Karolina Golab

Challenges in cryopreservation of regulatory T cells (Tregs) for clinical therapeutic applications

Promising results of initial studies applying ex-vivo expanded regulatory T cell (Treg) as a clinical intervention have increased interest in this type of the cellular therapy and several new clinical trials involving Tregs are currently on the way. Methods of isolation and expansion of Tregs have been studied and optimized to the extent that such therapy is feasible, and allows obtaining sufficient numbers of Tregs in the laboratory following Good Manufacturing Practice (GMP) guidelines. Nevertheless, Treg therapy could even more rapidly evolve if Tregs could be efficiently cryopreserved and stored for future infusion or expansions rather than utilization of only freshly isolated and expanded cells as it is preferred now. Currently, our knowledge regarding the impact of cryopreservation on Treg recovery, viability, and functionality is still limited. Based on experience with cryopreserved peripheral blood mononuclear cells (PBMCs), cryopreservation may have a detrimental effect on Tregs, can decrease Treg viability, cause abnormal cytokine secretion, and compromise expression of surface markers essential for proper Treg function and processing. Therefore, optimal strategies and conditions for Treg cryopreservation in conjunction with cell culture, expansion, and processing for clinical application still need to be investigated and defined.

FoxP3, Helios, and SATB1: Roles and relationships in regulatory T cells

Regulatory T cells (Treg) play pivotal role in the maintenance of immune homeostasis due to their suppressive abilities. It is important to understand the nature of Treg and the mechanisms by which they function. From recent studies, we can conclude that the development and function of Treg cells is strongly dependent on gene expression. Furthermore, a variety of transcription factors have been proposed to either maintain or inhibit their properties. As it was demonstrated a decade ago, Forkhead box P3 transcription factor (FoxP3), a Treg marker, has the ability to keep them on the right immunosuppressive track. Whether the Treg lineage has the ability of being suppressive or not depends on up- or down-regulation of the foxp3 gene. It can be controlled by other factors present inside the cell. Two of them, Helios and SATB1, are considered to be important in proper Treg development. Helios, a member of the Ikaros family, has been shown to up-regulate expression of FoxP3 protein, whereas SATB1 is known to inhibit its expression. In this review, we will discuss the relations between these three factors, and how they affect Treg development and function.

Influence of pharmacological immunomodulatory agents on CD4+CD25highFoxP3+ T regulatory cells in humans

T regulatory cells (Tregs) play a critical role in the immunologic tolerance to the graft in transplantation. Thus, due to their immunosuppressive capability, ex vivo expanded Tregs may be used as a cellular therapy and an attractive novel strategy to control chronic rejection and eliminate need for lifelong pharmacological immunosuppression. Since Treg therapy is still in its infancy, initially Tregs still need to be applied in combination with pharmacological agents to prevent rejection. Fortunately, some of the medications have been shown to enhance the function and number of Tregs. In the clinic, different immunosuppressive regimens are used for individual patients for different types of organ transplantation. In this review, we present the most commonly used pharmacological agents for immunosuppression and discuss how they affect the Treg population. It is extremely difficult to dissect the effect of single agent on Tregs population in clinical settings since usually the combination of several medications is applied at the same time for graft protection. Nevertheless, experimental and clinical data indicate that thymoglobulin as immunosuppressive induction and mTOR inhibitors as immunosuppressive maintenance agents have the most beneficial effect on Treg population in the blood. Among supplemental agents promoting Tregs, anti-TNFα preparations have been in clinical use (in autoimmune diseases) for many years, so they are optimal candidates for testing in transplant settings in combination with Treg based cellular therapy.

Application of Digital Image Analysis to Determine Pancreatic Islet Mass and Purity in Clinical Islet Isolation and Transplantation.

Pancreatic islet mass, represented by islet equivalent (IEQ), is the most important parameter in decision making for clinical islet transplantation. To obtain IEQ, the sample of islets is routinely counted under a microscope and discarded thereafter. Islet purity, another parameter in islet processing, is routinely assessed by estimation only. In this study, we validated our digital image analysis (DIA) system by using the software of Image Pro Plus and a custom-designed Excel template to assess islet mass and purity to better comply with current good manufacturing practice (cGMP) standards. Human islet samples (60 collected from a single isolation and 24 collected from 12 isolations) were captured as calibrated digital images for the permanent record. Seven trained technicians participated in determination of IEQ and purity by the manual counting method (manual image counting, Manual I) and DIA. IEQ count showed statistically significant correlations between the Manual I and DIA in all sample comparisons (r > 0.819 and p < 0.0001). A statistically significant difference in IEQ between Manual I and DIA was not found in all sample groups (p > 0.05). In terms of purity determination, statistically significant differences between assessment and DIA measurement were found in high-purity 100-μl samples (p < 0.005) and low-purity 100-μl samples (p < 0.001) of the single isolation. In addition, islet particle number (IPN) and the IEQ/IPN ratio did not differ statistically between Manual I and DIA. In conclusion, the DIA used in this study is a reliable technique to determine IEQ and purity. Islet sample preserved as a digital image and results produced by DIA can be permanently stored for verification, technical training, and information exchange among islet centers. Therefore, DIA complies better with cGMP requirements than the manual counting method. We propose DIA as a quality control tool to supplement the established standard manual method for islet counting and purity estimation.

BETA-2 Score Allows for Convenient and Precise Monitoring of Islet Function and Early Detection of Islet Dysfunction

Introduction BETA-2 was developed to more conveniently and precisely assess islet graft function than commonly used beta-score, which requires a stimulation test. After validation of BETA-2 in our cohort of patients in relation to 90-min glucose in a mixed meal tolerance test and beta-score, we decided to assess the practical utility of BETA-2 in monitoring islet allograft function in individual patients. Methods We retrospectively analyzed BETA-2 calculations during clinical evaluations in islet allotransplantation (ITx) recipients with up to 3 islet infusions. We specifically looked in reference to previously established BETA-2 cut-offs for the detection of glucose intolerance <18 and insulin independence >13. Results We analyzed 298 BETA-2 scores calculated in 14 patients (7 women and 7 men) with an average age of 42.9 ± 9.5 years. In these patients, BETA-2 correlated well with islets function. Four patients, who experienced stable, long-term insulin independence after only one transplant, had a BETA-2 continuously over 18 (Fig 1). Figure. No caption available. Another 3 patients required a second transplant to reach the same outcome with the same BETA-2 characteristic (Fig 2). Figure. No caption available. In those patients, despite only discrete changes in fasting glucose level, the BETA-2 decreased to below 18 and continued gradually declining. This drop in BETA-2 always predicted islet dysfunction, the need for insulin support and subsequent transplant, which became clinically obvious as BETA-2 dropped below 13 (Fig 3 and 4). Figure. No caption available. Figure. No caption available. In the remaining patients, even when BETA-2 eventually reached peak above 18 after subsequent transplant, islet function gradually declined without obvious reason within a year or 2 with BETA-2 below 13 requiring re-introduction of insulin support. (Fig 4). One of these patients has not been able to stop insulin completely despite 3 subsequent transplants but BETA-2 has never increased above 18, which confirms utility of BETA-2. 12% (14/121) of BETA-2 measurements above 18 were made during the early period after iTx, when insulin was administered irrespectively of beta-cell function, in order to facilitate islet engraftment. In 80.2% of cases (142/177) where BETA-2 value was above the cut-off of 13, patients were off-insulin. The remaining 19.8% were on insulin due to failing islet function with dropping BETA-2 or supporting post infusion islet engraftment as described above. BETA-2 calculations below 13 were in 94.4% (113/121) in patients receiving insulin. Remaining 6.6% of BETA-2 calculations (8/121) were below the cut-off of 13, yet patients were still off insulin due to their non-compliance to the recommendation to resume insulin therapy based on clinically evident suboptimal glucose control. Conclusion BETA-2 score, based on only a single fasting blood sample is a very reliable tool for islet function assessment and allows early detection of islet graft decline before obvious clinical symptoms. This work was supported by the Illinois Department 370 of Public Health Grant “Pancreatic Islet Transplantation” US Public Health Service Grant DK-020595 to the University of Chicago Diabetes Research Training Center.

Minimum information about T regulatory cells: A step toward reproducibility and standardization

Cellular therapies with CD4+ T regulatory cells (Tregs) hold promise of efficacious treatment for the variety of autoimmune and allergic diseases as well as posttransplant complications. Nevertheless, current manufacturing of Tregs as a cellular medicinal product varies between different laboratories, which in turn hampers precise comparisons of the results between the studies performed. While the number of clinical trials testing Tregs is already substantial, it seems to be crucial to provide some standardized characteristics of Treg products in order to minimize the problem. We have previously developed reporting guidelines called minimum information about tolerogenic antigen-presenting cells, which allows the comparison between different preparations of tolerance-inducing antigen-presenting cells. Having this experience, here we describe another minimum information about Tregs (MITREG). It is important to note that MITREG does not dictate how investigators should generate or characterize Tregs, but it does require investigators to report their Treg data in a consistent and transparent manner. We hope this will, therefore, be a useful tool facilitating standardized reporting on the manufacturing of Tregs, either for research purposes or for clinical application. This way MITREG might also be an important step toward more standardized and reproducible testing of the Tregs preparations in clinical applications.

Total Pancreatectomy with Islet Autotransplantation for the Ampullary Cancer. A Case Report

Total pancreatectomy (TP) leads to pancreatic exocrine deficiency and poorly controlled diabetes despite insulin treatment [1]. Simultaneous islet autotransplantation (IATx) can prevent diabetes in 30–40% of patients and improve glycemic control with insulin supplementation in an additional 30% of individuals leading to improvement in quality of life in the majority of patients [2]. Total pancreatectomy with islet transplantation (TPIAT) has been offered mostly as a last resort procedure to highly selected patients with chronic or recurrent acute pancreatitis and intractable pain despite medical, endoscopic, and other conventional surgical interventions. Although patients with advanced benign tumors who require TP also may receive IATx, application of TPIAT in the setting of pancreatic malignancy remains controversial due to the risk of contamination of the islet prep with tumor cells and possible dissemination of malignancy [1]. Nevertheless, encouraging results in single cases of IATx have been reported in those patients with pancreatic cancer, who required TP due to complications after initial Whipple procedure [3–7]. Here we present for the first time, a case report of a patient with a small, early-stage ampullary cancer without lymph node involvement, who developed disseminated neoplastic disease 6 months after TPIAT. Method

Flow cytometric assay for analysis of cytotoxic effects of potential drugs on human peripheral blood leukocytes

Toxicity test of new chemicals belongs to the first steps in the drug screening, using different cultured cell lines. However, primary human cells represent the human organism better than cultured tumor derived cell lines. We developed a very gentle toxicity assay for isolation and incubation of human peripheral blood leukocytes (PBL) and tested it using different bioactive oligopeptides (OP). Effects of different PBL isolation methods (red blood cell lysis; Histopaque isolation among others), different incubation tubes (e.g. FACS tubes), anticoagulants and blood sources on PBL viability were tested using propidium iodide-exclusion as viability measure (incubation time: 60 min, 36°C) and flow cytometry. Toxicity concentration and time-depended effects (10-60 min, 36 °C, 0-100 μg /ml of OP) on human PBL were analyzed. Erythrocyte lysis by hypotonic shock (dH2O) was the fastest PBL isolation method with highest viability (>85%) compared to NH4Cl-Lysis (49%). Density gradient centrifugation led to neutrophil granulocyte cell loss. Heparin anticoagulation resulted in higher viability than EDTA. Conical 1.5 mL and 2 mL micro-reaction tubes (both polypropylene (PP)) had the highest viability (99% and 97%) compared to other tubes, i.e. three types of 5.0 mL round-bottom tubes PP (opaque-60%), PP (blue-62%), Polystyrene (PS-64%). Viability of PBL did not differ between venous and capillary blood. A gentle reproducible preparation and analytical toxicity-assay for human PBL was developed and evaluated. Using our assay toxicity, time-course, dose-dependence and aggregate formation by OP could be clearly differentiated and quantified. This novel assay enables for rapid and cost effective multiparametric toxicological screening and pharmacological testing on primary human PBL and can be adapted to high-throughput-screening.°z