Assessment of cell viability, early apoptosis, and hematopoietic potential in umbilical cord blood units after storage

Quality Assessment of Cryopreserved Peripheral Blood Stem Cell Products: Evaluation of Two Methods for Flow Cytometric Viability Testing

INTRODUCTION

The standard flow cytometry method for viability testing using 7-aminoactinomycin D (7-AAD) determines cells in necrosis and late apoptosis. The colony-forming unit (CFU) assay, which evaluates the proliferation ability of HSCs, is also used in graft quality assessment despite known deficiencies that make this assay impractical in routine clinical settings. The aim was to compare the effectiveness of the flow cytometry 7-AAD/annexin V method with the 7-AAD method in assessing the quality of HSCs in autologous and allogeneic peripheral blood stem cell (PBSC) products.

METHODS

Thirty autologous and 30 allogeneic fresh and thawed cryopreserved PBSC products were included in this study. The viability of HSCs was determined using the 7-AAD method and 7-AAD/annexin V method on a flow cytometer, while their clonogenic capacity was assessed by CFU assay.

RESULTS

There was an excellent correlation for CD34+ cell viability between the 7-AAD and the 7-AAD/annexin V method for fresh samples (Rs = 0.930, p < 0.001) and a good correlation for thawed PBSC samples (Rs = 0.739, p < 0.001). Excellent correlation was observed for post-thaw CD34+ cell recovery between the two methods for viability (Rs = 0.980, p < 0.001). Statistical analysis showed a weak correlation between CFU-GM recovery and CD34+ cell recovery, regardless of which viability testing method was used (7-AAD method p = 0.021, Rs = 0.298; 7-AAD/annexin V method p = 0.029, Rs = 0.282).

CONCLUSIONS

Results of this study showed that in the quality assessment of cryopreserved PBSC product viability, the 7-AAD/annexin V method had no added value compared to the 7-AAD method, which was suitable enough for routine quality control of cryopreserved autologous and allogeneic PBSC samples.

Chemotherapy and cryopreservation affects DNA repair foci in lymphocytes of breast cancer patients

PURPOSE

Although breast cancer (BC) patients benefit from radiotherapy (RT), some radiosensitive (RS) patients suffer from side effects caused by ionizing radiation in healthy tissues. It is thought that RS is underlaid by a deficiency in the repair of DNA double-strand breaks (DSB). DNA repair proteins such as p53-binding protein 1 (53BP1) and phosphorylated histone H2AX (γH2AX), form DNA repair foci at the DSB locations and thus serve as DSB biomarkers. Peripheral blood lymphocytes (PBL) are commonly believed to be an appropriate cell system for RS assessment using DNA repair foci. The amount of DSB may also be influenced by chemotherapy (CHT), which is often chosen as the first treatment modality before RT. As it is not always possible to analyze blood samples immediately after collection, there is a need for cryopreservation of PBL in liquid nitrogen. However, cryopreservation may potentially affect the number of DNA repair foci. In this work, we studied the effect of cryopreservation and CHT on the amount of DNA repair foci in PBL of BC patients undergoing radiotherapy.

MATERIALS AND METHODS

The effect of cryopreservation was studied by immunofluorescence analysis of 53BP1 and γH2AX proteins at different time intervals after in vitro irradiation. The effect of chemotherapy was analyzed by fluorescent labelling of 53BP1 and γH2AX proteins in PBL collected before, during, and after RT.

RESULTS

Higher number of primary 53BP1/γH2AX foci was observed in frozen cells indicating that cryopreservation affects the formation of DNA repair foci in PBL of BC patients. In CHT-treated patients, a higher number of foci were found before RT, but no differences were observed during and after the RT.

CONCLUSIONS

Cryopreservation is the method of choice for analyzing DNA repair residual foci, but only similarly treated and preserved cells should be used for comparison of primary foci. CHT induces DNA repair foci in PBL of BC patients, but this effect disappears during radiotherapy.

How do I structure logistic processes in preparation for outsourcing of cellular therapy manufacturing?

As cell and gene therapies (CGT) assume center stage in early-phase clinical trials for several acute and chronic diseases, there is heightened interest in the standardization and automation of manufacturing processes in preparation for commercialization. Toward this goal, a hybrid and oftentimes geographically separated model comprising regional cell procurement and infusion facilities and a centralized cell manufacturing unit is gaining traction in the field. Although CGT processing facilities in academic institutions are not involved directly in the manufacturing of these therapies, they must be prepared to collaborate with commercial or contract manufacturing organizations (CMOs) and be ready to address several supply-chain challenges that have emerged for autologous and allogeneic CGT. Academic center cell-processing facilities must handle many events up- and downstream of manufacturing such as donor screening, cell collection, product labeling, cryopreservation, transportation, and thaw infusion. These events merit closer evaluation in the context of multifacility manufacturing since standard procedures have yet to be established. Based on our institutional experience, we summarize logistical challenges encountered in the handling and distribution of CGT products in early phase studies, specifically those involving CMO (outsourced) manufacturing. We also make recommendations to standardize processes unique to the CGT supply chain, emphasizing the need to maintain needle-to-needle traceability from product collection to infusion. These guidelines will inform the development of more complex supply-chain models for larger-scale cell and gene therapeutics.

Cryopreservation and thawing of hematopoietic stem cell CD34-induced apoptosis through caspase pathway activation: Key role of granulocytes

INTRODUCTION

Cell damage inescapably occurs during both the freezing and the thawing graft processes for autologous hematopoietic stem cell (HSC) transplantation. To estimate HSC injury, a quality control is performed including: (i) CD34⁺ quantification; (ii) percentage of CD34⁺ viability and (iii) evaluation of HSC functional ability to form colony forming unit-granulocyte macrophage (CFU-GM). Apoptosis involves complex pathways such as caspase enzymes. Here, we assess the extent of apoptosis that is caspase-dependent before and after cryoconservation of CD34⁺, using a Fluorescent Labeled Inhibitor of CAspases (FLICA).

METHODS

Caspase pathway activation status was evaluated in 46 patients (multiple myeloma [n = 24], lymphoma [n = 22]), by flow cytometry, using a 7-aminoactinomycin-D (7AAD)/FLICA staining test, in CD34⁺, CD3⁺, CD14⁺ and CD56⁺ cells. Viable 7AAD^-/FLICA⁺ cells were then correlated with various parameters.

RESULTS

We showed a significant caspase pathway activation, with 23% CD34⁺/7AAD^-/FLICA⁺ cells after thawing, compared with the 2% described in fresh CD34⁺ cells (P < 0.0001). Moreover, caspase pathway was significantly activated in thawing CD3⁺, CD56⁺ and CD14⁺ cells. We also report a significant correlation between the rate of CD34⁺/7AAD^-/FLICA⁺ cells and post-thawing granulocytes count (P = 0.042) and their potential to be differentiated into CFU-GM (P = 0.004).

DISCUSSION

Our results show substantial cell death, induced by the increase of caspase pathway activation, secondary to the thawing process, and across all study cell types. This observation may affect the immune response quality during recipient aplasia, without detecting a clinical impact. Moreover, caspase pathway activation through CD3⁺ and CD56⁺ subpopulations could modify the therapeutic result of donor lymphocytes infusion (DLI).

Evaluation of DMSO dextrose as a suitable alternative for DMSO dextran in cord blood cryopreservation

BACKGROUND AND OBJECTIVES

Umbilical cord blood is considered an alternative source of hematopoietic stem cells. Standard banking procedures use 50/55% DMSO in dextran 40 for cryopreservation and dextran-based solutions for thawing, however, due to the potential risk of crystallization of dextran, dextran 40 approved for clinical use has become limited or unavailable. This affects cryopreservation and thawing procedures. Carbohydrates, in particular sucrose, trehalose and glucose, have been shown to be effective in reducing cell damage during dehydration and have cryoprotective potential. We aim to study a 50/55% DMSO in 5% dextrose cryopreservation solution as an alternative to DMSO dextran.

MATERIALS AND METHODS

Eighteen samples were divided into two aliquots and cryopreserved, one using standard solution and the other with DMSO dextrose experimental solution. Both aliquots were thawed and diluted with PBS or saline. Total nucleated cells counts, 7-AAD viability of CD45⁺ cells and recovery of CD34⁺ viable cells were assessed on thawed samples and compared between pair of aliquots.

RESULTS

No differences were observed in the total nucleated cells recovery between cryopreservation solutions, however, higher viability and CD34⁺ viable cells recoveries were observed using the experimental solution.

CONCLUSION

Results showed that DMSO dextrose cryopreservation solution had better results than the standard solution when thawed in an isotonic solution. This indicates that DMSO dextrose is probably a better alternative for direct infusion or when dextran thawing solutions are unavailable. Viability of CD45⁺ cells and recovery of CD34⁺ viable cells have positive correlation with engraftment, highlighting the relevance of the optimization of the cryopreservation and thawing process.

Expansion of Gammadelta T Cells from Cord Blood: A Therapeutical Possibility

Gammadelta (γδ) T cells are found in both blood and tissues and have antiviral and antitumor properties. The frequency of γδ T cells in umbilical cord blood (UCB) is low, and the majority express δ1, in contrast to blood, whereas the main subset is δ2γ9 T cells. UCB γδ T cells are functionally immature, which together with their scarcity complicates the development of UCB γδ T cell therapies. We aimed to develop an effective expansion protocol for UCB γδ T cells based on zoledronate and IL-2. We found that culture with 5 μM zoledronate and 200 IU IL-2/ml medium for 14 days promoted extensive proliferation. The majority of the cultured cells were γ9δ2 T cells. The fold expansion of this, originally infrequent, subset was impressive (median and maximum fold change 253 and 1085, resp.). After culture, the cells had a polyclonal γδ T cell repertoire and the main memory subset was central memory (CD45RO⁺ CD27⁺). The cells produced cytokines such as IL-1B, IL-2, and IL-8 and displayed significant tumor-killing capacity. These results show that development of in vitro expanded UCB γδ T cell therapies is feasible. It could prove a valuable treatment modality for patients after umbilical cord blood transplantation.

Conditioned medium: a new alternative for cryopreservation of equine umbilical cord mesenchymal stem cells

Cryopreservation is a feasible alternative to maintaining several cell lines, particularly for immediate therapeutic use, transportation of samples, and implementation of new in vitro studies. This work parts from the hypothesis that the medium of cryopreservation composed by 90% of conditioned medium (CM) supports cryopreservation of equine umbilical cord intervascular matrix mesenchymal stem cells (UCIM-MSCs), allowing the maintenance of the biological properties for the establishment of cell banks intended for therapeutic use and in vitro studies. Thus, we evaluated the viability, apoptosis/necrosis rates, immunophenotypic profile (IP), chromosomal stability, clonicity, and differentiation potential of UCIM-MSCs cryopreserved with four different mediums (with FBS: M1, M3, M4 and without FBS: M2). After 3 months of cryopreservation, samples were thawed and analyzed. The potential of differentiation in the mesodermal lineages, clonicity, and the chromosomal stability were maintained after cryopreservation of UCIM-MSCs with medium containing FBS. Changes (P < 0.05) at IP for some markers were observed at cells cryopreserved with medium M1-M3. Only the UCIM-MSCs cryopreserved with the CM (M4) had similar viability post-thaw (P = 0.23) when compared with fresh cells. We proved the hypothesis that the medium of cryopreservation containing CM supports the cryopreservation of UCIM-MSCs, at the experimental conditions, being the medium that better maintains the biological characteristics observed at fresh cells. Thus, future studies of UCIM-MSCs secretome should be conducted to better understand the beneficial and protective effects of the CM during the freezing process.