Current and historical perspectives on methodological flaws in processing umbilical cord blood

Flow Cytometric Aldehyde Dehydrogenase Assay Enables a Fast and Accurate Human Umbilical Cord Blood Hematopoietic Stem Cell Assessment

Objective:

Colony-forming units of granulocytes/macrophages (CFU-GM) analysis is the most widely used method to determine the hematopoietic stem cell (HSC) content of human umbilical cord blood (CB) for prediction of engraftment potential. The measurement of aldehyde dehydrogenase (ALDH) activity is a more recent method for HSC qualification. Our aim was to correlate phenotypic and functional assays to find the most predictive method.

Materials and Methods:

In this study, flow cytometric quantitation of CD34⁺ cells and ALDH positivity along with CFU-GM capacity were assessed in fresh and post-thaw CB units.

Results:

Among 30 post-processing samples, for each CB unit the mean total number of nucleated cells (TNCs) was (93.8±30.1)x10⁷, CD34⁺ cells were (3.85±2.55)x10⁶, ALDH⁺ cells were (3.14±2.55)x10⁶, and CFU-GM count was (2.64±1.96)x10⁵. Among an additional 19 post-thaw samples the cell counts were as follows: TNCs, (32.79±17.27)x10⁷; CD34⁺, (2.18±3.17)x10⁶; ALDH⁺, (2.01±2.81)x10⁶; CFU-GM, (0.74±0.92)x10⁵. Our findings showed that in fresh samples TNCs, CD34⁺ cells, and ALDH correlated highly with counts of CFU-GM, CFU-erythroids/granulocytes-macrophages/megakaryocytic cells (GEMM), and burst forming units of erythroids (BFU-E) as follows: TNCs, r=0.47, r=0.35, r=0.41; CD34+, r=0.44, r=0.54, r=0.41; and ALDH, r=0.63, r=0.45, r=0.6, respectively. In terms of post-thaw samples, the correlations were as follows: TNCs, r=0.59, r=0.46, r=0.56; CD34⁺, r=0.67, r=0.48, r=0.61; and ALDH, r=0.61, r=0.67, r=0.67, for CFU-GM, CFU-GEMM, and BFU-E, respectively. All correlations were statistically significant.

Conclusion:

In our experience, HSC assessment by ALDH activity yields the highest correlation with conventional analytical methods, particularly for post-thaw samples. Thus, this fast, inexpensive method has the potential to overcome the weaknesses of other techniques.

Difficulties in hematopoietic progenitor cell collection from a patient with TEMPI syndrome and severe iatrogenic iron deficiency

BACKGROUND

Collection of hematopoietic progenitor cells by apheresis (HPC-A) requires separation of cells by density. Previous studies highlighted the challenges of HPC-A collection from patients with abnormal red blood cells (RBCs). TEMPI syndrome is a recently described condition defined by teleangiectasias, elevated erythropoietin and erythrocytosis, monoclonal gammopathy, perinephric fluid collections, and intrapulmonary shunting. Patients with TEMPI syndrome have responded to therapies used to treat plasma cell dyscrasias and may benefit from autologous HPC transplantation. We report HPC-A collection from a patient with TEMPI syndrome that was complicated by severe iron deficiency.

STUDY DESIGN AND METHODS

The patient received granulocyte-colony-stimulating factor (G-CSF) and plerixafor for HPC mobilization and underwent 3 days of HPC-A collection.

RESULTS

The patient presented for collection with a microcytic erythrocytosis. Over 3 days, approximately 50 L of whole blood was processed, and 2 × 10(8) CD34+ cells were collected (2.8 × 10(6) CD34+ cells/kg). The mean collection efficiency (CE), percentage of mononuclear cells, hematocrit (Hct), and RBC count were 18%, 90%, 14%, and 9 × 10(11) , respectively. Altering collection variables to avoid RBC contamination reduced CE. Ficoll preparations of the products after freeze-thaw showed RBC contamination and hemolysis. Postthaw viability exceeded 95%. The products were not RBC reduced or washed. There were no adverse reactions during or after infusion.

CONCLUSIONS

HPC-A collection from a patient with TEMPI syndrome was complicated by microcytic erythrocytosis, leading to RBC contamination and hemolysis in the product. Adequate HPCs were collected and the patient tolerated infusion without RBC depletion or washing. Our report highlights difficulties of HPC-A collection from iron-deficient patients.