The role of depletion of dimethyl sulfoxide before autografting: on hematologic recovery, side effects, and toxicity

Impact of lower concentrations of dimethyl sulfoxide on cryopreservation of autologous hematopoietic stem cells: a systematic review and meta-analysis of controlled clinical studies

BACKGROUND AIMS

Cryopreservation of hematopoietic stem cells (HSCs) is crucial for autologous transplantation, cord blood banking and other special circumstances. Dimethyl sulfoxide (DMSO) is used most commonly for cryopreserving HSC products but can cause infusional toxicities and affect cell viability and engraftment after transplant. A systematic review of controlled studies using lower concentrations of DMSO to cryopreserve HSC products in clinical transplant studies is needed to determine the effect of reducing DMSO concentrations on post-thaw cell viability, initial engraftment and adverse effects on patient health.

METHODS

All studies identified in our systematic search (to July 11, 2023) examining the use of cryopreserved peripheral blood stem cells (PBSCs) for autologous stem cell transplantation (AHCT) were included. Meta-analysis was performed to determine how varying the concentration of DMSO during cryopreservation effects post-thaw cell viability, initial engraftment and adverse effects on patient health.

RESULTS

A total of 1547 studies were identified in our systematic search, with seven published articles meeting eligibility for inclusion in meta-analysis. All patients underwent AHCT using (PBSCs) to treat hematologic malignancies. The viability of CD34+ cells post thaw was greater when cryopreserved with 5% DMSO compared with 10% DMSO, with lower rates of adverse side effects in patients. DMSO concentration had minimal impact on rates of initial engraftment. Significant heterogeneity in outcome reporting was observed and the potential for bias was identified in all studies.

CONCLUSIONS

Reducing the concentration of DMSO from 10% to 5% during cryopreservation of autologous PBSCs may improve cell viability and reduce DMSO-associated adverse effects in patients undergoing AHCT. Data from more studies with similar patients and standard outcome reporting are needed to increase confidence in our initial observations.

PROTOCOL REGISTRATION

PROSPERO; registration number CRD42023476809 registered November 8, 2023.

Pros and Cons of Cryopreserving Allogeneic Stem Cell Products

The COVID-19 pandemic has precipitously changed the practice of transplanting fresh allografts. The safety measures adopted during the pandemic prompted the near-universal graft cryopreservation. However, the influence of cryopreserving allogeneic grafts on long-term transplant outcomes has emerged only in the most recent literature. In this review, the basic principles of cell cryopreservation are revised and the effects of cryopreservation on the different graft components are carefully reexamined. Finally, a literature revision on studies comparing transplant outcomes in patients receiving cryopreserved and fresh grafts is illustrated.

Cryopreservation: A Comprehensive Overview, Challenges, and Future Perspectives

Cryopreservation is the most prevalent method of long-term cell preservation. Effective cell cryopreservation depends on freezing, adequate storage, and correct thawing techniques. Recent advances in cryopreservation techniques minimize the cellular damage which occurs while processing samples. This article focuses on the fundamentals of cryopreservation techniques and how they can be implemented in a variety of clinical settings. The article presents a brief description of each of the standard cryopreservation procedures, such as slow freezing and vitrification. Alongside that, the membrane permeating and nonpermeating cryoprotectants are briefly discussed, along with current advancements in the field of cryopreservation and variables influencing the cryopreservation process. The diminution of cryoinjury incurred by the cell via the resuscitation process will also be highlighted. In the end application of cryopreservation techniques in many fields, with a special emphasis on stem cell preservation techniques and current advancements presented. Furthermore, the challenges while implementing cryopreservation and the futuristic scope of the fields are illustrated herein. The content of this review sheds light on various ways to enhance the output of the cell preservation process and minimize cryoinjury while improving cell revival.

Determination of the relationship between CD34+ stem cell amount and DMSO in hematopoetic stem cell transplantation

It is important to calculate the CD34+ stem cell (SC) count at the right time in patients with hematological malignancies who will undergo Hematopoietic Stem Cell Transplantation (HSCT). The amount of SC infused into the patient affects the engraftment time and healing process of the patient. In this study, we aimed to compare which of the DMSO-not removed and DMSO-removed samples showed the CD34 + SC amount more accurately as the SC amount determination method after the SC was dissolved after cryopreservation in patients who will undergo HSCT. A total of 22 patients were included in the study. All 22 patients were transplanted from frozen samples using DMSO. After the SC products were dissolved in a 37 °C water bath, they were washed 2 times and the amount of CD34+ SC was studied from the samples taken by removing DMSO and without removing DMSO. In the findings, the amounts of CD34+ SC studied with both methods were compared. The increase in the number and percentage of CD34+ SC after DMSO-removed was found to be statistically significant both in terms of difference and proportionally, and the calculated effect sizes also showed that the increase was clinically significant (Cohen's d is between 0.43 and 0.677). After thawing the frozen SCs of the patients who will undergo HSCT, the analysis of CD34+ SCs from which DMSO is removed provides a more accurate calculation of the CD34+ SC amount in the AP.

Recent Developments in Cell Shipping Methods

As opposed to remarkable advances in the cell therapy industry, researches reveal inexplicable difficulties associated with preserving and post-thawing cell death. Post cryopreservation apoptosis is a common occurrence that has attracted the attention of scientists to use apoptosis inhibitors. Transporting cells without compromising their survival and function is crucial for any experimental cell-based therapy. Preservation of cells allows the safe transportation of cells between distances and improves quality control testing in clinical and research applications. The vitality of transported cells is used to evaluate the efficacy of transportation strategies. For many decades, the conventional global methods of cell transfer were not only expensive but also challenging and had adverse effects. The first determination of some projects is optimizing cell survival after cryopreservation. The new generation of cryopreservation science wishes to find appropriate and alternative methods for cell transportation to ship viable cells at an ambient temperature without dry ice or in media-filled flasks. The diversity of cell therapies demands new cell shipping methodologies and cryoprotectants. In this review, we tried to summarize novel improved cryopreservation methods and alternatives to cryopreservation with safe and viable cell shipping at ambient temperature, including dry preservation, hypothermic preservation, gel-based methods, encapsulation methods, fibrin microbeads, and osmolyte solution compositions. This article is protected by copyright. All rights reserved.

Innovative Approach in the Cryogenic Freezing Medium for Mesenchymal Stem Cells

The physical stresses during cryopreservation affect stem cell survival and further proliferation. To minimize or prevent cryoinjury, cryoprotective agents (CPAs) are indispensable. Despite the widespread use of 10% dimethyl sulfoxide (DMSO), there are concerns about its potential adverse effects. To bypass those effects, combinations of CPAs have been investigated. This study aimed to verify whether high-molecular-hyaluronic acid (HMW-HA) serves as a cryoprotectant when preserving human mesenchymal stem cells (hMSCs) to reduce the DMSO concentration in the cryopreservation medium. We studied how 0.1% or 0.2% HMW-HA combined with reduced DMSO concentrations (from 10% to 5%, and 3%) affected total cell count, viability, immunophenotype, and differentiation potential post-cryopreservation. Immediately after cell revival, the highest total cell count was observed in 10% DMSO-stored hMSC. However, two weeks after cell cultivation an increased cell count was seen in the HMW-HA-stored groups along with a continued increase in hMSCs stored using 3% DMSO and 0.1% HMW-HA. The increased total cell count corresponded to elevated expression of stemness marker CD49f. The HA-supplemented cryomedium did not affect the differential potential of hMSC. Our results will participate in producing a ready-to-use product for cryopreservation of mesenchymal stem cells.

Astragalus and human mesenchymal stem cells promote wound healing by mediating immunomodulatory effects through paracrine signaling

Background: Skin regeneration from an injury without a scar is still a challenge. Methods: A murine model of a skin wound was treated with a combination of extract of astragalus and exosomes of mesenchymal stem cells (MSCs). CD11b+ and CD45 macrophages were detected and levels of cytokines were tested. Results: The expression of growth factors VEGF, FGF2 and EGF was elevated after treatment administered to MSCs. The administration of ethanolic extract of astragalus decreased the expression of TNF-α, IL-1β and IL-6 and simultaneously increased the levels of IL-10. The combination sped up the process of wound healing. A sustained-release gel with both ingredients was developed to enhance restoration from granulation. Conclusion: The extract of astragalus promotes the efficacy of MSC-derived exosomes in skin repair.

Polymer-Mediated Cryopreservation of Bacteriophages

Bacteriophages (phages, bacteria-specific viruses) have biotechnological and therapeutic potential. To apply phages as pure or heterogeneous mixtures, it is essential to have a robust mechanism for transport and storage, with different phages having very different stability profiles across storage conditions. For many biologics, cryopreservation is employed for long-term storage and cryoprotectants are essential to mitigate cold-induced damage. Here, we report that poly(ethylene glycol) can be used to protect phages from cold damage, functioning at just 10 mg·mL-1 (∼1 wt %) and outperforms glycerol in many cases, which is a currently used cryoprotectant. Protection is afforded at both -20 and -80 °C, the two most common temperatures for frozen storage in laboratory settings. Crucially, the concentration of the polymer required leads to frozen solutions at -20 °C, unlike 50% glycerol (which results in liquid solutions). Post-thaw recoveries close to 100% plaque-forming units were achieved even after 2 weeks of storage with this method and kill assays against their bacterial host confirmed the lytic function of the phages. Initial experiments with other hydrophilic polymers also showed cryoprotection, but at this stage, the exact mechanism of this protection cannot be concluded but does show that water-soluble polymers offer an alternative tool for phage storage. Ice recrystallization inhibiting polymers (poly(vinyl alcohol)) were found to provide no additional protection, in contrast to their ability to protect proteins and microorganisms which are damaged by recrystallization. PEG's low cost, solubility, well-established low toxicity/immunogenicity, and that it is fit for human consumption at the concentrations used make it ideal to help translate new approaches for phage therapy.

Clinical trial of ABCB5+ mesenchymal stem cells for recessive dystrophic epidermolysis bullosa

BACKGROUND

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare, devastating, and life-threatening inherited skin fragility disorder that comes about due to a lack of functional type VII collagen, for which no effective therapy exists. ABCB5⁺ dermal mesenchymal stem cells (ABCB5⁺ MSCs) possess immunomodulatory, inflammation-dampening, and tissue-healing capacities. In a Col7a1^–/– mouse model of RDEB, treatment with ABCB5⁺ MSCs markedly extended the animals’ lifespans.

METHODS

In this international, multicentric, single-arm, phase I/IIa clinical trial, 16 patients (aged 4–36 years) enrolled into 4 age cohorts received 3 i.v. infusions of 2 × 10⁶ ABCB5⁺ MSCs/kg on days 0, 17, and 35. Patients were followed up for 12 weeks regarding efficacy and 12 months regarding safety.

RESULTS

At 12 weeks, statistically significant median (IQR) reductions in the Epidermolysis Bullosa Disease Activity and Scarring Index activity (EBDASI activity) score of 13.0% (2.9%–30%; P = 0.049) and the Instrument for Scoring Clinical Outcome of Research for Epidermolysis Bullosa clinician (iscorEB‑c) score of 18.2% (1.9%–39.8%; P = 0.037) were observed. Reductions in itch and pain numerical rating scale scores were greatest on day 35, amounting to 37.5% (0.0%–42.9%; P = 0.033) and 25.0% (–8.4% to 46.4%; P = 0.168), respectively. Three adverse events were considered related to the cell product: 1 mild lymphadenopathy and 2 hypersensitivity reactions. The latter 2 were serious but resolved without sequelae shortly after withdrawal of treatment.

CONCLUSION

This trial demonstrates good tolerability, manageable safety, and potential efficacy of i.v. ABCB5⁺ MSCs as a readily available disease-modifying therapy for RDEB and provides a rationale for further clinical evaluation.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03529877; EudraCT 2018-001009-98.

FUNDING

The trial was sponsored by RHEACELL GmbH & Co. KG. Contributions by NYF and MHF to this work were supported by the NIH/National Eye Institute (NEI) grants RO1EY025794 and R24EY028767.

Study of a new device for washing and concentrating cryopreserved hematopoietic stem cells and mononuclear cells: a single center experience

BACKGROUND AIMS

Cryopreserved cellular products, as parts of hematopoietic progenitor cell (HPC) transplants, mononuclear cell reinjections for donor lymphocyte infusion or extracorporeal photopheresis, can be washed before being reinjected into the patient or infused directly, depending on local practices. The aim of washing is to reduce the incidence and severity of adverse reactions (ARs) due to the dimethyl sulfoxide (DMSO) used as a cryoprotective agent and other factors, such as dead cell debris. At the authors' cell therapy laboratory (CTL) in Poitiers, France, as in 76% of Etablissement Français du Sang (EFS) CTLs, all cryopreserved products undergo thawing in a water bath followed by washing with the COBE 2991. As this device will soon cease to be available, an alternative process needs to be assessed.

METHODS

The authors compared two closed systems: the authors' semi-automatic system using the traditional centrifugation method (COBE 2991) and an automated device using spinning membrane filtration (Lovo). A total of 72 HPC bags available for research were used. The authors first performed a paired comparison, processing one or two HPC bags washed by each device. A second study was carried out to compare two different washing solutions generally used by EFS CTLs along with variable storage conditions. Finally, the authors studied the efficiency of the Lovo with three or four thawed bags. The main parameters studied were viable CD34+ cell recovery and viability, CD3+ cell recovery, stability up to 6 h after washing, DMSO elimination and center feasibility.

RESULTS

The Lovo device showed better CD34+ cell recovery compared with the COBE 2991 while maintaining CD34+ viability and stability over 6 h. Moreover, Lovo efficiency seemed to be independent of the number of thawed bags processed and washing solution used in the authors' study. CD3+ cell recovery met the authors' internal specifications (cell recovery >50%), with similar results seen when processing with either the COBE 2991 or Lovo. Additionally, on average, 97% of DMSO was removed after washing with Lovo, minimizing the risk of ARs. The storage conditions post-processing indicated preferred storage conditions of 7 ± 3°C. Finally, if processing time seemed shorter using COBE 2991 for one bag washed, the Lovo device required only one staff member regardless of the number of HPC bags processed.

CONCLUSIONS

The Lovo device seems to provide an opportunity to standardize HPC processing, ensuring patient safety, with, on average, 97% of DMSO removed, while improving recovery of cells of interest and maintaining viability over time in case of delayed transplant. The Lovo device consequently seems to be a serious alternative to the COBE 2991.

Post-Thaw Culture and Measurement of Total Cell Recovery Is Crucial in the Evaluation of New Macromolecular Cryoprotectants

The storage and transport of cells is a fundamental technology which underpins cell biology, biomaterials research, and emerging cell-based therapies. Inspired by antifreeze and ice-binding proteins in extremophiles, macromolecular (polymer) cryoprotectants are emerging as exciting biomaterials to enable the reduction and/or replacement of conventional cryoprotective agents such as DMSO. Here, we critically study post-thaw cellular outcomes upon addition of macromolecular cryoprotectants to provide unambiguous evidence that post-thaw culturing time and a mixture of assays are essential to claim a positive outcome. In particular, we observe that only measuring the viability of recovered cells gives false positives, even with non-cryoprotective polymers. Several systems gave apparently high viability but very low total cell recovery, which could be reported as a success but in practical applications would not be useful. Post-thaw culture time is also shown to be crucial to enable apoptosis to set in. Using this approach we demonstrate that polyampholytes (a rapidly emerging class of cryoprotectants) improve post-thaw outcomes across both measures, compared to poly(ethylene glycol), which can give false positives when only viability and short post-thaw time scales are considered. This work will help guide the discovery of new macromolecular cryoprotectants and ensure materials which only give positive results under limited outcomes can be quickly identified and removed.

Dimethyl sulfoxide-free cryopreservation for cell therapy: A review

Cell-based therapeutics promise to transform the treatment of a wide range of diseases including cancer, genetic and degenerative disorders, or severe injuries. Many of the commercial and clinical development of cell therapy products require cryopreservation and storage of cellular starting materials, intermediates and/or final products at cryogenic temperature. Dimethyl sulfoxide (Me₂SO) has been the cryoprotectant of choice in most biobanking situations due to its exceptional performance in mitigating freezing-related damages. However, there is concern over the toxicity of Me₂SO and its potential side effects after administration to patients. Therefore, there has been growing demand for robust Me₂SO-free cryopreservation methods that can improve product safety and maintain potency and efficacy. This article provides an overview of the recent advances in Me₂SO-free cryopreservation of cells having therapeutic potentials and discusses a number of key challenges and opportunities to motivate the continued innovation of cryopreservation for cell therapy.

Polyampholytes as Emerging Macromolecular Cryoprotectants

Cellular cryopreservation is a platform technology which underpins cell biology, biochemistry, biomaterials, diagnostics, and the cold chain for emerging cell-based therapies. This technique relies on effective methods for banking and shipping to avoid the need for continuous cell culture. The most common method to achieve cryopreservation is to use large volumes of organic solvent cryoprotective agents which can promote either a vitreous (ice free) phase or dehydrate and protect the cells. These methods are very successful but are not perfect: not all cell types can be cryopreserved and recovered, and the cells do not always retain their phenotype and function post-thaw. This Perspective will introduce polyampholytes as emerging macromolecular cryoprotective agents and demonstrate they have the potential to impact a range of fields from cell-based therapies to basic cell biology and may be able to improve, or replace, current solvent-based cryoprotective agents. Polyampholytes have been shown to be remarkable (mammalian cell) cryopreservation enhancers, but their mechanism of action is unclear, which may include membrane protection, solvent replacement, or a yet unknown protective mechanism, but it seems the modulation of ice growth (recrystallization) may only play a minor role in their function, unlike other macromolecular cryoprotectants. This Perspective will discuss their synthesis and summarize the state-of-the-art, including hypotheses of how they function, to introduce this exciting area of biomacromolecular science.

GMP-Compliant Human Schwann Cell Manufacturing for Clinical Application

Schwann cells as glial cells in the peripheral nervous system can participate in neurons protection and forming myelin. Additionally, they are important for nerve pulse conduction supporting along axons. On the other hand, it was demonstrated that they are promising cells for the treatment of demyelinating disorders and also central nervous system damages. Herein, for therapeutic application, Schwann cells should be manufactured based on good manufacturing practice standards to achieve safe and effective clinical products. In this respect, the current chapter tries to introduce a standard protocol for manufacturing of human GMP-compliant Schwann cells for clinical application.

Anti-CD19 CAR T-Cell Therapy for Adult Patients With Refractory Large B-Cell Lymphoma

Chimeric antigen receptor (CAR) T-cell therapies represent a new paradigm in targeted cancer therapy. T cells play a key role in immune surveillance, but tumors have developed multiple mechanisms for evading that surveillance. CAR T-cell technology aims to enhance the innate ability of the body to fight foreign invaders, and in this way, effectively fight cancer and potentially reduce the number of treatments required. In fact, many patients have had long-lasting clinical responses to therapy with a single treatment. The journey to receiving CAR T-cell therapy involves a number of steps prior to infusion, including an initial consultation and workup, apheresis, bridging therapy, and lymphodepletion. Patients are then closely monitored after infusion. Successful treatment requires collaboration between the patient, caregivers, and the multidisciplinary team. Here we discuss the biology of CAR T-cell technology, clinical trial data, and the path to accessing this revolutionary and potentially curative treatment.

The value of the post-thaw CD34+ count with and without DMSO removal in the setting of autologous stem cell transplantation

BACKGROUND

CD34+ cell count correlates with engraftment potency after autologous stem cell transplantation. Assessment of CD34+ mainly occurs after apheresis and before cryopreservation with dimethyl sulfoxide (DMSO). The influence of postthaw CD34+ cell numbers over time to engraftment is not well studied, and determination of postthaw CD34+ cell counts is challenging for a variety of reasons. The aim of this retrospective study was to systematically assess the value of postthaw CD34+ cell counts in autologous grafts with and without DMSO removal.

STUDY DESIGN AND METHODS

Between January 2008 and December 2015, 236 adult patients underwent a total of 292 autologous stem cell transplantations. Median age at transplantation was 56 years, and the main indication was multiple myeloma (60%). DMSO removal was done in 96 grafts (33%), either by centrifugation or by Sepax method.

RESULTS

Patients receiving grafts containing DMSO showed a significantly faster platelet (p = 0.02) and RBC (p = 0.001) engraftment. DMSO removal was not associated with fewer infusion-related adverse events. We observed a good correlation between CD34+ cell count after apheresis and CD34+ cell count after thawing/washing (r = 0.931). Ninety grafts (31%) showed a significant loss of viable CD34+ cells, which translated into a delayed engraftment.

CONCLUSION

DMSO removal was associated with delayed platelet and RBC engraftment without preventing adverse events. CD34+ cell enumeration after thawing remains difficult to perform, but grafts showing higher cell loss during cryopreservation and thawing are associated with slower engraftment. Prospective studies on the role of DMSO removal and postthaw CD34+ enumeration using defined protocols are needed.

Adverse reactions of dimethyl sulfoxide in humans: a systematic review

Background: Dimethyl sulfoxide (DMSO) has been used for medical treatment and as a pharmacological agent in humans since the 1960s. Today, DMSO is used mostly for cryopreservation of stem cells, treatment of interstitial cystitis, and as a penetrating vehicle for various drugs. Many adverse reactions have been described in relation to the use of DMSO, but to our knowledge, no overview of the existing literature has been made. Our aim was to conduct a systematic review describing the adverse reactions observed in humans in relation to the use of DMSO. Methods: This systematic review was reported according to the PRISMA-harms (Preferred Reporting Items for Systematic reviews and Meta-Analysis) guidelines. The primary outcome was any adverse reactions occurring in humans in relation to the use of DMSO. We included all original studies that reported adverse events due to the administration of DMSO, and that had a population of five or more. Results: We included a total of 109 studies. Gastrointestinal and skin reactions were the commonest reported adverse reactions to DMSO. Most reactions were transient without need for intervention. A relationship between the dose of DMSO given and the occurrence of adverse reactions was seen. Conclusions: DMSO may cause a variety of adverse reactions that are mostly transient and mild. The dose of DMSO plays an important role in the occurrence of adverse reactions. DMSO seems to be safe to use in small doses. Registration: PROSPERO CRD42018096117.

Adverse reactions of dimethyl sulfoxide in humans: a systematic review

Background: Dimethyl sulfoxide (DMSO) has been used for medical treatment and as a pharmacological agent in humans since the 1960s. Today, DMSO is used mostly for cryopreservation of stem cells, treatment of interstitial cystitis, and as a penetrating vehicle for various drugs. Many adverse reactions have been described in relation to the use of DMSO, but to our knowledge, no overview of the existing literature has been made. Our aim was to conduct a systematic review describing the adverse reactions observed in humans in relation to the use of DMSO.

Methods: This systematic review was reported according to the PRISMA-harms (Preferred Reporting Items for Systematic reviews and Meta-Analysis) guidelines. The primary outcome was any adverse reactions occurring in humans in relation to the use of DMSO. We included all original studies that reported adverse events due to the administration of DMSO, and that had a population of five or more.

Results: We included a total of 109 studies. Gastrointestinal and skin reactions were the commonest reported adverse reactions to DMSO. Most reactions were transient without need for intervention. A relationship between the dose of DMSO given and the occurrence of adverse reactions was seen.

Conclusions: DMSO may cause a variety of adverse reactions that are mostly transient and mild. The dose of DMSO plays an important role in the occurrence of adverse reactions. DMSO seems to be safe to use in small doses.

Registration: PROSPERO CRD42018096117.

The influence of cell concentration at cryopreservation on neutrophil engraftment after autologous peripheral blood stem cell transplantation

BACKGROUND

Peripheral blood stem cell concentrations are traditionally adjusted to 20-40 × 106 leukocytes/mL prior to freezing. This low cell concentration at cryopreservation implies larger volumes with more dimethyl sulfoxide being used, and higher cost and toxicity at the time of transplant. Higher cell concentrations have been reported but this is not widely accepted. Moreover, the influence of cell concentration on engraftment has not been well documented. Therefore, this study retrospectively analyzed the influence of peripheral blood stem cell concentration at freezing on engraftment after autologous hematopoietic stem cell transplantation.

METHOD

Leukapheresis products were plasma-depleted and cryopreserved with 5% dimethyl sulfoxide, 6% hydroxyethylamide solution and 4% albumin in a -80 °C freezer. Individual patient data from hospital records were reviewed.

RESULTS

Fifty consecutive patients with oncological diseases underwent 88 leukaphereses. Median age was six years (range: 1-32 years) and median weight was 19 kg (range: 8-94 kg). Median leukocyte concentration was 109 × 106/mL at collection and 359 × 106 (range: 58-676 × 106) at freezing with 78% viability (range: 53-95%); leukocyte recovery after thawing was 95% (range: 70-100%). In multivariate analysis, cell concentration (p-value = 0.001) had a negative impact on engraftment. Patients infused with bags frozen with <200 × 106 leukocytes/mL engrafted after a median of nine days (range: 8-12 days), 200-400 × 106 leukocytes/mL after 11 days (range: 9-20 days); 400-600 × 106 leukocytes/mL after 12 days (range: 8-19 days) and with cell concentrations >600 × 106 leukocytes/mL, engraftment was after 14 days (range: 13-22 days).

CONCLUSION

In patients with adequate CD34 cell collections, total leukocyte concentrations of 282 × 106/mL, freezing with 5% dimethyl sulfoxide and 6% hydroxyethylamide solution without a controlled-rate freezer, and storing cells at -80 °C yielded excellent engraftment. Further increases in cell concentration may delay engraftment, without affecting safety.

Comparison of time to engraftment between autologous patients receiving washed versus non-washed cryopreserved peripheral blood stem cell products

Washing cryopreserved peripheral blood stem cell (PBSC) products can decrease infusion-related adverse reactions but can also result in cell loss and reduced cell viability. To assess the risk and benefit of washing products, we compared the time to neutrophil and platelet engraftment between autologous patients that received washed products (n = 201) and non-washed products (n = 89). The effect of the other variables, including age, gender, diagnosis, transplant dose, method of stem cell mobilization, and growth factor support regimen post-transplant, was assessed. In multivariate analysis, direct thaw and infusion of non-washed products resulted in significantly faster neutrophil engraftment (p = .003) and platelet engraftment (p = .017) than washed products. The mean neutrophil and platelet engraftment times were 1.07 days faster and 2.27 days faster, respectively. In conclusion, direct thaw and infusion of cryopreserved PBSC without washing results in significantly shorter time to recovery of neutrophils and platelets after autologous transplantation.

Neurotoxicity Associated With Dimethyl Sulfoxide Used in Allogeneic Stem Cell Transplantation

Dimethyl sulfoxide (DMSO) is a cryoprotective agent used in storage of frozen stem cells in stem cell transplantation. Central nervous system side effects of DMSO such as epileptic seizures, stroke, transient global amnesia, and temporary leucoencephalopathy are rarely seen. Here, we report a pediatric patient who developed seizures after DMSO-cryopreserved stem cell infusion and whose magnetic resonance imaging of the brain demonstrated parietal and occipital focal cortical T2-signal intensity increase. DMSO toxicity should be kept in mind in patients who received cryopreserved stem cell infusion and magnetic resonance imaging may be helpful in differential diagnosis of central nervous system involvement.

Adverse events of cryopreserved hematopoietic stem cell infusions in adults: a single-center observational study

BACKGROUND

Autologous hematopoietic stem cell (HSC) transplantation has been used for almost three decades for the management of malignant hematologic diseases and some solid tumors. Dimethyl sulfoxide (DMSO) is used as a cryoprotective agent for hematopoietic progenitor cells (HPCs) collected by apheresis (HPC-A). We evaluated the factors contributing to the occurrence of adverse events (AEs) of cryopreserved HPC-A infusion.

STUDY DESIGN AND METHODS

Between January 2009 and June 2014, a total of 1269 (1191 patients) consecutive HPC-A infusions were given to adult patients undergoing autologous HSC transplantation at Barnes-Jewish Hospital. Only infusions on the first day of transplant were included in the analysis.

RESULTS

AEs were reported in 480 (37.8%) infusions. The most common AEs were facial flushing in 189 (39.4%) infusions, nausea and/or vomiting in 183 (38.1%) infusions, hypoxia requiring oxygen in 139 (29%) infusions, and chest tightness in 80 (16.7%) infusions. Multivariate analysis using logistic regression showed that female sex (odds ratio [OR], 1.78; 95% confidence interval [CI], 1.40-2.26; p < 0.0001), diagnosis other than multiple myeloma (OR, 1.44; 95% CI, 1.12-1.84; p = 0.004), larger volume of infusion per body weight (OR, 1.66; 95% CI, 1.29-2.15; p < 0.0001), and number of granulocytes infused per body weight (OR, 1.30; 95% CI, 1.01-1.67; p = 0.042) were significant predictors of occurrence of AEs during infusion.

CONCLUSION

AEs due to HPC-A infusion occurred in more than one-third of patients. Interventions need to be instituted to reduce AEs and thus improve the safety of HPC-A infusion. Many of these toxicities can be attributed to DMSO, and this is reflected in the volume of infusion. It might be warranted to consider implementing DMSO-reducing protocols before infusion.

Cryopreservation of Endothelial Cells in Various Cryoprotective Agents and Media - Vitrification versus Slow Freezing Methods

Vitrification of endothelial cells (MHECT-5) has not previously been compared with controlled slow freezing methods under standardized conditions. To identify the best cryopreservation technique, we evaluated vitrification and standardized controlled-rate -1°C/minute cell freezing in a -80°C freezer and tested four cryoprotective agents (CPA), namely dimethyl sulfoxide (DMSO), ethylene glycol (EG), propylene glycol (PG), and glycerol (GLY), and two media, namely Dulbecco's modified Eagle medium Ham's F-12 (DMEM)and K+-modified TiProtec (K+TiP), which is a high-potassium-containing medium. Numbers of viable cells in proliferation were evaluated by the CellTiter 96® AQueous One Solution Cell Proliferation Assay (Promega Corporation, Mannheim, Germany). To detect the exact frozen cell number per cryo vial, DNA content was measured by using Hoechst 33258 dye prior to analysis. Thus, results could be evaluated unconstrained by absolute cell number. Thawed cells were cultured in 25 cm2 cell culture flasks to confluence and examined daily by phase contrast imaging. With regard to cell recovery immediately after thawing, DMSO was the most suitable CPA combined with K+TiP in vitrification (99 ±0.5%) and with DMEM in slow freezing (92 ±1.6%). The most viable cells in proliferation after three days of culture were obtained in cells vitrificated by using GLY with K+TiP (308 ±34%) and PG with DMEM in slow freezing (280 ±27%).

Fatigue damage to pig erythrocytes during repeated swelling and shrinkage

During the removal of cryoprotectants from cryopreserved-thawed blood with the dialysis-based or dilution-filtration method, due to the change in the extracellular osmolality, erythrocytes usually undergo repeated swelling and shrinkage. However, the erythrocyte fatigue damage induced by this repeated volume change has not yet been studied. In this work, by successively loading hypotonic and hypertonic solutions, we mimicked the repeated swelling and shrinkage of pig erythrocytes and then examined the effect of the number of cycle loops on the steady-state volume and the mortality of the pig erythrocytes. The results suggest that because of cell leakage in the swelling process, the steady-state volume of the pig erythrocytes after one cycle is smaller than the volume before the cycle, even though the cell performs a self-protective regulatory procedure. If the number of cycle loops is increased, the repeated swelling and shrinkage will cause a continuous decrease in the steady-state volume, and the ability of the pig erythrocytes to resist osmotic damage will decrease; as a result, the mortality of the pig erythrocytes increases as the number of cycle loops increases. The viability of the cells is also affected by the hypotonic and isotonic processing times: a short processing time may contribute to a decrease in the mortality of the pig erythrocytes. This work is of significance to optimizing the process of removing cryoprotectants.

Febrile reaction associated with the infusion of haploidentical peripheral blood stem cells: incidence, clinical features, and risk factors

BACKGROUND

We reported febrile reaction after the infusion of haploidentical peripheral blood stem cells (PBSCs). The aim of this study was to better characterize this new clinical entity named by infusion-related febrile reaction (IRFR).

STUDY DESIGN AND METHODS

A retrospective analysis of 490 patients received allogeneic stem cell transplantation (SCT) between October 2009 and December 2011 at our institution.

RESULTS

The distribution of transplant type was 173 patients in HLA-identical siblings, 30 in unrelated, and 287 in haploidentical. IRFR was defined as unexplained fever of more than 38°C within 24 hours after the infusion of allogeneic PBSCs. We did not observe any IRFRs in patients undergoing HLA-identical sibling and unrelated transfusions. After excluding patients with a known source of infection, we classified haploidentical patients into IRFR and non-IRFR groups. Eighty-eight patients (30.7%) of 287 cases after the infusion of haploidentical PBSCs were diagnosed as IRFRs, chills in 3.5% (10/88), diarrhea in 21.6% (19/88), an erythematous skin rash in 0.3% (1/88), hypoxemia in 1.0% (3/88), and no other accompanying symptoms in 62.5% (55/88). Significantly higher elevation of C-reactive protein and complement C3 was seen in the IRFR group compared with the non-IRFR group. Multivariate analysis showed higher CD34+ dose was a significant predictor for IRFR (p = 0.023; hazard ratio = 1.848; 95% confidence interval, 1.087-3.142).

CONCLUSION

As a clinical feature belonging to haploidentical SCT, IRFR was associated with the higher numbers of CD34+ from PBSCs.

Effect of the polydispersity of RBCs on the recovery rate of RBCs during the removal of CPAs

In the process of removing cryoprotectants from cryopreserved blood, the theoretically optimal operating condition, which is based on the assumption that the distribution of red blood cells is uniform, is often used to reduce or even avoid the hypotonic damage to cells. However, due to the polydispersity of cells, the optimal condition is actually not reliable. In this study, based on the discrete concept developed in our previous work, the effect of the polydispersity on the recovery rate of cells in the dilution-filtration system was statistically investigated by assigning three random parameters, isotonic cell volume, cell surface area, and osmotically inactive cell volume, to cells in small units of blood. The results show that, due to the polydispersity, the real recovery rate deviates from the ideal value that is based on uniform distribution. The deviation significantly increases with the standard errors of cell parameters, and it can be also magnified by high cryoprotectant concentrations. Under the effect of polydispersity, the uniform distribution-based optimized blood or diluent flow rate is not perfect. In practice, one should adopt a more conservative blood or diluent flow rate so that the hypotonic damage to cells can be further reduced.

Statistical estimation of red blood cell osmotic damage during cryoprotective agent removal from cryopreserved blood

Statistical estimation of the osmotic damage of red blood cells (RBCs) during the removal of cryoprotective agents (CPAs) from cryopreserved blood has been a very difficult issue. In this paper, the discrete mass transfer model developed in our previous work is modified to study the volume variation of individual RBCs and thereby to estimate the osmotic damage of all RBCs statistically during CPA removal by the dilution-concentration method we proposed recently. The model is validated with respect to the experimental results either with or without RBCs. Then, it is used to investigate the effects of blood volume, hematocrit, blood and diluent flow rates on the osmotic damage of RBCs, as well as the washing time of CPAs. Our results show that both the increase of blood flow rates and the decrease of diluent flow rates can bring about a reduction in osmotic damage of RBCs; however, only the former can cause a decrease in the washing time of CPAs. The blood volume could also affect the osmotic damage of RBCs. For a given flow condition, there could exist an optimal blood volume range for the dilution-concentration system. The effect of blood volume could be alleviated by an increase in the dilution region volume. In addition, the osmotic damage of RBCs decreases as the hematocrit decreases. Therefore, in practice, the increase of blood flow rates is the best solution to reduce both the osmotic damage of RBCs and the washing time of CPAs simultaneously. A lower hematocrit in the cryopreserved blood and/or longer tubing in the dilution region are also recommended to achieve better performance for the dilution-concentration method.

Hematopoietic SCT with cryopreserved grafts: adverse reactions after transplantation and cryoprotectant removal before infusion

Transplantation of hematopoietic stem cells (HSCs) has been successfully developed as a part of treatment protocols for a large number of clinical indications, and cryopreservation of both autologous and allogeneic sources of HSC grafts is increasingly being used to facilitate logistical challenges in coordinating the collection, processing, preparation, quality control testing and release of the final HSC product with delivery to the patient. Direct infusion of cryopreserved cell products into patients has been associated with the development of adverse reactions, ranging from relatively mild symptoms to much more serious, life-threatening complications, including allergic/gastrointestinal/cardiovascular/neurological complications, renal/hepatic dysfunctions, and so on. In many cases, the cryoprotective agent (CPA) used-which is typically dimethyl sulfoxide (DMSO)-is believed to be the main causal agent of these adverse reactions and thus many studies recommend depletion of DMSO before cell infusion. In this paper, we will briefly review the history of HSC cryopreservation, the side effects reported after transplantation, along with advances in strategies for reducing the adverse reactions, including methods and devices for removal of DMSO. Strategies to minimize adverse effects include medication before and after transplantation, optimizing the infusion procedure, reducing the DMSO concentration or using alternative CPAs for cryopreservation and removing DMSO before infusion. For DMSO removal, besides the traditional and widely applied method of centrifugation, new approaches have been explored in the past decade, such as filtration by spinning membrane, stepwise dilution-centrifugation using rotating syringe, diffusion-based DMSO extraction in microfluidic channels, dialysis and dilution-filtration through hollow-fiber dialyzers and some instruments (CytoMate, Sepax S-100, Cobe 2991, microfluidic channels, dilution-filtration system, etc.) as well. However, challenges still remain: development of the optimal (fast, safe, simple, automated, controllable, effective and low cost) methods and devices for CPA removal with minimum cell loss and damage remains an unfilled need.

In situ spectroscopic quantification of protein-ice interactions

FTIR and confocal Raman microspectroscopy were used to measure interactions between albumin and ice in situ during quasi-equilibrium freezing in dimethyl sulfoxide (DMSO) solutions. At temperatures of -4 and -6 °C, albumin was found to be preferentially excluded from the ice phase during near-equilibrium freezing. This behavior reversed at lower temperatures. Instead, DMSO was preferentially excluded from the ice phase, resulting in an albumin concentration in the freeze-concentrated liquid phase that was lower than predicted. It is hypothesized that this was caused by the albumin in the freeze-concentrated liquid getting adsorbed onto the ice surface or becoming entrapped in the ice phase. It was observed that, under certain freezing protocols, as much as 20% of the albumin in solutions with starting concentrations of 32-53 mg/mL may be adsorbed onto the ice interface or entrapped in the ice phase.