Culture methods for the detection of minimal tumor contamination of hematopoietic harvests: a review

Detection of Breast Cancer Cells in the Bone Marrow or Peripheral Blood: Methods and Prognostic Significance

Tumor cells can reach every anatomic district, organ and tissue through the peripheral blood circulation. Tumor cell shedding is considered an early event in the multi-phase process of metastasis, and the possibility of detecting tumor cells in the bloodstream and/or bone marrow before clinical evidence of distant metastases needs to be explored. The use of new sophisticated diagnostic and investigative techniques has boosted the study of tumor cell contamination of bone marrow and peripheral blood. Molecular techniques, such as reverse-transcriptase polymerase chain reaction, may be useful tools to reach this target, but, today, immunocytochemistry is still considered the gold standard to assess new techniques to detect isolated tumor cells in hematopoietic tissue. Little is known about the biology of isolated tumor cells in the peripheral blood or bone marrow. Two crucial points need to be evaluated: the identification of specific markers of breast cancer cells with clonogenic potential and their biologic properties, and the prognostic impact of the detection of isolated tumor cells in the bone marrow or peripheral blood stem cell collections.

Hematopoietic cell transplantation in non-Hodgkin's lymphoma

OBJECTIVE

To explore the role and outcomes using hematopoietic cell transplantation (HCT) as a treatment option with aggressive, follicular, mantle, T-cell, and HIV related non-Hodgkin's lymphoma (NHL).

DATA SOURCES

Research and review articles and textbooks.

CONCLUSION

High-dose chemotherapy and/or radiation therapy followed by HCT has been used to overcome resistance to standard-dose therapy and has been explored over the past 40 years and has shown long-term survival of approximately 10% to 50% in patients with relapsed or refractory lymphoma.

IMPLICATIONS FOR NURSING PRACTICE

Nursing plays a significant role in the assessment and management of patients throughout the course of HCT.

Detection of disseminated epithelial cancer cells by liquid culture--factors interfering with the standardization of assays

BACKGROUND

Immunocytochemistry is the standard method for detection of disseminated breast-cancer cells. Tumor-cell enrichment by cell culture has been used by several investigators, however assays published have not been well-standardized.

METHODS

Breast-cancer cells from two lines were diluted in hemopoietic cells of varying origins and cultured in different media and different flasks. Factors influencing successful tumor-cell amplification by liquid culture were identified by investigation of 277 cultures. Parallel clinical samples, consisting of BM aspirations, leukapheresis samples and peripheral blood samples obtained from women with breast cancer, were investigated in 113 cultures. Cancer-cell detection by cell culture could be compared to immunocytochemistry in 101 cases.

RESULTS

The frequency of tumor-cell detection was not improved by liquid culture, but a significant correlation between conventional tumor-cell detection and detection after liquid culture was found. Factors influencing tumor-cell amplification in the dilution assay could not be transferred to the investigation of clinical samples. It was concluded that culture-enrichment of disseminated cancer cells was very complex, and could be influenced by a variety of factors-even when a model system was used.

DISCUSSION

It should be recognized that culture-enriched cancer cells probably represent a highly selected population of disseminated cancer cells, despite the significant correlation between tumor cells detected by conventional methods and following conventional methods after liquid culture. There is currently no evidence to suggest that cancer-cell amplification by cell culture could become a standardized technique for the detection of disseminated epithelial tumor cells.

CD34(+) cell enrichment depletes atypical CD30(+) cells from PBPC grafts in patients with HD

BACKGROUND

European Group for Blood and Marrow Transplantation (EBMT) registry data indicate that patients with relapsed HD given high-dose therapy (HDT), supported with PBPC might have a poorer outcome compared with those given BM. Since this can be due to the infusion of contaminating tumor cells in the PBPC products, we studied the presence of minimal residual disease and tested whether CD34(+) cell enrichment was able to remove atypical CD30(+) cells from PBPC grafts.

METHODS

Eighteen HD patients eligible for HDT were included in the study. By the use of immunocytochemistry (ICC), mononuclear cells from BM and peripheral blood (PB) before mobilization, PBPC products and selected CD34(+) fractions were stained using anti-CD30 MAb (Ber-H2) and the APAAP (alkaline phosphatase-anti-alkaline phosphatase) method. Cells scored as atypical CD30(+) cells were large- to medium-sized, with membranous, cytoplasmatic and/or Golgi positivity for CD30.

RESULTS

Nine out of 11 BM tested were positive, while 14 of 14 PB and 18 of 18 PBPC contained atypical CD30(+) cells. The total number of atypical CD30(+) cells was significantly higher in PBPC than in the corresponding BM. CD34(+) cell enrichment employing ISOLEX 300I gave a purity and yield of 99.2% (range 97.8-99.7) and 49.6% (range 30.0-78.4), respectively. After HDT a median of 5.8 x 10(6) (range 2.7-20) CD34(+) cells/kg was infused. Neutrophil counts of > 0.5 x 10(9)/L and platelet counts of > 20 x 10(9)/L were achieved at Day 12 (range 10-17) and at Day 10 (range 7-15), respectively. Sixteen of 18 CD34(+) selected products had no detectable atypical CD30(+) cells, while two had a low number. After HDT, the overall survival was 80% and the event-free survival was 69%, with a median follow-up of 24 months (range 1-36).

DISCUSSION

We show that contaminating atypical CD30(+) cells in PBPC can efficiently be removed by CD34(+) cell enrichment, and the use of such grafts following HDT gives fast and sustained engraftment.

High-dose therapy in patients with Hodgkin's disease: the use of selected CD34(+) cells is as safe as unmanipulated peripheral blood progenitor cells

Register data suggest that patients with Hodgkin's disease (HD) given high-dose therapy (HDT) with peripheral blood progenitor cells (PBPC) have a less favourable prognosis as compared to those given bone marrow as stem cell support. Since this can be due to infusion of tumour cells contaminating the PBPC grafts, we initiated a feasibility study in which PBPC grafts from HD patients were purged by CD34(+) cell enrichment. Controversy exists about whether the use of CD34(+) enriched stem cells leads to a delayed haematological and immune reconstitution. We compared these parameters, including risk of infections and clinical outcome after HDT, in patients with HD given either selected CD34(+) cells or unmanipulated PBPC as stem cell support. From October 1994 to May 2000, 40 HD patients with primary refractory disease or relapse were treated with HDT and supported with either selected CD34(+) cells (n = 21) or unmanipulated PBPC (n = 19) as stem cell support. All patients had chemosensitive disease at the time of transplantation. A median of 5.8 (range 2.7-20.0) vs 4.5 (range 2.3-17.6) x 10(6) CD34(+) cells per kilo were reinfused in the CD34(+) group and PBPC group, respectively. No difference was observed between the two groups with regard to time to haematological engraftment, reconstitution of B cells, CD56(+) cells and T cells at 3 and 12 months and infectious episodes after HDT. Two (5%) treatment-related deaths, one in each group, were observed. The overall survival at 4 years was 86% for the CD34(+)group and 74% for the PBPC group with a median follow-up of 37 months (range 1-61) and 46 months (range 4-82), respectively (P = 0.9). The results of this study demonstrate that the use of CD34(+) cells is safe and has no adverse effects either with respect to haematological, immune reconstitution or to infections after HDT.

Proliferation and Survival of Mammary Carcinoma Cells Are Influenced by Culture Conditions Used for Ex Vivo Expansion of CD34+Blood Progenitor Cells

Malignant cell contamination in autologous transplants is a potential origin of tumor relapse. Ex vivo expansion of CD34+ blood progenitor cells (BPC) has been proposed as a tool to eliminate tumor cells from autografts. To characterize the influence of culture conditions on survival, growth, and clonogenicity of malignant cells, we isolated primary mammary carcinoma cells from pleural effusions and ascites of patients with metastatic breast cancer and cultured them in the presence of stem cell factor (SCF), interleukin-1β (IL-1β), IL-3, IL-6, and erythropoietin (EPO), ie, conditions previously shown to allow efficient ex vivo expansion of CD34+ BPC. In the presence of serum, tumor cells proliferated during a 7-day culture period and no significant growth-modulatory effect was attributable to the presence of hematopoietic growth factors. When transforming growth factor-β1 (TGF-β1) was added to these cultures, proliferation of breast cancer cells was reduced. Expansion of clonogenic tumor cells was seen in the presence of SCF + IL-1β + IL-3 + IL-6 + EPO, but was suppressed by TGF-β1. Cocultures of tumor cells in direct cellular contact with hematopoietic cells showed that tumor cell growth could be stimulated by ex vivo expanded hematopoietic cells at high cell densities (5 × 105/mL). In contrast, culture under serum-free conditions resulted in death of greater than 90% of breast cancer cells within 7 days and a further decrease in tumor cell numbers thereafter. In the serum-free cultures, hematopoietic cytokines and cellular contact with CD34+ BPC could not protect the tumor cells from death. Therefore, ex vivo expansion of CD34+ BPC in serum-free medium provides an environment for efficient purging of contaminating mammary carcinoma cells. These results have clinical significance for future protocols in autologous progenitor cell transplantation in cancer patients.

Proliferation and Survival of Mammary Carcinoma Cells Are Influenced by Culture Conditions Used for Ex Vivo Expansion of CD34+Blood Progenitor Cells

Malignant cell contamination in autologous transplants is a potential origin of tumor relapse. Ex vivo expansion of CD34+ blood progenitor cells (BPC) has been proposed as a tool to eliminate tumor cells from autografts. To characterize the influence of culture conditions on survival, growth, and clonogenicity of malignant cells, we isolated primary mammary carcinoma cells from pleural effusions and ascites of patients with metastatic breast cancer and cultured them in the presence of stem cell factor (SCF), interleukin-1β (IL-1β), IL-3, IL-6, and erythropoietin (EPO), ie, conditions previously shown to allow efficient ex vivo expansion of CD34+ BPC. In the presence of serum, tumor cells proliferated during a 7-day culture period and no significant growth-modulatory effect was attributable to the presence of hematopoietic growth factors. When transforming growth factor-β1 (TGF-β1) was added to these cultures, proliferation of breast cancer cells was reduced. Expansion of clonogenic tumor cells was seen in the presence of SCF + IL-1β + IL-3 + IL-6 + EPO, but was suppressed by TGF-β1. Cocultures of tumor cells in direct cellular contact with hematopoietic cells showed that tumor cell growth could be stimulated by ex vivo expanded hematopoietic cells at high cell densities (5 × 105/mL). In contrast, culture under serum-free conditions resulted in death of greater than 90% of breast cancer cells within 7 days and a further decrease in tumor cell numbers thereafter. In the serum-free cultures, hematopoietic cytokines and cellular contact with CD34+ BPC could not protect the tumor cells from death. Therefore, ex vivo expansion of CD34+ BPC in serum-free medium provides an environment for efficient purging of contaminating mammary carcinoma cells. These results have clinical significance for future protocols in autologous progenitor cell transplantation in cancer patients.

Lymphoma cells associated with bone marrow stromal cells in culture exhibit altered growth and survival

The detection of clonal populations of lymphoma cells in histologically negative bone marrow using culture techniques is a predictor of poor outcome for patients undergoing high dose therapy and autologous transplantation. In positive cultures, lymphoma cells were observed as outgrowths in association with adherent stromal cells, whilst only stromal cells were observed in negative long-term cultures. This study developed an experimental model to further study the interactions occurring between lymphoma cells and stromal cells. Using random dot graticule analysis, 86% and 74%, respectively, of patient lymphoma cells grew in association with stromal cells in leukapheresis and bone marrow harvest cultures with the formation of cobblestone areas at sites of interaction between lymphoma cells and stromal cells. Secondary cultures showed that individual stromal cells were able to support the growth of a small number of lymphoma cells. Coculture of the human lymphoma cell lines with a murine bone marrow stromal cell line, MS-5 also resulted in the formation of cobblestone areas, which corresponded with the suppression of nonadherent cell production by the lymphoma cell lines. Upon interacting with MS-5 cells, the lymphoma cell lines formed pseudopodia and underwent pleiomorphic nuclear changes. Contiguous linear homotypic associations between lymphoma cells were evident, as opposed to focal contacts occurring in the heterotypic interactions between lymphoma cells and MS-5 cells. An increasing proportion of supernatant lymphoma cells underwent apoptosis as time in culture increased. These results demonstrate that bone marrow stromal cells alter the pattern of growth of lymphoma cells and may have an important role in the maintenance of occult lymphoma by inhibiting apoptosis.

Minimal residual disease in autologous hematopoietic harvests from breast cancer patients

The increasing use of high-dose chemotherapy with autologous hematopoietic transplantation for the treatment of solid malignancies has raised concern about the role of tumor cells contaminating the grafts. Minimal residual disease (MRD) in autologous grafts has became a dynamic and intensively studied field in oncology. This review discusses the current status of MRD in breast cancer autografts and presents existing data on detection methodology, clinical relevance, biologic characteristics and purging techniques.

Consensus conference on high-dose therapy with hematopoietic stem cell transplantation in diffuse large-cell lymphoma. Type of cells, optimal mobilization of stem cells--positive and negative selection

Stem cell transplantation has played a role in the management of diffuse large-cell lymphoma for decades. The optimal source of the stem cells and the proper composition of the cellular graft product has not been defined. The field is changing rapidly and the future is likely to hold improvements and requirements that will further benefit the patient!

Purging of Mammary Carcinoma Cells During Ex Vivo Culture of CD34+ Hematopoietic Progenitor Cells With Recombinant Immunotoxins

Tumor cells have been found in autologous hematopoietic cell transplants used after high-dose chemotherapy. To specifically eliminate contaminating mammary tumor cells during ex vivo expansion of CD34+ hematopoietic progenitor cells, we used recombinant immunotoxins (ITs) directed against cell-surface antigens expressed on mammary carcinoma cells. ITs were expressed from fusion cDNAs combining a single-chain antibody fragment (scFv) directed against the Erb-B2 or epidermal growth factor (EGF) receptors with a truncatedPseudomonas exotoxin A fragment devoid of its cell-binding domain. CD34+ hematopoietic progenitor cells did not express Erb-B2 and EGF receptors as detected by Western blotting. Ex vivo expansion of total hematopoietic cells or of colony-forming cells from CD34+ progenitors in the presence of stem-cell factor (SCF), interleukin-1 (IL-1), IL-3, IL-6, and erythropoietin (Epo) was not affected when ITs were added to the cultures. In contrast, MDA-MB 453 and MCF-7 mammary carcinoma cells were depleted in a dose- and time-dependent manner by more than 3 log in coculture with CD34+ cells over a period of 7 days in the presence of 100 to 1,000 ng/mL of anti–Erb-B2 IT. This included elimination of the subpopulations with regrowth potential. Similarly, addition of either anti–Erb-B2 or anti-EGF receptor ITs to primary breast cancer cells isolated from patients with metastatic disease resulted in elimination of cytokeratin-positive cells in seven of seven samples. ITs are highly efficient and convenient to use for the depletion of mammary tumor cells during ex vivo expansion of hematopoietic progenitor-cell autografts.

Purging of Mammary Carcinoma Cells During Ex Vivo Culture of CD34+ Hematopoietic Progenitor Cells With Recombinant Immunotoxins

Tumor cells have been found in autologous hematopoietic cell transplants used after high-dose chemotherapy. To specifically eliminate contaminating mammary tumor cells during ex vivo expansion of CD34+ hematopoietic progenitor cells, we used recombinant immunotoxins (ITs) directed against cell-surface antigens expressed on mammary carcinoma cells. ITs were expressed from fusion cDNAs combining a single-chain antibody fragment (scFv) directed against the Erb-B2 or epidermal growth factor (EGF) receptors with a truncatedPseudomonas exotoxin A fragment devoid of its cell-binding domain. CD34+ hematopoietic progenitor cells did not express Erb-B2 and EGF receptors as detected by Western blotting. Ex vivo expansion of total hematopoietic cells or of colony-forming cells from CD34+ progenitors in the presence of stem-cell factor (SCF), interleukin-1 (IL-1), IL-3, IL-6, and erythropoietin (Epo) was not affected when ITs were added to the cultures. In contrast, MDA-MB 453 and MCF-7 mammary carcinoma cells were depleted in a dose- and time-dependent manner by more than 3 log in coculture with CD34+ cells over a period of 7 days in the presence of 100 to 1,000 ng/mL of anti–Erb-B2 IT. This included elimination of the subpopulations with regrowth potential. Similarly, addition of either anti–Erb-B2 or anti-EGF receptor ITs to primary breast cancer cells isolated from patients with metastatic disease resulted in elimination of cytokeratin-positive cells in seven of seven samples. ITs are highly efficient and convenient to use for the depletion of mammary tumor cells during ex vivo expansion of hematopoietic progenitor-cell autografts.

The contribution of animal models to the development of treatments for hematologic recovery following myeloablative therapy: a review

This review describes the role that animal models have played in the development of clinical procedures for growth factor and hematopoietic cell therapies following high-dose cancer chemotherapy, radiotherapy or both. Data are discussed describing animal models that add to the understanding of human hematopoiesis, including myeloid and lymphoid lineage localization and in vivo maturation. Finally, current animal models of cytokine and cell therapies are presented in the context of their contributions to early clinical trials and future therapies. These studies underscore the past and current contributions animal investigations have made to improving clinical therapies.

Purging of autografts: methods and clinical significance

High-dose chemoradiotherapy with autologous haematopoietic progenitor cell support is being used with increasing frequency to treat patients with a variety of malignancies. The most common reason for the ultimate failure in patients treated with high-dose therapy with stem cell support is not lack of engraftment, toxicity of therapy, or infection, but rather relapse of disease. There is solid evidence that reinfusion of autografts containing clonogenic tumour cells can contribute to relapse and influence patient outcome after high-dose treatment. In patients undergoing high-dose treatment, tumour cell contamination can be observed in histologically normal bone marrow or peripheral blood by sensitive micrometastatic detection techniques. Consequently, methods for detection of minimal residual disease in the autografts, together with techniques to remove tumour cells from the harvest are considered to be important in patients receiving high-dose therapy with stem cell support.

Detection of occult tumour cells in bone marrow and blood in breast cancer patients--methods and clinical significance

Immunocytochemistry using tumour-associated monoclonal antibodies has led to improvements in the ability to detect occult breast cancer cells in bone marrow aspirates and peripheral blood. Nevertheless, the immunocytochemistry method needs to be further developed before it can be used routinely in the clinic. Reverse transcription polymerase chain reaction assays (RT-PCR) that screen for carcinoma-specific expression of mRNA in bone marrow and blood have been developed. However, it is not yet clear whether the most frequently employed RT-PCR assay for cytokeratin 19 has the specificity required to be safely used in the clinic. In spite of many unsolved standardization problems with micrometastatic detection methods, recent data show that the presence of occult tumour cells in the bone marrow at diagnosis and in the reinfused autograft after high-dose therapy appears to increase the rate of recurrence in the patients.

Purging of peripheral blood stem cell grafts

The shortage of HLA-matched sibling donors for bone marrow transplant patients has stimulated interest in the use of alternative donors. As a result, there has been a dramatic increase in the use of autologous marrow transplantation, which avoids the complications of graft-versus-host disease, but may deprive the patient of a potentially beneficial graft-versus-disease response and runs the risk of returning occult tumor cells with the graft. There is increasing evidence that these cells may be associated with disease relapse post-transplant, and many methods have been developed for their removal ex vivo. Combinations of negative and positive selection may achieve elimination of tumor cells to the limits of detection of the most sensitive assays currently available. The marked trend toward the use of autologous grafts derived from blood rather than marrow has raised the question as to whether peripheral blood stem cell (PBSC) preparations should be purged of tumor. Data indicate that these grafts generally contain a lower tumor burden, although the stem cell mobilization procedure may recruit tumor cells into the peripheral circulation. Enrichment of CD34+ cells from apheresis products appears, at present, to be less efficient than from marrow and provides at best about a 2-3 log depletion of tumor. This has prompted proposals to follow positive selection by a small-scale purging procedure. Technical issues, such as preprocessing and pooling of collections prior to purging, remain to be addressed. Ultimately, the development of successful purging procedures for PBSC grafts will simply reemphasize the necessity of improving the efficacy of high-dose therapy.