A versatile flow-based assay for immunocyte-mediated cytotoxicity

Alginate and chitosan-based polyamide 56 modified nanofiber membrane for highly effective capture of Escherichia coli: Antibacterial and cytotoxicity studies

In recent years, microbial fermentation has become a sustainable alternative to traditional petrochemical processes for producing biomass nylon 56 (i.e., PA56). This study is centered on creating a highly efficient antibacterial nanofiber membrane using bio-nylon 56 as the main material. The membrane was fabricated via a multi-step process involving sodium alginate, chitosan, and poly(hexamethylene biguanide) (PHMB). The PA56 nanofiber was chemically modified by sequential coupling with alginate (AG) and chitosan (CS), introducing a significant number of functional groups (-COOH and -NH2). This process resulted in the formation of PA56-AG and PA56-AG-CS nanofibers. Further modification with PHMB led to obtaining the PA56-AG-PHMB and PA56-AG-CS-PHMB antibacterial nanofiber membranes. The optimal preparation conditions for these membranes were determined, including the pH and concentration of AG, the molecular weight, pH, and concentration of CS, and the pH and concentration of PHMB. The PA56-based membranes demonstrated nearly 100 % antibacterial efficiency within a short time. However, the PA56-AG-PHMB membrane exhibited faster antibacterial rates and higher efficiency in repeated use compared to the PA56-AG-CS-PHMB membrane. The two-step coupling reaction in the preparation of PA56-AG-CS-PHMB may have reduced its surface accessibility to E. coli cells, resulting in slower bacterial attachment. Furthermore, the PA56-related membranes showed excellent biocompatibility, with a 100 % cell survival rate. Despite some limitations in reusability, biomass nylon PA56 stands out as an environmentally friendly material derived from renewable resources through microbial fermentation. It offers significant sustainability advantages over traditional petroleum-based nylons, as evidenced by the favorable cytotoxicity test results.

A novel thermostable beetle luciferase based cytotoxicity assay

Cytotoxicity assays are essential for the testing and development of novel immunotherapies for the treatment of cancer. We recently described a novel cytotoxicity assay, termed the Matador assay, which was based on marine luciferases and their engineered derivatives. In this study, we describe the development of a new cytotoxicity assay termed 'Matador-Glo assay' which takes advantage of a thermostable variant of Click Beetle Luciferase (Luc146-1H2). Matador-Glo assay utilizes Luc146-1H2 and D-luciferin as the luciferase-substrate pair for luminescence detection. The assay involves ectopic over-expression of Luc146-1H2 in the cytosol of target cells of interest. Upon damage to the membrane integrity, the Luc146-1H2 is either released from the dead and dying cells or its activity is preferentially measured in dead and dying cells. We demonstrate that this assay is simple, fast, specific, sensitive, cost-efficient, and not labor-intensive. We further demonstrate that the Matador-Glo assay can be combined with the marine luciferase-based Matador assay to develop a dual luciferase assay for cell death detection. Finally, we demonstrate that the Luc146-1H2 expressing target cells can also be used for in vivo bioluminescence imaging applications.

Antibacterial efficacy of quaternized chitosan/poly (vinyl alcohol) nanofiber membrane crosslinked with blocked diisocyanate

N-[(2-hydroxyl-3-trimethylammonium) propyl] chitosan chloride (HTCC), which is a type of chitosan derivative with quaternary ammonium groups, possesses a higher antibacterial activity as compared to the pristine chitosan. The nanofiber membranes made of HTCC are attractive for applications demanding for antibacterial function. However, the hydrophilic nature of HTCC makes it unsuitable for electrospinning of nanofibers. Hence, biodegradable polyvinyl alcohol (PVA) was proposed as an additive to improve the electrospinnability of HTCC. In this work, PVA/HTCC nanofiber membrane was crosslinked with the blocked diisocyanate (BI) to enhance the stability of nanofiber membrane in water. Microbiological assessments showed that the PVA/HTCC/BI nanofiber membranes possessed a good antibacterial efficacy (∼100 %) against E. coli. Moreover, the biocompatibility of PVA/HTCC/BI nanofiber membrane was proven by the cytotoxicity test on mouse fibroblasts. These promising results indicated that the PVA/HTCC/BI nanofiber membrane can be a promising material for food packaging and as a potential wound dressing for skin regeneration.

CRISPR/Cas9-Mediated GFP Reporter Knock-in in K562 and Raji Cell Lines for Tracking Immune Cell Killing Assay

Cell-mediated cytotoxicity plays an important role in several fundamental immunological processes and is crucial for biological evaluation in in vitro studies. In order to determine the immunological activities of the cells, an assay should be safe, reproducible, and cost-effective. Here, we present a simple and cost-effective approach for evaluation of natural killer (NK) cell-mediated cytotoxicity by generating a CRISPR/Cas9-mediated GFP reporter knock-in in the target cell line, K562, and the non-target cell line, Raji, using a plasmid-based transfection method. The GFP⁺ target cells facilitate tracking of the immune cell killing assay, which avoids the need for multiple cell labeling with fluorescent dyes. Our approach is also applicable to the genome editing of other target cell types for functional analysis of effector cells.

Real-Time Killing Assays to Assess the Potency of a New Anti-Simian Immunodeficiency Virus Chimeric Antigen Receptor T Cell

The success of chimeric antigen receptor (CAR) T cell therapies for treating leukemia has resulted in a booming interest for the technology. Expression of a CAR in T cells allows redirection of their natural cytolytic activity toward cells presenting a specific designated surface antigen. Although CAR T cell therapies have thus far shown promising results mostly in B cell malignancy trials, interest in their potential to treat other diseases is on the rise, including using CAR T cells to control human immunodeficiency virus infection. The assessment of CAR T cell potency toward specific targets in vitro is a critical preclinical step. In this study, we describe novel assays that monitor the cytotoxicity of candidate CAR T cells toward simian immunodeficiency virus (SIV) infected CD4 T cells. The assays involve live cell imaging using a fluorescence microscopy system that records in real time the disappearance or appearance of targets infected with SIV carrying a fluorescent protein gene. The assays are highly reproducible, and their rapid turn around and reduced cost present a significant advance regarding the efficient preclinical evaluation of CAR T cell constructs and are broadly applicable to potential human diseases that could benefit from CAR T cell therapy.

Recent advances in high-throughput flow cytometry for drug discovery

INTRODUCTION

High-throughput flow cytometry (HTFC) has proven to be an important technology in drug discovery. The use of HTFC enables multi-parametric screening of suspension cells containing heterogenous cell populations and coated particles for screening proteins of interest. Novel targets, novel cell markers and compound clusters for drug development have been identified from HTFC screens.

AREAS COVERED

In this article, the authors focus on reviewing the recent HTFC applications reported during the last 5-6 years, including drug discovery screens and studies for immune, immune-oncology, infectious and inflammatory diseases. The main HTFC approaches, development of HTFC systems, and automated sample preparation systems for HTFC are also discussed.

EXPERT OPINION

The advance of HTFC technology coupled with automated sample acquisition and sample preparation has demonstrated its utility in screening large numbers of compounds using suspension cells, facilitated screening of disease-relevant human primary cells, and enabled deep understanding of mechanism of action by analyzing multiple parameters. The authors see HTFC as a very valuable tool in immune, immune-oncology, infectious and inflammatory diseases where immune cells play essential roles.

New directions in chimeric antigen receptor T cell [CAR-T] therapy and related flow cytometry

Chimeric antigen receptor (CAR) T cells provide a promising approach to the treatment of hematologic malignancies and solid tumors. Flow cytometry is a powerful analytical modality, which plays an expanding role in all stages of CAR T therapy, from lymphocyte collection, to CAR T cell manufacturing, to in vivo monitoring of the infused cells and evaluation of their function in the tumor environment. Therefore, a thorough understanding of the new directions is important for designing and implementing CAR T-related flow cytometry assays in the clinical and investigational settings. However, the speed of new discoveries and the multitude of clinical and preclinical trials make it challenging to keep up to date in this complex field. In this review, we summarize the current state of CAR T therapy, highlight the areas of emergent research, discuss applications of flow cytometry in modern cell therapy, and touch upon several considerations particular to CAR detection and assessing the effectiveness of CAR T therapy.