Fibroblast growth factor 23 weakens chemotaxis of human blood neutrophils in microfluidic devices

Abstract

Neutrophil trafficking in tissues critically regulates the body’s immune response. Neutrophil migration can either play a protective role in host defense or cause health problems. Fibroblast growth factor 23 (FGF23) is a known biomarker for chronic kidney disease (CKD) and was recently shown to impair neutrophil arrest on endothelium and transendothelial migration. In the present study, we further examined the effect of FGF23 on human blood neutrophil chemotaxis using two new microfluidic devices. Our results showed that chemotaxis of FGF23 pre-treated neutrophils to a fMLP gradient, in the presence or absence of a uniform FGF23 background, is quantitatively lower compared to the control cells. This effect is accompanied with a stronger drifting of FGF23 pre-treated cells along the flow. However, without the FGF23 pre-treatment, the FGF23 background only reduces chemotaxis of transmigrated cells through the thin barrier channel to the fMLP gradient. The effect of FGF23 on neutrophil migration and the correlation between multiple cell migration parameters are further revealed by chemotactic entropy and principle component analysis. Collectively, these results revealed the effect of FGF23 on weakening neutrophil chemotaxis, which shed light on FGF23 mediated neutrophil migration with direct disease relevance such as CKD.

Microfluidic Devices for Studying the Effect of Netrin‐1 on Neutrophil and Breast Cancer Cell Migration

“…Using the triple‐channel microfluidic device (i.e., C 3 ‐Chip) ( Figure 1 A), dose‐dependent chemokinetic migration of purified untouched human blood neutrophils in response to uniform f MLP and netrin‐1 was assessed. It is known that f MLP is a potent chemoattractant for neutrophils and can stimulate cell motility .…”

“…To further examine the effect of netrin‐1 on neutrophil chemotaxis, a triple‐unit gradient‐generating microfluidic device with a cell docking structure that we recently developed (i.e., D 3 ‐Chip) was used ( Figure 4 A) . The D 3 ‐Chip is similar to the C 3 ‐Chip in their device fabrication, channel dimensions, flow condition, and throughput.…”

“…When a chemical gradient is applied, cells will be stimulated to crawl under the thin barrier channel and migrate into the gradient channel. The pressure balance design of this device can quickly generate stable chemical gradients without requiring external pumps (Figure S1, Supporting information) . We use 10 × 10 −9 m f MLP to test neutrophil chemotaxis, as it induces increased cell speed in our chemokinesis experiments on fibronectin.…”

“…In this study, we employed a microfluidics‐based approach and designed the experiments to address these above defined questions. First, two new microfluidic devices we recently developed were employed for cell migration experiments . These microfluidic devices allow standalone stable gradient generation and parallel cell migration analysis on a single chip, which is important for reliable comparison of different netrin‐1 fields and substrate conditions including fibronectin and collagen.…”

Microfluidic devices for neutrophil chemotaxis studies

“…Another type of gradient generators with three main channels are common devices for neutrophil chemotaxis studies [67][68][69][70]. The parallel side channels are usually set as the source and sink channel, which are connected to the middle gradient channel through barrier structure such as microgroove channels.…”