Evaluation of hematological reconstitution potential of autologous peripheral blood progenitor cells cryopreserved by a simple controlled-rate freezing method

A novel and simple procedure for the controlled-rate cryopreservation of peripheral blood progenitor cells (PBPCs) was introduced. A freezing bag housed in a protective aluminum canister was placed on top of a styrene foam box in the -85 degrees C electric freezer. A second set of samples was kept in cryotubes placed in a double styrene foam box in the same electric freezer. Measurement of the freezing rate in the PB bags and cryotubes demonstrated that this simple method for PBPC cryopreservation provided optimal conditions for both large-scale and small-scale cryopreservation. Within several days after autologous peripheral blood stem cell transplantation, we thawed the cells in the small sample tubes and evaluated the cell viability, the cell recovery, and the recovery rates of hematopoietic progenitor cells (HPCs), such as CD34+ cells and colony-forming unit-granulocyte/macrophage (CFU-GM) colonies. The median duration of cryopreservation was 59 days (range, 14-365 days). According to our analysis, infusions of more than 2 x 10(6) CD34+ cells/kg body weight and 0.5 x 10(6) CFU-GM colonies/kg body weight after thawing had favorable influences on the neutrophil engraftment. We have therefore established a simple freezing method for cryopreservation of human PBPCs, which ensures the transplantability of hematopoietic progenitors even after thawing. In vitro HPC assay after thawing is important to evaluate the quality of cryopreservation procedures.     

Cryopreservation impact on blood progenitor cells: influence of diagnoses, mobilization treatments, and cell concentration

BACKGROUND: The aim of this study was to analyze the impact of cryopreservation in series of peripheral blood progenitor cells stratified by diagnosis, mobilization treatments, and cell concentration, as well as the accuracy of the control aliquots. STUDY DESIGN AND METHODS: Viability and colony‐forming unit–granulocyte‐macrophage (CFU‐GM), CD34+ cell, lymphocyte, monocyte, and granulocyte counts and recovery were analyzed in 397 leukapheresis procedures before freezing and after thawing. Data from control cryotubes were compared to those from infusing bags. RESULTS: Cell viability decreased after thawing. Viability recovery was lower in cryotubes than in bags in non‐Hodgkin's lymphoma (NHL), in cyclophosphamide plus granulocyte–colony‐stimulating factor (Cy+G‐CSF) mobilization, and in cell concentration of median or greater. Viability recovery in cryotube was higher in NHL (92.1%) than in Hodgkin's disease (HD; 87.3%) and in G‐CSF (95.9%) than Cy+G‐CSF mobilization (91.3%). The number of CD34+ cells decreased after thawing in total group, Cy+G‐CSF mobilization, and cell concentration less than median subgroups. CD34+ cell recovery was higher in cryotubes (111.3%) than in bags (99.6%) in multiple myeloma (MM; p = 0.015). CFU‐GM decreased after thawing in all groups. CFU‐GM recovery was lower in cryotubes than in bags in MM (26.0% vs. 59.3%) and in Cy+G‐CSF mobilization (49.8% vs. 76.3%). CFU‐GM recovery in cryotubes was lower in MM compared with NHL (61.5%), HD (45.1%), and breast cancer (84.0%). Lymphocytes, monocytes, and granulocytes showed differences in the subgroups. CONCLUSION: Cryopreservation negatively impacts in cell viability, CD34+ cell recovery, granulocytes, and CFU‐GM, although slight differences between the groups were observed. Cryotubes satisfactorily reflected the quality of the infused cells.     

Trehalose ameliorates the cryopreservation of cord blood in a preclinical system and increases the recovery of CFUs,long-term culture-initiating cells,and nonobese diabetic-SCID repopulating cells

BACKGROUND: The cryopreservation of HPCs in DMSO has been practiced by cord blood (CB) banks worldwide. Inevitably, some detriment to biologic function occurs as the result of freezing injuries and DMSO toxicity. Trehalose, a disaccharide, is a natural cryoprotectant in organisms capable of surviving extreme dehydration and cold. The objective of this study was to establish the cryopreservation of CB under preclinical conditions using trehalose as a supplement to DMSO. STUDY DESIGN AND METHODS: In a preclinical protocol, the effects of 5-percent trehalose with 10-percent DMSO or 5-percent DMSO on the cryopreservation of CB MNCs or nucleated cells (NCs) were further evaluated. The read-out system consisted of a panel of HPCs: early progenitors (CFU-GEMM, long-term culture-initiating cells [LTC-IC]) and committed progenitors (CFU-GM, CFU/BFU-E, CFU-megakaryocyte [CFU-MK]). The homing and engraftment capacity of these cells were assessed in nonobese diabetic (NOD)-SCID mice. RESULTS: Trehalose increased the recoveries of CFU-GM, CFU/BFU-E, CFU-GEMM, and LTC-IC by over 7.25 percent (mean), 11.9 percent, 19.2 percent, and 12.9 percent, respectively, when compared with those in paired CB samples cryopreserved in 10-percent DMSO. Freezing and thawing reduced the yields of CFU-MK by 35.5 percent (mean) and 28.4 percent in MNC and NC samples, respectively, and the inclusion of 5-percent trehalose significantly retrieved these progenitor cells to over 90 percent of fresh samples. The improved recovery of functional HPLs was reflected by their multilineage engraftment in NOD-SCID mice. CONCLUSION: Trehalose at 5 percent significantly ameliorates the cryopreservation of CB progenitor cells at a preclinical protocol. The increased recoveries of these cells might potentially improve the engraftment outcomes of CB transplants.     

Direct immunomagnetic method for CD34+ cell selection from cryopreserved cord blood grafts for ex vivo expansion protocols

BACKGROUND: Cord blood is a useful source of HPCs for allogeneic transplantation. HPC ex vivo expansion of a cord blood graft has been proposed as a way to increase the speed of engraftment and thus to reduce the occurrence of transplantation-related complications. OBJECTIVE: The purpose of this study was to optimize a method for CD34+ cell selection of thawed cord blood grafts under clinical grade conditions, intended for application in a static, serum-free expansion culture. MATERIAL AND METHODS: Twelve samples were thawed and washed with dextran, albumin, and rHu-deoxyribo-nuclease I (RHu-DNase) to avoid clumping. CD34+ cells were selected by using a sensitized immunomagnetic bead and 9C5 MoAb complex. A buffer containing rHu-DNase, citrate, albumin, and immunoglobulin in PBS was used during the procedure. CD34+ cells were eluted and detached by using an immunomagnetic cell selection device. Cells from the enriched fraction were cultured for 6 days in serum-free medium supplemented with rHu-SCF, rHu-IL-3, rHu fetal liver tyrosine kinase 3 ligand, and rHu thrombopoietin (50 ng/mL each). Cells were expanded in well plates and in two semipermeable bags. RESULTS: A mean of 1.94 x 10(6) (+/- 1.55) CD34+ cells was obtained, yielding a CD34+ cell recovery of 52 +/- 12 percent. Nonspecific loss of CD34+ cells was 32 +/- 10 percent. CFU-GM and BFU-E/CFU-Mixed recoveries were 33 +/- 15 percent and 27 +/- 12 percent, respectively. CD34+ cells obtained were functionally comparable with fresh CD34+ cells selected for clonogenic potential. The capacity for expansion was not significantly different in the two types of bags studied. HPCs in wells were expanded 33 +/- 14-fold for CD34+ cells and 42 +/- 19-fold for overall colonies. The expansion rates observed in wells were significantly superior to those obtained in bags. CONCLUSION: The feasibility of a clinical-scale cord blood selection procedure based on a direct immunomagnetic method after thawing, followed by an ex vivo expansion culture using semipermeable bags, is shown. After 6 days of expansion, it was possible to generate a 9-fold increase in CD34+ cells, a 6-fold increase in CFU-GM and a 13-fold increase in BFU-E/CFU-Mixed colonies.     

深低温冻存不同时间对脐血细胞质量的影响

本研究旨在探讨不同冻存时间的脐血干细胞复苏后的回收率,并分析冷冻复苏的细胞对患者植入速度的影响。20份经-196℃液氮低温保存1-10年的脐血干细胞标本,比较冻存前（脐血库提供资料）和复苏后的细胞活率、总有核细胞数（TNC）、CD34＋细胞和粒-巨噬细胞集落形成单位（CFU-GM）的数量,并分析复苏后的细胞回收对移植受者植入速度的影响。结果表明,不同冻存时间对复苏后干细胞的回收率没有影响。经冻存复苏后,细胞活存率为（92．75±2．55）％,TNC、CD34＋细胞数和CFU-GM的回收率分别为89．9％、84．8％和84．3％,与冻存前相比明显减少（P=0．000）,但细胞数量的下降对移植患者中性粒细胞和血小板的植入时间均无影响。冻存后TNC和CD34＋细胞数量与冻存前数量有很大的相关性（r=0．954;r=0．931,P=0．000）,而CFU-GM的相关性弱（r=0．285,P=0．223）。结论：冻存和复温过程会-定程度上损伤脐血干细胞,导致细胞丢失,但不会影响移植的效果。     

Hematologic recovery after autologous PBPC transplantation: importance of the number of postthaw CD34+ cells

BACKGROUND: The implementation of a quality-assurance program is a major requirement to ensure quality and safety of the final PBPC components intended for clinical use. It is not clear whether the quantification of CFU-GM and CD34+ cells should be done on fresh components and after cryopreservation, which better represents the actual composition of the graft. STUDY DESIGN AND METHODS: Correlation between prefreeze and postthaw MNCs, CD34+ cells, and CFU-GM collected from 126 patients undergoing BMT (n=43) or PBPC (n =83) transplantation were evaluated. The statistical incidence of prefreeze and postthaw parameters as well as patient characteristics and conditioning regimens on hematologic recovery were analyzed. RESULTS: By multivariate analysis, prefreeze and postthaw CD34+ cells were the only two variables significantly and independently correlated to hematologic recovery. Low prefreeze and postthaw CD34+ cell numbers associated to a low CD34+ yield characterize PBPC grafts from patients who have the slowest hematologic recovery. The postthaw PBPC CD34+ cell number can be estimated before conditioning regimen by thawing a small aliquot of the graft. CONCLUSION: In association to prefreeze CD34+ cell number and to CD34+ yield, postthaw CD34+ cell number may be useful in monitoring cell loss during processing and identifying patients at risk of slow PBPC engraftment.     

Dextran sedimentation in a semi-closed system for the clinical banking of umbilical cord blood

BACKGROUND: The results of current processing procedures for reducing volume and recovering HPCs from umbilical cord blood (UCB) before cryopreservation vary. STUDY DESIGN AND METHODS: Dextran was added to bags containing UCB, followed by sedimentation for 30 minutes. The processed UCB was then frozen. RBCs, nucleated cells, MNCs, CD34+ cells, CFUs and long-term culture-initiating cells (LTC-ICs), viability, and sterility were evaluated. Fractionations in ficoll-hypaque and hydroxyethyl starch (HES) were also run in parallel for comparison. RESULTS: The nucleated cell (NC) recovery and RBC depletion were 86.1 percent and 94.3 percent, respectively (n = 50). Sedimentation with dextran also enabled the recovery of 80.7 percent MNCs and 82.6 percent CD34+ cells (n = 30). Postsedimentation samples displayed no impairment of CFU growth (n = 42, 108.7% CFU-C, 104.6% CFU-GEMM, 107% CFU-GM, and 95.7% BFU-E). Long-term cultures on five paired samples before and after sedimentation generated similar numbers of CFU-C each week (p = 0.88). Limiting dilution analysis of 12 paired pre/postsedimentation samples showed comparable median proportions of LTC-ICs (1/6494 vs. 1/5236; p = 0.18). The cell viability of 24 samples of thawed UCB after sedimentation was 90.3 percent (77.5-96%) and the recovery of CFU-C, CFU-GEMM, CFU-GM, and BFU-E of 11 postsedimentation samples was 93.4 percent, 84.9 percent, 92.3 percent, and 83.4 percent, respectively. NC recovery was significantly higher after treatment with dextran than with ficoll-hypaque (n = 30; 88.5% vs. 29.1%; p<0.005) and HES treatment (n = 21; 88.5% vs. 76.4%; p = 0.004). However, MNCs, CD34+ cells, CFUs, LTC-ICs, and RBCs were comparable. Two cycles of dextran sedimentation recovered 93.9 percent of NCs with cell viability of 98.6 percent (96.5-100%), whereas 11.7 percent of RBCs were retained (n = 20). The final yield volume was 33.5 (28-41) mL. CONCLUSION: In a semi-closed system, dextran sedimentation enabled volume reduction of UCB without significant quantitative and qualitative losses of HPCs.     

气相液氮罐内温度差异对脐带血造血干细胞保存质量的影响

目的 研究气相液氮罐内因位置不同而导致的温度差异对脐带血造血干细胞保存质量的影响.方法 选取位于液氮中的脐血干细胞20份作为对照组A组,保存在气相液氮罐内最低温度保存处的20份样本为实验B组,最高温度保存处的20组样品为实验C组.各组细胞解冻复苏后进行有核细胞计数、有核细胞活性、CD34+％、CFU-GM等检测,进行单...     

Prior cryopreservation of ex vivo-expanded cord blood cells is not detrimental to engraftment as measured in the NOD-SCID mouse model

Cytokine-mediated expansion has been proposed and successfully used to facilitate engraftment post transplantation. This study examined whether cryopreservation following expansion has a detrimental effect on the ability of cells to engraft, using the NOD-SCID mouse model. Cord blood (CB) CD34(+) cells were incubated for 7 days with stem cell factor (SCF), flt-3 ligand (FL), and megakaryocyte growth and development factor (MGDF). Expanded CD34(+) cells were transplanted into NOD-SCID mice either fresh or following cryopreservation and thawing. After thawing, recovery of nucleated cells was 94%, of CD34 cells was 63%, and of day-14 progenitors was 17%. The loss of day-14 progenitor cells among the thawed expanded cells did not influence the kinetics of human engraftment in the mouse. Bone marrow (BM) of mice transplanted with thawed expanded CD34(+) cells (14 +/- 3.9%) showed significantly higher levels of human engraftment than mice transplanted with fresh expanded CD34(+) cells (1.5 +/- 0.5%, p = 0.0064). Thawed expanded CD34(+) cells had significantly higher SCID Engrafting Potential (SEP) than freshly expanded CD34(+) cells (p < 0.001). Results suggest that prior cryopreservation does not prevent expanded cells engrafting in NOD-SCID mice.     

脐血造血干细胞短期冻存效果的评价

为了探讨脐血造血干细胞在液氮中短期冻存复苏后的效果，分别将各自为8例冻存6个月、1年、2年的脐血千细胞进行复苏，观察造血干细胞活性。有核细胞(NC)计数采用自动血细胞分析仪测定，CD34^ 细胞采用流式细胞技术测定，用体外造血细胞培养技术分析粒一巨噬细胞集落生成单位(CFU-GM)产率，台盼蓝染色法判断造血细胞存活率。结果表明：脐血造血干细胞在液氮中冻存6个月、1年、2年后解冻，其有核细胞、CD34^ 细胞、细胞活率、CFU-GM产率在3个不同冻存时间的差异无显著性。结论：脐血干细胞于液氯中短期冻存，其干细胞数量和细胞活性没有明显的变化，冻存效果较好。     

Cryopreservation of hematopoietic progenitor cells with 5-percent dimethyl sulfoxide at −80 degrees C without rate-controlled freezing

BACKGROUND: Cryopreservation of hematopoietic cells with the rate- controlled method is used in the majority of centers. In recent years, there has been a trend toward the simplification of the process. STUDY DESIGN AND METHODS: A simplified method for cryopreservation was developed with 5-percent dimethyl sulfoxide (DMSO) as the sole cryoprotectant without rate-controlled freezing. Experiments were done with progressive concentrations of DMSO, ranging from 0 to 10 percent. With DMSO concentrations from 5- to 10-percent, the best recovery and viability for hematopoietic progenitor cells were observed. Hematopoietic progenitor cells with plasma and 5-percent DMSO were frozen and stored in a -80 degrees C mechanical freezer. Ten patients with solid and hematologic malignancies underwent transplantation with autologous hematopoietic progenitor cells. RESULTS: The median number of transfused mononuclear cells and CD34+ cells was 3.70 (3.1-8.2) × 10(8) per kg and 1.70 (0.8-6.5) × 10(6) per kg, respectively. The median number of transfused colony-forming units-granulocyte-macrophage was 12.45 (3.4-55.3) × 10(4) per kg. All patients showed rapid and sustained engraftment. The mean times to reach a neutrophil count of 0.5 × 10(9) per L and a platelet count of 50 × 10(9) per L were 11.50 +/− 1.70 and 13.90 +/− 3.98 days, respectively. All patients are alive and without transfusion requirements in complete remission 2 to 8 months after transplantation. CONCLUSION: This simplified cryopreservation technique will be useful for institutions without rate- controlled freezing facilities. Moreover, this method diminishes the amount of DMSO infused to patients, as well as its toxicity.     

5% Dimethyl sulfoxide (DMSO) and pentastarch improves cryopreservation of cord blood cells over 10% DMSO

BACKGROUND: Cell number and viability are important in cord blood (CB) transplantation. While 10% dimethyl sulfoxide (DMSO) is the standard medium, adding a starch to freezing medium is increasingly utilized as a cytoprotectant for the thawing process. Similar to hetastarch, pentastarch has the advantages of faster renal clearance and less effect on the coagulation system. STUDY DESIGN AND METHODS: We compared a lower DMSO concentration (5%) containing pentastarch with 10% DMSO and performed cell viability assay, colony‐forming units (CFUs), and transplantation of CB cells in NOD/SCID IL2Rγ^null mice. RESULTS: CB cells in 5% DMSO/pentastarch had similar CD34+, CD3+, and CD19+ cell percentages after thawing as fresh CB cells. CB cells in 5% DMSO/pentastarch had higher viability (83.3 ± 9.23%) than those frozen in 10% DMSO (75.3 ± 11.0%, p < 0.05). We monitored cell viability postthaw every 30 minutes. The mean loss in the first 30 minutes was less in the 5% DMSO/pentastarch group. At the end of 3 hours, the viability decreased by a mean of 7.75% for the 5% DMSO/pentastarch and 17.5% for the 10% DMSO groups. CFUs were similar between the two cryopreserved groups. Frozen CB cells engrafted equally well in IL2Rγ^null mice compared to fresh CB cells up to 24 weeks, and CB cells frozen in 5% DMSO/pentastarch engrafted better than those in 10% DMSO. CONCLUSION: Our data indicate that the lower DMSO concentration with pentastarch represents an improvement in the CB cryopreservation process and could have wider clinical application as an alternate freezing medium over 10% DMSO.     

NEW HORIZONS ON STEM CELL CRYOPRESERVATION THROUGH THE ARTIFICIAL EYES OF CD 34+, USING MODERN FLOW CYTOMETRY TOOLS

Hematopoietic stem cell (HSC) cryopreservation is a critical step in autologous and cord blood transplantation (CBT). In most circumstances, cryopreservation is performed in a mixture containing dimethyl sulfoxide (DMSO), since DMSO is necessary to secure cell viability. Most centers use a controlled rate (slow) freezing before the long-term storage at vapor phase liquid nitrogen (LN₂) temperatures (≤ −160 °C). The primary objectives for laboratories supporting HSCT programs are to provide secure storage for leukapheresis and cord blood products, and to adequately characterize the functional properties of the grafts before their infusion. In the autologous setting, the large majority of the published results dealt with the assessment of the graft before cryopreservation. On the contrary, in CBT, before a CB unit is released, a sample obtained from a contiguous segment of that CB unit needs to be tested to verify HLA type and cell viability. The effects of graft handling, cryopreservation, storage and thawing on the recovery of CD34+ cells needs to be carefully analyzed and standardized on a global level. Some technical unresolved issues still limit the application of the ISHAGE derived single platform flow cytometry protocol for the assessment of the thawed material; based on these considerations, an adaptation of both the acquisition setting and the gating strategyis necessary for reliable measurement of CD34-expressing HSC in cryopreserved grafts. Artificial intelligence applied to “big data” may provide a new tool for improving advanced processing procedures and quality management guidelines in this area of investigation.     

从单核细胞分化的树突状细胞的低温保存及其临床应用

树突状细胞（ｄｅｎｄｒｉｔｉｃｃｅｌｌｓ，ＤＣｓ）作为专职的抗原递呈细胞，已被广泛地应用于临床的肿瘤疫苗治疗，目前的临床方案大多为分次给病人注射〉１０＾６个细胞／次，不同批次培养的ＤＣｓ，连续４－６周，为了提高疗效，简化治疗程主规范疗程，有必要将ＤＣｓ低温保存，使患在治疗过程中得到同批次的培养的ＤＣｓ，本实验从患外周血采取单个核细胞，经细胞淘洗分离核细胞，在８００Ｕ／ｍｌＧＭ－ＣＳＦ＋１００ｎｇ／ｍｌＩＬ－１３的培养条件下，将单核细胞于Ｔｅｆｌｏｎ疏水袋中导产出ＤＣｓ，将ＤＣｓ以一１℃梯度降温及不控温两种方式将ＤＣｓ冻存于－８０℃及液氮中，１个月后，４２℃快速复温，检测其免疫表型（ＣＤ１ａ，ＣＤ１４，ＣＤ４０，ＣＤ８０，ＣＤ８３，ＣＤ８６，ＣＤ５４，ＣＤ５８，ＣＤ１６，ＣＤ３２，ＣＤ６４，ＨＬＡ－ＤＲ）及其     

TRANSPLANTATION AND CELLULAR ENGINEERING: Association of stress‐related perinatal factors and cord blood unit hematopoietic progenitors is dependent on delivery mode

BACKGROUND: Perinatal characteristics, variably utilized in cord blood (CB) selection for banking, affect CB hematopoietic progenitor cells (HPCs). The association between perinatal stress factors and CB unit HPCs was evaluated. STUDY DESIGN AND METHODS: Umbilical arterial (UA) pH, absolute and relative birth weight (BW) and placental weight (PW), and PW/BW ratio of 167 healthy, full‐term infants were compared with CB unit prefreeze total nucleated cells (TNCs), total CD34+ (TCD34+) cells, and total colony‐forming unit (CFU‐TOT) number. Cesarean section (C‐section, n = 104) and vaginal delivery subgroups were also analyzed. RESULTS: UA pH (median, 7.28; range, 7.04‐7.40) correlated with CB unit CFU‐TOT number (n = 166; r = ?0.32, p < 0.0001), TCD34+ cells (r = ?0.31, p < 0.0001), and TNCs (r = ?0.29, p = 0.0002). Similarly, BW, PW, and PW/BW ratio correlated with HPCs. In multiple linear regression analysis, CFU‐TOT number was predicted by collected CB TNCs and UA pH in vaginal deliveries (R² = 0.53), in contrast with TNCs, PW, and BW in C‐sections (R² = 0.37). TCD34+ cells were predicted by adding UA pH (vaginal deliveries, R² = 0.75) or PW (C‐sections, R² = 0.36) to collected CB TNCs. CONCLUSIONS: Stress‐related perinatal factors, particularly UA pH, are associated with CB unit HPCs and may improve unit selection. Multiple linear regression models may prove useful for predicting HPCs. Mode of delivery affects model choice; UA pH has a strong effect on HPCs in vaginal deliveries.     

Flow cytometric CD34+ determination in stem cell transplantation: before or after cryopreservation of grafts?

Various attempts have been made to standardize and improve the reproducibility of flow cytometric determination of CD34+ hematopoietic progenitor cells. It is still not clear, however, whether the quantification of CD34+ cells in a stem cell graft should be done before or after cryopreservation. To address this issue, we investigated 78 unselected and 32 immunomagnetically selected autologous and allogeneic leukapheresis products (LA) before and after cryopreservation using pilot vials. Cell numbers were quantified within a Neubauer chamber, and CD34+ content was determined by flow cytometry; propidium iodide staining was used to exclude dead cells from analysis. Before freezing, the mean viable CD34 cell content in the unselected samples was 1.22% and increased after thawing to a mean of 2.16% of viable cells. Taking into account cell loss and cell death, the overall recovery of viable cells was 64.5%; all CD34+ cells could be recovered. Mean purity in the CD34-selected cell fraction was 85% (48-97) before and 91.3% (67-99) after thawing. The number of viable cells was 86.8% before and 86.1% after freezing with a 93.9% recovery of total cells. This leads to a mean 93.7% (SD +/- 23.1) recovery of viable cells and 100% (SD +/- 22.3) recovery of viable CD34+ cells. There was no significant difference in tolerance to freeze/thaw stress between cells from heavily pretreated autologous patients and healthy allogeneic donors. Our data show that freezing significantly increases the percentage of CD34(+) cells in unmanipulated LA, probably due to the death of granulocytes and mononuclear cells (MNCs). Nevertheless, the overall number of viable CD34+ cells in unselected as well as selected samples remains unchanged. Thus, CD34 data from different laboratories, for example, within multicenter trials, should be comparable independent of the different time points of acquisition.     

Prediction of engraftment after autologous peripheral blood progenitor cell transplantation: CD34, colony‐forming unit–granulocyte‐macrophage,or both?

BACKGROUND: The rate of hematologic recovery after peripheral blood progenitor cell (PBPC) transplantation is influenced by the dose of progenitor cells. Enumeration of cells that express CD34+ on their surface is the most frequently used method to determine progenitor cell dose. In vitro growth of myeloid progenitor cells (colony-forming unit-granulocyte-macrophage [CFU-GM]) requires more time and resources, but may add predictive information. STUDY DESIGN AND METHODS: A series of 323 patients, who underwent autologous PBPC transplantation for multiple myeloma, malignant lymphoma, or locally advanced breast cancer, were studied for the effect of CD34+ dose and CFU-GM dose on hematologic recovery. Measures for engraftment were days to absolute granulocyte and platelet (PLT) counts to greater than 500 per muL and than 20 x 10(9) per L, respectively, and number of PLT transfusions and red cell units required. RESULTS: The CD34+ dose had a median of 8.4 x 10(6) per kg, and the CFU-GM dose a median of 84.9 x 10(4) per kg. The CD34+ and CFU-GM doses showed significant correlation (R = 0.63; p < 0.0001) but a wide variation in the ratio of CD34+ and CFU-GM. Both CD34+ and CFU-GM doses had significant correlation with the measures of engraftment, but for all measures the relationship of CD34+ was stronger. Multivariate analysis and subgroup analysis of patients receiving CD34+ doses of less than 5 x 10(6) per kg also did not reveal an independent predictive value for CFU-GM. CONCLUSION: For prediction of hematologic recovery after autologous PBPC transplantation, determination of CFU-GM dose does not add to the predictive value of the CD34+ dose.     

Long-term storage at −80 degrees C of hematopoietic progenitor cells with 5-percent dimethyl sulfoxide as the sole cryoprotectant

BACKGROUND: Hematopoietic progenitor cells (HPCs) can be cryopreserved and stored below -120 degrees C in liquid nitrogen or at -80 degrees C in mechanical freezers. STUDY DESIGN AND METHODS: The feasibility of long-term storage of HPCs at -80 degrees C was investigated. The studies included a comparison of 5- and 10-percent dimethyl sulfoxide (DMSO) as cryoprotectant at various lengths of storage time. Mononuclear cell (MNC) recovery and viability and colony-forming unit- granulocyte-macrophage (CFU-GM) and burst-forming unit-erythroid (BFU- E) recovery assays were performed. The peripheral blood HPCs of 24 consecutive patients included in the program of autologous transplantation were studied. RESULTS: The MNC viability decreased progressively with the length of time from cryopreservation, reaching 32 percent after 31 months of storage. The recovery rates of CFU-GM and BFU-E also decreased progressively with the duration of frozen storage, to 50 and 43.5 percent, respectively, after 12 months and to 0 percent (both) after 24 months. At 6 months of storage, MNC viability was 80 percent, and CFU-GM and BFU-E recovery was 63.5 and 80.5 percent, respectively. There were no differences between MNCs cryopreserved with 5- or 10-percent DMSO in terms of cell viability. There were no differences between CFU-GM recovery or BFU-E recovery from HPCs cryopreserved in 5- or 10-percent DMSO. Patients given HPCs stored in these conditions for periods ranging between 123 and 202 days showed a complete and rapid hematologic recovery. CONCLUSION: HPCs can be cryopreserved at -80 degrees C with 5-percent DMSO and stored at -80 degrees C no longer than 6 months. A 5-percent DMSO concentration is comparable to a with 10-percent concentration in terms of recovery and MNC viability.     

Hematopoietic recovery in cancer patients after transplantation of autologous peripheral blood CD34+ cells or unmanipulated peripheral blood stem and progenitor cells

BACKGROUND: A study of CD34+ cell selection and transplantation was carried out with particular emphasis on characteristics of short- and long-term hematopoietic recovery. STUDY DESIGN AND METHODS: Peripheral blood stem and progenitor cells (PBPCs) were collected from 32 patients, and 17 CD34+ cell-selection procedures were carried out in 15 of the 32. One patient in whom two procedures failed to provide 1 × 10(6) CD34+ cells per kg was excluded from further analysis. After conditioning, patients received CD34+ cells (n = 10, CD34 group) or unmanipulated (n = 17, PBPC group) PBPCs containing equivalent amounts of CD34+ cells or progenitors. RESULTS: The yield of CD34+ cells was 53 percent (18–100) with a purity of 63 percent (49–82). The CD34+ fraction contained 66 percent of colony-forming units-granulocyte- macrophage (CFU-GM) and 58 percent of CFU of mixed lineages, but only 33 percent of burst-forming units-erythroid (BFU-E) (p < 0.05). Early recovery of neutrophils and reticulocytes was identical in the two groups, although a slight delay in platelet recovery may be seen with CD34+ cell selection. Late hematopoietic reconstitution, up to 1.5 years after transplant, was also similar. The two groups were thus combined for analyses of dose effects. A dose of 40 × 10(4) CFU-GM per kg ensured recovery of neutrophils to a level of 1 × 10(9) per L within 11 days, 15 × 10(4) CFU of mixed lineages per kg was associated with platelet independence within 11 days, and 100 × 10(4) BFU-E per kg predicted red cell independence within 13 days. However, a continuous effect of cell dose well beyond these thresholds was apparent, at least for neutrophil recovery. CONCLUSION: CD34+ cell selection, despite lower efficiency in collecting BFU-E, provides a suitable graft with hematopoietic capacity comparable to that of unmanipulated PBPCs. In both groups, all patients will eventually show hematopoietic recovery of all three lineages with 1 × 10(6) CD34+ cells per kg or 5 × 10(4) CFU-GM per kg, but a dose of 5 × 10(6) CD34+ cells or 40 × 10(4) CFU-GM per kg is critical to ensure rapid recovery.     

Albumin-based solution is the ideal post-thawing suspension medium for cord blood hematopoietic stem cells: A stability and proliferative evaluation

Background

Cryopreservation and thawing protocols represent key factors for the efficacy of cellular therapy products, such as hematopoietic stem cells (HSCs). While the HSC cryopreservation has already been standardized, the thawing procedures have been poorly studied. This study aimed to evaluate the thawing and washing protocol of cord blood (CB) derived HSCs or the HPC(CB), by selecting the optimal thawing solution and determining CD34+ cells' stability over time.

Study Design and Methods

Seven cryopreserved CB products were thawed, washed, and resuspended in three different solutions (10% Dextran40 in NaCl equally prepared with 5% human albumin; 5% human albumin in PBS/EDTA; and normal saline) and stored at 4°C (±2°C). Mononuclear cell (MNC) count, CD45+/CD34+ cell enumeration, and cell viability were tested at 0, 1, 2, 4, 6, 8, 12, 24, 36, and 48 h. The protocol with the selected solution was further validated on additional 10 CB samples. The above parameters and the colony-forming unit (CFU) assay were analyzed at time points 0, 2, 4, 6, and 8 h.

Results and Discussion

The results showed that the 5% human albumin was the most suitable thawing solution. MNCs were stable up to 4 h (p = 0.009), viable CD45+ cells were unstable even at 2 h (p = 0.013), and viable CD34+ cells were stable until 6 h (p = 0.019). The CFU assay proved the proliferative potential up to 8 h, although significantly decreased after 4 h (p = 0.013), and correlated with the viable CD34+ cell counts. We demonstrated that the post-thawed and washed HPC(CB) using 5% human albumin is stable for up to 4 h.