A GMP-compliant manufacturing method for Wharton's jelly-derived mesenchymal stromal cells

BACKGROUND

Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) hold great therapeutic potential in regenerative medicine. Therefore, it is crucial to establish a Good Manufacturing Practice (GMP)-compliant methodology for the isolation and culture of WJ-MSCs. Through comprehensive research, encompassing laboratory-scale experiments to pilot-scale studies, we aimed to develop standardized protocols ensuring the high yield and quality of WJ-MSCs manufacturing.

METHODS

Firstly, optimization of parameters for the enzymatic digestion method used to isolate WJ-MSCs was conducted. These parameters included enzyme concentrations, digestion times, seeding densities, and culture media. Additionally, a comparative analysis between the explant method and the enzymatic digestion method was performed. Subsequently, the consecutive passaging of WJ-MSCs, specifically up to passage 9, was evaluated using the optimized method. Finally, manufacturing processes were developed and scaled up, starting from laboratory-scale flask-based production and progressing to pilot-scale cell factory-based production. Furthermore, a stability study was carried out to assess the storage and use of drug products (DPs).

RESULTS

The optimal parameters for the enzymatic digestion method were a concentration of 0.4 PZ U/mL Collagenase NB6 and a digestion time of 3 h, resulting in a higher yield of P0 WJ-MSCs. In addition, a positive correlation between the weight of umbilical cord tissue and the quantities of P0 WJ-MSCs has been observed. Evaluation of different concentrations of human platelet lysate revealed that 2% and 5% concentrations resulted in similar levels of cell expansion. Comparative analysis revealed that the enzymatic digestion method exhibited faster outgrowth of WJ-MSCs compared to the explant method during the initial passage. Passages 2 to 5 exhibited higher viability and proliferation ability throughout consecutive passaging. Moreover, scalable manufacturing processes from the laboratory scale to the pilot scale were successfully developed, ensuring the production of high-quality WJ-MSCs. Multiple freeze-thaw cycles of the DPs led to reduced cell viability and viable cell concentration. Subsequent thawing and dilution of the DPs resulted in a significant decrease in both metrics, especially when stored at 20-27 °C.

CONCLUSION

This study offers valuable insights into optimizing the isolation and culture of WJ-MSCs. Our scalable manufacturing processes facilitate the large-scale production of high-quality WJ-MSCs. These findings contribute to the advancement of WJ-MSCs-based therapies in regenerative medicine.

Overview of current adipose-derived stem cell (ADSCs) processing involved in therapeutic advancements: flow chart and regulation updates before and after COVID-19

Adipose-derived stem cells (ADSCs) have raised big interest in therapeutic applications in regenerative medicine and appear to fulfill the criteria for a successful cell therapy. Their low immunogenicity and their ability to self-renew, to differentiate into different tissue-specific progenitors, to migrate into damaged sites, and to act through autocrine and paracrine pathways have been altogether testified as the main mechanisms whereby cell repair and regeneration occur. The absence of standardization protocols in cell management within laboratories or facilities added to the new technologies improved at patient's bedside and the discrepancies in cell outcomes and engraftment increase the limitations on their widespread use by balancing their real benefit versus the patient safety and security. Also, comparisons across pooled patients are particularly difficult in the fact that multiple medical devices are used and there is absence of harmonized assessment assays despite meeting regulations agencies and efficient GMP protocols. Moreover, the emergence of the COVID-19 breakdown added to the complexity of implementing standardization. Cell- and tissue-based therapies are completely dependent on the biological manifestations and parameters associated to and induced by this virus where the scope is still unknown. The initial flow chart identified for stem cell therapies should be reformulated and updated to overcome patient infection and avoid significant variability, thus enabling more patient safety and therapeutic efficiency. The aim of this work is to highlight the major guidelines and differences in ADSC processing meeting the current good manufacturing practices (cGMP) and the cellular therapy-related policies. Specific insights on standardization of ADSCs proceeding at different check points are also presented as a setup for the cord blood and bone marrow.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition)

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.

A standardized flow cytometry network study for the assessment of circulating endothelial cell physiological ranges

Circulating endothelial cells (CEC) represent a restricted peripheral blood (PB) cell subpopulation with high potential diagnostic value in many endothelium-involving diseases. However, whereas the interest in CEC studies has grown, the standardization level of their detection has not. Here, we undertook the task to align CEC phenotypes and counts, by standardizing a novel flow cytometry approach, within a network of six laboratories. CEC were identified as alive/nucleated/CD45negative/CD34bright/CD146positive events and enumerated in 269 healthy PB samples. Standardization was demonstrated by the achievement of low inter-laboratory Coefficients of Variation (CVL), calculated on the basis of Median Fluorescence Intensity values of the most stable antigens that allowed CEC identification and count (CVL of CD34bright on CEC ~ 30%; CVL of CD45 on Lymphocytes ~ 20%). By aggregating data acquired from all sites, CEC numbers in the healthy population were captured (medianfemale = 9.31 CEC/mL; medianmale = 11.55 CEC/mL). CEC count biological variability and method specificity were finally assessed. Results, obtained on a large population of donors, demonstrate that the established procedure might be adopted as standardized method for CEC analysis in clinical and in research settings, providing a CEC physiological baseline range, useful as starting point for their clinical monitoring in endothelial dysfunctions.

Gating mass cytometry data by deep learning

MOTIVATION

Mass cytometry or CyTOF is an emerging technology for high-dimensional multiparameter single cell analysis that overcomes many limitations of fluorescence-based flow cytometry. New methods for analyzing CyTOF data attempt to improve automation, scalability, performance and interpretation of data generated in large studies. Assigning individual cells into discrete groups of cell types (gating) involves time-consuming sequential manual steps, untenable for larger studies.

RESULTS

We introduce DeepCyTOF, a standardization approach for gating, based on deep learning techniques. DeepCyTOF requires labeled cells from only a single sample. It is based on domain adaptation principles and is a generalization of previous work that allows us to calibrate between a target distribution and a source distribution in an unsupervised manner. We show that DeepCyTOF is highly concordant (98%) with cell classification obtained by individual manual gating of each sample when applied to a collection of 16 biological replicates of primary immune blood cells, even when measured across several instruments. Further, DeepCyTOF achieves very high accuracy on the semi-automated gating challenge of the FlowCAP-I competition as well as two CyTOF datasets generated from primary immune blood cells: (i) 14 subjects with a history of infection with West Nile virus (WNV), (ii) 34 healthy subjects of different ages. We conclude that deep learning in general, and DeepCyTOF specifically, offers a powerful computational approach for semi-automated gating of CyTOF and flow cytometry data.

AVAILABILITY AND IMPLEMENTATION

Our codes and data are publicly available at https://github.com/KlugerLab/deepcytof.git.

CONTACT

yuval.kluger@yale.edu.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

A Closed System for Islet Isolation and Purification Using the COBE2991 Cell Processor May Reduce the Need of Clean Room Facilities

During the isolation of human islets of Langerhans the digest has repeated direct contact with the ambient atmosphere. In order to fulfill GMP requirements in clinical applications, the entire cell preparation must be performed in clean room facilities. We hypothesized that the use of a closed system, which avoids the direct exposure of tissue to the atmosphere, would significantly ease the preparation procedure. To avoid the direct atmosphere exposure we tested a modification of the isolation and purification process by performing all islet preparation steps in a closed system. In this study we compared the isolation outcome of the traditional open preparation technique with the new closed system. Pancreata from 6-month-old hybrid pigs were procured in the local slaughterhouse. After digestion/filtration the digest was cooled, collected, and concentrated in centrifugation containers and purified thereafter in the COBE2991 by top loading (control). In the control group 502 ± 253 IEQ per gram pancreas were purified. The total preparation time amounted to 12 h. In the closed system the digest was cooled and directly pumped into the COBE2991 for centrifugation followed by supernatant expelling. Bag filling, centrifugation, and expelling were repeated several times. Islets in pellet form were than purified by adding a gradient (bottom loading). Using this closed system 1098 ± 489 IEQ per gram pancreas were purified with a total cell viability of 67 ± 10% and a β-cell viability of 41 ± 13%. The total preparation time reduced to 6 h. After 24 h of cell culture the viability of β-cells was still 56 ± 10% and was only reduced after the addition of proapoptotic IL-1 and TNF-α to 40 ± 4%, indicating that freshly isolated islets are not apoptotic. In conclusion, the closed system preparation is much faster, more effective, and less expensive than the traditional islet preparation. The closed system may be applicable for human islets preparations to restrict the need of clean room facilities for islet preparations to a minimum and may open the way for islet preparations without clean room demand.

Optimization of cGMP purification and expansion of umbilical cord blood-derived T-regulatory cells in support of first-in-human clinical trials

BACKGROUND AIMS

Thymic-derived regulatory T cells (tTreg) are critical regulators of the immune system. Adoptive tTreg transfer is a curative therapy for murine models of autoimmunity, graft rejection, and graft-versus-host disease (GVHD). We previously completed a "first-in-human" clinical trial using in vitro expanded umbilical cord blood (UCB)-derived tTreg to prevent GVHD in patients undergoing UCB hematopoietic stem cell transplantation (HSCT). tTreg were safe and demonstrated clinical efficacy, but low yield prevented further dose escalation.

METHODS

To optimize yield, we investigated the use of KT64/86 artificial antigen presenting cells (aAPCs) to expand tTreg and incorporated a single re-stimulation after day 12 in expansion culture.

RESULTS

aAPCs increased UCB tTreg expansion greater than eightfold over CD3/28 stimulation. Re-stimulation with aAPCs increased UCB tTreg expansion an additional 20- to 30-fold. Re-stimulated human UCB tTreg ameliorated GVHD disease in a xenogeneic model. Following current Good Manufacturing Practice (cGMP) validation, a trial was conducted with tTreg. tTreg doses up to >30-fold higher compared with that obtained with anti-CD3/28 mAb coated-bead expansion and Foxp3 expression was stable during in vitro expansion and following transfer to patients. Increased expansion did not result in a senescent phenotype and GVHD was significantly reduced.

DISCUSSION

Expansion culture with cGMP aAPCs and re-stimulation reproducibly generates sufficient numbers of UCB tTreg that exceeds the numbers of T effector cells in an UCB graft. The methodology supports future tTreg banking and is adaptable to tTreg expansion from HSC sources. Furthermore, because human leukocyte antigen matching is not required, allogeneic UCB tTreg may be a useful strategy for prevention of organ rejection and autoimmune disease.

An evaluation of methods correcting for cell-type heterogeneity in DNA methylation studies

BACKGROUND

Many different methods exist to adjust for variability in cell-type mixture proportions when analyzing DNA methylation studies. Here we present the result of an extensive simulation study, built on cell-separated DNA methylation profiles from Illumina Infinium 450K methylation data, to compare the performance of eight methods including the most commonly used approaches.

RESULTS

We designed a rich multi-layered simulation containing a set of probes with true associations with either binary or continuous phenotypes, confounding by cell type, variability in means and standard deviations for population parameters, additional variability at the level of an individual cell-type-specific sample, and variability in the mixture proportions across samples. Performance varied quite substantially across methods and simulations. In particular, the number of false positives was sometimes unrealistically high, indicating limited ability to discriminate the true signals from those appearing significant through confounding. Methods that filtered probes had consequently poor power. QQ plots of p values across all tested probes showed that adjustments did not always improve the distribution. The same methods were used to examine associations between smoking and methylation data from a case-control study of colorectal cancer, and we also explored the effect of cell-type adjustments on associations between rheumatoid arthritis cases and controls.

CONCLUSIONS

We recommend surrogate variable analysis for cell-type mixture adjustment since performance was stable under all our simulated scenarios.

Optimization of Pathogen Capture in Flowing Fluids with Magnetic Nanoparticles

Magnetic nanoparticles have been employed to capture pathogens for many biological applications; however, optimal particle sizes have been determined empirically in specific capturing protocols. Here, a theoretical model that simulates capture of bacteria is described and used to calculate bacterial collision frequencies and magnetophoretic properties for a range of particle sizes. The model predicts that particles with a diameter of 460 nm should produce optimal separation of bacteria in buffer flowing at 1 L h(-1) . Validating the predictive power of the model, Staphylococcus aureus is separated from buffer and blood flowing through magnetic capture devices using six different sizes of magnetic particles. Experimental magnetic separation in buffer conditions confirms that particles with a diameter closest to the predicted optimal particle size provide the most effective capture. Modeling the capturing process in plasma and blood by introducing empirical constants (ce ), which integrate the interfering effects of biological components on the binding kinetics of magnetic beads to bacteria, smaller beads with 50 nm diameters are predicted that exhibit maximum magnetic separation of bacteria from blood and experimentally validated this trend. The predictive power of the model suggests its utility for the future design of magnetic separation for diagnostic and therapeutic applications.

Rmax: A systematic approach to evaluate instrument sort performance using center stream catch

Sorting performance can be evaluated with regard to Purity, Yield and/or Recovery of the sorted fraction. Purity is a check on the quality of the sample and the sort decisions made by the instrument. Recovery and Yield definitions vary with some authors regarding both as how efficient the instrument is at sorting the target particles from the original sample, others distinguishing Recovery from Yield, where the former is used to describe the accuracy of the instrument's sort count. Yield and Recovery are often neglected, mostly due to difficulties in their measurement. Purity of the sort product is often cited alone but is not sufficient to evaluate sorting performance. All of these three performance metrics require re-sampling of the sorted fraction. But, unlike Purity, calculating Yield and/or Recovery calls for the absolute counting of particles in the sorted fraction, which may not be feasible, particularly when dealing with rare populations and precious samples. In addition, the counting process itself involves large errors. Here we describe a new metric for evaluating instrument sort Recovery, defined as the number of particles sorted relative to the number of original particles to be sorted. This calculation requires only measuring the ratios of target and non-target populations in the original pre-sort sample and in the waste stream or center stream catch (CSC), avoiding re-sampling the sorted fraction and absolute counting. We called this new metric Rmax, since it corresponds to the maximum expected Recovery for a particular set of instrument parameters. Rmax is ideal to evaluate and troubleshoot the optimum drop-charge delay of the sorter, or any instrument related failures that will affect sort performance. It can be used as a daily quality control check but can be particularly useful to assess instrument performance before single-cell sorting experiments. Because we do not perturb the sort fraction we can calculate Rmax during the sort process, being especially valuable to check instrument performance during rare population sorts.

GMP-compliant human adipose tissue-derived mesenchymal stem cells for cellular therapy

Stem cells, which can be derived from different sources, demonstrate promising therapeutic evidences for cellular therapies. Among various types of stem cell, mesenchymal stem cells are one of the most common stem cells that are used in cellular therapy. Human subcutaneous adipose tissue provides an easy accessible source of mesenchymal stem cells with some considerable advantages. Accordingly, various preclinical and clinical investigations have shown enormous potential of adipose-derived stromal cells in regenerative medicine. Consequently, increasing clinical applications of these cells has elucidated the importance of safety concerns regarding clinical transplantation. Therefore, clinical-grade preparation of adipose-derived stromal cells in accordance with current good manufacturing practice guidelines is an essential part of their clinical applications to ensure the safety, quality, characteristics, and identity of cell products. Additionally, GMP-compliant cell manufacturing involves several issues to provide a quality assurance system during translation from the basic stem cell sciences into clinical investigations and applications. On the other hand, advanced cellular therapy requires extensive validation, process control, and documentation. It also evidently elucidates the critical importance of production methods and probable risks. Therefore, implementation of a quality management and assurance system in accordance with GMP guidelines can greatly reduce these risks particularly in the higher-risk category or "more than minimally manipulated" products.

GMP-grade human fetal liver-derived mesenchymal stem cells for clinical transplantation

Stem cell therapy seems a promising avenue in regenerative medicine. Within various stem cells, mesenchymal stem cells have progressively used for cellular therapy. Because of the age-related decreasing in the frequency and differentiating capacity of adult MSCs, fetal tissues such as fetal liver, lung, pancreas, spleen, etc. have been introduced as an alternative source of MSCs for cellular therapy. On the other hand, using stem cells as advanced therapy medicinal products, must be performed in compliance with cGMP as a quality assurance system to ensure the safety, quality, and identity of cell products during translation from the basic stem cell sciences into clinical cell transplantation. In this chapter the authors have demonstrated the manufacturing of GMP-grade human fetal liver-derived mesenchymal stem cells.

Production of good manufacturing practice-grade human umbilical cord blood-derived mesenchymal stem cells for therapeutic use

Human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) are multipotent stem cells that can be differentiated into several specific cell types such as adipocytes, osteoblasts, and chondroblasts. They also were demonstrated to trans-differentiate into other cell lineages such as muscle cells and neurons. Thus, they are considered a promising stem cell source for therapeutic use. Here, we describe a method for production of good manufacturing practice-grade human UCB-MSCs for therapeutic use. The obtained UCB-MSCs are free of allogenous or xenogenous proteins. In addition, these MSCs could maintain the MSC phenotype in long-term culture.

Optimizing isolation culture and freezing methods to preserve Wharton's jelly's mesenchymal stem cell (MSC) properties: an MSC banking protocol validation for the Hellenic Cord Blood Bank

BACKGROUND

Mesenchymal stem or stromal cells (MSCs) are a heterogeneous population that can be isolated from many tissues including umbilical cord Wharton's jelly (UC-WJ). Although initially limited in studies such as a hematopoietic stem cell transplantation adjuvant, an increasing number of clinical trials consider MSCs as a potential anti-inflammatory or a regenerative medicine agent. It has been proposed that creating a repository of MSCs would increase their availability for clinical applications. The aim of this study was to assess the optimal isolation and cryopreservation procedures to facilitate WJ MSC banking.

STUDY DESIGN AND METHODS

Cells were isolated from UC-WJ using enzymatic digestion or plastic adhesion methods. Their isolation efficacy, growth kinetics, immunophenotype, and differentiation potential were studied, as well as the effects of freezing. Flow cytometry for common MSC markers was performed on all cases and differentiation was shown with histocytochemical staining. Finally, the isolation efficacy on cryopreserved WJ tissue fragments was tested.

RESULTS

MSC isolation was successful using both isolation methods on fresh UC-WJ tissue. However, UC-WJ MSC isolation from frozen tissue fragments was impossible. Flow cytometry analysis revealed that only MSC markers were expressed on the surface of the isolated cells while differentiation assays showed that they were capable of trilinear differentiation. All the above characteristics were also preserved in isolated UC-WJ MSCs over the cryopreservation study period.

CONCLUSION

These data showed that viable MSCs can only be isolated from fresh UC-WJ tissue, setting the foundation for clinical-grade banking.

International Society for the Advancement of Cytometry cell sorter biosafety standards

Flow cytometric cell sorting of biological specimens has become prevalent in basic and clinical research laboratories. These specimens may contain known or unknown infectious agents, necessitating precautions to protect instrument operators and the environment from biohazards arising from the use of sorters. To this end the International Society of Analytical Cytology (ISAC) was proactive in establishing biosafety guidelines in 1997 (Schmid et al., Cytometry 1997;28:99-117) and subsequently published revised biosafety standards for cell sorting of unfixed samples in 2007 (Schmid et al., Cytometry Part A J Int Soc Anal Cytol 2007;71A:414-437). Since their publication, these documents have become recognized worldwide as the standard of practice and safety precautions for laboratories performing cell sorting experiments. However, the field of cytometry has progressed since 2007, and the document requires an update. The new Standards provides guidance: (1) for laboratory design for cell sorter laboratories; (2) for the creation of laboratory or instrument specific Standard Operating Procedures (SOP); and (3) on procedures for the safe operation of cell sorters, including personal protective equipment (PPE) and validation of aerosol containment.

How to develop a standard operating procedure for sorting unfixed cells

Written standard operating procedures (SOPs) are an important tool to assure that recurring tasks in a laboratory are performed in a consistent manner. When the procedure covered in the SOP involves a high-risk activity such as sorting unfixed cells using a jet-in-air sorter, safety elements are critical components of the document. The details on sort sample handling, sorter set-up, validation, operation, troubleshooting, and maintenance, personal protective equipment (PPE), and operator training, outlined in the SOP are to be based on careful risk assessment of the procedure. This review provides background information on the hazards associated with sorting of unfixed cells and the process used to arrive at the appropriate combination of facility design, instrument placement, safety equipment, and practices to be followed.

Optimized processing of growth factor mobilized peripheral blood CD34+ products by counterflow centrifugal elutriation

Cell separation by counterflow centrifugal elutriation has been described for the preparation of monocytes for vaccine applications, but its use in other current good manufacturing practice (cGMP) operations has been limited. In this study, growth factor-mobilized peripheral blood progenitor cell products were collected from healthy donors and processed by elutriation using a commercial cell washing device. Fractions were collected for each product as per the manufacturer's instructions or using a modified protocol developed in our laboratory. Each fraction was analyzed for cell count, viability, and blood cell differential. Our data demonstrate that, using standard elutriation procedures, >99% of red blood cells and platelets were removed from apheresis products with high recoveries of total white blood cells and enrichment of CD34+ cells in two of five fractions. With modification of the basic protocol, we were able to collect all of the CD34+ cells in a single fraction. The CD34-enriched fractions were formulated, labeled with a ferromagnetic antibody to CD34, washed using the Elutra device, and transferred directly to a magnetic bead selection device for further purification. CD34+ cell purities from the column were extremely high (98.7 ± 0.9%), and yields were typical for the device (55.7 ± 12.3%). The processes were highly automated and closed from receipt of the apheresis product through formulation of target-enriched cell fractions. Thus, elutriation is a feasible method for the initial manipulations associated with primary blood cell therapy products and supports cGMP and current good tissue practice-compliant cell processing.

From skin biopsy to neurons through a pluripotent intermediate under Good Manufacturing Practice protocols

The clinical application of human-induced pluripotent stem cells (hiPSCs) requires not only the production of Good Manufacturing Practice-grade (GMP-grade) hiPSCs but also the derivation of specified cell types for transplantation under GMP conditions. Previous reports have suggested that hiPSCs can be produced in the absence of animal-derived reagents (xenobiotics) to ease the transition to production under GMP standards. However, to facilitate the use of hiPSCs in cell-based therapeutics, their progeny should be produced not only in the absence of xenobiotics but also under GMP conditions requiring extensive standardization of protocols, documentation, and reproducibility of methods and product. Here, we present a successful framework to produce GMP-grade derivatives of hiPSCs that are free of xenobiotic exposure from the collection of patient fibroblasts, through reprogramming, maintenance of hiPSCs, identification of reprogramming vector integration sites (nrLAM-PCR), and finally specification and terminal differentiation of clinically relevant cells. Furthermore, we developed a primary set of Standard Operating Procedures for the GMP-grade derivation and differentiation of these cells as a resource to facilitate widespread adoption of these practices.

Functional assessment of automatically sorted pancreatic islets using large particle flow cytometry

The size composition of human islet preparations has been attributed to functional potency, islet survival and transplantation outcomes. In the early post-transplantation phase islets are supplied with oxygen by diffusion only and are at risk of critical hypoxia. The high rate of early islet graft dysfunction is in part attributed to this condition. It has been presumed that islets with smaller diameter, and therefore smaller diffusion distance, are superior to large islets regarding early survival rate and graft function. In this study we aimed to evaluate Complex Object Parametric Analysis and Sorting (COPAS) as a device for automated sorting of human islets. The use of COPAS was validated for accuracy and sensitivity using polystyrene beads of known diameters. Based on time of flight relative to particle isolated islets were then automatically sorted and analyzed for viability and function using handpicked islets as control. Our results suggest that COPAS enables the automated and accurate sorting of islets with no negative impact on their integrity and viability. Thus, COPAS is an adequate tool for size-specific analysis of pancreatic islets and may be considered as part of a platform for automated high-throughput screening of pancreatic islets.

Isolation and culture of ovarian cancer cells and cell lines

Ovarian carcinomas show considerable heterogeneity of origin, both in terms of site and tissue. The most important and also most frequent of these tumors arise from the coelomic epithelium and are therefore characterized as epithelial ovarian carcinomas (EOC). EOC is often large and advanced at the time of presentation, so that cells are readily obtainable from surgical specimens or effusions. While the primary tumor may be chemosensitive, they often develop resistance and may do so rapidly. Due to the easy access to tumor cells and its biological behavior, EOC is considered to be an ideal model to investigate principal mechanisms of both antineoplastic drug sensitivity and resistance. Although studies on primary EOC cells are now preferred for many of these investigations, EOC cell line studies remain important too. This chapter gives an overview over major techniques required to establish and maintain primary EOC cell cultures and to initiate and cultivate permanently growing EOC cell lines.

Comparing cooling systems for the COBE 2991 cell separator used in the purification of human pancreatic islets of Langerhans

Two different approaches of controlled cooling of the COBE 2991 cell-separator for islet purification were evaluated. The first method is the new Geneva COBE cooling system (GCCS), which consists of an electronically controlled liquid nitrogen injection system. The second is the University of Illinois at Chicago cooling system (UICCS), which consists of a specially designed "Cold Room" maintained at 1-8 C. For the GCCS, the mean temperatures of the gradient solutions were measured at the beginning and end of centrifugation were found to be 7 +/-0.7 C and 6.8 +/-0.6 C respectively. For the UICCS, the mean temperature of the gradients at the beginning and end of centrifugation were 4.7 +/-0.53 C and 7.03 C+/-0.91 C respectively. The presented COBE cooling systems can easily be adapted to a COBE 2991 cell-separator and are efficient in maintaining gradient solutions at a defined low temperature during centrifugation.

Number of counting cells and cytospins selection influences on bronchoalveolar lavage cell profiles

Bronchoalveolar lavage (BAL) fluid cells count provides information about presence or absence of interstitial lung diseases. BAL fluid samples were taken from 50 patients hospitalized in University Hospital for Lung Diseases "Jordanovac" in Zagreb, Croatia. The samples of BAL fluid were prepared by cytocentrifuge. From each sample two cytospin were selected (C1 and C2) and after determing adequacy, counted up to 200 and 400 cells. After air drying, samples were stained according to May Grünwald Giemsa (MGG). Cells were counted by light microscope at magnification of 400x. Obtained results were analyzed in Statistics version 6 and Med Calc. Results for bronchial epithelial cells, alveolar macrophages, lymphocytes and neutrophilic granulocytes showed insignificant statistical differences between groups (p > 0.05). Eosinophils percentages showed borderline insignificant statistical difference between groups of these cells (p = 0.052.). As it was exemplificated, the percentages of differentiated cells do not significant differ according to differentiation on 200 and 400 cells and cytospin selection.

Consistency of the initial cell acquisition procedure is critical to the standardization of CD34+ cell enumeration by flow cytometry: results of a pairwise analysis of umbilical cord blood units and cryopreserved aliquots

BACKGROUND

The CD34+ cell content is a predictive factor for engraftment and survival after umbilical cord blood (UCB) transplantation. The high variability in the CD34 assay results in different recommended cell doses for infusion across transplant centers and also limits the clinical utility of the CD34+ cell counts provided by cord blood banks (CBBs). This bi-institutional study was intended to understand the sources of this variability.

STUDY DESIGN AND METHODS

The level of CD34 agreement between the University of Minnesota (UM) and the Madrid CBB (MCBB) was evaluated on 50 UCB units before and after cryopreservation. Two cryopreserved vials per unit were thawed and processed at both laboratories. Dual-platform ISHAGE-based flow cytometry was used for CD34 enumeration.

RESULTS

Postthaw nucleated cell recoveries were similar. However, whereas CD34+ cell enumeration before freezing was 0.35 +/- 0.22 percent, the results after thawing were 0.98 +/- 0.65 and 0.57 +/- 0.39 percent at UM and MCBB, respectively. Bland-Altman plots analysis ruled out the interchangeability of MCBB and UM CD34 values. Differences in the initial cell acquisition settings accounted for most of the CD34 discrepancy, which was no longer present after normalization of the forward scatter threshold for cell acquisition.

CONCLUSIONS

The standardization of CD34+ cell enumeration by flow cytometry is strongly reliant on a consistent initial cell acquisition procedure. The interlaboratory variation can be minimized by using frozen cell aliquots as reference samples. Both requisites should be considered for CD34 testing and UCB unit selection by regulatory institutions involved with cord blood banking and transplantation.