Flow cytometric enumeration of CD34+ hematopoietic stem cells: A comparison between single- versus dual-platform methodology using the International Society of Hematotherapy and Graft Engineering protocol

Peripheral blood lymphocyte immunophenotyping (TBNK) - a comparison of BD FACSCanto II and BD FACSLyric flow cytometry analysers

Introduction

Flow cytometry immunophenotyping is a common laboratory technique for evaluating lymphocyte subpopulations. Its result remains an important diagnostic tool in various medical fields. Cytometric tests are performed in many laboratories, making the comparability between different devices using the same method an important aspect. We aimed to compare the results of lymphocyte immunophenotyping (lymphocytes B, T, Th and Tc, NK cells) between two different flow cytometers.

Material and methods

The study included 93 patients of the Children's Teaching Hospital of the Medical University of Warsaw and 9 Multi-Check control results. The method of lymphocyte subpopulation assessment was based on fluorescent flow cytometry immunophenotyping, using a BD Multitest 6-color TBNK kit (Becton Dickinson). We compared BD FACSCanto II and BD FACSLyric analysers (Becton Dickinson). For data analysis, we used Spearman's rank correlation, Bland-Altman plot and Passing-Bablok regression.

Results

Spearman's rank correlation showed a strong interrelation for all analysed parameters (0.808-0.985). In the Passing-Bablok regression analysis, all examined parameters showed linear dependence with the slope values close to 1 (0.940-1.134). Bland-Altman coefficient values were within the range of 2.94-8.62% with half of them being above 5% (T, Tc, Th, B, NKT absolute values and B percentage values).

Conclusions

The results from both cytometers can be considered equivalent, but it should be noted that one of the statistical methods showed some deviations, presumably primarily due to the evaluators' different gating techniques. The training of specialists performing these tests requires more attention.

Developing an Allogeneic Hematopoietic Progenitor Cell Transplant Service in a Resource-Limited Country: Challenges and Outcomes

Introduction Allogeneic stem cell transplant has curative potential for many hematological disorders. Building an allogeneic hematopoietic progenitor cell transplant (HPCT) unit requires huge investment, infrastructure, equipment, medical supplies, and training of health care professionals. The key objective of this study is to share our experience of developing an allogeneic HPCT service at our tertiary care cancer hospital in a low-middle-income country. In addition, this study presents the outcomes of the first 30 allogeneic HPCTs done at our center. Methods This retrospective observational study included adult patients 18 years old or older with hematological malignancies who underwent allogeneic HPCT between July 2019 and April 2023 at Shaukat Khanum Memorial Cancer Hospital and Research Centre. Result Of the 30 patients, 24 underwent matched sibling donor (MSD) transplants in which a myeloablative-conditioning regimen (MAC) was used in 19, and a reduced conditioning regimen (RIC) was used in one. Of the six haploidentical-related donor transplants, four received MAC, and two received RIC. The median recipient age at HPCT was 23 and 21 years for MSD and Haplo-related donor transplants, respectively. The median follow-up duration was 12 months (Range: 10 days - 33 months). The overall survival rate at one year was 71.3% among all allogeneic stem cell transplant patients, whereas the disease-free survival rate at one year was 63.7%. In the acute lymphoblastic leukemia group, the disease-free survival rate at one year post allograft was 51.5%, while in the acute myeloid leukemia group, it was 78.7%. Conclusion This study demonstrates the successful development of an allogeneic bone marrow transplant unit at our hospital despite significant financial constraints. This has allowed us to provide a potentially curative and life-saving treatment to a substantial number of cancer patients. The bone marrow transplant outcomes of this study are comparable to those reported by international bone marrow transplant registries.

Role of flow cytometry in evaluation of the cellular therapy products used in haematopoietic stem cell transplantation

Cellular therapy nowadays includes various products from haematopoietic stem cells (HSC) collected from bone marrow, peripheral blood, and umbilical cord blood to more complex adoptive immune therapy for the treatment of malignant diseases, and gene therapy for inherited immune deficiencies. Broader utilization of cellular therapy requires extensive quality testing of these products that should fulfil the same requirements regarding composition, purity, and potency nevertheless they are manufactured in various centres. Technical improvements of the flow cytometers accompanied by the increased number of available reagents and fluorochromes used to conjugate monoclonal antibodies, enable detailed and precise insight into the function of the immune system and other areas of cell biology, and allows cell evaluation based on size, shape, and morphology or assessment of cell surface markers, as well as cell purity and viability, which greatly contributes to the development and progress of the cell therapy. The aim of this paper is to give an overview of the current use and challenges of flow cytometry analysis in quality assessment of cellular therapy products, with regard to basic principles of determining HSC and leukocyte subpopulation, assessment of cells viability and quality of thawed cryopreserved HSC as well as the importance of validation and quality control of flow cytometry methods according to good laboratory practice.

Determination of mononuclear cell count using peripheral smear and flow cytometry in peripheral blood stem cell products: A retrospective study from an Indian cancer center

BACKGROUND:

Mononuclear cells (MNCs) are considered equivalent to hematopoietic stem cells, and differential count using peripheral smear was routinely practiced to enumerate MNC. Flow cytometry plots used for CD34 enumeration assay can also be used in MNC enumeration as it counts more WBC events than manual methods. The aim was to determine the relationship and degree of agreement between peripheral smear and flow cytometry in MNC enumeration of peripheral blood stem cell (PBSC) products.

METHODS:

In 63 patients, 73 PBSC products were collected between January 2017 and September 2019. The differences in MNC count estimated by peripheral smear method and from flow cytometry plots used for CD34 enumeration were analyzed using Mann–Whitney test. Agreement between the two methods for MNC enumeration was determined by regression analysis. Receiver operating characteristic curve was performed to determine MNC threshold in peripheral blood and PBSC product for adequate mobilization and harvest.

RESULTS:

There was no difference in enumeration of median MNC count between peripheral smear and flow cytometry (52% vs. 59%, P = 0.185) in PBSC product. However, regression analysis indicated a constant and proportional difference between the methods with r = 0.52. Cumulative sum test for linearity showed deviation from linearity (P = 0.04). MNC counts in peripheral blood failed to achieve discrimination capacity in predicting adequate CD34+ yield/kg body weight in product.

CONCLUSION:

Peripheral smear estimated lower MNC counts than flow cytometry with weaker agreements between the two methods. Hence, MNC count derived from flow cytometry plot can substitute peripheral smear method for MNC dose calculations. MNC dose at 3.4 × 10⁸/kg consistently predicted >2 × 10⁶/kg CD34+ cells collected.

Non-Classical Effects of the cAMP Accumulation Activators In Vivo

Purpose: Wound-healing dipyridamole- and papaverine-based aerosols (D1/D2) as activators of the accumulation of cyclic adenosine monophosphate are promising drugs that can accelerate wound healing in wound processes of various origins. Methods: 128 rats were used in the study, including 38 in a pharmacological experiment on a model of stencil wounds and 90 in an experiment that studied the effect of spray on the number of CD34 cells in the blood of rats with chemically induced immunodeficiency. Immunodeficiency was caused by the fivefold administration of cyclophosphamide and prednisone. The expression level of CD34 was determined using flow cytofluorimeter. Results: Dipyridamole- and papaverine-based aerosols of two compositions (with and without ascorbic acid) have pronounced reparative properties, significantly accelerating epithelialization and healing of stencil wounds in rats. In terms of this type of action, they are somewhat superior to dexpanthenol. Dipyridamole- and papaverine-based aerosols have the ability to produce beneficial effect on the entire body's immune system by stimulating the division of pluripotent CD34 cells. The combined effect of papaverine and dipyridamole on tissues leads to selective stimulation of the division of pluripotent cells in the wound, and contributes to a six-fold acceleration of restoration of the animal's immune system after induced immunodeficiency. Conclusion: Topical application of D1/D2 aerosol samples on the skin of rats contributed to a statistically significant acceleration of regeneration processes. In terms of the appearance of granulations and epithelialization of wounds, D1/D2 aerosols were superior to dexpanthenol ointment.