Apheresis techniques for collection of peripheral blood progenitor cells

Apheresis collection of mononuclear cells for chimeric-antigen receptor therapies

Collections of lymphocytes to be genetically modified to treat hematologic malignancies have seen a dramatic increase over the last few years as commercial products have been approved. Reports of new products in development that can possibly treat solid organ malignancies represent a massive change in the field. Apheresis is at the center of the collection of cells for the manufacture of these chimeric-antigen receptor therapy products. The expansion of these collections represents one of the areas of apheresis procedures growth. This review will summarize concepts important to this type of collection and variables that need to be optimized to obtain desired cell yields while increasing patients' safety.

Small volume bone marrow aspirates with high progenitor cell concentrations maximize cell therapy dose manufacture and substantially reduce donor hemoglobin loss

BACKGROUND

Bone marrow (BM) transplantation is a life-saving therapy for hematological diseases, and the BM harbors also highly useful (progenitor) cell types for novel cell therapies manufacture. Yet, the BM collection technique is not standardized.

METHODS

Benchmarking our collection efficiency to BM collections worldwide (N = 1248), we noted a great variability of total nucleated cell (TNC) yields in BM products (HPC-M) with superior performance of our center, where we have implemented a small volume aspirate policy. Thus, we next prospectively aimed to assess the impact of BM collection technique on HPC-M quality. For each BM collection (N = 20 donors), small volume (3 mL) and large volume (10 mL) BM aspirates were sampled at 3 time points and analyzed for cell composition.

RESULTS

Compared to large volume aspirates, small volume aspirates concentrated more TNCs, immune cells, platelets, hematopoietic stem/progenitor cells, mesenchymal stromal cells (MSCs), and endothelial progenitors. Inversely, the hemoglobin concentration was higher in large volume aspirates indicating more hemoglobin loss. Manufacturing and dosing scenarios showed that small volume aspirates save up to 42% BM volume and 44% hemoglobin for HPC-M donors. Moreover, MSC production efficiency can be increased by more than 150%.

CONCLUSIONS

We propose to consider small volume BM aspiration as standard technique for BM collection.

Stem cells: Haemobiology and clinical data summarising: A critical review

Stem cells (SC) are the unique and "key-cells" in the human body "working" as a source of producing a large number (proliferation) of mature (differentiation) cells inside different tissues ("cytopoiesis") - while at the same time maintaining the ability to "reproduce" themselves (self-renewal). These events are balanced by interactive signals from the extracellular matrix, as well as microenvironment provided by stromal cells. On the other hand, SC plasticity (so-called "inter-systemic plasticity") is the ability of the most "primitive" (immature) adult SCs to switch to novel identities. The phrase SC plasticity also involves phenotypic potential of these cells, broader than spectrum of phenotypes of differentiated cells in their original tissues. Recent increasing clinical use of cell-mediated therapeutic approaches has resulted in enlarged needs for both, higher quantity of SCs and improved operating procedures during extracorporeal manipulations. The aim of harvesting procedures is to obtain the best SC yield and viability. The goal of optimised cryopreservation is to minimise cellular thermal damages during freeze/thaw process (cryoinjury). Despite the fact that different SC collection, purification and cryopreservation protocols are already in routine use - a lot of problems related to the optimal SC extracorporeal manipulations are still unresolved. The objective of this paper is to provide an integral review of early haemobiological and cryobiological research in the unlimited "SC-field" with emphasis on their entities, recent cell-concepts, extracorporeal manipulative and "graft-engineering" systems. Their therapeutic relevance and efficacy in "conventional" SC transplants or regenerative medicine will be briefly summarised. Finally, in this paper original results will not be pointed out - related to neither SC transplants nor regenerative medicine - but a light will be shed on some of them.

Quantity, quality, and functionality of peripheral blood cells derived from residual blood of different apheresis kits

BACKGROUND

Research with primary human white blood cell (WBC) subpopulations requires high quantity, quality, and functionality of peripheral blood mononuclear cells (PBMCs) as a source to further characterize cellular subpopulations such as T and B lymphocytes, monocytes, or natural killer cells. Apart from buffy coats derived from whole blood, residual blood from preparative hemapheresis kits are used as a source for PBMCs, but knowledge on the yield and functionality of cells from different devices is limited.

STUDY DESIGN AND METHODS

We evaluated quantity and quality of PBMCs isolated from apheresis kits of two apheresis devices (AMICUS, Fenwal; and Trima Accel, Terumo BCT), the latter being our standard source for many years. PBMCs derived from Trima or AMICUS were tested for yield and subtype composition by flow cytometry. Functionality was assessed by cytokine induction of CD4⁺ and CD8⁺ T cells and by degranulation. Moreover, cytotoxic activity of natural killer cells was quantified by a real-time killing assay.

RESULTS

Mean numbers of isolated cells were 5.5 ± 2.4 × 10⁸ for AMICUS, and 10.3 ± 6.4 × 10⁸ for Trima Accel, respectively. The proportion of WBC subtypes corresponded to well-known numbers from whole blood, with minor differences between the two apheresis systems. Likewise, minor differences in cytokine induction were found in stimulated CD4⁺ or CD8⁺ T cells. Finally, PBMCs derived from the two systems showed comparable cytotoxic activity.

CONCLUSION

PBMC derived from residual blood of the AMICUS and Trima Accel apheresis devices serve as an economic and easily accessible source for functional PBMCs with comparable quantity and quality to PBMCs derived from whole blood.

Attempt to Harvest a Sufficient Number of Mononuclear Cells in an Appropriate Blood Product Volume By Modification of the Default Apheresis Setting

To harvest for T cell therapy, a 1.6-fold higher number of CD3⁺ T cells was collected with MNC mode (N = 10) compared with Auto PBSC mode (N = 5) in COBE Spectra cell separator, but the blood product volume was increased by 3.5-fold. For therapeutic angiogenesis therapy, apheresis was initially performed using Auto PBSC mode (N = 4) to fine tune the blood product volume to omit cell concentration, but the collected number of mononuclear cells was lower than expected. However, an increase of the harvest cycle number from 3.8 ± 0.5 to 7.4 ± 2.0 cycles (N = 19) resulted in a 2.1-fold higher number of collected mononuclear cells (8.7 ± 4.1 × 10⁹ vs. 4.1 ± 1.0 × 10⁹ cells, P < 0.05). The increase in blood product volume by this modification appeared to be lower than that expected with MNC mode. These data show that optimal harvesting can be achieved by modification of default collection settings.

A retrospective study of autologous stem cell mobilization to guide an immediate salvage protocol using plerixafor for patients who mobilize stem cells poorly

The addition of plerixafor to G-CSF decreases the risk of failed stem cell collection, but at considerable extra cost. Using a logistic regression model based on 354 autologous mobilizations, we have identified a local minimum peripheral blood CD34 count at which the probability of a successful collection is 50%. This seems an appropriate CD34 count at which to add immediate salvage plerixafor.

Stem cell collection in unmanipulated HLA-haploidentical/mismatched related transplantation with combined granulocyte-colony stimulating factor-mobilised blood and bone marrow for patients with haematologic malignancies: the impact of donor characteristics and procedural settings

Unmanipulated haploidentical/mismatched related transplantation with combined granulocyte-colony stimulating factor-mobilised peripheral blood stem cells (G-PBSCs) and granulocyte-colony stimulating factor-mobilised bone marrow (G-BM) has been developed as an alternative transplantation strategy for patients with haematologic malignancies. However, little information is available about the factors predicting the outcome of peripheral blood stem cell (PBSC) collection and bone marrow (BM) harvest in this transplantation. The effects of donor characteristics and procedure factors on CD34⁺ cell yield were investigated. A total of 104 related healthy donors received granulocyte-colony stimulating factor (G-CSF) followed by PBSC collection and BM harvest. Male donors had significantly higher yields compared with female donors. In multiple regression analysis for peripheral blood collection, age and flow rate were negatively correlated with cell yield, whereas body mass index, pre-aphaeresis white blood cell (WBC) and circulating immature cell (CIC) counts were positively correlated with cell yields. For BM harvest, age was negatively correlated with cell yields, whereas pre-BM collection CIC counts were positively correlated with cell yield. All donors achieved the final product of ≥6 ×10⁶ kg⁻¹ recipient body weight. This transplantation strategy has been shown to be a feasible approach with acceptable outcomes in stem cell collection for patients who received HLA-haploidentical/mismatched transplantation with combined G-PBSCs and G-BM. In donors with multiple high-risk characteristics for poor aphaeresis CD34⁺ cell yield, BM was an alternative source.

Collection of mobilized peripheral blood stem cells from a donor with severe iron deficient anemia

We report a 45-year-old woman with iron deficient anemia (IDA) who underwent a collection of allogeneic peripheral blood stem cells (PBSCs) induced by granulocyte-colony stimulating factor (G-CSF) after a rapid improvement of IDA by iron replacement. Her peripheral red blood cells (RBCs) after iron therapy were composed of two different-sized subpopulations; one consisted of microcytes, which were iron deficient RBCs, and another of normocytes, which were produced after iron replacement. On the first day of PBSC collection, the interface setting was maintained aiming at 2% hematocrit as usual; however, PBSCs could not be collected adequately. Sedimentation of iron deficient, lighter RBCs under centrifugation within a blood cell separator could be similar to that of mononuclear cells, and the lighter RBCs could contaminate the mononuclear cell layer, resulting in the collection of the lighter layers of mononuclear cells than desired. On the second day, we succeeded in obtaining enough PBSCs by collecting heavier layers than those collected on the first day by using a 4% hematocrit and monitoring white blood cell counts of the collection line serially. It should be noted that the lighter RBCs from a donor with a history of IDA could complicate collection of PBSCs.

Peripheral blood hematopoietic stem cells: Biology, apheresis collection and cryopreservation

Introduction Hematopoiesis is a continuous, dynamic and highly complex process resulting in production of various mature blood cells from a small population of pluripotent stem and progenitor cells through diverse proliferative and differentiative events. Numerous studies have demonstrated that a complex network of interactive cytokines regulates the survival, maturation, and proliferation of hematopoietic stem and progenitor cells (HSPCs). Application of cell-mediated therapy Massive application of different cell-mediated therapeutic methods has resulted in an increased need for both specific HSPCs and operating procedures providing minimal cell damage during collection, processing and storage in a liquid or frozen state. Therefore, the basic aim of cell harvesting, selection, as well as cryopreservation is to minimize cell damage during these procedures. HSPCs are cells which exhibit extensive self-renewal and proliferative capacity, associated with the capacity to differentiate into all blood cells and other cell lineages (plasticity of HSPC). Thanks to these properties, stem cells can provide complete and permanent restoration of hematopoiesis, which is the basis for clinical employment of HSPC transplantation. In addition, totipotent stem cells can be used for the so called "cell-therapy" in different clinical settings (e.g. myocardial regeneration after acute infarction). Conclusion Despite the fact that HSPC transplantation is already in routine use, some questions related to the optimal blood progenitor/cell collection, selection, storage and clinical use are still unresolved. Therefore, this review only briefly discusses the therapeutic use of HSPCs in different clinical areas and focuses on the recommendations, as well as the specific transfusion policies related to HSPC collection, processing, and cryopreservation with an emphasis on quality control.

Apheresis in donor and therapeutic settings: Recruitments vs. possibilities—a multicenter study

In our country, the first apheresis was performed in the late 1960s (by manual technique), and the first cell separator was used in 1979. The number of blood component collections performed from 1994 to 2004 was: 11,170 (total), i.e., 8540 (NBTI), 1180 (IT-MMA), 1050 (BTI of Novi Sad) and 400 (BTI Nis). The number of PBSC harvests during 1996-2004 was 386 for treatment of 272 patients. For treatment of myocardial infarction, "cell-therapy" by autologous stem cells was introduced in 2004 at the MMA. The results of PE treatments performed (7632 sessions) by our group for various immune-mediated and other disorders were generally beneficial, but the effect is not associated with bone marrow remission. TC procedures (total number=1279) resulted in a significant fall in the blood cell counts and hemorheological improvement, as well as the removal and replacement of abnormal red blood cells. Greater standardization of different apheresis protocols is required.