Impact of culture conditions on the proliferative lifespan of human T cells in vitro

Autologous plasma versus fetal calf serum as a supplement for the culture of neutrophils

OBJECTIVE

Currently, the replacement of fetal calf serum (FCS) by a more suitable alternative is a sought aim in the field of tissue and cell culture research. Autologous plasma (AP) and especially autologous serum (AS) have been shown to be effective substitutes of FCS in culture media for some of the cell types. Nevertheless, there is no comparative data on the most appropriate supplement for cell media in neutrophil studies, it is now unclear whether AP have a relatively equal, superior or inferior performance to FCS in neutrophil cell culture. In the present study, human blood neutrophils were isolated and cultured in FCS- or AP-supplemented medium. After 12, 36 and 60 h of incubation, cell viability, oxidative burst and CD11b expression were determined by flow cytometry.

RESULTS

Compared to the culture of neutrophils in FCS 10% medium, the culture of neutrophils in a medium with AP 10% could prolong their life span without affecting their function. The findings introduce AP as a better supplement for human neutrophil cell culture than FCS and propose a simple and economical procedure for neutrophil isolation and culture.

Extensive Proliferation of Cd4+ Lymphocyte by Both Phytohaemagglutinin A and Anti-Cd2/Cd3/ Cd28 Macsibeads

Background: Lymphocytes proliferate considerably following appropriate stimulation in vitro. Autologous T cells are obtained from whole blood or tissue sites in relatively limited amounts. We need a method to expand these cells efficiently, study their functions and manipulate them to create appropriate cells for transferring to the patient with infection and cancer. Objectives: The aim of this study is to determine proliferation ability of two different stimulators on CD4+ lymphocytes. Methods: Lymphocytes were isolated from blood samples of healthy donors after removing adherent cells (monocytes).The efficacy of MACSiBead™ coated with anti-CD2, anti-CD3, anti-CD28 (anti-CD2/CD3/CD28) was compared with Phytohaemagglutinin A (PHA) on CD4+ lymphocytes proliferation using carboxyfluorescein diacetate succinimidyl ester (CFSE) in cell culture media. The percentage of proliferating cells was analyzed using flow cytometry. Results: Both stimulators induced extensive proliferation of CD4+ lymphocytes but proliferation ability of PHA was higher compared to stimulation by anti-CD2/CD3/CD28 MACSiBead™. The proliferation rate of cells stimulated by PHA was 93.8% ± 3.37% whereas it was 85.2% ± 4.7% in cells stimulated by anti-CD2/CD3/CD28 MACSiBead™. Conclusions: Our results show that MACSiBead™ along with PHA can be used to obtain a large number of expanded CD4+ lymphocytes.

In Vitro Evaluation of Glycoengineered RSV-F in the Human Artificial Lymph Node Reactor

Subunit vaccines often require adjuvants to elicit sustained immune activity. Here, a method is described to evaluate the efficacy of single vaccine candidates in the preclinical stage based on cytokine and gene expression analysis. As a model, the recombinant human respiratory syncytial virus (RSV) fusion protein (RSV-F) was produced in CHO cells. For comparison, wild-type and glycoengineered, afucosylated RSV-F were established. Both glycoprotein vaccines were tested in a commercial Human Artificial Lymph Node in vitro model (HuALN^®). The analysis of six key cytokines in cell culture supernatants showed well-balanced immune responses for the afucosylated RSV-F, while immune response of wild-type RSV-F was more Th1 accentuated. In particular, stronger and specific secretion of interleukin-4 after each round of re-stimulation underlined higher potency and efficacy of the afucosylated vaccine candidate. Comprehensive gene expression analysis by nCounter gene expression assay confirmed the stronger onset of the immunologic reaction in stimulation experiments with the afucosylated vaccine in comparison to wild-type RSV-F and particularly revealed prominent activation of Th17 related genes, innate immunity, and comprehensive activation of humoral immunity. We, therefore, show that our method is suited to distinguish the potency of two vaccine candidates with minor structural differences.

Serum and supplement optimization for EU GMP-compliance in cardiospheres cell culture

Cardiac progenitor cells (CPCs) isolated as cardiospheres (CSs) and CS-derived cells (CDCs) are a promising tool for cardiac cell therapy in heart failure patients, having CDCs already been used in a phase I/II clinical trial. Culture standardization according to Good Manufacturing Practices (GMPs) is a mandatory step for clinical translation. One of the main issues raised is the use of xenogenic additives (e.g. FBS, foetal bovine serum) in cell culture media, which carries the risk of contamination with infectious viral/prion agents, and the possible induction of immunizing effects in the final recipient. In this study, B27 supplement and sera requirements to comply with European GMPs were investigated in CSs and CDCs cultures, in terms of process yield/efficiency and final cell product gene expression levels, as well as phenotype. B27− free CS cultures produced a significantly reduced yield and a 10-fold drop in c-kit expression levels versus B27+ media. Moreover, autologous human serum (aHS) and two different commercially available GMP AB HSs were compared with standard research-grade FBS. CPCs from all HSs explants had reduced growth rate, assumed a senescent-like morphology with time in culture, and/or displayed a significant shift towards the endothelial phenotype. Among three different GMP gamma-irradiated FBSs (giFBSs) tested, two provided unsatisfactory cell yields, while one performed optimally, in terms of CPCs yield/phenotype. In conclusion, the use of HSs for the isolation and expansion of CSs/CDCs has to be excluded because of altered proliferation and/or commitment, while media supplemented with B27 and the selected giFBS allows successful EU GMP-complying CPCs culture.

Predicting cytotoxic T-cell age from multivariate analysis of static and dynamic biomarkers

Adoptive T-cell transfer therapy relies upon in vitro expansion of autologous cytotoxic T cells that are capable of tumor recognition. The success of this cell-based therapy depends on the specificity and responsiveness of the T cell clones before transfer. During ex vivo expansion, CD8+ T cells present signs of replicative senescence and loss of function. The transfer of nonresponsive senescent T cells is a major bottleneck for the success of adoptive T-cell transfer therapy. Quantitative methods for assessing cellular age and responsiveness will facilitate the development of appropriate cell expansion and selection protocols. Although several biomarkers of lymphocyte senescence have been identified, these proteins in isolation are not sufficient to determine the age-dependent responsiveness of T cells. We have developed a multivariate model capable of extracting combinations of markers that are the most informative to predict cellular age. To acquire signaling information with high temporal resolution, we designed a microfluidic chip enabling parallel lysis and fixation of stimulated cell samples on-chip. The acquisition of 25 static biomarkers and 48 dynamic signaling measurements at different days in culture, integrating single-cell and population based information, allowed the multivariate regression model to accurately predict CD8+ T-cell age. From surface marker expression and early phosphorylation events following T-cell receptor stimulation, the model successfully predicts days in culture and number of population doublings with R2=0.91 and 0.98, respectively. Furthermore, we found that impairment of early signaling events following T cell receptor stimulation because of long term culture allows prediction of costimulatory molecules CD28 and CD27 expression levels and the number of population divisions in culture from a limited subset of signaling proteins. The multivariate analysis highlights the information content of both averaged biomarker values and heterogeneity metrics for prediction of cellular age within a T cell population.

Telomeres and aging

Telomeres play a central role in cell fate and aging by adjusting the cellular response to stress and growth stimulation on the basis of previous cell divisions and DNA damage. At least a few hundred nucleotides of telomere repeats must "cap" each chromosome end to avoid activation of DNA repair pathways. Repair of critically short or "uncapped" telomeres by telomerase or recombination is limited in most somatic cells and apoptosis or cellular senescence is triggered when too many "uncapped" telomeres accumulate. The chance of the latter increases as the average telomere length decreases. The average telomere length is set and maintained in cells of the germline which typically express high levels of telomerase. In somatic cells, telomere length is very heterogeneous but typically declines with age, posing a barrier to tumor growth but also contributing to loss of cells with age. Loss of (stem) cells via telomere attrition provides strong selection for abnormal and malignant cells, a process facilitated by the genome instability and aneuploidy triggered by dysfunctional telomeres. The crucial role of telomeres in cell turnover and aging is highlighted by patients with 50% of normal telomerase levels resulting from a mutation in one of the telomerase genes. Short telomeres in such patients are implicated in a variety of disorders including dyskeratosis congenita, aplastic anemia, pulmonary fibrosis, and cancer. Here the role of telomeres and telomerase in human aging and aging-associated diseases is reviewed.