Characteristics of haemopoietic progenitor cells related to CD34 epitope class expression

A randomized study of transendocardial injection of autologous bone marrow mononuclear cells and cell function analysis in ischemic heart failure (FOCUS-HF)

BACKGROUND

Autologous bone marrow mononuclear cell (ABMMNC) therapy has shown promise in patients with heart failure (HF). Cell function analysis may be important in interpreting trial results.

METHODS

In this prospective study, we evaluated the safety and efficacy of the transendocardial delivery of ABMMNCs in no-option patients with chronic HF. Efficacy was assessed by maximal myocardial oxygen consumption, single photon emission computed tomography, 2-dimensional echocardiography, and quality-of-life assessment (Minnesota Living with Heart Failure and Short Form 36). We also characterized patients' bone marrow cells by flow cytometry, colony-forming unit, and proliferative assays.

RESULTS

Cell-treated (n = 20) and control patients (n = 10) were similar at baseline. The procedure was safe; adverse events were similar in both groups. Canadian Cardiovascular Society angina score improved significantly (P = .001) in cell-treated patients, but function was not affected. Quality-of-life scores improved significantly at 6 months (P = .009 Minnesota Living with Heart Failure and P = .002 physical component of Short Form 36) over baseline in cell-treated but not control patients. Single photon emission computed tomography data suggested a trend toward improved perfusion in cell-treated patients. The proportion of fixed defects significantly increased in control (P = .02) but not in treated patients (P = .16). Function of patients' bone marrow mononuclear cells was severely impaired. Stratifying cell results by age showed that younger patients (≤60 years) had significantly more mesenchymal progenitor cells (colony-forming unit fibroblasts) than patients >60 years (20.16 ± 14.6 vs 10.92 ± 7.8, P = .04). Furthermore, cell-treated younger patients had significantly improved maximal myocardial oxygen consumption (15 ± 5.8, 18.6 ± 2.7, and 17 ± 3.7 mL/kg per minute at baseline, 3 months, and 6 months, respectively) compared with similarly aged control patients (14.3 ± 2.5, 13.7 ± 3.7, and 14.6 ± 4.7 mL/kg per minute, P = .04).

CONCLUSIONS

ABMMNC therapy is safe and improves symptoms, quality of life, and possibly perfusion in patients with chronic HF.

Phenotyping studies of clonotypic B lymphocytes from patients with multiple myeloma by flow cytometry

CONTEXT

Clonotypic B lymphocytes, monoclonal B lymphocytes sharing identical, rearranged IGH-CDR3 sequences with the patient's myeloma cells, have been detected in the peripheral blood of patients with multiple myeloma. These cells have been postulated to act as a therapy-resistant tumor reservoir that drives recurrence.

OBJECTIVE

To characterize clonotypic B lymphocytes for future investigation of their role in myeloma pathogenesis.

DESIGN

Harvests of cryopreserved peripheral blood stem-cells from 20 myeloma patients were enriched for clonotypic B lymphocytes. Cytoplasmic immunoglobulin light chain and surface immunophenotype were analyzed by flow cytometry. IGH-CDR3 gene-rearrangement pattern was performed to determine clonality. Posttransplant remission rate was compared with the percentage of clonotypic B lymphocytes.

RESULTS

Clonotypic B lymphocytes expressing CD34(+/-), CD38(+), CD184(+), CD31(+/-), CD50(+/-), CD138(-), CD19(-), CD20(-), and the same immunoglobulin light chain as the patients' known myeloma cells were identified in 12 of 20 patients (60%). Progenitor B lymphocytes expressing similar surface immunophenotype but opposite light chains were identified in the same patients. Polymerase chain reaction for IGH rearrangement showed clonal rearrangement pattern in clonotypic lymphocytes but not in B lymphocytes expressing light chains opposite to myeloma cells. There was no statistically significant correlation between the percentage of clonotypic B lymphocytes and response to autologous transplant.

CONCLUSIONS

Clonotypic B lymphocytes expressing CD34, but not CD19, were identified in stem cell harvests from patients with myeloma and could represent progenitor cells of neoplastic plasma cells. However, the same or similar immunophenotyping can be detected in both clonotypic B lymphocytes and benign progenitor B cells, suggesting clonality analysis might be needed to determine clonotypic B lymphocytes in patients with myeloma. Further studies are warranted to study the role of clonotypic B lymphocytes in the pathogenesis of myeloma.

Selection of Stem Cells by Using Antibodies That Target Different CD34 Epitopes Yields Different Patterns of T-Cell Differentiation

The objective of this study was to compare the patterns of T-cell differentiation from CD34(+) human stem cells selected with different classes of antibody targeting the CD34 molecule. We compared signal-joint T-cell receptor excision circle (sjTREC) production in thymocytes selected with different classes of anti-CD34 antibody. Based on these results, we studied immune reconstitution in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice using human stem cells selected with the same antibodies that yielded variation in the thymocytes. Human CD34(+) stem cells were immunomagnetically selected using the class II QBEnd antibody (prevalent in clinical graft engineering) and the class III 8G12 antibody (common in diagnostic tests). Engraftment and T-cell reconstitution were examined after transplantation. Thymocytes selected with the 8G12 class III antibody have a higher TREC production than those selected with the QBEnd class II antibody. Of mice transplanted with cells selected using the 8G12 antibody, 50% had sjTREC production, compared with 14% of mice transplanted with cells selected using the clinically common antibody QBEnd. 8G12 thymic progenitors are characterized by higher quality in thymic distribution and higher activity in T-cell differentiation. Using class III antibody targeting the CD34 molecule resulted in increased T-cell reconstitution in the NOD/SCID mouse. Use of a single antibody epitope targeting the CD34 molecule may lead to loss of cells that might provide richer T-cell reconstitution. Use of different or multiple epitopes, targeting of alternate stem cell markers, or use of cell-depletion strategies might prevent this loss.

Searching for common stem cells of the hepatic and hematopoietic systems in the human fetal liver: CD34+ cytokeratin 7/8+ cells express markers for stellate cells

BACKGROUND/AIMS

The hematopoietic and hepatic systems are intertwined in the liver during fetal life. Cells expressing the hematopoietic stem cell marker CD34 and cytokeratin 7/8 (CK7/8) are hypothesized to be common stem cells for the hematopoietic and hepatic systems. Our aim was to determine if human fetal liver cells expressing CD34 and CK7/8 represent a common stem cell for both the hematopoietic and hepatic systems.

METHODS

CD34+CK7/8+ cells from midgestation livers were analyzed for the expression of various markers by flow cytometry and isolated based on their expression of CD34, nerve growth factor receptor (NGFR) and lack of CD45 expression. CD34+CD38- hematopoietic stem cells were also isolated and cultured in the presence of various hepatopoietins.

RESULTS

CD34+CK7/8+ cells comprised 3.4-8.5% of the erythrocyte-depleted liver. CD34+CK7/8+ cells had unique light-scatter properties compared to hematopoietic precursors and did not express most markers associated with hematopoietic cells. They did stain with CD13, CD59, NGFR, desmin and alpha-smooth muscle actin. In culture, these cells had a stellate appearance. Cultured hematopoietic stem cells failed to generate hepatocytes.

CONCLUSIONS

CD34+CK7/8+ cells are not common stem cells but rather appear to be hepatic stellate cells. A link between the hematopoietic and hepatic systems during fetal life requires further investigation.

Immunophenotypic analyses of CD34(+) cell subsets in bone marrow from HIV-infected patients during highly- active antiretroviral therapy

BACKGROUND

Because increased bone marrow lymphopoiesis might contribute to immunologic reconstitution during highly-active antiretroviral therapy (HAART), we examined the effect of HAART on CD34(+) cell subsets in bone marrow from HIV-infected patients.

MATERIALS AND METHODS

In 12 HIV-infected patients, bone marrow and peripheral blood were collected before then 4 and 26 weeks after initiating HAART. Bone marrow in 28 HIV-seronegative controls was also examined. Immunophenotypic analyses of CD34(+) cell subsets in bone marrow were performed by flow cytometry.

RESULTS

Our main findings in bone marrow were: (i) HIV-infected patients had increased proportions of CD34(+)cells expressing T- and B-cell markers before initiating HAART; (ii) in contrast, these patients had decreased proportions of CD34(+) cells expressing myeloid-associated markers; (iii) although HAART induced an increase in peripheral T-cell counts, the percentage of CD34(+)cells expressing T-cell markers tended to decrease during such therapy; (iv) HAART induced a decrease in serum IgG accompanied by a slight decrease in the proportion of CD34(+)cells expressing B-cell markers; (v) in contrast, HAART induced a significant increase in peripheral granulocyte counts, accompanied by a slightly increased proportion of CD34(+) cells expressing myeloid-associated molecules.

CONCLUSION

Our findings are compatible with an HIV-related block in T-cell differentiation, leading to accumulation of T-cell progenitors in bone marrow, and such a block may be removed by HAART.