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Figure 1. FACS Histogram Results Using RosetteSep™ Human CD4+ T Cell Enrichment Cocktail
Starting with fresh human whole blood, the CD4+ (CD3+CD4+) T cell content of the enriched fraction is typically 94.7 ± 2.4% (mean ± SD). In the above example, the purities of the start and final enriched fractions are 15.1% and 95.0%, respectively.
RosetteSep™ is a rapid cell separation procedure for the isolation of purified cells directly from whole blood, without columns or magnets.
How does RosetteSep™ work?
The antibody cocktail crosslinks unwanted cells to red blood cells (RBCs), forming rosettes. The unwanted cells then pellet with the free RBCs when centrifuged over a density centrifugation medium (e.g. Ficoll-Paque™ PLUS, Lymphoprep™).
What factors affect cell recovery?
The temperature of the reagents can affect cell recovery. All reagents should be at room temperature (sample, density centrifugation medium, PBS, centrifuge) before performing the isolations. Layering can also affect recovery so be sure to carefully layer the sample to avoid mixing with the density centrifugation medium as much as possible. Be sure to collect the entire enriched culture without disturbing the RBC pellet. A small amount of density centrifugation medium can be collected without worry.
Which cell samples can RosetteSep™ be used with?
RosetteSep™ can be used with leukapheresis samples, bone marrow or buffy coat, as long as: the concentration of cells does not exceed 5 x 107 per mL (can dilute if necessary); and there are at least 100 RBCs for every nucleated cell (RBCs can be added if necessary).
Can RosetteSep™ be used with previously frozen or cultured cells?
Yes. Cells should be re-suspended at 2 - 5 x 107 cells / mL in PBS + 2% FBS. Fresh whole blood should be added at 250 µL per mL of sample, as a source of red cells.
Can RosetteSep™ be used to enrich progenitors from cord blood?
Yes. Sometimes cord blood contains immature nucleated red cells that have a lower density than mature RBCs. These immature red cells do not pellet over Ficoll™, which can lead to a higher RBC contamination than peripheral blood separations.
Does RosetteSep™ work with mouse cells?
No, but we have developed EasySep™, a magnetic-based cell isolation system which works with mouse and other non-human species.
Which anticoagulant should be used with RosetteSep™?
Peripheral blood should be collected in heparinized Vacutainers. Cord blood should be collected in ACD.
Should the anticoagulant be washed off before using RosetteSep™?
No, the antibody cocktail can be added directly to the sample.
Regulatory T Cells Boost Efficacy of Post-Infarction Pluripotent Stem Cell-Derived Cardiovascular Progenitor Cell Transplants
A. D. D. Lima et al.
Cells 2025 Jun
Abstract
Cell therapy is promising for heart failure treatment, with growing interest in cardiovascular progenitor cells (CPCs) from pluripotent stem cells. A major challenge is managing the immune response, due to their allogeneic source. Regulatory T cells (Treg) offer an alternative to pharmacological immunosuppression by inducing immune tolerance. This study assesses whether Treg therapy can mitigate the xeno-immune response, improving cardiac outcomes in a mouse model of human CPC intramyocardial transplantation. CPCs stimulated immune responses in allogeneic and xenogeneic settings, causing proliferation in T cell subsets. Tregs showed immunosuppressive effects on T lymphocyte populations when co-cultured with CPCs. Post infarction, CPCs were transplanted intramyocardially into an immune-competent mouse model 3 weeks after myocardial infarction. Human or murine Tregs were intravenously administered on transplantation day and three days later. Control groups received CPCs without Tregs or saline (PBS). CPCs with Tregs improved LV systolic function in three weeks, linked to reduced myocardial fibrosis and enhanced angiogenesis. This was accompanied by decreased splenocyte NK cell populations and pro-inflammatory cytokine levels in cardiac tissue. Treg therapy with CPC transplantation enhances cardiac functional and structural outcomes in mice. Though it does not directly avert graft rejection, it primarily affects NKG2D+ cytotoxic cells, indicating systemic immune modulation and remote heart repair benefits.
Replication competent HIV-guided CRISPR screen identifies antiviral factors including targets of the accessory protein Nef
Nature Communications 2024 May
Abstract
Innate antiviral factors are essential for effective defense against viral pathogens. However, the identity of major restriction mechanisms remains elusive. Current approaches to discover antiviral factors usually focus on the initial steps of viral replication and are limited to a single round of infection. Here, we engineered libraries of >1500 replication-competent HIV-1 constructs each expressing a single gRNAs to target >500 cellular genes for virus-driven discovery of antiviral factors. Passaging in CD4+ T cells robustly enriched HIV-1 encoding sgRNAs against GRN, CIITA, EHMT2, CEACAM3, CC2D1B and RHOA by >50-fold. Using an HIV-1 library lacking the accessory nef gene, we identified IFI16 as a Nef target. Functional analyses in cell lines and primary CD4+ T cells support that the HIV-driven CRISPR screen identified restriction factors targeting virus entry, transcription, release and infectivity. Our HIV-guided CRISPR technique enables sensitive discovery of physiologically relevant cellular defense factors throughout the entire viral replication cycle. Innate immune mechanisms are critical for antiviral defense. Here, the authors developed a CRISPR/Cas9-based HIV-driven approach to identify cellular factors compromising viral transcription, assembly, release or infectivity in human T cells. They identify targets of the Nef protein as antiviral factors.
The immunosuppressive tuberculosis-associated microenvironment inhibits viral replication and promotes HIV-1 latency in CD4 + T cells
S. Cronin et al.
iScience 2024 Jun
Abstract
Mycobacterium tuberculosis ( Mtb ), the causative agent of tuberculosis (TB), is the most common coinfection among people living with HIV-1. This coinfection is associated with accelerated HIV-1 disease progression and reduced survival. However, the impact of the HIV-1/TB coinfection on HIV-1 replication and latency in CD4 + T cells remains poorly studied. Using the acellular fraction of tuberculous pleural effusion (TB-PE), we investigated whether viral replication and HIV-1 latency in CD4 + T cells are affected by a TB-associated microenvironment. Our results revealed that TB-PE impaired T cell receptor-dependent cell activation and decreased HIV-1 replication in CD4 + T cells. Moreover, this immunosuppressive TB microenvironment promoted viral latency and inhibited HIV-1 reactivation. This study indicates that the TB-induced immune response may contribute to the persistence of the viral reservoir by silencing HIV-1 expression, allowing the virus to persist undetected by the immune system, and increasing the size of the latent HIV-1 reservoir. Subject areas: Immunology, Virology
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