A technique for the concentration of nucleated bone marrow cells for in vitro manipulation or cryopreservation using the IBM 2991 blood cell processor

Concentration of Human Hematopoietic Stem Cells in Bone Marrow Transplantation: Results of a Multicenter Study Using Baxter CS 3000 plus Cell Separator

Preliminary BM processing to produce an enriched MNC fraction from large BM volumes improves subsequent pharmacological and/or immunological “ex vivo” treatment and cryopreservation. We detail on a multicenter study (6 Transplant Centers) performed to establish an effective and reliable protocol using a CS 3000 continuous flow separator on a large series of BM processed for autologous (96) and allogeneic (12) transplantation. The reduction in volume was 78.6+7.2% while 28.9+12.4% of the original nucleated cells were found in the final product. A mean of 84.3+13.2% of the starting MNC was yielded in a fraction containing over 81% MNC. Cloning efficiency indicated than the final graft was highly enriched in progenitor cells committed to the granulocyte/macrophage pathway (> 100%) as assessed in vitro (CFU-GM). Removal of RBC and PLT was 98.3+1.1 and 37.7+14.6%, respectively. The mean dose of MNC and CFU-GM was 0.6+0.37 x 108 and 0.96+1 x 108 recipient weight. The entire process was accomplished in 87.5+20 min. We concluded that this automated device is a simple and reproducible method for BM processing suitable as first step for further “ex vivo” automated negative and/or positive cell selections.

Enrichment of Marrow Hemopoietic Progenitor Cells using a Blood Cell Processor

A total of 93 bone marrows (BM) from normal donors and patients were processed using the IBM-COBE 2991 blood cell washer to produce a concentrated buffy coat (BC) for either bone marrow transplantation (BMT) or cryopreservation for subsequent autologous BMT. The reduction in volume was 73.3 ± 8.5% and nucleated blood cells (NBC) recovery was 87.1 ± 9.1% of original marrow. Red blood cell (RBC) and platelet (PLT) contamination was reduced 64.5 ± 10.9% and 41.2 ± 24.1%, respectively. Clonogenic activity indicated that the NBC fraction was highly enriched in hematopoietic progenitor cells (> 100%) as assessed in vitro (CFU-GM). Results were not affected by diagnosis, initial marrow volume or cell count of the BM suspension. We conclude that this is a simple and reproducible method using blood bank, facilities and permits BC preparation from BM without significant loss of hematopoietic progenitor cells.

Inverted spin method for removing RBCs from BM buffy coat products

BACKGROUND

Inverted spin is a method of removing RBCs that historically has been part of blood banking practice. We investigated the feasibility of using this method for RBC depletion of BM buffy coat products in situations where recipient RBC Abs have been identified to donor RBC Ags.

METHODS

The BM buffy coat product was placed in a transfer pack, inverted, centrifuged at 600 g for 10 min, suspended and the RBCs removed slowly into another transfer pack. Nine patients treated between April 1998 and February 2001 received products prepared by our version of the inverted spin procedure.

RESULTS

We removed a median value of 81.2% of the RBCs, while still recovering a median of 94.3% of the mononuclear cells (median: 0.35 x 10(8)/kg; range: 0.17-0.9 x 10(8)/kg). The median volume of RBCs remaining in the product was 15.0 mL (range: 7.3-21.9 mL). The CD34(+) cell dose of the final product ranged from 1.0 x 10(6)/kg to 4.8 x 10(6) cells/kg (median: 1.9 x 10 6/kg). Granulocyte recovery (defined as ANC count >or=500/microL for a period of 3 consecutive days) ranged from 18-30 days post-infusion of the allograft (median: 24.0 days). One patient died shortly after his transplant from complications of his disease. No patient had any evidence of an acute hemolytic reaction.

DISCUSSION

Advantages of the inverted spin method include no need for additives (e.g. hydroxyethyl starch, HSA, or O negative RBC), and use of equipment readily available in most processing laboratories.

Bone marrow processing using the fenwal CS-3000 plus blood cell separator: results of 99 procedures

BMT is used as an established therapy for patients with malignant and nonmalignant diseases. Many techniques for ex vivo treatment have been developed, but these techniques must be preceded by BM processing. We report our experience in processing 99 BM using the Fenwal CS-3000 Plus cell separator using the 1-special program. Ninety-nine procedures were performed in BM harvested from 73 patients and 26 healthy donors. The number of nucleated cells (NC), mononuclear cells (MNC), RBC, platelets, colony-forming units-granulocyte-macrophage (CFU-GM), CD34+ cells, relative purity of MNC and PMN, and volume were determined in the unprocessed BM and in the final product. BM processing resulted in NC, MNC, CFU-GM, and CD34+ cell recoveries of 31%, 82.2%, 117.6%, and 97.8%, respectively. RBC, PMN, platelets, and volume removal, respectively, were 96%, 92%, 37.2%, and 85.1%. In pediatric patients, the volume reduction was significantly lower than in adult patients (79.6% versus 88.8%). No other significant differences were found between pediatric and adult results. We conclude that BM processing with the Fenwal CS-3000 Plus cell separator provides a product that can undergo further ex vivo treatments or cryopreservation.

Processing of major ABO-incompatible bone marrow for transplantation by using dextran sedimentation

BACKGROUND

Various open and semi-closed methods are used for red cell (RBC) depletion and hematopoietic progenitor cell (HPC) enrichment of bone marrow (BM) in vitro, but with variable efficacy. A simple, efficient, and safe method using dextran 110k was developed.

STUDY DESIGN AND METHODS

An equal volume of 4.5-percent dextran was applied to major ABO-incompatible BM in transfer bags and sedimentation was allowed for 30 minutes. RBCs, nucleated cells (NCs), and mononuclear cells (MNCs) from BM allografts before and after dextran sedimentation (DS) were counted. Flow cytometry, short-term cultures, and long-term cultures were performed to assay the respective recovery of CD34+ cells, colony-forming units (CFUs), and long-term culture-initiating cells (LTC-ICs).

RESULTS

Sixteen BM collections were processed. The mean volume was 666 mL (range, 189-1355 mL). The mean +/-1 SD post-DS NC, MNC, CD34+ cell, and CFU counts per kg of the recipient's body weight were 4.11 +/-1.74 x 10(8), 8.98 +/- 3.68 x 10(7), 2.90 +/- 1.95 x 10(6), and 2.03 +/- 2.01 x 10(5), respectively, with the corresponding post-DS recovery being 90.6 percent, 90 percent, 92.4 percent, and 100.8 percent. The numbers of LTC-ICs in cultures (up to 12 weeks) of pre-DS and post-DS samples of five BM allografts were comparable (p = 0.91). Residual RBCs were 5.1 +/- 4.6 (0.1-14) mL with depletion of 96.5 +/- 3.2 percent. There was no significant difference in the mean absolute RBC count in post-DS BM allografts and in four ficoll-treated BM allografts (8.09 x 10(10) vs. 4.9 x 10(9); p = 0.206) and in eight major ABO-incompatible peripheral blood HPC collections (8.09 x 10(10) vs. 9.81 x 10(10); p = 0.87). No posttransplant hemolysis was encountered. Engraftment occurred at 22 +/- 7 days, which is similar to that of four transplants with ficoll-treated BM allografts (22 +/- 9; p = 0.611) and 54 unprocessed BM allografts (19 +/- 6; p = 0.129).

CONCLUSION

DS is an efficient method of depleting RBCs in major ABO-incompatible BM allografts without significant loss of HPCs.

Analysis for recovery and loss of mononuclear cells and colony-forming units granulocyte-macrophage during ex vivo processing of autologous bone marrow

During ex vivo processing of autologous bone marrow (BM) substantial loss of stem and progenitor cells should be avoided to achieve rapid and sustained hematopoietic reconstitution after high-dose radio-/chemotherapy. We processed 25 autologous BM grafts with the Fresenius AS104 cell separator for cryopreservation and we determined recoveries for mononuclear cells (MNC) and colonyforming units granulocyte-macrophage (CFU-GM) in the BM concentrates. To identify cell loss in BM fractions not cryopreserved, we investigated the MNC and CFU-GM content of BM fat and BM blood. MNC and CFU-GM recovery yielded a mean ( +/- SEM) of 42 +/- 12 and 54 +/- 20% in the BM concentrate. BM fat showed a mean loss of 7 +/- 5% for MNC and 4 +/- 3% for CFU-GM, BM blood 30 +/- 12% for MNC and 13 +/- 13% for CFU-GM, respectively. CFU-GM recovery was significantly higher in the BM concentrate of patients with hematologic malignancy (HM) compared with patients suffering from germ cell cancer (GCC): 66 +/- 21 vs. 43 +/- 12% (p < 0.02). Seventeen patients (7 GCC, 10 HM) underwent high-dose chemotherapy or radio-/chemotherapy and were autografted with 0.8 +/- 0.2 x 10(8) MNC/kg and 3.7 +/- 2.0 x 10(4) CFU-GM/kg. All patients achieved engraftment with neutrophils > 0.5 x 10(9)/l at a mean of 14 +/- 6 days. We conclude that: (1) ex vivo processing of autologous BM with a mean of recovery of 42% for MNC and 54% for CFU-GM in the BM concentrate can result in a cell population capable of sustained hematopoietic reconstitution, (2) CFU-GM recovery is significantly higher in patients with HM than in patients with GCC and (3) 37% MNC and 17% CFU-GM represent in fact cell losses recovered from BM fractions not cryopreserved (BM fat, BM blood). Furthermore, it is likely that MNC and CFU-GM not recovered from BM concentrate, BM fat and BM blood are cell losses related to the cell separator.

Transplantation of CD34+ hematopoietic progenitor cells

We have developed an avidin-biotin immunoadsorption technique in conjunction with a monoclonal anti-CD34 antibody that is capable of selecting CD34+ progenitor cells from marrow and mobilized peripheral blood. Clinical studies with these CD34+ selected cells have shown that the cells are capable of rapid and durable engraftment. In addition, there is significantly less infusional toxicity to the patient because the volume in which the CD34+ selected cells are contained is much less than that of a typical marrow or apheresis buffy coat. Selection of CD34+ progenitor cells also offers other potential advantages, including T-cell depletion of allografts and tumor cell depletion of autografts. CD34+ selection can also be used to facilitate other manipulations of marrow and peripheral blood, including gene transfection, ex vivo stem cell expansion, tumor purging, and progenitor cell banking. Future graft engineering studies are expected to clarify these relationships and enable refinement of the graft to the point at which GVHD can be minimized, graft survival maximized, and relapse-free survival prolonged.

Autologous bone marrow transplantation

Autologous bone marrow transplantation has become a very popular and successful treatment for many patients with lymphomas and other malignancies. The current indications, pretreatment regimes, and laboratory manipulations are discussed as well as the application of gene transfer to eliminate selected genetic diseases and detect disease relapse.

A fully automated method for mononuclear bone marrow cell concentration

We describe our experience in processing 40 bone marrow aspirates harvested for autotransplantation from patients with several hematological diseases using the CS-3000 blood cell separator. The bone marrow of the first 30 patients was processed by a semiautomated method, and a fully automated procedure was used for the remaining 10 cases. Both procedures were developed in our laboratory and yielded a similar average mononuclear cell recovery of 87.78% and 86.98%, respectively, and similar nucleated cell recovery (27.39% and 27.11%). The cloning efficiency of hematopoietic progenitor cells, measured as the total CFU-GM colony recovery in the in vitro cultures, did not differ between processed and recovered mononuclear cells. On the other hand, all the patients with transplants showed complete hematologic recovery, and the time to engraftment was similar to that described for other procedures. The automated procedure resulted in an average red cell removal of 97.81%, similar to the semiautomated procedure (94.19%), though with a narrower range (96.31-98.6% vs. 80.34-98.34%). The time taken to process a similar amount of bone marrow cell suspension was very different for each method: 1 hour for the fully automated vs. 2 1/2 hours for the semiautomated method to process 1,000 ml. Furthermore, the semiautomated procedure required the addition of homologous or irradiated plasma in a laminar air flow chamber, while the automated method is performed in a closed sterile system. We conclude that our procedure using the CS-3000 processor is an efficient method for fully automated large-scale processing of human bone marrow cells.

Quality assurance and standards in hematopoietic progenitor processing

Bone marrow transplantation is an increasingly important therapeutic procedure. As more laboratories have become involved in the processing of hematopoietic progenitor cells from marrow or blood, it has been recognized that standards are required for hematopoietic progenitor processing, storage, and handling. Quality assurance is the process of monitoring whether laboratory procedures, equipment, and personnel fulfill their expected functions, and the aim of quality assurance is to ensure compliance with standards. Some standards for hematopoietic progenitor processing have recently been issued by professional organizations. Although these standards are not comprehensive, where applicable they should be met or exceeded. In the absence of published standards, principles of good laboratory practice should guide quality assurance programs. This article presents concepts of quality assurance in hematopoietic progenitor processing, based on standard laboratory practice and published standards.

BEAM autografting in lymphoma--experience at one centre

Since December 1987, we have examined the use of high-dose chemotherapy and unpurged bone marrow rescue in 31 patients with advanced or refractory lymphoma. Twenty-one patients had Hodgkin's disease (HD) and 10 had Non-Hodgkin's lymphoma (NHL). At ABMT, 22 patients had relapsed or resistant disease. All patients, excluding 3 early deaths, engrafted. There was no relationship between cell numbers harvested, CFU-GM and bone marrow recovery. The mean times to 0.5 x 10(9)/l neutrophils and 50 x 10(9)/l platelets were 20 d and 43 d respectively. However, 5 patients with HD had a significantly slower platelet recovery time of up to 203 days (p = 0.05). Disease-free survival was 72% for HD and 40% for NHL at 40 months. Relapsed or refractory disease at ABMT, bulky disease, extensive salvage therapy and Karnofsky scores below 80% were all associated with a poorer outcome. The most striking observation has been the dramatic radiological response of some patients with advanced/refractory disease.

Bone marrow processing for transplantation

As indications for BMT increase, so do variations in bone marrow processing and manipulation techniques. Many centers have their own unique methods of mononuclear cell purification, concentration and storage. This is particularly evident in the processing of bone marrow for autologous BMT to allow dose intensification as salvage therapy for malignant disease. Unique procedures have been developed to maximize yields, concentrate mononuclear cells necessary for engraftment, and reduce the likelihood of GVH disease. Graft rejection and disease relapse still remain a problem in some of these "manipulated" marrows. Newer procedures may allow titration of the optimum numbers of immune reconstituting cells; however, at this time, these techniques are not precise and the balance between preventing GVH disease at the expense of graft failure or relapse may still jeopardize disease-free survival. Innovative purging techniques that include pharmacologic and immunologic methods, continue to evolve, necessitating standards for bone marrow processing that are flexible yet practical. Quality control and viability assays are essential to verify the biologic proliferative potential of progenitor cells capable of marrow reconstitution. Although no standards are yet established, all centers should have criteria to monitor the quality of the processed marrow. Blood banks and transfusion services are well versed in regulations governing processing, labeling, storage, and quality control of blood components. Bone marrow is the ultimate blood component, and it stands to reason that methods outlined in this article be integrated into transfusion medicine.

Collection and cryopreservation of human stem and progenitor cells for bone marrow transplantation

Bone marrow collection was undertaken from human organ donors (Group 1: n = 7) to develop a closed-system single-step technique for stem and progenitor cell enrichment, using the Cobe 2997 continuous-flow blood-cell separator. The effects of programmed freezing, storage in liquid nitrogen, and thawing were then defined using these grafts. Once standardised, this method was extended to autografting following cryopreservation of a comparable fraction (Group 2: n = 8) and then to allogeneic transplantation after ex vivo exposure to the lytic monoclonal antibody. Campath-1 IgM and human complement, but without cryopreservation (Group 3; n = 9). The median number of mononuclear cells harvested was 5.0 x 10(6)/mL (n = 24), and this was not significantly different in the three groups. The ex vivo graft, composing marrow rich anticoagulated whole blood, was recirculated in the separator at a flow rate of 60 mL/minute, with a centrifuge speed of 1,100 r.p.m., and the mononuclear cell fractions were collected at the rate of 1.5 mL/minute. The average procedure time from formation of the interface in the single disposable channel to achievement of the final volume was 90 minutes. The mean recovery of the mononuclear cells was 101.4% (SD 38.0) and the GM:CFUc was 91% (SD 43.86). These figures were not significantly influenced by subsequent cryopreservation (Group 1; n = 7 and Group 2; n = 8) or following exposure to the monoclonal antibody. Campath-1 IgM (Group 3; n = 9).(ABSTRACT TRUNCATED AT 250 WORDS)

Hematopoietic stem cell processing and storage

The techniques to collect, process, and store HSC in anticipation of transplantation are now widely available. Important unresolved issues revolve around the as yet imperfect identification and classification of totipotential progenitors. However, much progress has been and will continue to be made despite this limitation. Research priorities of present and future stem cell processing laboratories should include: 1. Optimization of liquid (nonfrozen) storage techniques. This will permit more complex cell-specific manipulations, such as T-lymphocyte subset selection, isolation of CD34+ populations, treatment in vitro with growth factors, gene transfer experiments, and long-range transport of HSC, to be performed while preserving HSC integrity. 2. A better understanding of the regulation and kinetics of peripheral blood and umbilical cord HSC, to allow optimum collection procedures that do not require marrow harvesting. 3. An intensive study into the optimum conditions of collection, processing, and storage of megakaryocytic progenitors to decrease the long platelet-transfusion dependency of the myeloablated patient. 4. A search for a simple in vitro correlate of engraftment potential of a stem cell preparation. This will greatly improve the quality control functions of the laboratory as well as contribute to better patient selection for transplantation.

Continuous flow cell separator use for bone marrow processing

Many techniques have been described for processing bone marrow prior to transplantation, purging or cryopreservation. Effective techniques incorporate centrifugation and, or, density separation to produce an ideal marrow concentrate. We report on the use of a continuous flow cell separator (COBE Spectra) for marrow processing. Preliminary results indicate that the improved technology incorporated in this machine together with the new algorithm control of its collection functions allows for rapid collection of an ideal marrow concentrate. The addition of an inert sedimenting agent prior to processing enhances differential mononuclear cell collection and elimination of red blood cells and granulocytes. By this technique a volume depletion of 87% was achieved with recovery of 76.4% mononuclear cells and 86.5% CFU-GM progenitor cells. Marrow processed in this manner has been successfully transplanted; patients receiving such marrow show no delay in engraftment and their grafts have been sustained.

A simple method to obtain low density marrow cells for human marrow transplantation

Removal of more than 99% of the erythrocytes and 74% of the nucleated cells from marrow grafts was achieved by density floatation separation in Percoll gradients with a density of 1.070 g/ml in eight 250-ml tubes, containing up to 3 X 10(9) nucleated cells per gradient. More than 90% of the myeloid and erythroid progenitor cells were recovered in the low density fraction. It appeared mandatory to use a centrifuge with the possibility of a gradual acceleration and deceleration. Twenty-five patients received a marrow graft from a histocompatible sibling after additional lymphocyte depletion by counterflow centrifugation, and 5 patients with T lymphoblastic malignancies received an autograft after in vitro purging with immunotoxins. All evaluable patients engrafted within normal limits, except 1 patient with an autoimmune pancytopenia who responded to steroids and 1 patient with a CMV infection. Four patients died too early for complete evaluation. The described separation method is easy, cheap and requires only 2 h for the complete processing of a marrow graft.

Standardization of the processing of human bone marrow for allogeneic transplantation

Allogeneic bone marrow transplantation has been undertaken within this centre on 62 patients with acute or chronic leukaemia. Employing the standard separation protocol described, all bone marrows were processed on the 2991 Blood Cell Processor to isolate the 'buffy coat' cells and subsequently the mononuclear cell component using a density separation medium of Ficoll-metrizoate. Following the mononuclear cell separation, the cells were identified for their T lymphocyte component using a combination of two murine monoclonal antibodies, MBG6 reacting with a pan T cell antigen (CD6) and RFT8 detecting the 'cytotoxic/supressor' cell antigen (CD8). The numerical results for nucleated cells, red blood cells, T lymphocytes and colony forming units-granulocyte macrophage are presented.

Concentration of hematopoietic progenitor cells from human bone marrow by a new type of blood component separator

A new type of blood component separator (BCS) was used for the isolation of hematopoietic progenitor cells from human bone marrow aspirates. The BCS was filled with 100-150 ml bone marrow and centrifuged to prepare a buffy coat. This buffy coat was isolated in 10-15% of the original bone marrow volume and contained 64 +/- 8% of the nucleated cells (NC). Morphological examination revealed that the buffy coat was highly enriched for myeloblasts, promyelocytes, lymphocytes and monocytes, whereas the contamination with granulocytes was reduced to 46 +/- 8% of the granulocytes initially present in the bone marrow suspension. In addition the contamination with red blood cells (RBC) was very low; the buffy coat contained only 6 +/- 2% of the RBC. Furthermore it was demonstrated by means of colony assays that the buffy coat was highly enriched for hematopoietic progenitor cells. It contained 91 +/- 6% of the granulocyte/monocyte progenitor cells (CFU-GM) and 87 +/- 9% of the erythroid progenitor cells (BFU-E). These results are comparable to those obtained with continuous or semicontinuous blood cell processors. The advantages of the BCS is that it is a simple and inexpensive apparatus which fits in a normal blood bank centrifuge. It permits efficient preparation and isolation of a buffy coat from human bone marrow without substantial loss of hematopoietic progenitor cells.