Adaptation of semiautomated circulating tumor cell (CTC) assays for clinical and preclinical research applications

The majority of cancer-related deaths occur subsequent to the development of metastatic disease. This highly lethal disease stage is associated with the presence of circulating tumor cells (CTCs). These rare cells have been demonstrated to be of clinical significance in metastatic breast, prostate, and colorectal cancers. The current gold standard in clinical CTC detection and enumeration is the FDA-cleared CellSearch system (CSS). This manuscript outlines the standard protocol utilized by this platform as well as two additional adapted protocols that describe the detailed process of user-defined marker optimization for protein characterization of patient CTCs and a comparable protocol for CTC capture in very low volumes of blood, using standard CSS reagents, for studying in vivo preclinical mouse models of metastasis. In addition, differences in CTC quality between healthy donor blood spiked with cells from tissue culture versus patient blood samples are highlighted. Finally, several commonly discrepant items that can lead to CTC misclassification errors are outlined. Taken together, these protocols will provide a useful resource for users of this platform interested in preclinical and clinical research pertaining to metastasis and CTCs.

Effect of 3.2 vs. 3.8% sodium citrate concentration on anti-Xa levels for patients on therapeutic low molecular weight heparin

In this study, we compared the effect of sodium citrate, a sample collection variable, on the anti-Xa levels of patients (n = 28) on dalteparin, a low molecular weight heparin. The median anti-Xa level for 3.2% sodium citrate was 0.235 U/ml while the median level for 3.8% sodium citrate was 0.230 U/ml. We conclude that different sodium citrate concentrations give statistically equivalent anti-Xa levels for the same samples. This conclusion is in contrast to the findings of the effect of sodium citrate concentration on International Normalized Ratio (INR) and activated partial-thromboplastin time (aPTT). In accordance with previous recommendations, we advocate the exclusive use of 3.2% sodium citrate in an effort to standardize coagulation testing.

Lactation curves and effect of pup removal on milk fat of C57Bl/6J mice fed different diet fats

Groups of C57Bl/6J mice, fed either a cis (C-Diet) or trans diet (T-Diet) were milked without preconditioning at 6, 8, 10 and 12 days postpartum. On day 10, groups of mice were also milked 4, 6 and 18 h after separation of the pups. Except for the 18-h separation, all T-Diet fed animals produced milk of lower fat content than did the C-Diet animals (P < 0.001) throughout the lactation period measured. In the C-Diet mice, the 6-h separation period resulted in a decrease (P < or = 0.03) in fat, but the diet-depressed milk fat of T-Diet animals was not decreased further until the 18-h separation period. Milk volume increased as lactation progressed and was greatly increased as a result of preconditioning (P < or = 0.001), even at 4 h of separation when fat was not reduced, and was always greater for T-Diet animals. Within diet groups, fatty acid composition was similar throughout the lactation period studied and was not affected by preconditioning except in the 18-h separation period, when de novo fatty acids were significantly reduced (P < or = 0.05). The data are consistent with the hypothesis that preconditioning results in lowered milk fat values and that preconditioning techniques can explain discrepancies in literature values for murine milk fat.

A multicenter study evaluation of the ClearLLab 10C panels

Multiparameter flow cytometry plays an important role in the diagnosis, staging, and monitoring of patients with a suspected hematological malignancy. The ClearLLab 10C Panels consist of four reagent panels (B-Lineage Tube, T-Lineage Tube, and 2 Myeloid Lineage Tubes), each consisting of 10 color/10 antibody conjugates utilizing Beckman Coulters proprietary dry format optimized for investigating patients with suspected leukemia or lymphoma. A multicenter study was conducted to evaluate the performance of the ClearLLab 10C Panels for qualitative assessment of normal versus abnormal phenotype in peripheral blood, bone marrow, and lymph node samples with suspected hematological malignancies. ClearLLab 10C was compared to laboratory developed tests (LDTs) and final clinical diagnosis. Four clinical sites were used to enroll patient's spent specimens (n = 453); three laboratories in North America and one in Europe. Of the 453 specimens, 198 had no malignancy and 255 contained an abnormal population. The diagnostic accuracy of the ClearLLab 10C Panels was achieved with sensitivity of 96% and specificity of 95% with respect to patient final clinical diagnosis. The agreement of phenotyping between ClearLLab10C Panels and LDTs was 98%. Any differences noted between ClearLLab 10C and LDT were due to either the presence of populations below the level of detection, the lack of clinical information provided to the evaluators, or marker(s) not present in these panels. Overall, the ClearLLab 10C demonstrated excellent agreement to LDTs and diagnosis. These four reagent panels can be adopted by individual laboratories to assess the presence or absence of malignancy.

Screening of patients with idiopathic venous thromboembolism for paroxysmal nocturnal hemoglobinuria clones

Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon disorder characterized by hemolysis, thrombosis and marrow failure. Whereas venous and arterial thrombosis is a very common symptom of the disease, the frequency of PNH clones in patients with unexplained venous thromboembolism, including deep vein thrombosis and pulmonary embolism, has not been studied. We conducted a cross sectional study evaluating the presence of PNH clones in patients with prevalent venous thromboembolism using a high sensitivity flow cytometry assay for erythrocytes and neutrophils. Among the 388 patients enrolled in the study one patient had a detectable PNH clone of 0.02% in the neutrophil population (0.26%; 95% CI 0.05 to 1.45) and no detectable erythrocyte clone. We conclude that the presence of PNH clones in patients with idiopathic venous thrombosis is rare. Screening for PNH clones among VTE patients might be better reserved for patients with signs of hemolysis.

Performance Characteristics of the Coulter LH 500 Hematology Analyzer

The challenge for modern hematology laboratories is to provide accurate and reproducible results, with seamless performance between facilities, in a cost-effective manner. Beckman Coulter recently developed the Coulter LH 500 to meet the needs of smaller laboratories or serve as a backup in larger laboratories. The principal goal of this study was to validate all parameters and performance specifications of the LH 500 compared to the Coulter LH 750 predicate analyzer. A total of 245 spent clinical samples from the London Health Sciences Centre (LHSC) and 251 from the University of Pittsburgh Medical Center Health System (UPMCHS) were analyzed during the study. The samples were selected to include 75% abnormal and 25% normal blood samples. According to the results of a rank sum test, there was no significant difference between the LH 500 and LH 750 for all complete blood count parameters (P > .05) except the red cell distribution width, which showed a slight negative bias on the LH 500. Differential parameters comparing the LH 500 to a 400-cell manual differential showed correlation coefficients (r2) from 0.75 to 0.99 for all parameters except basophils. Of the samples run on the LH 500 at LHSC, the false-positive differential flagging rate was 17.32% and the false-negative rate was 3.03%. Sensitivity was 82.93%, specificity 78.95%, and efficiency 79.65%. At UPMCHS, the false-positive differential flagging rate was 13.37% and false-negative rate 2.97%. Sensitivity was 91.89%, specificity 78.91%, and efficiency 83.66%. Overall, the LH 500 performed accurately and reproducibly compared to the LH 750 and the reference procedures. It would be an excellent second instrument for larger laboratories concerned with harmonization of instrumentation and reagents or as a primary instrument for smaller hematology laboratories with limited space.

Initial performance evaluation of the UniCel® DxH slide maker/stainer Coulter® cellular analysis system

INTRODUCTION

Despite the advancements in instrumentation within hematology laboratories, there is still a need for review of a peripheral blood film (PBF). For a thorough PBF evaluation, it is critical that a well spread and stained film is available.

METHODS

In this study, we evaluated an automatic slide maker/stainer (DxH-SMS, Beckman Coulter) compared with manually prepared blood films on 124 normal and abnormal samples. The primary goal of the study was to determine whether or not the DxH-SMS was able to consistently and reproducibly prepare and stain blood films of exemplary quality, without carryover between specimens. Additionally, repeatability of white blood cell distribution, comparability of morphology to reference methodologies, and grading of acceptance criteria outlined in the CLSI document H20-A2 were assessed.

RESULTS

Carryover was not an issue and repeatability was within expected limits. There was excellent agreement of the 5-part differential between the automated blood films made by the DxH-SMS compared with the manually prepared reference blood film. There was no difference in identification and enumeration of blasts, variant lymphocytes, or nucleated red blood cells (P < 0.05). Red cell morphology showed excellent agreement.

CONCLUSION

Blood films prepared by the DxH-SMS are of excellent quality, reproducible, and compare well with manually prepared slides. Introduction to our laboratory has improved and standardized slide quality.

Programming stem cells for therapeutic angiogenesis using biodegradable polymeric nanoparticles

Controlled vascular growth is critical for successful tissue regeneration and wound healing, as well as for treating ischemic diseases such as stroke, heart attack or peripheral arterial diseases. Direct delivery of angiogenic growth factors has the potential to stimulate new blood vessel growth, but is often associated with limitations such as lack of targeting and short half-life in vivo. Gene therapy offers an alternative approach by delivering genes encoding angiogenic factors, but often requires using virus, and is limited by safety concerns. Here we describe a recently developed strategy for stimulating vascular growth by programming stem cells to overexpress angiogenic factors in situ using biodegradable polymeric nanoparticles. Specifically our strategy utilized stem cells as delivery vehicles by taking advantage of their ability to migrate toward ischemic tissues in vivo. Using the optimized polymeric vectors, adipose-derived stem cells were modified to overexpress an angiogenic gene encoding vascular endothelial growth factor (VEGF). We described the processes for polymer synthesis, nanoparticle formation, transfecting stem cells in vitro, as well as methods for validating the efficacy of VEGF-expressing stem cells for promoting angiogenesis in a murine hindlimb ischemia model.

Human-derived D-dimer for external quality assessment: results of four surveys in Ontario

External quality assessment (EQA) of D-dimer assays has been limited by a lack of standardized human-derived testing material. In 2006 and 2007, the Quality Management Program--Laboratory Services, Toronto, Canada, investigated the use of commercially prepared lyophilized human plasma spiked with human-derived D-dimer components manufactured by Affinity Biologicals, Hamilton, Canada. Four surveys were performed. Participants reported the level or presence of D-dimer using quantitative or qualitative methods. Participants performing quantitative testing provided their unit of measure and reference interval. Results were considered correct if they fell within the range appropriate for each sample (normal/negative or abnormal/positive). Overall, survey results were excellent, with 4.0% (95% confidence interval [CI], 1.3%-9.1%), 0.8% (CI, 0.0%-1.5%), 2.3% (CI, 0.5%-6.6%), and 2.3% (CI, 0.4%-6.6%) of participants reporting an incorrect result in the first, second, third, and fourth surveys, respectively. A commercially prepared D-dimer is a suitable material for EQA testing.

Comparison of two methods to detect P-glycoprotein in patients with chronic lymphocytic leukaemia

P-glycoprotein (Pgp) is a transmembrane protein associated with multiple drug resistance. Pgp can be detected by several monoclonal antibodies or its activity inferred by measuring drug uptake. We compared two methods for quantitating Pgp in 32 patients with chronic lymphocytic leukaemia. The monoclonal antibody 4E3, which recognizes an external epitope of Pgp, was detected by flow cytometry. Intracellular daunorubicin (DNR) accumulation was measured by flow cytometry in the presence (treated) and absence (control) of cyclosporin, an agent known to inhibit Pgp. Correlation between the degree of positivity on the drug uptake assay and Pgp detected by monoclonal antibody 4E3 was poor (r = 0.06). No association with previous drug exposure or lymphocyte doubling time and Pgp positivity was found in this series of patients. Poor correlation between assays might reflect a lack of sensitivity of the DNR uptake assay. Drug accumulation may be influenced by other cellular efflux pumps unrelated to Pgp, making the DNR assay non-specific.

Participation in the College of American Pathologists Laboratory Accreditation Program Decreases Variability in B-Lymphoblastic Leukemia and Plasma Cell Myeloma Flow Cytometric Minimal Residual Disease Testing: A Follow-up Survey

CONTEXT.—

Minimal residual disease (MRD) testing by flow cytometry is ubiquitous in hematolymphoid neoplasm monitoring, especially B-lymphoblastic leukemia (B-ALL), for which it provides predictive information and guides management. Major heterogeneity was identified in 2014. Subsequently, new Flow Cytometry Checklist items required documentation of the sensitivity determination method and required lower level of detection (LLOD) inclusion in final reports. This study assesses Laboratory Accreditation Program (LAP) participation and new checklist items' impact on flow cytometry MRD testing.

OBJECTIVES.—

To survey flow cytometry laboratories about MRD testing for B-ALL and plasma cell myeloma. In particular, enumerate the laboratories performing MRD testing, the proportion performing assays with very low LLODs, and implementation of new checklist items.

DESIGN.—

Supplemental questions were distributed in the 2017-A mailing to 548 flow cytometry laboratories subscribed to the College of American Pathologists FL3 Proficiency Testing Survey (Flow Cytometry-Immunophenotypic Characterization of Leukemia/Lymphoma).

RESULTS.—

The percentage of laboratories performing MRD studies has significantly decreased since 2014. Wide ranges of LLOD and collection event numbers were reported for B-ALL and plasma cell myeloma. Most laboratories determine LLOD by using dilutional studies and include it in final reports; a higher proportion of LAP participants used these practices than nonparticipants.

CONCLUSIONS.—

Several MRD testing aspects vary among laboratories receiving FL3 Proficiency Testing materials. After the survey in 2014, new checklist items were implemented. As compared to 2014, fewer laboratories are performing MRD studies. While LLOD remains heterogeneous, a high proportion of LAP subscribers follow the new checklist requirements and, overall, target LLOD recommendations from disease-specific working groups are met.

Validation of a single point flow cytometric assay for determining P-glycoprotein activity in multidrug resistant cell lines

P-glycoprotein, a transmembrane protein which acts as an energy dependent efflux pump, has been implicated as one mechanism of multidrug resistance (MDR) in human tumours. Commonly employed assays measure P-glycoprotein immunohistochemically or mdr1 messenger RNA. In this study we compared a single point flow cytometric assay for determining activity of P-glycoprotein with cellular expression of P-glycoprotein determined by Western blot. Five cell lines, with varying levels of multiple drug resistance, were incubated with daunorubicin (DNR) in the presence (treated) and absence (control) of cyclosporine or verapamil, agents known to inhibit the activity of P-glycoprotein. The treated cell lines, along with non-treated controls were examined for intracellular concentrations of DNR measured by fluorescence intensity using a flow cytometer. The ratio of fluorescence intensity expressed in the treated/control was used as an index of functional activity of P-glycoprotein. Functional activity of the P-glycoprotein as determined by flow cytometry correlates highly with cellular content of P-glycoprotein measured by western blot (correlation coefficients of r = 0.90-0.98 for the various cell line combinations). This method represents a rapid single point flow cytometric assay which may be suitable for screening clinical samples for P-glycoprotein activity.

Single platform flow cytometric absolute CD34+ cell counts based on the ISHAGE guidelines. International Society of Hematotherapy and Graft Engineering

In concert with the International Society of Hematotherapy and Graft Engineering (ISHAGE), we previously described a set of guidelines for detection of CD34+ cells based on a four-parameter flow cytometry method (CD45 FITC/CD34 PE staining, side and forward angle light scatter). With this procedure, an absolute CD34+ count is generated by incorporating the leukocyte count from an automated hematology analyser (two-platform method). In the present study, we modified the basic ISHAGE method with the addition of a known number of Flow-Count fluorospheres. To reduce errors inherent to sample washing/centrifugation, we implemented ammonium chloride lyse, no-wash no-fix sample processing. These modifications convert the basic protocol into a single-platform method to determine the absolute CD34 count directly from a flow cytometer and form the basis of the Stem-Kit from Coulter/Immunotech. A total of 72 samples of peripheral blood, apheresis packs, and cord blood were analysed and compared using the ISHAGE protocol with or without the addition of fluorescent microspheres. Comparison of methods showed a high correlation coefficient (r=0.99), with no statistically significant difference or bias between methods (P > 0.05). Linearity of the absolute counting method generated an R2 value of 1.00 over the range of 0-250/microl. Precision of the absolute counting method measured at three concentrations of CD34+-stabilised KG1 a cells (Stem-Trol, COULTER) generated a coefficient of variation (C.V.) ranging from 4% to 9.9%. In a further modification of the single-platform method, the viability dye 7-amino actinomycin D was included and demonstrated that both viable and nonviable CD34+ cells could be identified and quantitated. Together, these modifications combine the accuracy and sensitivity of the original ISHAGE method with the ability to produce an absolute count of viable CD34+ cells. It is the accurate determination of this value that is most clinically relevant in the transplant setting. These modifications may improve the interlaboratory reproducibility of CD34 determinations due to the reduction in sample handling and calculation of results.

Study of Octaplex dosing accuracy: an in vitro analysis

Prothrombin complex concentrates (PCC) are recommended for urgent warfarin reversal. However, disagreement exists regarding the proper dosing strategy (i.e. fixed vs. weight-based). We measured the in vitro effect of PCC dosing on international normalised ratio (INR) and factor activity. Plasma from warfarin-anticoagulated patients with stable INRs was collected. PCC doses of 1,000, 2,000 and 3,000 IU were added to the samples, and INR and factor activity were analysed before and after PCC. Twenty-three of thirty subjects enrolled had complete data for analysis. INRs were below 1.5 in all samples post-1,000 IU, and decreased further with subsequent doses (p<0.001). Factors II, VII, and X increased with consecutive doses (p<0.01). Linear correlation was seen between INR and factors II, VII and X. Factor IX did not increase consistently nor show correlation with INR reversal. Weight-based dosing was then estimated; INRs were all <1.2 (0.9-1.2) and activity >0.50 IU for factors II, VII and X (0.96-1.52, 0.51-1.45 and 0.81-1.38, respectively). Factor IX did not uniformly correct above 0.50 IU (0.31-1.31). We confirm in vitro that 1,000 IU of Octaplex(®) is able to correct INR to <1.5 but factors were not uniformly >0.50 IU until 2,000 IU, and not >1.00 IU until 3,000 IU. This suggests that INR correction alone may not accurately reflect factor activity, and lends support for weight-based dosing.

Prognostic significance of cellular proliferation in renal cell carcinoma: a comparison of synthesis-phase fraction and proliferating cell nuclear antigen index

DNA aneuploidy has repeatedly been shown to be a significant prognostic indicator in renal cell carcinoma; however, few studies have emphasized the importance of measurements of cellular proliferation. This study evaluated 55 patients treated by radical nephrectomy and for whom clinical follow-up was available. There were 36 men and 19 women with a mean age of 61 yr. Robson stage distribution was I, 38 cases; II, five cases; and III, 12 cases. Flow cytometric analysis in 44 cases revealed 29 DNA diploid and 15 DNA aneuploid tumors with a median synthesis-phase fraction (SPF) of 4.4% (range 1.0 to 31.4%). The median proliferating cell nuclear antigen index was 3.9% (range 0.1 to 58.0%). There was a significant correlation between SPF and proliferating cell nuclear antigen index (R = 0.769) in the 33 cases in which both were available. Cellular proliferation, as determined by SPF, was a significant prognostic indicator (P < 0.02), but proliferating cell nuclear antigen index did not correlate with outcome (P > 0.05). Other significant predictors in this study were Robson stage (P = 0.03) and nuclear grade (P = 0.0003). DNA ploidy did not correlate with outcome (P > 0.05). We conclude that cellular proliferation, as measured by SPF analysis, is a significant predictor of outcome for renal cell carcinoma. Although the proliferating cell nuclear antigen index correlated with SPF, it did not achieve statistical significance as a prognostic indicator.

Inactivation of p53 sensitizes U87MG glioma cells to 1,3-bis(2-chloroethyl)-1-nitrosourea

We examined the effect of p53 inactivation on the response of U87MG glioma cells to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). These studies were motivated by three observations: (a) some human astrocytomas are sensitive to BCNU and some are resistant; (b) chemosensitive astrocytomas are more likely to be found in young adults whose tumors are more likely to harbor a p53 mutation; and (c) mouse astrocytes lacking the p53 gene are more sensitive to BCNU than wild-type cells. Here, we observed that p53 inactivation by transfection with pCMV-E6 sensitized U87MG cells to BCNU. Compared with control U87MG-neo cells with intact p53 function, the clonogenic survival of U87MG-E6 cells exposed to BCNU was reduced significantly. In U87MG-E6 cells, sensitization to BCNU was associated with failure of p21(WAF1) induction, transient cell cycle arrest in S phase, accumulation of polyploid cells, and significant cell death. In contrast, resistance to BCNU in U87MG-neo cells was associated with up-regulation of p53, prolonged induction of p21(WAF1), sustained cell cycle arrest in S phase, and enhancement of DNA repair. U87MG cells with disrupted p53 function were less able to repair BCNU-induced DNA damage and survive this chemotherapeutic insult. The question arises of whether p53 dysfunction might be a chemosensitizing genetic alteration in human astrocytic gliomas.