Neutrophil Lifespan Extension with CLON-G and an In Vitro Spontaneous Death Assay
May 12th, 2023
This protocol details the preparation of CLON-G to extend the neutrophil lifespan to greater than 5 days and provides a reliable procedure for evaluating neutrophil death with flow cytometry and confocal fluorescence microscopy.
Our protocol provides a cocktail medium to prolong the neutrophil lifespan to more than five days without compromising the neutrophil functions. It also offers reliable in vitro dialysis for neutrophils. CLON-G treatment expands the possibilities of neutrophil preservation, transportation, and gene manipulation, which can accelerate research in the neutrophil community.
To begin, prepare the basic medium by adding RPMI 1640 FBS and pen-strep to a 50 milliliter tube. Simultaneously, thaw all the stock solutions of the CLON-G components on ice. Then dilute HSP 70 and 200 micrograms per milliliter of G-CSF in the basic medium.
Transfer 976 microliters of basic medium to a 15 milliliter centrifuge tube. To this, add the CLON-G components to prepare one milliliter of 2x CLON-G medium as described in the manuscript. Next, prepare the neutrophil culture by suspending the isolated mouse neutrophils in the basic medium.
Add CLON-G medium, followed by the basic medium to 24 well non tissue cultured plates. Then add 100 microliters of the prepared cell suspension and gently pipet three to four times. Incubate the culture plate at 37 degrees Celsius with 5%carbon dioxide supply.
Stain the cultured neutrophils with cytospin and analyze them using a light microscope. For flow cytometry analysis, add one milliliter of cell medium to the neutrophil cell culture grown overnight. Mix the cell culture medium by gently pipetting it five to seven times and transfer 100 microliters of this mixture to a flow cytometry tube at the desired time points.
Simultaneously, vortex the counting beads and pipet 10 microliters of bead solution to the same flow cytometry tube containing cell medium. Add 10 microliters of a pre-prepared staining mix to this flow cytometry tube and incubate for five minutes in the refrigerator under dark. Then add 100 microliters of saline to the tube and mix well for even distribution of the counting beads and cells.
Finally, perform the flow cytometry analysis of the cell suspension as described in the text manuscript. For fluorescent images assay, add two milliliters of cell suspension per confocal plate and incubate at 37 degrees Celsius and 5%carbon dioxide. Meanwhile, dissolve one gram of calcium chloride in 45 milliliters of saline and filter it with a 0.2 micrometer filtering unit.
Gently remove the confocal plate at the required time point. Stain the cells with 10 microliters of FITC-Annexin-V, PI and calcium chloride for five minutes at room temperature. Then using a confocal fluorescence microscope, capture the images using the desired channels.
In the present study, the morphology of neutrophils was not affected in the CLON-G medium even after five days. Moreover, the fax phenotypes demonstrated intact cells after the treatment. The flow cytometry analysis showed a positive population of untreated neutrophils in Annexin-V and the population loss could be due to ethylene diamine tetraacetic acid in the cell medium.
However, the viability of the CLON-G treated neutrophils at 24 hours was approximately more than 90%The fluorescent image assays also confirmed the cell viability of CLON-G treated neutrophils. The neutrophils cultured in the basic medium for 24 hours showed puffed cells and the loss of these cells might have resulted from the shaking or pipetting of the confocal plate. CLON-G compound concentrations and effects can significantly impact neutrophil tests.
If at all possible, avoid modulating them. Neutrophil investigations are laborious, expensive, and extremely limited in clinical application due to their short life span. This method partially overcomes these obstacles.
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Overview
This study presents a protocol for preparing CLON-G, a medium that extends the lifespan of neutrophils to over five days while maintaining their functionality. The methodology enables reliable assessment of neutrophil death through flow cytometry and confocal fluorescence microscopy.
Key Study Components
Research Area
- Neutrophil biology
- Cell lifespan extension
- Flow cytometry and microscopy
Background
- Neutrophils have a short lifespan, limiting their research applications.
- Current methods for neutrophil preservation are often inadequate.
- CLON-G represents a potential solution for extended neutrophil viability.
Methods Used
- Preparation of a cocktail medium (CLON-G) for neutrophil culture
- Isolation and culturing of mouse neutrophils
- Use of flow cytometry and confocal microscopy for analysis
Main Results
- Neutrophils treated with CLON-G showed over 90% viability after 24 hours.
- CLON-G did not affect cell morphology or function over the extended period.
- The protocol allows for effective neutrophil preservation for further experimental manipulation.
Conclusions
- This study demonstrates the utility of CLON-G in extending neutrophil lifespan.
- The findings have significant implications for future neutrophil-related research, potentially enhancing experimental outcomes.
Frequently Asked Questions
Executive Industry Relevance
Short neutrophil lifespan has historically constrained both mechanistic studies and translational research in immunology and inflammation. The CLON-G cocktail and associated in vitro spontaneous death assay enable extended neutrophil viability, supporting more robust target validation and functional interrogation across early discovery and preclinical workflows. This capability enhances predictive confidence and continuity for programs reliant on neutrophil biology.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables extended functional studies of neutrophil pathways for target validation.
- Supports mechanistic de-risking by allowing multi-day interrogation of cell death processes.
- Facilitates hypothesis testing on neutrophil survival and death mechanisms.
Screening & Assay Development
- Provides a standardized, reproducible system for neutrophil-based assays.
- Improves assay window and throughput by maintaining cell viability beyond 24 hours.
- Enables quantitative readouts via flow cytometry and confocal microscopy.
Translational & Preclinical Research
- Supports disease-relevant modeling of neutrophil function and survival.
- Allows for extended manipulation and phenotypic screening of neutrophils in vitro.
- Improves translational continuity for inflammation and immune modulation programs.
Pipeline & Workflow Integration
The CLON-G protocol positions neutrophil studies for integration from early discovery through preclinical validation, bridging functional assays and mechanistic studies.
- Discovery Biology: Extends the timeframe for hypothesis-driven neutrophil experiments and pathway analysis.
- Screening: Enables robust, reproducible neutrophil-based assays with quantitative viability outputs.
- Analytics: Provides flow cytometry and confocal microscopy data for comparative condition analysis.
- Translational Research: Facilitates alignment with disease-relevant neutrophil phenotypes and survival endpoints.
- Enterprise Reuse: Establishes a reusable platform for neutrophil preservation, manipulation, and transport across projects.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces ambiguity in neutrophil-targeted studies.
- Operational Value: Standardizes neutrophil handling, improving reproducibility and scalability.
- Strategic Value: Enables more informed go/no-go decisions for neutrophil-centric programs.
- Portfolio Impact: Supports risk-adjusted prioritization of inflammation and immune modulation assets.
Implementation Considerations
- Requires expertise in neutrophil isolation and culture techniques.
- Needs access to flow cytometry and confocal microscopy infrastructure.
- Demands cross-team standardization of CLON-G preparation and assay protocols.
- Adaptation to other granulocyte models may require protocol optimization.
- Compound concentrations and handling can significantly impact assay outcomes.
