role in allogeneic hematopoietic cell transplantation. Any appreciation of the immunological mechanism involved in engraftment, GVHD, the development of tolerance, immune reconstitution, and the control of malignancy requires some understanding of the immunologic basis for immune reactions provoked by grafting tissue from one individual to another. In the future it should be possible to learn what gene(s) must be activated and which must be repressed to force stem cells into division without maturation; to engineer a mechanism into the cells that stops proliferation and sets the stage for amplification; to search if there could be a universal donor cell line, neatly packaged and stabilized in sealed vials and distributed by the pharmaceutical industry; to modify the transplanted cells in such a way that they have a proliferative advantage over those of the host and to deliver the lethal blow against the neoplasm, perhaps the cells that are infused will be engineered in such a way as to be able to distinguish between normal host cells and tumor.

Predictors of the yield of mobilized peripheral blood CD34+ cells in HLA-matched sibling donor

We examined the donor factors that may affect the yield of peripheral blood stem cell (PBSC) mobilized from healthy donors. Pre-apheresis PB-CD34(+) cell count was the only factor that correlated with PBSC yield. Leukocyte count (LC) and monocyte count (MC) correlated with PB-CD34(+) cell. Male gender and PB-CD34(+) cell count of at least 87.1/μL and 69.8/μL on day-4 and -5 of G-CSF were associated with the ability to harvest at least 5×10(6)/kg CD34(+) cells after one apheresis. We concluded that gender and PB-CD34(+) cell count are important predictors of PBSC yield. LC and MC may serve as surrogate markers for estimating the PB-CD34(+) cell count.

Higher doses of CD34+ progenitors are associated with improved overall survival without increasing GVHD in reduced intensity conditioning allogeneic transplant recipients with clinically advanced disease

OBJECTIVE

The influence of CD34+ cell dose on the outcome of allogeneic peripheral blood stem cell (PBSC) transplantation after reduced intensity conditioning (RIC) remains controversial. The impact of the number of CD34+ hematoprogenitors infused on transplant outcome and on the incidence of graft versus host disease (GVHD) was analyzed.

MATERIALS AND METHODS

Data of 138 patients with advanced hematological diseases who received an allogeneic PBSC transplant after RIC were analyzed. Donors were mobilized with granulocyte colony-stimulating factor and underwent one to three apheresis procedures. Incidence of acute and chronic GVHD and overall and event-free survival (OS and EFS) was determined.

RESULTS

The median number of CD34+ cells infused was 5.57 × 10(6) kg(-1) (range: 1.1-15.6). There was no relationship between CD34+ cell dose and neutrophil or platelet engraftment. Patients receiving ≥5 × 10(6) kg(-1) CD34+ cells had a 63.1% 5-year OS when compared with 48.2% for those receiving a lower number (P = 0.024). At 5-year follow-up, there was no significant difference in EFS between the groups (44% vs. 42.8%, P = 0.426). No relationship between CD34+ cell dose and acute GVHD was found (P = 0.1). Relapse rate was the same in patients with and without acute GVHD (P = 0.117). A nonsignificant improvement on OS and EFS in patients who developed chronic GVHD was found (P = 0.57 and 0.41).

CONCLUSION

A CD34+ cell dose ≥5 × 10(6) kg(-1) was associated with a significantly higher OS, but no improved EFS in high-risk patients. The number of CD34+ progenitors infused had no influence on the incidence of acute or chronic GVHD.

Higher infused CD34+ cell dose and overall survival in patients undergoing in vivo T-cell depleted, but not t-cell repleted, allogeneic peripheral blood hematopoietic cell transplantation

BACKGROUND AND OBJECTIVES

Understanding the effect of cellular graft composition on allogeneic hematopoietic cell transplantation (AHCT) outcomes is an area of great interest. The objective of the study was to analyze the correlation between transplant-related outcomes and administered CD34+, CD3+, CD4+ and CD8+ cell doses in patients who had undergone peripheral blood, AHCT and received either in vivo T-cell depleted or T-cell replete allografts.

DESIGN AND SETTING

Comparison of consecutive patients who underwent peripheral blood AHCT in our institution between January 2003 and December 2009.

PATIENTS AND METHODS

The cohort of 149 patients was divided into two groups; non T-cell depleted (NTCD) (n=54) and T-cell depleted (TCD) (n=95). Study endpoints were overall survival (OS), progression free survival (PFS), engraftment kinetics (neutrophil and platelet recovery), incidence of acute graft versus host disease (acute GVHD), chronic GVHD, nonrelapse mortality (NRM) and disease relapse.

RESULTS

Multivariate analysis showed that higher infused CD34+ cell dose improved OS (relative risk 0.58, 95% CI 0.34-0.98, P=.04), PFS (relative risk 0.59, 95% CI 0.35-1.00, P=.05) and NRM (relative risk 0.49, 95% CI 0.24-0.99, P=.048) in the TCD group. By multivariate analysis, there was no difference in engraftment, grades II-IV acute GVHD, extensive chronic GVHD and relapse in the two groups relative to the infused cell doses. There was a trend towards improved OS (relative risk 0.54, 95% CI 0.29-1.01, P=.05) with higher CD3+ cell dose in the TCD group.

CONCLUSION

Our findings suggest that higher CD34+ cell dose imparts survival benefit only to in vivo TCD peripheral blood AHCT recipients.

The effect of CD34 count and clonogenic potential of hematopoietic stem cells on engraftment

In this study we have determined that the number of the CD34 (+) cells in the grafts that were infused to 48 patients who underwent autologous and allogeneic hematopoietic cell transplantation and evaluated the number of colony forming units in vitro. Our aim was to determine whether there is a relation between these cell counts and post transplantation engraftment kinetics. A negative correlation was detected (p<0.05) between the CD34 (+) cell count and all colony forming units. A correlation between the CD34 (+) cell count and the kinetics of engraftment could not be demonstrated. In the autologous group, only a weak negative correlation between the CFU-GEMM and neutrophil engraftment was detected. In the allogeneic group, colony forming units did not determine the engraftment.

Is a boosting dose of granulocyte-colony-stimulating factor necessary for healthy PBSC donors undergoing secondary apheresis? An institute's experience

Successful allogeneic PBSC transplantation depends upon the infusion of an adequate number of CD34+ cells to patients. Granulocyte-colony-stimulating factors (G-CSF) mobilized PBSC were harvested on 5th day after stimulation from donors. When the CD34+ cell target yield was not achieved; secondary apheresis was performed the following day. Before September 2006, 67 donors (Group A) received five doses of G-CSF. After September 2006, a sixth dose of G-CSF was administered to 35 donors (Group B) to improve CD34+ yield. The mean CD34+-cell concentration of the second PBSC harvest was significantly higher in Group B (1,087 x 10(6)/l vs. 767 x 10(6)/l; P = 0.031).

How to calculate the quantity of CD34+ cells infused? A single center cohort study based on actual, ideal or adjusted ideal body weight

Transplant physicians are generally using the recipient's actual body weight (ABW) for the calculation of the content of CD34+ cells in the harvest material in hematopoietic stem cell transplantation (HSCT). As a reference center performing both the stem cell collection and HSCTs, we aimed to evaluate whether there were any differences for neutrophil recovery by calculating the CD34+ cell content in the graft according to actual, ideal (IBW) or adjusted IBW (AIBW) of the recipients in both autologous (n=148) and allogeneic stem cell collection setting (n=234). We observed a negative correlation between the neutrophil recovery and the cell doses infused as to each of these BWs in the allo-HSCT group, but not in the auto-HSCT group. This negative correlation was stronger for IBW and AIBW rather than for ABW in allo-HSCT group. In addition, calculations for both IBW and AIBW in autologous and allogeneic transplants revealed a significant difference in comparison to ABW for different cut-off values of infused CD34+ cells. Consequently, we suggested that both IBW and AIBW based calculations of CD34+ cells infused are better predictors of neutrophil recovery in comparison to ABW in allo-HSCT. We were not able to show this impact in autologous transplants.

Mobilizing stem cells from normal donors: is it possible to improve upon G-CSF?

Currently, granulocyte colony stimulating factor (G-CSF) remains the standard mobilizing agent for peripheral blood stem cell (PBSC) donors, allowing the safe collection of adequate PBSCs from the vast majority of donors. However, G-CSF mobilization can be associated with some significant side effects and requires a multi-day dosing regimen. The other cytokine approved for stem cell mobilization, granulocyte-macrophage colony stimulating factor (GM-CSF), alters graft composition and may reduce the development of graft-versus-host disease, but a significant minority of donors fails to provide sufficient CD34+ cells with GM-CSF and some experience unacceptable toxicity. AMD3100 is a promising new mobilizing agent, which may have several advantages over G-CSF for donor mobilization. As it is a direct antagonist of the interaction between the chemokine stromal-derived factor-1 and its receptor CXCR4, AMD3100 mobilizes PBSCs within hours rather than days. It is also well tolerated, with no significant side effects reported in any of the clinical trials to date. Studies of autologous and allogeneic transplantation of AMD3100 mobilized grafts have demonstrated prompt and stable engraftment. Here, we review the current state of stem cell mobilization in normal donors and discuss novel strategies for donor stem cell mobilization.

Does continuous flow apheresis influence viability in allogeneic hematopoietic stem cell harvest?

One of the important clinical variables determining the success of hematopoietic stem cell transplantation is the number of viable CD34+ stem cells transfused to the patient. G-CSF mobilized peripheral blood stem cells from 17 healthy donors were collected by continuous flow apheresis. The median (range) proportions of early apoptotic (Annexin V-FITC(pos)/7-AAD(neg)) and viable (Annexin V-FITC(neg)/7-AAD(neg)) CD45(dim)CD34+ stem cells were 1.5 (0.9-3.7)% and 97.7 (82.8-100)% in the peripheral blood before apheresis and 2.6 (0.8-7.9)% and 97.3 (91.9-99)% in the apheresis products, respectively. Despite an increase in the number of apoptotic cells among all cell compartments, this was statistically significant only in CD34+ cells and granulocytes. The majority of the cells still retained their viability.

CD34, CD4, and CD8 cell doses do not influence engraftment, graft-versus-host disease, or survival following myeloablative human leukocyte antigen-identical peripheral blood allografting for hematologic malignancies

OBJECTIVES

Optimal granulocyte colony-stimulating factor-mobilized peripheral blood progenitor cell (G-PBMC) graft compositions for myeloablative allogeneic hematopoietic cell transplantation (AHCT) have not been identified. G-PBMC cell contents were analyzed for influence on outcomes.

PATIENTS AND METHODS

Human leukocyte antigen(HLA)-identical related donor AHCT was used to treat 101 patients with hematologic malignancies at a single institution between 1995 and 2002. CD34+, CD3+, CD4+, and CD8+ cell doses were enumerated by flow cytometry and evaluated by univariate analysis.

RESULTS

Categorized by the median of cell doses infused, no G-PBMC cell dose significantly correlated with neutrophil and platelet engraftment. Incidence of grade II to IV acute graft-versus-host disease (GVHD) was 24.6% (95% confidence interval [CI]: 15.9-33.3) and was not significantly influenced by evaluated G-PBMC cell doses. With a median follow-up time of 18 months for surviving patients, estimates for extensive chronic GVHD was 43.8% (95% CI: 31.4-56.2), for freedom from progression was 69.5% (95% CI: 58.1-80.9), and for overall survival was 46.9% (95% CI: 35.5-58.3). CD34+, CD3+, CD4+, and CD8+ cell doses were not significantly predictive of extensive chronic GVHD, freedom from progression or overall survival. Additionally, comparing patients receiving the upper versus lower 33rd percentiles of CD34+ cell dose, associations with extensive chronic GVHD remained insignificant (p=0.21; relative risk (RR)=1.7; 95% CI: 0.7-3.9).

CONCLUSIONS

G-PBMC graft content does not influence outcomes after myeloablative AHCT. In particular, no significant association between extensive chronic GVHD was identified with any G-PBMC cell dose, including CD34.

Impact of CD34 subsets on engraftment kinetics in allogeneic peripheral blood stem cell transplantation

Our objective was to evaluate, probably for the first time, the impact of CD34 subsets on engraftment kinetics in allogeneic PBSC transplantation (PBSCT). PBSC graft components were analyzed in 62 cases for the absolute count/kg of total CD34+ and the following subsets: DR- and +, CD71+/-, CD38+/-, CD33+/- and CD61+/-. Time to ANC >0.5 and >1 x 10(9)/l and platelets >20 and >50 x 10(9)/l was reported. The median value for each parameter was used to discriminate rapid from slow engraftment. Four parameters showed significant predictive power of early neutrophil engraftment, namely CD34+ /DR- (P = 0.002), CD34+/38- (P = 0.02), CD34+/CD61- (P = 0.04) and total CD34+ cell dose (P = 0.04). Four parameters showed significant predictive power of early platelet engraftment, namely CD34+/CD61+ (P = 0.02), CD34+ /CD38- and total CD34+ cell dose (P = 0.04) and CD34+ /CD71- (P = 0.05). Comparing patients who received > to those who received < the threshold dose(s), only CD34+ /CD38- lost its significance for neutrophil engraftment; and only CD34+ /CD61+ retained its significance for platelet engraftment (P = 0.03); furthermore, the former group required significantly fewer platelet transfusions (P = 0.018). We concluded that in allogeneic PBSCT, the best predictor of early neutrophil engraftment is the absolute CD34+ /DR- and for early platelet engraftment is the absolute CD34+ /CD61+ cell dose.

Peripheral blood stem cell apheresis for allogeneic transplants: Ibni Sina experience

BACKGROUND

The rate of utilizing peripheral blood stem cells (PBSC) as a source for allogeneic stem cells is growing rapidly. We aimed to demonstrate our 4 years experience as the largest apheresis center in Turkey and analyzed the content of the apheresis material.

PATIENTS AND METHODS

From 1998 to the end of April 2002, 151 leukopheresis procedures were performed on 116 healthy donors (M/F:66/50) with a median age of 30 years (14-53). The HLA identical sibling donors received rhG-CSF 10 microg/kg/day sc. for 4 days and at the 5th day leukopheresis was started until collecting >4 x 10e6/kg CD34+ cells. Two times the donors' total blood volume was processed in 195 min (178-245) on continuous flow cell separators using peripheral venous access.

RESULTS

Preapheresis WBC was 51.5 x 10e9/L (range, 13.11-91.3). Mono nuclear cell, CD34 and CD3 quantity of the harvest material were 5.35 x 10e8/kg (range, 0.45-23.46), 6.4 x 10e6/kg (range, 2.49-33.27) and 2.79 x 10e8/kg (range, 0.46-30.95), respectively. We were able to reach the target CD34 count after 1st cycle in 39% and 2nd cycle 61% of the procedures. In all donors with a peripheral blood CD34 count >80/mcl we succeeded to collect enough stem cells with only one leukopheresis.

CONCLUSION

Collection of peripheral blood stem cells with continuous flow cell separators is well tolerated, with no mobilization failures or poor mobilizers. We collected high values of CD34+ cells (med. 6.4 x 10e6/kg) at the expense of high CD3+lymphocytes (med. 2.79 x 10e8/kg), which may increase the risk of acute and chronic GVHD after allogeneic hemapoietic cell transplantation.

HLA-identical stem cell transplantation: is there an optimal CD34 cell dose?

A review of the published literature, supplemented with a recent analysis of Fred Hutchinson data, has been undertaken to investigate the association of infused CD34 cell dose with various clinical outcomes after HLA-identical transplantation. Separate assessments for unrelated vs related donors and the use of bone marrow or mobilized G-PBMC have been incorporated. The three primary findings are: (1) higher CD34 dose results in better neutrophil and platelet recovery in all settings; (2) high CD34 doses (>8 x 10(6)/kg) are associated with the development of more chronic GVHD when using related G-PBMC; (3) higher CD34 dose is correlated with improved survival after bone marrow transplantation, especially with unrelated donors. This is not seen when using G-PBMC. The data suggest that the CD34 content of the graft can have a significant impact on clinical outcome after allogeneic transplantation, but optimal dose is dependent on both donor type and stem cell source.

Cryopreservation of umbilical cord blood: 2. Tolerance of CD34(+) cells to multimolar dimethyl sulphoxide and the effect of cooling rate on recovery after freezing and thawing

Cryopreservation protocols for umbilical cord blood have been based on methods established for bone marrow (BM) and peripheral blood stem cells (PBSC). The a priori assumption that these methods are optimal for progenitor cells from UCB has not been investigated systematically. Optimal cryopreservation protocols utilising penetrating cryoprotectants require that a number of major factors are controlled: osmotic damage during the addition and removal of the cryoprotectant; chemical toxicity of the cryoprotectant to the target cell and the interrelationship between cryoprotectant concentration and cooling rate. We have established addition and elution protocols that prevent osmotic damage and have used these to investigate the effect of multimolar concentrations of Me(2)SO on membrane integrity and functional recovery. We have investigated the effect of freezing and thawing over a range of cooling rates and cryoprotectant concentrations. CD34(+) cells tolerate up to 60 min exposure to 25% w/w (3.2M) Me(2)SO at +2 degrees C with no significant loss in clonogenic capacity. Exposure at +20 degrees C for a similar period of time induced significant damage. CD34(+) cells showed an optimal cooling range between 1 degrees C and 2.5 degrees C/min. At or above 1 degrees C/min, increasing the Me(2)SO concentration above 10% w/w provided little extra protection. At the lowest cooling rate tested (0.1 degrees C/min), increasing the Me(2)SO concentration had a statistically significant beneficial effect on functional recovery of progenitor cells. Our findings support the conclusion that optimal recovery of CD34(+) cells requires serial addition of Me(2)SO, slow cooling at rates between 1 degrees C and 2.5 degrees C/min and serial elution of the cryoprotectant after thawing. A concentration of 10% w/w Me(2)SO is optimal. At this concentration, equilibration temperature is unlikely to be of practical importance with regard to chemical toxicity.

Soluble adhesion molecules (sICAM-1, sL-Selectin, sE-Selectin, sCD44) in healthy allogenic peripheral stem-cell donors primed with recombinant G-CSF

BACKGROUND

We analysed the effects of rhG-CSF (Amgen-Roche, USA) on serum changes of four soluble adhesion molecules (SAM) (sICAM-1, sL-Selectin, sE-Selectin and sCD44) in healthy peripheral allogeneic stem-cell transplantation donors and their correlation with acute GvHD and effect on engraftment kinetics.

METHODS

Serum SAM of 15 consecutive healthy HLA identical-sibling donors (median age 30 years, male:female ratio, 7:8) were monitored using a commercial ELISA Kit (Bender Med, Austria) prior to, on the day of first apheresis and 24 h after the cessation of rhG-CSF (10 microg/kg/day s.c. on 5 days) administration. Leukapheresis was started on the fifth day of rhG-CSF administration, using a continuous-flow blood separator (Cobe Spectra, COBE BCT, Inc, Lakewood, CO). Apheresis cycles were continued daily until a target of 4.0 x 10(6) CD34(+) cells/kg was reached.

RESULTS

The results indicate a steady rise of sL-Selectin, sE-Selectin, and sCD44, but not of sICAM-1. Median number of mononuclear cells (MNC) and CD34(+) cells transfused were 7.7x 10(8)/kg and 6.0 x 10(6)/kg, respectively. There was a near-significant correlation between the sL-Selectin levels and CD34(+) cell yield (r = 0.49, 0.06). Median granulocyte and platelet engraftment days were 11 (10-18) and 12 (9-33), respectively. There was a significant inverse correlation between the CD34(+) cell dose and granulocyte levels (r = -0.68, p = 0.022), but not for platelet engraftment. The only correlation between SAM levels and engraftment was for sICAM-1 levels. Increasing sICAM-1 levels were a sign of prolonged neutropenia (r = 0.72, p = 0.011). No correlation between the apheresis day serum levels of adhesion molecules and acute GvHD was documented.

DISCUSSION

Analysis of sICAM-1, sL-Selectin, sE-Selectin and sCD44 levels during allogeneic PBSC apheresis did not reveal any significant effect on engraftment and GvHD, except the correlation of sL-Selectin levels and collected CD34(+) cells. More research and data about the role of not only SAM levels, but also antigenic expression of SAM are required to enlighten leukocyte-endothelial cell interactions and egress of stem cells during G-CSF administration.

Peripheral blood stem cells for allogeneic transplantation: a review

Peripheral blood stem cells (PBSCs) have become increasingly popular for use in hematopoietic stem cell transplantation. PBSCs are readily collected by continuous-flow apheresis from patients and healthy donors after the administration of s.c. recombinant colony-stimulating factors with only minimal morbidity and discomfort. Although the precise identification of PBSCs remains elusive, they can be phenotypically identified as a subset of all circulating CD34(+) cells. There are important phenotypic and biologic distinctions between PBSCs and bone marrow (BM)-derived progenitor cells. PBSCs express more lineage-specific antigens but are less metabolically active than their BM-derived counterparts. The use of PBSCs for allogeneic transplantation has been compared to BM in several randomized trials and cohort studies. The use of PBSCs in leukemia, myeloma, non-Hodgkin's lymphoma, and myelodysplasia has resulted in shorter times to neutrophil and platelet engraftment at the expense of increased rates of chronic graft-versus-host disease. The increase in graft-versus-host disease is mainly due to a log-fold increase in donor T cells transferred with the graft. Relapse rates after transplantation may be lower after PBSC transplantation but a convincing survival advantage has not been demonstrated overall. It is possible that a stronger graft-versus-tumor effect may exist with PBSCs when compared with BM although the mechanisms leading to this effect are not clear.

Larger numbers of CD4(bright) dendritic cells in donor bone marrow are associated with increased relapse after allogeneic bone marrow transplantation

Relapse is the major cause of death after allogeneic bone marrow transplantation (BMT). This study tested the hypothesis that the numbers of donor mononuclear cells, lymphocytes, and CD34(+) cells influence relapse and event-free survival (EFS) after BMT. The study population consisted of 113 consecutive patients with hematologic malignancies who underwent non-T-cell-depleted BMT from HLA-matched siblings. Sixty-four patients had low-risk diagnoses (ALL/AML CR1, MDS RA/RARS, and CML CP1); 49 patients had high-risk diagnoses (all others). CD34(+) cells, T cells, B cells, natural killer cells, monocytes, and a rare population of CD3(-), CD4(bright) cells in the allografts were measured by flow cytometry. The CD3(-), CD4(bright) cells in bone marrow had the same frequency and phenotype as CD123(bright) type 2 dendritic cell (DC) progenitors, and they differentiated into typical DCs after short-term culture. Cox regression analyses evaluated risk strata, age, gender, and the numbers of nucleated cells, CD3(+) T cells, CD34(+) hematopoietic cells, and CD4(bright) cells as covariates for EFS, relapse, and nonrelapse mortality. Recipients of larger numbers of CD4(bright) cells had significantly lower EFS, a lower incidence of chronic graft-versus-host disease (cGVHD), and an increased incidence of relapse. Recipients of larger numbers of CD34(+) cells had improved EFS; recipients of fewer CD34(+) cells had delayed hematopoietic engraftment and increased death from infections. In conclusion, the content of donor CD4(bright) cells was associated with decreased cGVHD and graft-versus-leukemia effects in recipients of allogeneic bone marrow transplantation, consistent with a role for donor DCs in determining immune responses after allogeneic BMT.