The use of plerixafor in hematopoietic progenitor cell collection in pediatric patients: a single center experience

Background aimsPlerixafor was recently approved for use in combination with granulocyte–colony-stimulating factor (G-CSF) for hematopoietic progenitor cell (HPC) collection by apheresis in adults with multiple myeloma (MM) or non-Hodgkin lymphoma (NHL). However, its efficacy in pediatric patients is not well-studied; thus, we report on our institutional experience with this population. Methods. A retrospective observational analysis was performed using both stem cell-processing laboratory information as well as apheresis charts and medical records on all pediatric patients who received plerixafor as part of the mobilization regimen between December 2006 and December 2010. The primary outcome was collection yield. Secondary outcomes included the ability to undergo autologous hematopoietic stem cell transplantation (auto-HSCT) and engraftment status. Results. Eighteen HPC collections by apheresis representing seven mobilization courses were performed on five pediatric patients with poor mobilization status (three males, two females; median age 14 years). Median pre-harvest peripheral blood CD34⁺ cell (PB CD34⁺) count was 6.88/μL. A strong correlation between pre-harvest PB CD34⁺ count and collection yield was observed. Median total collection yield was 2.26 × 10⁶ CD34⁺ cells/kg. Four patients achieved a minimum collection of 2 × 10⁶ CD34⁺ cells/kg. Three patients underwent auto-HSCT with a median neutrophil and platelet engraftment of 12 and 34 days, respectively. No major adverse events with plerixafor administration or apheresis collections were reported. Conclusions. Plerixafor in combination with G-CSF is a safe and potentially helpful mobilization agent in poor mobilizers. Further studies should be done to evaluate the true efficacy of plerixafor in the pediatric population.     

Study of a new device for washing and concentrating cryopreserved hematopoietic stem cells and mononuclear cells: a single center experience

Background aimsCryopreserved cellular products, as parts of hematopoietic progenitor cell (HPC) transplants, mononuclear cell reinjections for donor lymphocyte infusion or extracorporeal photopheresis, can be washed before being reinjected into the patient or infused directly, depending on local practices. The aim of washing is to reduce the incidence and severity of adverse reactions (ARs) due to the dimethyl sulfoxide (DMSO) used as a cryoprotective agent and other factors, such as dead cell debris. At the authors’ cell therapy laboratory (CTL) in Poitiers, France, as in 76% of Etablissement Français du Sang (EFS) CTLs, all cryopreserved products undergo thawing in a water bath followed by washing with the COBE 2991. As this device will soon cease to be available, an alternative process needs to be assessed.MethodsThe authors compared two closed systems: the authors’ semi-automatic system using the traditional centrifugation method (COBE 2991) and an automated device using spinning membrane filtration (Lovo). A total of 72 HPC bags available for research were used. The authors first performed a paired comparison, processing one or two HPC bags washed by each device. A second study was carried out to compare two different washing solutions generally used by EFS CTLs along with variable storage conditions. Finally, the authors studied the efficiency of the Lovo with three or four thawed bags. The main parameters studied were viable CD34+ cell recovery and viability, CD3+ cell recovery, stability up to 6 h after washing, DMSO elimination and center feasibility.ResultsThe Lovo device showed better CD34+ cell recovery compared with the COBE 2991 while maintaining CD34+ viability and stability over 6 h. Moreover, Lovo efficiency seemed to be independent of the number of thawed bags processed and washing solution used in the authors’ study. CD3+ cell recovery met the authors’ internal specifications (cell recovery >50%), with similar results seen when processing with either the COBE 2991 or Lovo. Additionally, on average, 97% of DMSO was removed after washing with Lovo, minimizing the risk of ARs. The storage conditions post-processing indicated preferred storage conditions of 7 ± 3°C. Finally, if processing time seemed shorter using COBE 2991 for one bag washed, the Lovo device required only one staff member regardless of the number of HPC bags processed.ConclusionsThe Lovo device seems to provide an opportunity to standardize HPC processing, ensuring patient safety, with, on average, 97% of DMSO removed, while improving recovery of cells of interest and maintaining viability over time in case of delayed transplant. The Lovo device consequently seems to be a serious alternative to the COBE 2991.     

Long-term effects of cryopreservation on clinically prepared hematopoietic progenitor cell products

Background aimsThe question of how long hematopoietic progenitor cells (HPCs) destined for clinical applications withstand long-term cryopreservation remains unanswered. To increase our basic understanding about the stability of HPC products over time, this study focused on characterizing long-term effects of cryopreservation on clinically prepared HPC products.MethodsCryovials (n = 233) frozen for an average of 6.3 ± 14.2 years (range, 0.003–14.6 years) from HPC products (n = 170) representing 75 individual patients were thawed and evaluated for total nucleated cells (TNCs), cell viability, viable CD34+ (vCD34+) cells and colony-forming cells (CFCs). TNCs were determined by use of an automated cell counter, and cell viability was measured with the use of trypan blue exclusion. Viable CD34 analysis was performed by means of flow cytometry and function by a CFC assay.ResultsSignificant losses in TNCs, cell viability, vCD34+ cells and CFC occurred on cryopreservation. However, once frozen, viable TNCs, vCD34+ cells and CFC recoveries did not significantly change over time. The only parameter demonstrating a change over time was cell viability, which decreased as the length of time that an HPC product was stored frozen increased. A significant negative correlation (correlation coefficient = −0.165) was determined between pre-freeze percent granulocyte content and post-thaw percent viability (n = 170; P = 0.032). However, a significant positive correlation was observed between percent viability at thaw and pre-freeze lymphocyte concentration.ConclusionsOnce frozen, HPC products were stable for up to 14.6 years at <−150°C. Post-thaw viability was found to correlate negatively with pre-freeze granulocyte content and positively with pre-freeze lymphocyte content.     

A cross-sectional study of umbilical cord blood donor profiles and their influence on umbilical cord blood collection in a Brazilian hospital

Background aimsUmbilical cord blood (UCB) cells are a new alternative to bone marrow source for hematopoietic stem cell transplantation and their use has increased in the last decade. Thus efforts are being made to improve the umbilical cord blood unit's quality. Besides compatibility, other factors, such as the total nucleated cell (TNC) count and the percentage of CD34⁺ cells in the product, are very important for a successful transplant outcome. Our aim was to describe our donor population and assess the best cord blood collection technique at Hospital Israelita Albert Einstein's cord blood bank (São Paulo, Brazil).MethodsThis was a retrospective study in which all analyses were performed simultaneously. A Student's t-test was used for qualitative variables for non-matched samples. For qualitative analyses, we used either the chi-square test or the exact Fisher's test.ResultsThe stratification of the population characteristics allowed us to determine which ones had an impact on unit volume, TNC count and percentage of CD34⁺ cells. A significant correlation was observed between donor characteristics and the quality of UCB units as related to maternal and gestational age, type of pregnancy, route of delivery, cord blood collection technique and birth weight.ConclusionsWe found that cord blood collection technique and newborn weight were significantly correlated with the TNC content. The collection technique used at our institution significantly improved the UCB unit volume and consequently the TNC count. Some findings, such as the impact of maternal age and newborn weight, have led us to re-evaluate our protocol in order to achieve better results.     

Feasibility and cost analysis of day 4 granulocyte colony-stimulating factor mobilized peripheral blood progenitor cell collection from HLA-matched sibling donors

BackgroundGuidelines recommend treatment with 4–5 days of granulocyte colony-stimulating factor (G-CSF) for optimal donor peripheral blood progenitor cell (PBPC) mobilization followed by day 5 collection. Given that some autologous transplant recipients achieve adequate collection by day 4 and the possibility that some allogeneic donors may maximally mobilize PBPC before day 5, a feasibility study was performed evaluating day 4 allogeneic PBPC collection.MethodsHLA-matched sibling donors underwent collection on day 4 of G-CSF for peripheral blood (PB) CD34⁺ counts ≥0.04 × 10⁶/mL, otherwise they underwent collection on day 5. Those with inadequate collected CD34⁺ cells/kg recipient weight underwent repeat collection over 2 days. Transplant and PBPC characteristics and cost analysis were compared with a historical cohort collected on day 5 per our prior institutional algorithm.ResultsOf the 101 patient/donor pairs, 50 (49.5%) had adequate PBPC collection on day 4, with a median PB CD34⁺ cell count of 0.06 × 10⁶/mL. Day 4 donors were more likely to develop bone pain and require analgesics. Median collected CD34⁺ count was significantly greater, whereas total nucleated, mononuclear and CD3⁺ cell counts were significantly lower, at time of transplant infusion for day 4 versus other collection cohorts. There were no significant differences in engraftment or graft-versus-host disease. Cost analysis revealed 6.7% direct cost savings for day 4 versus historical day 5 collection.DiscussionDay 4 PB CD34⁺ threshold of ≥0.04 × 10⁶/mL identified donors with high likelihood of adequate PBPC collection. Day 4 may be the optimal day of collection for healthy donors, without adverse effect on recipient transplant outcomes and with expected cost savings.     

Variations in novel cellular therapy products manufacturing

Background aimsAt the frontier of transfusion medicine and transplantation, the field of cellular therapy is emerging. Most novel cellular therapy products are produced under investigational protocols with no clear standardization across cell processing centers. Thus, the purpose of this study was to uncover any variations in manufacturing practices for similar cellular therapy products across different cell processing laboratories worldwide.MethodsAn exploratory survey that was designed to identify variations in manufacturing practices in novel cellular therapy products was sent to cell processing laboratory directors worldwide. The questionnaire focused on the manufacturing life cycle of different cell therapies (i.e., collection, purification, in vitro expansion, freezing and storage, and thawing and washing), as well as the level of regulations followed to process each product type.ResultsThe majority of the centers processed hematopoietic progenitor cells (HPCs) from peripheral blood (n = 18), bone marrow (n = 16) or cord blood (n = 19), making HPCs the most commonly processed cells. The next most commonly produced cellular therapies were lymphocytes (n = 19) followed by mesenchymal stromal cells (n = 14), dendritic cells (n = 9) and natural killer (NK) cells (n = 9). A minority of centers (<5) processed pancreatic islet cells (n = 4), neural cells (n = 3) and induced-pluripotent stem cells (n = 3). Thirty-two laboratories processed products under an investigational status, for either phase I/II (n = 27) or phase III (n = 17) clinical trials. If purification methods were used, these varied for the type of product processed and by institution. Environmental monitoring methods also varied by product type and institution.ConclusionThis exploratory survey shows a wide variation in cellular therapy manufacturing practices across different cell processing laboratories. A better understanding of the effect of these variations on the quality of these cell-based therapies will be important to assess for further process evaluation and development.     

Modifications in the synthesis of membrane-associated chondroitin sulfate proteoglycans in hemopoietic progenitor cells are accompanied by alterations in their adhesive properties

In vitro studies in our laboratory have indicated that murine hemopoietic progenitor cell (HPC) lines, irrespective of their differentiation stage, synthesize and accumulate in the cell membrane a unique species of chondroitin sulfate proteoglycan (CS-PG). It has been postulated that CS-PG participates in HPC adhesion to pericellular stromal fibronectin by interacting with its heparin-promoting binding region. To further support this contention, we first attempted to modify CS-PG synthesis in HPC by the use of chlorate and p-nitrophenyl (β-D-xyloside), which inhibit sulfation and glycosaminoglycan (GAG) addition in proteoglycans, respectively. We then studied the effect that these modifications may have in the adhesive capacity of HPC to interact with fibronectin and its cell- and heparin-promoting binding chymotryptic fragments. Treatment with chlorate which resulted in a decreased sulfation of membrane-associated 35 S-labeled CS-PG, as judged by ion exchange chromatography, did not affect HPC adhesion to fibronectin or its fragments. However, β-xyloside treatment which reduces the abundance of membrane-associated CS-PG, as evidenced by molecular sieve chromatography, produced a major and specific decrease in HPC adhesion to the heparin-promoting binding fragment of fibronectin. These results indicate that CS-PG are involved in HPC interaction with fibronectin, in a mode that seems to be dependent on the differentiation stage of HPC. © 1994 wiley-Liss, Inc.     

Spontaneous and granulocyte–colony-stimulating factor-enhanced marrow response and progenitor cell mobilization in mice after myocardial infarction

Background aimsHematopoietic (HPC), mesenchymal (MPC) and/or endothelial (EPC) progenitor cells are being studied to repair the myocardium after acute or chronic ischemia. We examined marrow response to myocardial infarction (MI) and the ability of granulocyte–colony-stimulating factor (G-CSF) to enhance mobilization of HPC, MPC and EPC in peripheral blood (PB) and bone marrow (BM) of MI mice.MethodsWe induced MI in C57Bl/6 mice, while sham-operated (SO) animals were similarly operated on but without coronary artery ligation. Animals were treated with either saline or G-CSF, from day ?5 to day +5 after MI or from day 0 to day +5. Progenitor cell numbers in PB and BM were evaluated by fluorescence-activated cell sorting (FACS) analysis and cell culture.ResultsWhite blood cells (WBC) decreased in BM and increased in PB after MI; G-CSF amplified this effect in BM but not in PB. HPC numbers decreased in BM after MI, while HPC and granulocyte–macrophage colony-forming units (GM-CFU) increased in PB only after G-CSF treatment, and more prominently so in MI than in SO mice. MPC and fibroblast–colony-forming units (F-CFU) as well as EPC were mobilized into the PB after MI and further after G-CSF treatment. Plasma troponin T concentrations decreased after G-CSF treatment.ConclusionsBM is globally affected by acute MI, but not simple body injury, with intense mobilization of marrow MPC and EPC into the PB but inhibition of HPC. Progenitor cell entry into the PB may be paralleled by depletion of their BM pools. G-CSF is required for HPC mobilization and enhances MPC and EPC entry into the PB.     

Short-term exposure of umbilical cord blood CD34+ cells to granulocyte–macrophage colony-stimulating factor early in culture improves ex vivo expansion of neutrophils

Background aimsDespite the availability of modern antibiotics/antimycotics and cytokine support, neutropenic infection accounts for the majority of chemotherapy-associated deaths. While transfusion support with donor neutrophils is possible, cost and complicated logistics make such an option unrealistic on a routine basis. A manufactured neutrophil product could enable routine prophylactic administration of neutrophils, preventing the onset of neutropenia and substantially reducing the risk of infection. We examined the use of pre-culture strategies and various cytokine/modulator combinations to improve neutrophil expansion from umbilical cord blood (UCB) hematopoietic stem and progenitor cells (HPC).MethodsEnriched UCB HPC were cultured using either two-phase pre-culture strategies or a single phase using various cytokine/modulator combinations. Outcome was assessed with respect to numerical expansion, cell morphology, granulation and respiratory burst activity.ResultsPre-culture in the absence of strong differentiation signals (e.g. granulocyte colony-stimulating factor; G-CSF) failed to provide any improvement to final neutrophil yields. Similarly, removal of differentiating cells during pre-culture failed to improve neutrophil yields to an appreciable extent. Of the cytokine/modulator combinations, the addition of granulocyte–macrophage (GM)-colony-stimulating factor (CSF) alone gave the greatest increase. In order to avoid production of monocytes, it was necessary to remove GM-CSF on day 5. Using this strategy, neutrophil expansion improved 2.7-fold.ConclusionsAlthough all cytokines and culture strategies employed have been reported previously to enhance HPC expansion, we found that the addition of GM-CSF alone was sufficient to improve total cell yields maximally. The need to remove GM-CSF on day 5 to avoid monocyte differentiation highlights the context and time-dependent complexity of exogenous signaling in hematopoietic cell differentiation and growth.     

Anticoagulation in large-volume leukapheresis: comparison between citrate- versus heparin-based anticoagulation on safety and CD34 (+) cell collection efficiency

Background aimsLittle is known of the effect of anticoagulation on peripheral blood progenitor cell (PBPC) harvest during large-volume leukapheresis (LVL). Because of the interaction of heparin with stromal cell-derived factor (SDF)-1α, it has been proposed that a heparin-based anticoagulation may result in an increased PBPC collection efficiency compared with standard citrate-based anticoagulation.MethodsWe conducted a prospective randomized trial to address the effect of both anticoagulation regimes on safety, subjective comfort and CD34 ⁺ collection efficiency in 90 adult patients undergoing standardized LVL. Anticoagulation consisted of either citrate (group C) or a combination of heparin and low-dose citrate (group H).ResultsThe overall incidence of adverse reactions (AR) during LVL was 17%. AR consisted only of citrate-related AR; no bleeding complications were observed. Determination of parameters of the acid–base balance revealed a higher frequency of metabolic alkalosis in group C. Analysis of serum SDF-1α revealed no differences in SDF-1α plasma levels. There were no differences in the CD34 ⁺ cell collection efficiency, resulting in the harvest of equal CD34 ⁺ cell yields independent of the anticoagulation used.ConclusionsOur data show no clinical relevant effect of a heparin containing anticoagulation in terms of an increased overall CD34 ⁺ cell collection during LVL, although this regime shows some benefits in terms of the incidence and subjective tolerance towards AR. Based on our results the decision between a citrate- and heparin-substituted anticoagulation for LVL should be driven by patient-related factors, and should concern potential contraindications of both methods.     

Validation plan of bone marrow collection,processing and distribution using the failure mode and effect analysis methodology: a technical report

Background aimsBone marrow (BM) is commonly used in the pediatric and adult setting as a source of hematopoietic stem cells (HSCs). The standards of the Joint Accreditation Committee of the International Society for Cell & Gene Therapy & European Society for Blood and Marrow Transplantation (JACIE) include specific requirements regarding BM collection, processing and distribution. To run this process, each transplant team develops a series of JACIE-compliant procedures, customizing them with regard to local settings and paths. Moreover, JACIE standards require that transplant teams validate and periodically revise their procedures to keep the entire process under control. In this article, the authors describe the methodology adopted in our center to fulfill the aforementioned JACIE requirements.MethodsThe authors developed a validation plan based on the failure mode and effect analysis (FMEA) methodology. According to the FMEA approach, the authors carefully revised activities and procedures connected to BM collection, processing and distribution at our institution. The entire process was initially divided into five main phases (assessment of donor eligibility, perioperative autologous blood donation, preparation of BM collection kit, BM harvesting and BM processing and distribution), comprising 17 subphases and 22 activities.ResultsFor each activity, one or more failure modes were identified, for a total of 28 failure modes, and a risk priority number (RPN) was then assigned to each failure mode. Although many procedures were validated, others were subjected to substantial changes according to the RPN rating. Moreover, specific indicators were identified for subsequent monitoring to contain the risk of failure of steps emerging as critical at FMEA.ConclusionsThis is the first study describing use of the FMEA methodology within an HSC transplant program. Shaping the risk analysis based on local experience may be a trustworthy tool for identifying critical issues, directing strict monitoring of critical steps or even amending connected procedures. Overall, the FMEA approach enabled the authors to improve our process, checking its consistency over time.     

Stability of cytokines,chemokines and soluble activation markers in unprocessed blood stored under different conditions

BackgroundBiomarkers such as cytokines, chemokines, and soluble activation markers can be unstable when processing of blood is delayed. The stability of various biomarkers in serum and plasma was investigated when unprocessed blood samples were stored for up to 24 h at room and refrigerator temperature.MethodsBlood was collected from 16 healthy volunteers. Unprocessed serum, EDTA and heparinized blood was stored at room (20–25 °C) and refrigerator temperature (4–8 °C) for 0.5, 2, 4, 6, 8, and 24 h after collection before centrifugation and separation of serum and plasma. Samples were batch tested for various biomarkers using commercially available immunoassays. Statistically significant changes were determined using the generalized estimating equation.ResultsIFN-γ, sIL-2Rα, sTNF-RII and β₂-microglobulin were stable in unprocessed serum, EDTA and heparinized blood samples stored at either room or refrigerator temperature for up to 24 h. IL-6, TNF-α, MIP-1β and RANTES were unstable in heparinized blood at room temperature; TNF-α, and MIP-1β were unstable in unprocessed serum at room temperature; IL-12 was unstable in unprocessed serum at refrigerator temperature; and neopterin was unstable in unprocessed EDTA blood at room temperature. IL-1ra was stable only in unprocessed serum at room temperature.ConclusionAll the biomarkers studied, with the exception of IL-1ra, were stable in unprocessed EDTA blood stored at refrigerator temperature for 24 h. This indicates that blood for these biomarkers should be collected in EDTA and if delays in processing are anticipated the unseparated blood should be stored at refrigerator temperature until processing.     

Defining “poor mobilizer” in pediatric patients who need an autologous peripheral blood progenitor cell transplantation

The definition of poor mobilizers is not clear in pediatric patients undergoing autologous peripheral blood hematopoietic progenitor cell (HPC) mobilization. Most studies conducted in children define those variables related to the collection of HPC after leukapheresis, but the information regarding exclusively the mobilization process is scarce. In our experience, most children (92.2%) reach the target CD34⁺ cell dose for autologous peripheral blood progenitor cell transplantation if CD34⁺ cell count was higher than 10/μL. No differences were observed between those with >20 CD34⁺ cells/μL and 11–20 CD34⁺ cells/μL. In this study, we analyzed the variables that influence CD34⁺ cell count; we found that prior use of radiotherapy was the main variable related to poor mobilization. Patients diagnosed with Ewing sarcoma, treated with radiotherapy and mobilized with standard doses of granulocyte colony-stimulating factor (G-CSF) were also at a high risk of mobilization failure. In these patients, we should consider mobilization with high dose G-CSF and be prepared with new mobilization agents to avoid delay on their course of chemotherapy.     

Clinical scale ex vivo manufacture of neutrophils from hematopoietic progenitor cells

Dose‐intensive chemotherapy results in an obligatory period of severe neutropenia during which patients are at high risk of infection. While patient support with donor neutrophils is possible, this option is restricted due to donor availability and logistic complications. To overcome these problems, we explored the possibility of large scale ex vivo manufacture of neutrophils from hematopoietic progenitor cells (HPC). CD34⁺ HPC isolated from umbilical cord blood (UCB) and mobilized peripheral blood (mPB) were expanded in serum‐free medium supplemented with stem cell factor, granulocyte colony stimulating factor, and a thrombopoietin peptide mimetic. After 15 days of cultivation a 5,800‐fold expansion in cell number was achieved for UCB, and up to 4,000‐fold for mPB, comprising 40% and 60% mature neutrophils respectively. Ex vivo expanded neutrophils exhibited respiratory burst activity similar to that for donor neutrophils, and were capable of killing Candida albicans in vitro. These yields correspond to a more than 10‐fold improvement over current methods, and are sufficient for the production of multiple neutrophil transfusion doses per HPC donation. To enable clinical scale manufacture, we adapted our protocol for use in a wave‐type bioreactor at a volume of 10 L. This is the first demonstration of a large scale bioprocess suitable for routine manufacture of a mature blood cell product from HPC, and could enable prophylactic neutrophil support for chemotherapy patients. Biotechnol. Bioeng. 2009; 104: 832–840 © 2009 Wiley Periodicals, Inc.     

Adyuvant fractionated radiotherapy after resection of intracranial hemangiopericytoma

AimReview of literature and adjuvant treatment in Hemangiopericytoma after complete resection.BackgroundIntracranial hemangiopericytoma (HPC) is an uncommon malignant vascular tumor arising from mesenchymal cells with pericytic differentiation. Surgery remains the mainstay treatment, and adjuvant radiation therapy appears to be appropriate for patients with high grade tumors or incomplete resection. We present our experience and review of the literature.Materials and methodsWe describe two cases of intracranial hemangiopericytoma located in the frontal lobe of the CNS. Both patients underwent complete tumor resection followed by adjuvant fractionated radiotherapy and completed treatment without interruptions.ResultsA local recurrence was observed in one of these cases and fractionated stereotactic radiotherapy was performed. Both patients are alive and disease has been under control up to date.ConclusionThe treatment of choice for intracranial hemangiopericytoma is a complete surgical resection as long as possible. Adjuvant radiotherapy of HPC can result in increased tumor control and should be considered as an effective treatment for patients with high grade or demonstrated residual tumor in the postoperative period. Salvage treatment using limited-field fractionated radiotherapy for local recurrence treatment is considered an acceptable option.     

Un-LINQed: Spontaneous extrusion of newer generation implantable loop recorders

BackgroundInsertable cardiac monitors (ICMs) are often used for long-term monitoring of cardiac rhythm. The Medtronic’s LINQ Reveal ™ is a new generation wireless, automated, and patient responsive subcutaneous ECG monitoring device. Despite several advantages to its small size we have noted an unusually high incidence of extrusion at our center.Methods& Results: We conducted a retrospective case analysis to review Reveal LINQs implanted at our center. All devices were inserted using the provided insertion tools. Patients with extruded devices were identified and details regarding the site and technique of insertion, incision closure, use of peri-operative antibiotics, and follow-up details were collected. 81 patients underwent 85 Reveal LINQ implants at a tertiary care University Hospital referral center. The most common reason for implant was suspected arrhythmia with or without structural heart disease or unexplained syncope. There were 4 spontaneous extrusions occurring within 7–24 days after insertion with an incidence rate of 4.7%. One extruded device was anchored to subcutaneous tissue, and no pocket/device infections or hematomas were noted.ConclusionsDevice migration and erosion through skin are important potential adverse events for the Reveal LINQ implantable loop recorder. This study reports an unexpectedly high rate of extrusion without infection. The authors suggest that the depth of the incision is the main factor impacting extrusions. Larger studies are recommended, however, and a proposed measure to avoid spontaneous extrusion is the design of a longer manufacturer’s blade in order to increase the depth of the incision and insertion.     

Automated Good Manufacturing Practice–compliant generation of human monocyte-derived dendritic cells from a complete apheresis product using a hollow-fiber bioreactor system overcomes a major hurdle in the manufacture of dendritic cells for cancer vaccines

BackgroundAlthough dendritic cell (DC)–based cancer vaccines represent a promising treatment strategy, its exploration in the clinic is hampered due to the need for Good Manufacturing Practice (GMP) facilities and associated trained staff for the generation of large numbers of DCs. The Quantum bioreactor system offered by Terumo BCT represents a hollow-fiber platform integrating GMP-compliant manufacturing steps in a closed system for automated cultivation of cellular products. In the respective established protocols, the hollow fibers are coated with fibronectin and trypsin is used to harvest the final cell product, which in the case of DCs allows processing of only one tenth of an apheresis product.Materials and ResultsWe successfully developed a new protocol that circumvents the need for fibronectin coating and trypsin digestion, and makes the Quantum bioreactor system now suitable for generating large numbers of mature human monocyte-derived DCs (Mo-DCs) by processing a complete apheresis product at once. To achieve that, it needed a step-by-step optimization of DC-differentiation, e.g., the varying of media exchange rates and cytokine concentration until the total yield (% of input CD14⁺ monocytes), as well as the phenotype and functionality of mature Mo-DCs, became equivalent to those generated by our established standard production of Mo-DCs in cell culture bags.ConclusionsBy using this new protocol for the Food and Drug Administration–approved Quantum system, it is now possible for the first time to process one complete apheresis to automatically generate large numbers of human Mo-DCs, making it much more feasible to exploit the potential of individualized DC-based immunotherapy.     

Improved survival of mesenchymal stromal cell after hypoxia preconditioning: role of oxidative stress

AimsTo investigate the mechanisms underlying the beneficial effect of hypoxia preconditioning (HPC) on mesenchymal stromal cells (MSCs) and optimize novel non-invasive methods to assess the effect of biological interventions aimed to increased cell survival.Main methodsMSCs from rat femur, with or without HPC, were exposed to hypoxic conditions in cell culture (1% O₂ for 24 h) and cell survival (by the LDH release assay and Annexin-V staining) was measured. Oxidant status (conversion of dichloro-fluorescein-DCF- and dihydro-ethidium-DHE-, protein expression of oxidant enzymes) was characterized, together with the mobility pattern of cells under stress. Furthermore, cell survival was assessed non-invasively using state-of-the-art molecular imaging.Key findingsCompared to controls, Hypoxia resulted in increased expression of the oxidative stress enzyme NAD(P)H oxidase (subunit 67^phox: 0.05 ± 0.01 AU and 0.48 ± 0.02 AU, respectively, p < 0.05) and in the amount of ROS (DCF: 13 ± 1 and 42 ± 3 RFU/μg protein, respectively, p < 0.05) which led to a decrease in stem cell viability. Hypoxia preconditioning preserved cell biology, as evidenced by preservation of oxidant status (16 ± 1 RFU/μg protein, p < 0.05 vs. hypoxia), and cell viability. Most importantly, the beneficial effect of HPC can be assessed non-invasively using molecular imaging.SignificanceHPC preserves cell viability and function, in part through preservation of oxidant status, and its effects can be assessed using state-of-the-art molecular imaging. Understanding of the mechanisms underlying the fate of stem cells will be critical for the advancement of the field of stem cell therapy.     

Genome-wide analysis of epigenetic dynamics across human developmental stages and tissues

Background

Epigenome is highly dynamic during the early stages of embryonic development. Epigenetic modifications provide the necessary regulation for lineage specification and enable the maintenance of cellular identity. Given the rapid accumulation of genome-wide epigenomic modification maps across cellular differentiation process, there is an urgent need to characterize epigenetic dynamics and reveal their impacts on differential gene regulation.

Methods

We proposed DiffEM, a computational method for differential analysis of epigenetic modifications and identified highly dynamic modification sites along cellular differentiation process. We applied this approach to investigating 6 epigenetic marks of 20 kinds of human early developmental stages and tissues, including hESCs, 4 hESC-derived lineages and 15 human primary tissues.

Results

We identified highly dynamic modification sites where different cell types exhibit distinctive modification patterns, and found that these highly dynamic sites enriched in the genes related to cellular development and differentiation. Further, to evaluate the effectiveness of our method, we correlated the dynamics scores of epigenetic modifications with the variance of gene expression, and compared the results of our method with those of the existing algorithms. The comparison results demonstrate the power of our method in evaluating the epigenetic dynamics and identifying highly dynamic regions along cell differentiation process.