Long-Term Cryopreservation of Peripheral Blood Stem Cell Harvest Using Low Concentration (4.35%) Dimethyl Sulfoxide with Methyl Cellulose and Uncontrolled Rate Freezing at -80 °C: An Effective Option in Resource-Limited Settings

Long-term cryopreservation of peripheral blood stem cells (PBSCs) is highly useful in the setting of tandem/multiple transplantations or treatment of relapse in the autologous hematopoietic stem cell transplantation (HSCT) setting. Even in allogeneic HSCT, donor lymphocyte infusions may be stored for months to years if excess stem cells are collected from donors. Cryopreservation is a delicate, complex, and costly procedure, and higher concentrations of dimethyl sulfoxide (DMSO), a commonly used cryoprotectant, can be toxic to cells and cause adverse effects in the recipient during infusions. In this study, we examined the effect of long-term cryopreservation using 4.35% DMSO (as final concentration) with methyl cellulose and uncontrolled rate freezing in a mechanical freezer (-80 °C) on the viability and colony-forming ability of CD34+ human PBSCs. For patients undergoing autologous HSCT, PBSCs were cryopreserved using DMSO (final concentration of 4.35%) with methyl cellulose. The post-thaw viability of PBSCs was determined using Trypan blue exclusion and flow cytometry-based 7-amino-actinomycin-D (FC-7AAD) methods. Concentrations of CD34+ stem cells and immune cell subsets in post-thaw PBSC harvest samples were assessed using multicolor flow cytometry, and the clonogenic potential of post-thaw stem cells was studied using a colony-forming unit (CFU) assay. CD34+ stem cell levels were correlated with the prestorage CD34 levels using the Pearson correlation test. The viability results in the Trypan blue dye exclusion method and the flow cytometry-based method were compared using Bland-Altman plots. We studied 26 PBSC harvest samples with a median cryopreservation duration of 6.6 years (range, 3.8 to 11.5 years). The median viability of post-thaw PBSCs was >80% using both methods, with a weak agreement between them (r = .03; P = .5). The median CD34+ stem cell count in the post-thaw samples was 9.13 × 106/kg (range, .44 to 26.27 × 106/kg). The CFU assay yielded a good proliferation and differentiation potential in post-thaw PBSCs, with a weak correlation between granulocyte macrophage CFU and CD34+ stem cell levels (r = .4; P = .05). Two samples that had been cryopreserved for >8 years showed low viability. Cryopreservation of PBSCs using 4.35% DMSO with methyl cellulose and uncontrolled freezing in a mechanical freezer at -80 °C allows the maintenance of long-term viability of PBSC for up to 8 years.

Optimizing a fully automated and closed system process for red blood cell reduction of human bone marrow products

BACKGROUND AIMS

Hematopoietic stem cell transplantation using bone marrow as the graft source is a common treatment for hematopoietic malignancies and disorders. For allogeneic transplants, processing of bone marrow requires the depletion of ABO-mismatched red blood cells (RBCs) to avoid transfusion reactions. Here the authors tested the use of an automated closed system for depleting RBCs from bone marrow and compared the results to a semi-automated platform that is more commonly used in transplant centers today. The authors found that fully automated processing using the Sepax instrument (Cytiva, Marlborough, MA, USA) resulted in depletion of RBCs and total mononuclear cell recovery that were comparable to that achieved with the COBE 2991 (Terumo BCT, Lakewood, CO, USA) semi-automated process.

METHODS

The authors optimized the fully automated and closed Sepax SmartRedux (Cytiva) protocol. Three reduction folds (10×, 12× and 15×) were tested on the Sepax. Each run was compared with the standard processing performed in the authors' center on the COBE 2991. Given that bone marrow is difficult to acquire for these purposes, the authors opted to create a surrogate that is more easily obtainable, which consisted of cryopreserved peripheral blood stem cells that were thawed and mixed with RBCs and supplemented with Plasma-Lyte A (Baxter, Deerfield, IL, USA) and 4% human serum albumin (Baxalta, Westlake Village, CA, USA). This "bone marrow-like" product was split into two starting products of approximately 600 mL, and these were loaded onto the COBE and Sepax for direct comparison testing. Samples were taken from the final products for cell counts and flow cytometry. The authors also tested a 10× Sepax reduction using human bone marrow supplemented with human liquid plasma and RBCs.

RESULTS

RBC reduction increased as the Sepax reduction rate increased, with an average of 86.06% (range of 70.85-96.39%) in the 10×, 98.80% (range of 98.1-99.5%) in the 12× and 98.89% (range of 98.80-98.89%) in the 15×. The reduction rate on the COBE ranged an average of 69.0-93.15%. However, white blood cell (WBC) recovery decreased as the Sepax reduction rate increased, with an average of 47.65% (range of 38.9-62.35%) in the 10×, 14.56% (range of 14.34-14.78%) in the 12× and 27.97% (range of 24.7-31.23%) in the 15×. COBE WBC recovery ranged an average of 53.17-76.12%. Testing a supplemented human bone marrow sample using a 10× Sepax reduction resulted in an average RBC reduction of 84.22% (range of 84.0-84.36%) and WBC recovery of 43.37% (range of 37.48-49.26%). Flow cytometry analysis also showed that 10× Sepax reduction resulted in higher purity and better recovery of CD34+, CD3+ and CD19+ cells compared with 12× and 15× reduction. Therefore, a 10× reduction rate was selected for the Sepax process.

CONCLUSIONS

The fully automated and closed SmartRedux program on the Sepax was shown to be effective at reducing RBCs from "bone marrow-like" products and a supplemented bone marrow product using a 10× reduction rate.

The 1,000th Transplant for Multiple Sclerosis and Other Autoimmune Disorders at the HSCT-México Program: A Myriad of Experiences and Knowledge

After gaining experience conducting both auto and allografts in persons with hematological diseases in the HSCT programs in Puebla and Monterrey, México, this study outlines subsequent program autografting patients with autoimmune conditions. The first transplant in multiple sclerosis was conducted in Puebla on July 5, 2006. From 2015 we increased activity autografting persons with autoimmune conditions in the two campuses of the HSCT-México program: Puebla and Monterrey. By December 6, 2020, patient number 1,000 in the program was autografted. In our experience, a significant reduction in the expanded disability status scale score was achieved in all of the three phenotypes of the disease (from a median of 5.1 to 4.5 points), whereas the response rate (defined as a decrease of at least 0.5 of EDSS score regardless of baseline EDSS, or unchanged EDSS) was 83, 78, and 73% after 12 months in the relapsing-remitting, primary-progressive and secondary-progressive forms of multiple sclerosis, respectively. In addition to analyzing the viability, safety, and efficacy of our method, this study contributes new knowledge to the field of both stem cell transplantation and multiple sclerosis.

Severe Hypoxemia in a Healthy Donor for Allogeneic Hematopoietic Stem Cell Transplantation after Only the First Administration of Granulocyte-Colony Stimulating Factor

BACKGROUND

Granulocyte-colony stimulating factor (G-CSF) is widely used to mobilize peripheral blood stem cells (PBSCs) in healthy donors. A few reports have shown that some healthy donors developed acute respiratory distress syndrome or capillary leak syndrome after more than several rounds of G-CSF administration or leukapheresis.

CASE REPORT

We report the case of a healthy donor for allogeneic stem cell transplantation who developed severe hypoxemia 1 h after only the first administration of G-CSF. The donor was administered 10 μg/kg G-CSF (lenograstim) subcutaneously for PBSC mobilization. 1 h after the first administration of G-CSF, the donor suddenly presented with dry cough and dyspnea. The oxygen saturation by pulse oximetry (SpO₂) in the room air was 88%. An electrocardiogram and chest radiography revealed no abnormalities. We excluded other causes of severe hypoxemia and diagnosed the donor with hypoxemia due to G-CSF administration, which was subsequently terminated. The donor was administered 2 l/min oxygen via a nasal cannula and 100 mg hydrocortisone intravenously. He subsequently recovered, and SpO₂ in the room air returned to 98% 10 h after hypoxemia.

CONCLUSION

These respiratory symptoms might be related to anaphylactoid or hypersensitivity reaction. The donors should be observed for at least 1 h after the first administration of G-CSF.