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.

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.

Gating-ML: XML-based gating descriptions in flow cytometry

The lack of software interoperability with respect to gating due to lack of a standardized mechanism for data exchange has traditionally been a bottleneck, preventing reproducibility of flow cytometry (FCM) data analysis and the usage of multiple analytical tools. To facilitate interoperability among FCM data analysis tools, members of the International Society for the Advancement of Cytometry (ISAC) Data Standards Task Force (DSTF) have developed an XML-based mechanism to formally describe gates (Gating-ML). Gating-ML, an open specification for encoding gating, data transformations and compensation, has been adopted by the ISAC DSTF as a Candidate Recommendation. Gating-ML can facilitate exchange of gating descriptions the same way that FCS facilitated for exchange of raw FCM data. Its adoption will open new collaborative opportunities as well as possibilities for advanced analyses and methods development. The ISAC DSTF is satisfied that the standard addresses the requirements for a gating exchange standard.

Toward maximizing the success rates of human islet isolation: influence of donor and isolation factors

In order to make islet transplantation a therapeutic option for patients with diabetes there is an urgent need for more efficient islet cell processing to maximize islet recovery. Improved donor management, organ recovery techniques, implementation of more stringent donor criteria, and improved islet cell processing techniques may contribute to enhance organ utilization for transplantation. We have analyzed the effects of donor and islet processing factors on the success rate of human islet cell processing for transplantation performed at a single islet cell processing center. Islet isolation outcomes improved when vasopressors, and in particular pitressin, and steroids were used for the management of multiorgan donors. Higher islet yields were obtained from adult male donors, BMI >25 kg/m2, adequate glycemic control during hospital stay, and when the pancreas was retrieved by a local surgical team. Successful isolations were obtained in 58% of the cases when > or = 4 donor criteria were met, and even higher success rates (69%) were observed when considering > or = 5 criteria. Our data suggest that a sequential, integrated approach is highly desirable to improve the success rate of islet cell processing.

Data standards for flow cytometry

Flow cytometry (FCM) is an analytical tool widely used for cancer and HIV/AIDS research, and treatment, stem cell manipulation and detecting microorganisms in environmental samples. Current data standards do not capture the full scope of FCM experiments and there is a demand for software tools that can assist in the exploration and analysis of large FCM datasets. We are implementing a standardized approach to capturing, analyzing, and disseminating FCM data that will facilitate both more complex analyses and analysis of datasets that could not previously be efficiently studied. Initial work has focused on developing a community-based guideline for recording and reporting the details of FCM experiments. Open source software tools that implement this standard are being created, with an emphasis on facilitating reproducible and extensible data analyses. As well, tools for electronic collaboration will assist the integrated access and comprehension of experiments to empower users to collaborate on FCM analyses. This coordinated, joint development of bioinformatics standards and software tools for FCM data analysis has the potential to greatly facilitate both basic and clinical research--impacting a notably diverse range of medical and environmental research areas.

Derivation of GMP raw materials for use in regenerative medicine: hESC-based therapies, progress toward clinical application

The potential of somatic cell therapies from human embryonic stem cells (hESCs) as alternatives to traditional drug-based remedies for treating some of mankind's most debilitating diseases has resulted in the need to translate rapidly proof-of-principle and basic research into clinical application. Consequently, researchers and regulatory bodies are now facing one of the major obstacles of the field: the efficient and reproducible generation of clinical-grade cells suitable for producing therapeutic cell types to administer to patients in phase-I and phase-II clinical trials.

Data quality assessment of ungated flow cytometry data in high throughput experiments

BACKGROUND

The recent development of semiautomated techniques for staining and analyzing flow cytometry samples has presented new challenges. Quality control and quality assessment are critical when developing new high throughput technologies and their associated information services. Our experience suggests that significant bottlenecks remain in the development of high throughput flow cytometry methods for data analysis and display. Especially, data quality control and quality assessment are crucial steps in processing and analyzing high throughput flow cytometry data.

METHODS

We propose a variety of graphical exploratory data analytic tools for exploring ungated flow cytometry data. We have implemented a number of specialized functions and methods in the Bioconductor package rflowcyt. We demonstrate the use of these approaches by investigating two independent sets of high throughput flow cytometry data.

RESULTS

We found that graphical representations can reveal substantial nonbiological differences in samples. Empirical Cumulative Distribution Function and summary scatterplots were especially useful in the rapid identification of problems not identified by manual review.

CONCLUSIONS

Graphical exploratory data analytic tools are quick and useful means of assessing data quality. We propose that the described visualizations should be used as quality assessment tools and where possible, be used for quality control.

International Society for Analytical Cytology biosafety standard for sorting of unfixed cells

BACKGROUND

Cell sorting of viable biological specimens has become very prevalent in laboratories involved in basic and clinical research. As these samples can contain infectious agents, precautions to protect instrument operators and the environment from hazards arising from the use of sorters are paramount. To this end the International Society of Analytical Cytology (ISAC) took a lead in establishing biosafety guidelines for sorting of unfixed cells (Schmid et al., Cytometry 1997;28:99-117). During the time period these recommendations have been available, they have become recognized worldwide as the standard practices and safety precautions for laboratories performing viable cell sorting experiments. However, the field of cytometry has progressed since 1997, and the document requires an update.

METHODS

Initially, suggestions about the document format and content were discussed among members of the ISAC Biosafety Committee and were incorporated into a draft version that was sent to all committee members for review. Comments were collected, carefully considered, and incorporated as appropriate into a draft document that was posted on the ISAC web site to invite comments from the flow cytometry community at large. The revised document was then submitted to ISAC Council for review. Simultaneously, further comments were sought from newly-appointed ISAC Biosafety committee members.

RESULTS

This safety standard for performing viable cell sorting experiments was recently generated. The document contains background information on the biohazard potential of sorting and the hazard classification of infectious agents as well as recommendations on (1) sample handling, (2) operator training and personal protection, (3) laboratory design, (4) cell sorter set-up, maintenance, and decontamination, and (5) testing the instrument for the efficiency of aerosol containment.

CONCLUSIONS

This standard constitutes an updated and expanded revision of the 1997 biosafety guideline document. It is intended to provide laboratories involved in cell sorting with safety practices that take into account the enhanced hazard potential of high-speed sorting. Most importantly, it states that droplet-based sorting of infectious or hazardous biological material requires a higher level of containment than the one recommended for the risk group classification of the pathogen. The document also provides information on safety features of novel instrumentation, new options for personal protective equipment, and recently developed methods for testing the efficiency of aerosol containment.

White-blood-cell-containing allogeneic blood transfusion and postoperative infection or mortality: an updated meta-analysis

BACKGROUND

Additional randomized controlled trials (RCTs) comparing recipients of non-white-blood-cell-(WBC)-reduced and WBC-reduced allogeneic red blood cells (RBCs) have been reported since the undertaking of previous meta-analyses of the association of allogeneic blood transfusion (ABT) with postoperative infection and/or mortality. Because no further RCTs are underway, a final meta-analysis of all available RCTs was conducted.

METHODS

RCTs reporting on the association of ABT with postoperative infection and/or short-term (up to 3-month post-transfusion), all-cause mortality were retrieved. Twelve RCTs reporting on infection and 11 RCTs reporting on mortality were eligible for meta-analysis. Summary odds ratios (ORs) of infection or mortality in recipients of WBC-containing ABT vs. WBC-reduced ABT were calculated across the studies.

RESULTS

An association of ABT with postoperative infection was demonstrated across RCTs transfusing RBCs WBC-reduced after storage [summary OR = 2.25; 95% confidence interval (CI), 1.12-4.25] but not before storage (summary OR = 1.06; 95% CI, 0.91-1.24). An association of ABT with mortality was demonstrated across RCTs conducted in cardiac surgery (summary OR = 1.72, 95% CI, 1.05-2.81) and across RCTs transfusing buffy-coat-reduced RBCs vs. RBCs WBC-reduced before storage (summary OR = 1.60; 95% CI, 1.14-2.24), but not across RCTs transfusing non-buffy-coat-reduced RBCs vs. RBCs WBC-reduced before storage (summary OR = 1.01; 95% CI, 0.73-1.40).

CONCLUSIONS

An association between ABT and postoperative infection or short-term mortality is not detected across all clinical settings and transfused RBC products. An association between ABT and mortality is detected in cardiac surgery, but the other associations found in subgroup analyses contradict current theories about mechanism(s) of the ABT effect.

Optimal method for isolation of human peritoneal mesothelial cells from clinical samples of omentum

INTRODUCTION

Human peritoneal mesothelial cells (HPMC) are a valuable research tool for understanding the molecular biology of several pathologies, in both monolayer and three dimensional models. We compared different methods of HPMC isolation and assessed their outcome as well as fibroblast contamination, a common problem encountered during isolation.

METHODS

1-3cm(3) samples of omentum were collected from 40 consenting patients undergoing elective gastrointestinal surgery. A total of 11 samples were incubated in 0.05% trypsin solution for 20 minutes at 37 degrees C (group A) and 29 in 0.25% trypsin (15 samples for 10 minutes (group B) and 14 for 20 minutes (group C)). Following digestion cells were re-suspended and cultured in supplemented Ham's F-12 medium containing 10% foetal calf serum (FCS), penicillin-streptomycin, glutamine, insulin, transferrin and hydrocortisone. Positive outcomes were absence of fibroblast contamination and satisfactory HPMC growth to confluence in a characteristic cobblestone pattern. Cytokeratins 5, 8, 18, Vimentin, Ber-Ep4 and Factor VIII were used to characterise HPMC and fibroblasts by immunohistochemistry.

RESULTS

None of the 11 samples in group A yielded HPMC. 14 of 29 samples digested with 0.25% trypsin yielded HPMC: 10 of 14 yielded HPMC in group C versus four of 15 samples in group B (p = 0.02). Fibroblast contamination occurred in eight samples in group B versus three in group C.

CONCLUSION

Optimal results are achieved with a 20 minute digestion in 0.25% trypsin. Fibroblast contamination could not be avoided completely. Other factors may minimise fibroblast contamination such as minimal tissue manipulation and early collection during surgery.

Good manufacturing practice-compliant validation and preparation of BM cells for the therapy of acute myocardial infarction

BACKGROUND

Intracoronary application of BM-derived cells for the treatment of acute myocardial infarction (AMI) is currently being studied intensively. Simultaneously, strict legal requirements surround the production of cells for clinical studies. Thus good manufacturing practice (GMP)-compliant collection and preparation of BM for patients with AMI was established by the Cytonet group.

METHODS

As well as fulfillment of standard GMP requirements, including a manufacturing license, validation of the preparation process and the final product was performed. Whole blood (n=6) and BM (n=3) validation samples were processed under GMP conditions by gelafundin or hydroxyethylstarch sedimentation in order to reduce erythrocytes/platelets and volume and to achieve specifications defined in advance. Special attention was paid to the free potassium (<6 mmol/L), some rheologically relevant cellular characteristics (hematocrit <0.45, platelets <450 x 10(6)/mL) and the sterility of the final product.

RESULTS

The data were reviewed and GMP compliance was confirmed by the German authorities (Paul-Ehrlich Institute). Forty-five BM cell preparations for clinical use were carried out following the validated methodology and standards. Additionally three selections of CD34+ BM cells for infusion were performed. All specification limits were met. Discussion In conclusion, preparation of BM cells for intracoronary application is feasible under GMP conditions. As the results of sterility testing may not be available at the time of intracoronary application, the highest possible standards to avoid bacterial and other contaminations have to be applied. The increased expense of the GMP-compliant process can be justified by higher safety for patients and better control of the final product.

The road to providing human embryo stem cells for therapeutic use: the UK experience

Harnessing the unparalleled properties of human embryo stem cells (hESCs) for the therapeutic treatment of disease and injury will require a convergence of scientific developments with regulatory standards. In the case of the latter, it is especially critical that standards for clinically assisted reproduction be harmonized with those governing human cell and tissue transplantation, most notably with respect to procurement, donation, testing, processing, preservation, storage and distribution of cells. In the UK, existing infrastructure to address these considerations is undergoing extensive reorganization to keep pace with evolving European Union standards. The present best paradigm for defining standards for the therapeutic use of embryo-derived stem cells is experience with adult haematopoietic stem cells (HSC). However, compared with adult-derived stem cell, the origin of embryo-derived stem cells from limiting quantities of tissue and their absolute dependence on in vitro culture to realise their therapeutic potential, makes optimization of their isolation and cultivation of even greater importance. Most notable is the requirement to create animal cell product-free culture environments to reduce the risk of cross-specific disease transmission. In the present paper, we review present and emerging standards in the isolation and banking of human embryo-derived stem cells for therapeutic use in the UK and international progress in the development of defined culture systems for this purpose.

Flow cytometry of the Side Population: tips & tricks

Background: The Side Population (SP) has become an important hallmark for the definition of the stem cell compartment, especially in the detection of these cells and in their physical isolation by fluorescence-activated cell sorting (FACS). SP cells are CD34^neg and were discovered using ultraviolet excitation based on the efflux of Hoechst 33342 (Ho342). Although the method works as originally described, we believe that this method is difficult for most investigators. First, because the ability to discriminate SP cells is based on the differential retention of Ho342 during a functional assay; second, because of the difficulties in setting the right experimental and acquisition conditions; and third, because the analysis of the acquired data requires an extensive expertise on flow cytometry to accurately detect the SP events. Methods: First of all and mainly for the SP application, the laser beam paths were exhaustively checked to ensure the lowest coefficients of variation. Blood suspensions were prepared by erythrocyte lysis with ammonium chloride and hematopoietic cells were labeled with Ho342. Results: The Ho342 concentration and the staining procedure are critical for the optimal resolution of the SP cells. Although UV laser alignment is very important to resolve the dim tail that outlines the SP, the problem with Ho342 excitation is not the Hoechst Blue emission, but rather the Hoechst Red's (because of the weak emission). Conclusions: Each laboratory must establish its own expected ranges based on its instrument and results may vary slightly due to instrument differences such as the narrowness of the band pass filters, laser power, laser emission wavelength, nozzle type, differential of pressure, light collection system (cuvette versus jet-in-air) and beam shaping optics.

Comparing the Multi-ZSC one-step standardized swim-up method to the double-wash swim-up method with regard to the effects of sperm separation on morphology, head morphometry, and acrosome reaction inducibility

The objective of this study was to test the efficacy of the new Multi-ZSC system on human sperm separation compared with the commonly used double-wash swim-up method. It was found that the double-wash swim-up method selects sperm with better head morphometry and acrosome reaction inducibility than the upper fractions of the Multi-ZSC.

The heterogeneity of human mesenchymal stem cell preparations--evidence from simultaneous analysis of proteomes and transcriptomes

OBJECTIVE

Mesenchymal stem cells (MSC) raise high hopes in clinical applications. However, the lack of common standards and a precise definition of MSC preparations remains a major obstacle in research and application of MSC. Whereas surface antigen markers have failed to precisely define this population, a combination of proteomic data and microarray data provides a new dimension for the definition of MSC preparations.

METHODS

In our continuing effort to characterize MSC, we have analyzed the differential transcriptome and proteome expression profiles of MSC preparations isolated from human bone marrow under two different expansion media (BM-MSC-M1 and BM-MSC-M2).

RESULTS

In proteomics, 136 protein spots were unambiguously identified by MALDI-TOF-MS and corresponding cDNA spots were selected on our "Human Transcriptome cDNA Microarray." Combination of datasets revealed a correlation in differential gene expression and protein expression of BM-MSC-M1 vs BM-MSC-M2. Genes involved in metabolism were more highly expressed in BM-MSC-M1, whereas genes involved in development, morphogenesis, extracellular matrix, and differentiation were more highly expressed in BM-MSC-M2. Interchanging culture conditions for 8 days revealed that differential expression was retained in several genes whereas it was altered in others.

CONCLUSION

Our results have provided evidence that homogeneous BM-MSC preparations can reproducibly be isolated under standardized conditions, whereas culture conditions exert a prominent impact on transcriptome, proteome, and cellular organization of BM-MSC.

[A novel model for isolation of Walker's tumoral cells using the Ficoll-Hypaque gradient]

PURPOSE

The purpose was to evaluate a novel technique for isolation of Walker's tumoral cells using a Ficoll-Hypaque gradient and its further influence on tumor development.

METHODS

Twenty male Wistar rats have been divided in 2 groups: G1= without ficoll, G2= with ficoll. Tumor was excised, homogenized and suspended in lactate ringer. A sample of the cell suspension was adjusted at a concentration of 1x10(6) cells/ml (G1). A second sample was centrifuged on a Ficoll-Hypaque gradient and the cell concentration was then adjusted (G2). Tumor was implanted by subcutaneous injection of 1.0 ml in the right armpit of rats. Tumor volume (TV) and tumor weight (TW) were compared in two groups.

RESULTS

There were no differences between the two groups in TV (G1=17.9+/-3.8 cm3 vs. G2=17.2+/-4.4 cm3; p=0.190) and TW (G1=7.0+/-1.8 g vs. G2=7.3+/-2.8 g; p=0.569). The histological analysis showed similar patterns of infiltration by small-undifferentiated cells and necrosis in both groups. However, a mild to moderate granulocytic exudate was more frequent in the animals whose tumors derived from Ficoll-isolated cells. Hemorrhage from slight to moderate was only observed in this group.

CONCLUSION

A Ficoll-Hypaque gradient can provide more adequate isolation of Walker's tumor and the cell suspension obtained by this technique has lower contamination by other cell types.

Specialization, kinetics, and repertoire of type 1 interferon responses by human plasmacytoid predendritic cells

Recent studies suggest plasmacytoid predendritic cells (pDCs) and myeloid dendritic cells (mDCs) have the functional plasticity to produce similar amounts of type 1 interferons (IFNs) and interleukin-12 (IL-12), challenging the concept and existence of DC subsets with distinct function. In this study, we demonstrate that previous studies showed human pDCs produce large amounts of IL-12 because of contaminating mDCs. Using highly purified human DC subsets, we found that although pDCs make 300 times more IFN-alpha than mDCs and mDCs make 13 times more IL-12 p70 than pDCs in response to all the toll-like receptor ligands and CD40 ligands, pDCs rapidly make large amounts of IFN-alpha within the first 12 hours of activation and become refractory to further stimulation. pDCs preferentially expressed the transcriptional factors critical for type 1 IFN, but not for IL-12 transcription, and they dedicated 60% of new transcriptional activity to make 19 type 1 IFN subtypes. This study provides formal proof that the plasticity of DC subsets is limited and that different DC subsets evolve to perform distinct functions in linking innate and adaptive immunity.

Large-scale isolation of human hepatocytes for therapeutic application

During the last decade, hepatocyte transplantation has been suggested as a safe and potentially effective clinical option for the treatment of acute or decompensating chronic liver failure as well as for hereditary liver disease. Currently, one of the major limiting factors for clinical application is the insufficient access to suitable liver cell preparations. In cooperation with the German and Catalane organ procurement organizations, a routine procedure for the isolation of hepatocytes from donor organs rejected for transplantation (n = 117) has been established. The process is performed according to the current EC Guidelines for Good Manufacturing Practice (cGMP) and all corresponding national laws and regulations concerning donor organ and tissue procurement. In about 50% of the cases (n = 58) the three-step perfusion procedure has been completed with an average total cell yield of 5.9 x 10(9) cells per organ, the cell preparations displaying a mean viability of 64%. The mean specific yield was 3.6 x 10(6) total and 2.6 x 10(6) viable cells per gram liver tissue, respectively. Specific cell yields from three infantile donor livers were considerably higher. No correlation between isolation efficiency and cold ischemia time or donor age was found within the adult organ donors. In contrast, organs with a severe steatosis generally did not result in successful cell isolation. Results of sterility and endotoxin determination are also presented. In summary, a standardized and cGMP conform method of hepatocyte isolation from nontransplantable liver organs was established, which reproducibly yields large amounts of hepatocytes suitable for therapeutic application.

Object-oriented image analysis for high content screening: Detailed quantification of cells and sub cellular structures with the Cellenger software

BACKGROUND

Detailed image analysis still is a considerable bottleneck for many cellular assays, and automated solutions to the problem are desirable. However, dealing with the complexity and variability of structures in cellular images makes detailed and reliable analysis a nontrivial task.

METHODS

Therefore, based on the object-oriented image analysis approach, a novel image analysis technology, a flexible and reliable system for image analysis in cellular assays was developed. It contains a library of predefined, adaptable modules, each of them developed for a specific analysis task. The system can be configured easily by combining appropriate modules and adapting them interactively to the specific image data, if necessary. By representing cells and sub cellular structures within a network of interlinked image objects, a large number of parameters can be derived that describe shape, intensity, and relevant structural and relational aspects of any chosen class of structures.

RESULTS

Thus, multi-parameter analysis and multiplexing are supported. A sample application based on this approach demonstrates that GFP signals can be distinguished based on their properties and the relative location within the cell.

Prospective randomised comparison of the COBE Spectra version 6 and Haemonetics MCS+ cell separators for hematopoietic progenitor cells leucapheresis in patients with multiple myeloma

A randomised crossover trial of two separators was undertaken to compare the mononuclear cell, CD34(+) cell and CFU-GM yield, in patients (<61 years) with previously untreated symptomatic multiple myeloma. After first-line therapy, all patients received mobilising chemotherapy (cyclophosphamide 4 g/m(2)) and daily G-CSF. The first leucapheresis was performed on the first day the peripheral blood absolute CD34(+) cell count was > 20 cells/microl. All patients underwent 2 leucaphereses on consecutive days. The patients were randomised to undergo either the first or second leucapheresis using the COBE Spectra. The target duration of the procedure on the COBE Spectra was 2 total blood volumes, and for the Haemonetics MCS(+) it was 20 cycles with four recirculations. Between September 2003 and March 2005, 60 patients were entered in the study. COBE Spectra version 6 processed significantly larger volumes of blood than the Haemonetics MCS(+) (8,845 and 5,680 ml, respectively, P < 0.01). The absolute yield of mononuclear cells (2.1 vs. 1.5 x 10(8)/kg, P = 0.04), CFU-GM (11 vs. 3 x 10(4)/kg, P = 0.01) and CD34(+) cells (3 vs. 1.7 x 10(6)/kg, P = 0.02) were all significantly higher with the COBE Spectra version 6, as were the yields per unit volume of blood processed. In conclusion, our study shows that COBE Spectra Version 6 is faster and has a better yield than the Haemonetics MCS(+), in patients with multiple myeloma.

Isolation and characterization of human embryonic stem cells

The derivation of human embryonic stem (hES) cells is a challenging procedure. The isolation and maintenance of hES is visually and manually complicated, involving mechanical or enzymatic passaging using either collagenase or trypsin. This chapter describes detailed protocols that have been used for the derivation, maintenance, and characterization of hES cells in vitro along with protocols to test their differentiation potential in vivo. When used as a guideline, these protocols will assist researchers in setting up a hES cell laboratory.

Factors influencing yield of plateletpheresis using intermittent flow cell separator

Platelet recovery in the recipient is influenced by the transfused dose of platelets, which in turn is dependent on the quality of single donor platelets (SDPs) in terms of platelet yield. Various donor factors such as predonation platelet count and Hemoglobin (Hb) concentration affect the platelet yield. A total of 61 plateletpheresis procedures performed on intermittent flow cell separator (MCS3p, Hemonetics) were evaluated for platelet yield. A relationship between predonation platelet count and Hb concentration with yield of platelets was studied using Pearson Correlation. The mean platelet yield was 2.9 +/- 0.64 x 10(11). While a direct relationship was observed between predonation platelet count and yield (r = 0.51, P < 0.001), no such correlation was noticed with donor Hb concentration (r = -0.05, P > 0.005). The yield was > or =3 x 10(11) in >80% of procedures when the predonation platelet count was > or =250 x 10(3)/mm. Optimization of platelet yield, which is influenced by predonation platelet count, is an emerging issue in blood transfusion services. However, further studies in this regard are needed using more advanced cell separators.

Marker-specific sorting of rare cells using dielectrophoresis

Current techniques in high-speed cell sorting are limited by the inherent coupling among three competing parameters of performance: throughput, purity, and rare cell recovery. Microfluidics provides an alternate strategy to decouple these parameters through the use of arrayed devices that operate in parallel. To efficiently isolate rare cells from complex mixtures, an electrokinetic sorting methodology was developed that exploits dielectrophoresis (DEP) in microfluidic channels. In this approach, the dielectrophoretic amplitude response of rare target cells is modulated by labeling cells with particles that differ in polarization response. Cell mixtures were interrogated in the DEP-activated cell sorter in a continuous-flow manner, wherein the electric fields were engineered to achieve efficient separation between the dielectrophoretically labeled and unlabeled cells. To demonstrate the efficiency of marker-specific cell separation, DEP-activated cell sorting (DACS) was applied for affinity-based enrichment of rare bacteria expressing a specific surface marker from an excess of nontarget bacteria that do not express this marker. Rare target cells were enriched by >200-fold in a single round of sorting at a single-channel throughput of 10,000 cells per second. DACS offers the potential for automated, surface marker-specific cell sorting in a disposable format that is capable of simultaneously achieving high throughput, purity, and rare cell recovery.

High-purity lineage selection of embryonic stem cell-derived neurons

The derivation of somatic cell types from pluripotent and self-renewing embryonic stem (ES) cells offers attractive prospects for basic research, compound development, and regenerative medicine. A key prerequisite for biomedical applications of ES cells is the ability to differentiate and isolate defined somatic cell populations at high purity. In this study, we explore the potential of the Talpha1- enhanced green fluorescent protein (EGFP) transgene and polysialic acid (PSA)-neural cell adhesion molecule (NCAM) as lineage selection markers for the derivation of ES cell-derived neurons. Upon controlled in vitro differentiation, ES cells engineered to express EGFP under control of the Talpha1-tubulin promoter exhibited exclusive transgene expression in neurons. Similarly, PSA-NCAM expression during the early stages of ES cell differentiation was restricted to neuronal progeny. Talpha1- EGFP- and PSA-NCAM-positive neurons comprised both inhibitory and excitatory phenotypes. Compared to Talpha1-EGFP, the expression of PSA-NCAM was initiated at slightly earlier stages of neural differentiation. FACSorting of Talpha1-EGFP-positive cells and immunopanning of PSA-NCAMexpressing cells yielded neuronal populations at purities up to 99.6% and 96.9%, respectively. These findings depict Talpha1-EGFP and PSA-NCAM as suitable markers for high-purity selection of early ES cell-derived neurons.

Chemiluminescence: comparison of whole blood with isolated polymorphonuclear leukocytes after major trauma

INTRODUCTION

Neutrophil (PMN) mediated tissue injury is central to the development of post-traumatic ARDS/MOF. Changes in activity caused by PMN isolation may be avoided by studying respiratory burst activity using whole blood chemiluminescence (WBCL).

METHODS

WBCL and PMNCL were measured in 5 normal laboratory volunteers (NLV) and 9 patients sustaining major trauma, within 2 hours of admission. Receptor mediated (STZ) and independent (PMA) activating agents were used.

RESULTS

PMA activation confirmed significant priming both in WBCL and PMNCL after major trauma. With STZ, priming was confirmed in the WBCL study, but the trauma patient PMNCL showed no difference in response to those of NLV. Although the study population was small, those patients later developing ARDS demonstrated significantly greater STZ activated WBCL, 8 hours after admission.

CONCLUSION

PMN isolation alters behavior in vitro. This may lead to important differences of in vivo PMN function being obscured when studied in the laboratory setting. Further study of CL response and surface receptor expression is clearly warranted, both in WB and PMN preparations.