Density gradient isolation of peripheral blood mononuclear cells using a blood cell processor

Recent Advances in Good Manufacturing Practice-Grade Generation of Dendritic Cells

Dendritic cells (DCs) are pivotal regulators of immune responses, specialized in antigen presentation and bridging the gap between the innate and adaptive immune system. Due to these key features, DCs have become a pillar of the continuously growing field of cellular therapies. Here we review recent advances in good manufacturing practice strategies and their individual specificities in relation to DC production for clinical applications. These take into account both small-scale experimental approaches as well as automated systems for patient care.

Manufacturing Dendritic Cells for Immunotherapy: Monocyte Enrichment

Dendritic cells play a key role in activation of the immune system as potent antigen-presenting cells. This pivotal position, along with the ability to generate dendritic cells from monocytes and ready uptake of antigen, makes them an intriguing vehicle for immunotherapy for a variety of indications. Since the first reported trial using dendritic cells in 1995, they have been used in trials all over the world for a plethora of indications. Monocyte-derived dendritic cells are generated from whole blood or apheresis products by culturing enriched monocytes in the presence of interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF). A variety of methods can be used for enrichment of monocytes for generation of clinical-grade dendritic cells and are summarized herein.

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.

Effect of L-phenylalanine methyl ester on the colony formation of hematopoietic progenitor cells from human bone marrow

We have previously shown that L-phenylalanine methyl ester (PME) is capable of removing monocytes and enhancing the growth of hematopoietic colonies from human peripheral blood (PB) mononuclear cells (MNC). In the present study, we further compared the effect of PME on the colony formation of bone marrow (BM) and PB. Low density (less than or equal to 1.077 g/ml) MNC were obtained by Ficoll-diatrizoate density gradient centrifugation. Granulocyte/macrophage colony-forming units (CFU-gm) and erythroid burst-forming units (BFU-e) were cultured in agarose with conditioned media (CM) and/or interleukin 3 (IL-3), granulocyte colony-stimulating factor (G-CSF) and granulocyte/macrophage-CSF (GM-CSF). Treatment of BM MNC with 5 mM PME for 15 min at room temperature yielded a nucleated cell recovery of 44.8 +/- 5.0% (mean +/- SE; N = 8). CFU-gm were enriched 2.7-fold (range 2.0 to 4.8). Using CM or CM supplemented with G-CSF or GM-CSF has minimal effect on the enrichment. Leukocyte differentials revealed that 94.3 +/- 3.05% of the monocytes, as well as 91.2 +/- 1.60% of the cells in the neutrophilic maturation series were removed by PME. Incubation for 40 min in PME abolished CFU-gm formation. BFU-e were not enriched by the PME treatment. In contrast, 40 min incubation of PB MNC produced higher enrichment of CFU-gm than that obtained from 15 min of treatment, although lower cell recovery was obtained with the longer treatment time. In conclusion, we have demonstrated that phagocytic cells can be removed from BM or PB MNC by PME treatment.(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.

Removal of peripheral blood monocytes by phenylalanine methyl ester has no effect on the colony growth of hematopoietic progenitor cells

Purification of hematopoietic cells often includes an adherence step for the removal of monocytes. Recent studies have shown that some hematopoietic cells are adherent and that plastic adhesion might activate monocyte/macrophage for cytokine production. We investigated the possibility of using L-phenylalanine methyl ester (PME) as an alternative approach to monocyte removal, particularly for large-scale cell separations. Cell yield, extent of monocyte removal and cloning efficiency of colony-forming progenitor cells were compared to that produced by plastic adhesion. Starting with mononuclear cells (MNC) from adult peripheral blood, cell recovery after PME treatment was higher than that achieved with adherence and fewer monocytes were present. Cloning efficiency of the granulocyte-monocyte colony-forming progenitor cells (CFU-gm) was not affected by the PME treatment. PME treatment and plastic adhesion of low-density cord blood cells produced comparable cell recovery, monocyte depletion and cloning efficiencies for CFU-gm and burst forming units for erythroid progenitor cells (BFU-e). The PME procedure was optimized for the purification of hematopoietic cells from large quantities (less than 1 x 10(9)) of low density. T cell-depleted peripheral blood MNC containing 60% to 85% monocytes. Compared to two cycles of plastic adhesion, PME treatment permitted higher cell recovery (5.9% vs. 1.3%), lower monocyte contamination (4.5% vs. 10.7%) and substantial cost, time and labor savings without compromising CFU-gm growth.

Generation of lymphokine activated killer cells in a new high density dialyzing culture apparatus

In order to establish an efficient culture system for the generation of lymphokine activated killer (LAK) cells, we have developed a new device which is essentially based on a continuous dialyzing culture vessel. LAK cells grown in such a system showed higher cytotoxicity than those grown under conventional culture conditions. By using this new apparatus with continuous regulation of infused interleukin 2, nutritional medium, and pO(2) and pCO(2), yields of 2×10(7) cells/ml were achieved and maintained for more than 21 days. These cells also showed a significant increase of LAK activity on a per cell basis.