Optimizing a reliable ex vivo human blood model to analyze expression of Staphylococcus epidermidis genes

Susana Brás; Ângela França; Nuno Cerca

doi:10.7717/peerj.9295

Optimizing a reliable ex vivo human blood model to analyze expression of Staphylococcus epidermidis genes

PeerJ. 2020 Jun 15:8:e9295. doi: 10.7717/peerj.9295. eCollection 2020.

Authors

Susana Brás¹, Ângela França¹, Nuno Cerca¹

Affiliation

¹ Centre of Biological Engineering (CEB), Laboratory of Research in Biofilms Rosário Oliveira (LIBRO), University of Minho, Braga, Portugal.

Abstract

Human blood is often used as an ex vivo model to mimic the environment encountered by pathogens inside the host. A significant variety of experimental conditions has been reported. However, optimization strategies are often not described. This study aimed to evaluate key parameters that are expected to influence Staphylococcus epidermidis gene expression when using human blood ex vivo models. Our data confirmed that blood antimicrobial activity was dependent on initial bacterial concentration. Furthermore, blood degradation over time resulted in lower antimicrobial activity, with a 2% loss of leukocytes viability correlating with a 5-fold loss of antimicrobial activity against S. epidermidis. We further demonstrated that the volume of human blood could be reduced to as little as 0.18 mL without affecting the stability of gene expression of the tested genes. Overall, the data described herein highlight experimental parameters that should be considered when using a human blood ex vivo model for S. epidermidis gene expression analysis.

Keywords: Bacterial survival; Gene expression; Human blood ex vivo model; Staphylococcus epidermidis; Volume of human blood.

Grants and funding

This work was supported by the Portuguese Foundation for Science and Technology (FCT) by the funded project PTDC/BIA-MOL/29553/2017, under the scope of COMPETE2020 [POCI-01-0145-FEDER-02955 and by the strategic funding of unit UIDB/04469/2020 and by European funds under BioTecNorte operation [NORTE-01-0145-FEDER-000004 funded by European Regional Development Fund under the scope of Norte2020. Susana Brás is supported by a fellowship granted by a Doctoral Advanced Training [Norte 69-2015-15 funded by the European Social Fund under the scope of Norte2020. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.