Diane Kadidlo

Massive ex Vivo Expansion of Human Natural Regulatory T Cells (T regs ) with Minimal Loss of in Vivo Functional Activity

A good manufacturing grade–compatible approach generates massive numbers of natural regulatory T cells that retain suppressive function in vivo. Cross-Checking Graft-Versus-Host Disease Fighting in hockey is a long-standing tradition: Stitches and gap-toothed smiles are badges of honor among these aggressive athletes. Yet, a balance must be maintained between the occasional high stick and an all-out melee. Black-and-white striped referees serve to uphold this balance, breaking up fights and preventing the bench-clearing brawl. Regulatory T cells (Tregs) are the referees of the adaptive immune system. They prevent the enforcers, cytotoxic T cells, from an overly exuberant response and, in the case of a bone marrow transplant, from attacking the patient’s own tissues. This process, called graft-versus-host disease (GVHD), is one of the risks of transplantation and differs from organ rejection. However, using Tregs to prevent GVHD has been limited by low Treg numbers and altered function after expansion in vitro. Hippen et al. now report a new way to expand Tregs to numbers much larger than those previously achieved while maintaining their ability to selectively suppress self-attacking cytotoxic T cells in vivo. Umbilical cord blood can be used to expand functional natural Tregs (nTregs); however, the initial number of nTregs in cord blood is limited. Therefore, the authors used peripheral blood as a source of nTregs for expansion. Using good manufacturing practice conditions and artificial antigen-presenting cells designed to stimulate T cell expansion, Hippen et al. expanded nTregs 80-fold after only one stimulation; they then showed that these multiplied cells maintained suppressor function. Stimulation of the nTreg population up to four times expanded the numbers of functional cells ~50 million–fold. When injected into mice at the same time as human T cells, these expanded Tregs significantly reduced mortality resulting from GVHD. Such large numbers of functional nTregs could be used to establish donor banks that would keep human GVHD and autoimmunity in check. Graft-versus-host disease (GVHD) is a frequent and severe complication after hematopoietic cell transplantation. Natural CD4+CD25+ regulatory T cells (nTregs) have proven highly effective in preventing GVHD and autoimmunity in murine models. Yet, clinical application of nTregs has been severely hampered by their low frequency and unfavorable ex vivo expansion properties. Previously, we demonstrated that umbilical cord blood (UCB) nTregs could be purified and expanded in vitro using good manufacturing practice (GMP) reagents; however, the initial number of nTregs in UCB units is limited, and average yield after expansion was only 1 × 109 nTregs. Therefore, we asked whether yield could be increased by using peripheral blood (PB), which contains far larger quantities of nTregs. PB nTregs were purified under GMP conditions and expanded 80-fold to yield 19 × 109 cells using anti-CD3 antibody–loaded, cell-based artificial antigen-presenting cells (aAPCs) that expressed the high-affinity Fc receptor and CD86. A single restimulation increased expansion to ~3000-fold and yield to >600 × 109 cells while maintaining Foxp3 expression and suppressor function. nTreg expansion was ~50 million–fold when flow sort–purified nTregs were restimulated four times with aAPCs. Indeed, cryopreserved donor nTregs restimulated four times significantly reduced GVHD lethality induced by the infusion of human T cells into immune-deficient mice. The capability to efficiently produce donor cell banks of functional nTregs could transform the treatment of GVHD and autoimmunity by providing an off-the-shelf, cost-effective, and proven cellular therapy.

Cell loss and recovery in umbilical cord blood processing: a comparison of postthaw and postwash samples

BACKGROUND: Engraftment after umbilical cord blood (UCB) transplantation is highly dependent on nucleated cell (NC) and CD34+ cell content. Current standard postthaw (PT) processing includes a wash step to remove dimethyl sulfoxide (DMSO), lysed red cells, and stroma. The contribution of the wash step to cell loss and ultimately the dose of cells available for transplant have yet to be systematically reported. This study examines the effect of the wash step as well as that of PT storage on various quality control variables of UCB units.

Good manufacturing practices production of natural killer cells for immunotherapy: A six-year single-institution experience

BACKGROUND: Natural killer (NK) cells, a subset of lymphocytes and part of the innate immune system, play a crucial role in defense against cancer and viral infection. Herein is a report on the experience of clinical‐scale, good manufacturing practices (GMPs) production of NK cells to treat advanced cancer.

Results of a phase 1, randomized, double-blind, placebo-controlled trial of bone marrow mononuclear stem cell administration in patients following ST-elevation myocardial infarction.

BACKGROUND Initial clinical trials from Europe have demonstrated that the administration of bone marrow-derived mononuclear cells (BMCs) may improve left ventricular (LV) function in patients following ST-elevation myocardial infarction (STEMI). However, results from trials performed in the United States have not yet been presented. METHODS We developed a phase 1, randomized, placebo-controlled, double-blind trial to investigate the effects of BMC administration in patients following STEMI on recovery of LV function using cardiac magnetic resonance imaging (cMRI). Forty patients with moderate to large anterior STEMIs were randomized to 100 million intracoronary BMCs versus placebo 3 to 10 days following successful primary angioplasty and stenting (percutaneous coronary intervention) of the left anterior descending coronary artery. RESULTS Administration of BMC was safely performed in a high-risk cohort with minimal major adverse clinical event rates, and all patients remain alive to date. Left ventricular ejection fraction increased from 49.0% +/- 9.5% at baseline to 55.2% +/- 9.8% at 6 months by cMRI in the BMC group (P < .05), which was not different from the increase in the placebo group (48.6% +/- 8.5% to 57.0% +/- 13.4%, P < .05). Left ventricular end-diastolic volume decreased by 4 mL/m(2) in the BMC group at 6 months but increased significantly in the placebo group (17 mL/m(2), P < .01). CONCLUSIONS This phase 1 study from the United States confirms the ongoing safety profile of BMC administration in patients following STEMI. The improvement in LV ejection fraction at 6 months by cMRI in the cell therapy group was not different than the placebo group. However, BMC administration had a favorable effect on LV remodeling at 6 months.

Patient care during infusion of hematopoietic progenitor cells.

From the Division of Transfusion Medicine, Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, Minnesota; and Cell Therapy Laboratory, St. Paul, Minnesota. Address reprint requests to: Jeffrey McCullough, MD, Department of Laboratory Medicine and Pathology, Medical School, Box 609 Mayo, 420 Delaware Street SE, Minneapolis, MN 55455–0385; E-mail: mccul001@umn.edu. Received for publication July 10, 2003; revision received February 5, 2004, and accepted February 9, 2004. TRANSFUSION 2004;44:907-916. T R A N S P L A N T A T I O N A N D C E L L U L A R E N G I N E E R I N G

Issues in the quality of umbilical cord blood stem cells for transplantation

BACKGROUND: Because the frequency of umbilical cord blood (UCB) stem cell transplantation has increased, the quality of UCB available in banks is an important part of the success of UCB stem cell transplants.

A multicenter comparison study between the Endosafe® PTS™ rapid-release testing system and traditional methods for detecting endotoxin in cell-therapy products

BACKGROUND Rapid-release testing reduces the waiting period for administration of time-sensitive cell-therapy products. Current assay systems are labor intensive and time consuming. The Endosafe portable test system (PTS) is a chromogenic Limulus amebocyte lysate (LAL) portable endotoxin detection system that provides quantitative results in approximately 15 min. To evaluate Endosafe performance with cell-therapy products, side-by-side testing of traditional LAL systems and the Endosafe system was conducted at the Production Assistance for Cellular Therapies (PACT) facilities and the National Institutes of Healths Department of Transfusion Medicine, USA. METHODS Charles River Laboratories provided each center with a PTS reader and two commercially prepared lyophilized reference standard endotoxin (RSE) vials. All samples tested with the Endosafe system used 0.05-5.0 endotoxin unit/mL (EU/mL) sensitivity cartridges provided by Charles River. Each vial was reconstituted with LAL water and tested in triplicate using the Endosafe and in-house LAL methods. Subsequently, each center tested the endotoxin content of standard dilutions of cell-therapy products, thus creating paired test results for each sample. Additionally, fabricated endotoxin-positive samples containing varying concentrations of endotoxin were prepared and shipped to all centers to perform blinded testing. RESULTS Valid paired results, based on each centers LAL method and the Endosafe system criteria, were analyzed. Endotoxin detection between paired results was equivalent in most cases. DISCUSSION The Endosafe system provided reliable results with products typically produced in cell-therapy manufacturing facilities, and would be an appropriate test on which to base the release of time-sensitive cell-therapy products.

Mislabeled units of umbilical cord blood detected by a quality assurance program at the transplantation center

We instituted procedures to check the identity of cord blood unit provided for transplantation by carrying out ABO and human leukocyte antigen (HLA) typing of the thawed units before transplantation. ABO typing is done using standard techniques. Rapid HLA class I serology is with monoclonal antibody trays (One Lambda Inc) using standard incubations. One mislabeled umbilical cord blood (UCB) unit was detected on the day of intended transplantation by repeat ABO typing of the thawed unit at our transplantation center. Because ABO typing will not detect all labeling errors, the rapid serologic class I HLA typing procedure was done on thawed units just before transplantation for all units without an attached segment. This procedure identified a second mislabeled unit. In a 6-year period, 2 of 871 (0.2%) cord blood units sent to us for transplantation were mislabeled and potentially would have been transplanted incorrectly. This error rate of 1 per 249 (0.4%) patients could have potentially devastating consequences.

Autologous Stem Cell Transplant Recipients Tolerate Haploidentical Related-Donor Natural Killer Cell Enriched Infusions

BACKGROUND: In the setting of allogeneic stem cell transplantation (SCT), infusing natural killer (NK) cells from a major histocompatibility complex (MHC)‐mismatched donor can mediate an antileukemic effect. The graft‐versus‐tumor effect after autologous stem cell transplantation (ASCT) may result in less disease relapse.

Improved progenitor assay standardization using peripheral blood progenitor cells from a donor treated with granulocyte–colony‐stimulating factor

BACKGROUND: Progenitor assays are the principal method for evaluating hematopoietic cell function. The magnitude of assay variability and the assay steps contributing to variability were determined, and modifications intended to increase assay consistency were evaluated.