T Cells Chemotaxis Migration Studies with a Multi-Channel Microfluidic Device.

Immune surveillance is dependent on lymphocyte migration and targeted recruitment. This can involve different modes of cell motility ranging from random walk to highly directional environment-guided migration driven by chemotaxis. This study protocol describes a flow-based microfluidic device to perform quantitative multiplex cell migration assays with the potential to investigate in real time the migratory response of T cells at the population or single-cell level. The device also allows for subsequent in situ fixation and direct fluorescence analysis of the cells in the microchannel.

Investigations on T cell transmigration in a human skin-on-chip (SoC) model.

A microfluidics-based three-dimensional skin-on-chip (SoC) model is developed in this study to enable quantitative studies of transendothelial and transepithelial migration of human T lymphocytes in mimicked skin inflammatory microenvironments and to test new drug candidates. The keys results include 1) CCL20-dependent T cell transmigration is significantly inhibited by an engineered CCL20 locked dimer (CCL20LD), supporting the potential immunotherapeutic use of CCL20LD for treating skin diseases such as psoriasis; 2) transepithelial migration of T cells in response to a CXCL12 gradient mimicking T cell egress from the skin is significantly reduced by a sphingosine-1-phosphate (S1P) background, suggesting the role of S1P for T cell retention in inflamed skin tissues; and 3) T cell transmigration is induced by inflammatory cytokine stimulated epithelial cells in the SoC model. Collectively, the developed SoC model recreates a dynamic multi-cellular micro-environment that enables quantitative studies of T cell transmigration at a single cell level in response to physiological cutaneous inflammatory mediators and potential drugs.

Mucus-penetrating PEGylated polysuccinimide-based nanocarrier for intravaginal delivery of siRNA battling sexually transmitted infections.

Intravaginal delivery of siRNA for prevention of sexually transmitted infections faces obstacles such as the acidic environment and vaginal mucus barrier. To achieve effective protection and delivery of siRNA, we developed a polysuccinimide (PSI)-based nanocarrier (PSI-PEG-API-PMA, PPAP) by conjugating methoxy polyethylene glycol amine (Me-PEG-NH2, Mw 5000), 1-(3-aminopropyl)imidazole (API), and 1-pyrenemethylamine hydrochloride (PMA) to PSI. PPAP demonstrated a spherical self-assembled nanostructure before and after encapsulation of a model siRNA. Variable electrostatic interaction between API and siRNA at acidic vs. neutral pH accomplished significantly lower burst release at pH 4.2 (4 ±â€¯1%) than pH 7.0 (26 ±â€¯5%) within 1 h. PEGylation enabled siRNA-PPAP to achieve higher mucus penetration efficiency (64 ±â€¯17%) than free siRNA (27 ±â€¯5%) for 24 h. Moreover, in vitro study showed minimal toxicity, successful internalization of siRNA-PPAP in HeLa cells and improved gene knockdown (97.5 ±â€¯0.4%). Overall, PPAP is promising for developing preventative treatments for battling sexually transmitted infections.

TILRR Promotes Migration of Immune Cells Through Induction of Soluble Inflammatory Mediators.

TILRR has been identified as an important modulator of inflammatory responses. It is associated with NF-κB activation, and inflammation. Our previous study showed that TILRR significantly increased the expression of many innate immune responsive genes and increased the production of several pro-inflammatory cytokines/chemokines by cervical epithelial cells. In this study, we evaluated the effect of TILRR-induced pro-inflammatory cytokines/chemokines on the migration of immune cells. The effect of culture supernatants of TILRR-overexpressed cervical epithelial cells on the migration of THP-1 monocytes and MOLT-4 T-lymphocytes was evaluated using Transwell assay and a novel microfluidic device. We showed that the culture supernatants of TILRR-overexpressed HeLa cells attracted significantly more THP-1 cells (11-40%, p = 0.0004-0.0373) and MOLT-4 cells (14-17%, p = 0.0010-0.0225) than that of controls. The microfluidic device-recorded image analysis showed that significantly higher amount with longer mean cell migration distance of THP-1 (p < 0.0001-0.0180) and MOLT-4 (p < 0.0001-0.0025) cells was observed toward the supernatants of TILRR-overexpressed cervical epithelial cells compared to that of the controls. Thus, the cytokines/chemokines secreted by the TILRR-overexpressed cervical epithelial cells attracted immune cells, such as monocytes and T cells, and may potentially influence immune cell infiltration in tissues.

Applications of microfluidic devices in advancing NK-cell migration studies.

Understanding how NK cells interact with tumor cells under specific microenvironment will be informative in development of NK-cell based immunotherapy. Applications of microfluidic devices in in vitro studies of NK-cell migrations offer unique opportunities to examine NK-cell migrations at single-cell under controlled cellular microenvironments. Novel devices can be created and engineered to present precise configuration that mimics cellular microenvironments for cell migration studies. We established previously the first application of a simple Y-shaped device for imaging and analysis of the abilities of the immature and mature DC to regulate murine IL-2 activated NK cell migrations. Here we reported the application of our recent technical development of a novel microfluidic device, which is also called the triple docking device (i.e., D3-Chip), for the studies of NK-cell migrations in NK-4T1 breast cancer cell interactions in vitro. Key features of this microfluidic device are its pump-free gradient generation, and the three-parallel units design that supports easy setup and parallel comparison of multiple experimental conditions. The cell docking structure enables the prealignment of all NK cells at the same "start" position before their exposures to the test conditions. As a result, quantification of cell displacement toward a chemical gradient can be quantified by enumeration of the number of cells migrated out of the docking structure and their displacements. Such microfluidic devices can be further modified in future to mimic the complex in vivo microenvironments to support more advanced investigations of NK-cell migratory responses in vitro.

Sputum from chronic obstructive pulmonary disease patients inhibits T cell migration in a microfluidic device.

Chronic obstructive pulmonary disease (COPD) is a common lung disease characterized by narrowed airways, resulting in serious breathing difficulty. Previous studies have demonstrated that inflammatory infiltration of leukocytes in the airway is associated with the pathogenesis of COPD. In the present study, we employed a microfluidic approach to assess the effect of COPD sputum on activated human peripheral blood T cell migration and chemotaxis under well-controlled gradient conditions. Our results showed considerable basal migration of T cells derived from peripheral blood of COPD patients and healthy controls in the medium control groups. By contrast, the migration of T cells from COPD patients and healthy controls was significantly inhibited in the presence of a gradient of sputum supernatant from COPD patients. Furthermore, chemotaxis of T cells from COPD patients or healthy subjects toward an SDF-1α gradient was clearly inhibited by sputum samples from the COPD patients. The inhibition effect revealed by the microfluidic cell migration experiments provides new information about the complex involvement of T cell trafficking in COPD.

Cell Migration Research Based on Organ-on-Chip-Related Approaches.

Microfluidic devices have been widely used for cell migration research over the last two decades, owing to their attractive features in cellular microenvironment control and quantitative single-cell migration analysis. However, the majority of the microfluidic cell migration studies have focused on single cell types and have configured microenvironments that are greatly simplified compared with the in-vivo conditions they aspire to model. In addition, although cell migration is considered an important target for disease diagnosis and therapeutics, very few microfluidic cell migration studies involved clinical samples from patients. Therefore, more sophisticated microfluidic systems are required to model the complex in-vivo microenvironment at the tissue or organ level for cell migration studies and to explore cell migration-related clinical applications. Research in this direction that employs organ-on-chip-related approaches for cell migration analysis has been increasingly reported in recent years. In this paper, we briefly introduce the general background of cell migration and organ-on-chip research, followed by a detailed review of specific cell migration studies using organ-on-chip-related approaches, and conclude by discussing our perspectives of the challenges, opportunities and future directions.

Targeting the WASF3-CYFIP1 Complex Using Stapled Peptides Suppresses Cancer Cell Invasion.

Activation of the WASF3 protein by extracellular stimuli promotes actin cytoskeleton reorganization and facilitates cancer cell invasion, whereas WASF3 depletion suppresses invasion and metastasis. In quiescent cells, the interaction between WASF3 and a complex of proteins, including CYFIP1, acts as a conformational restraint to prevent WASF3 activation. Therefore, we took advantage of this endogenous regulatory mechanism to investigate potential sites that disrupt WASF3 function. Here, we show that genetic knockdown of CYFIP1 in cancer cells led to the destabilization of the WASF3 complex, loss of WASF3 function, and suppressed invasion. Based on existing crystallographic data, we developed stapled peptides, referred to as WASF Helix Mimics (WAHM), that target an α-helical interface between WASF3 and CYFIP1. Treatment of highly invasive breast and prostate cancer cells with WAHM inhibitor peptides significantly reduced motility and invasion in vitro. Mechanistic investigations revealed that these inhibitors suppressed the interaction between Rac and the WASF3 complex, which has been shown to promote cell migration. Furthermore, peptide-mediated inhibition of WASF3 also resulted in the dysregulation of known downstream targets such as MMP-9 and KISS1. Finally, we demonstrate that this invasive phenotype is specific to WASF3 as depletion of WASF1 and WASF2, which can also bind to CYFIP1, did not affect invasion. Collectively, our findings suggest that targeting WASF3 function with WAHM peptides could represent a promising therapeutic strategy for preventing tumor invasion and metastasis.

Lens defects and age-related fiber cell degeneration in a mouse model of increased AbetaPP gene dosage in Down syndrome.

Early-onset cataract and Alzheimer's disease occur with high frequency in Down syndrome (trisomy 21), the most common chromosome duplication in human live births. Previously, we used in vivo and lens organ culture models to demonstrate Alzheimer pathophysiology in oxidative stress-related lens degeneration. Currently, well-characterized Alzheimer transgenic mouse models are used to extend these findings. Here, we report on mice carrying a complete copy of a wild-type human AbetaPP (hAbetaPP) gene from the Down syndrome critical region on chromosome 21. hAbetaPP mice produce fiber cell membrane defects similar to those described in human cataracts and increased age-related lens degeneration. hAbetaPP expression and mRNA alternative splicing in human and mouse lens and cornea favor longer, potentially more amyloidogenic forms. Endogenous mouse AbetaPP expression is increased in transgenic lenses, consistent with the cycle of oxidative stress proposed in the mechanism of Alzheimer pathophysiology. Alternative splicing previously designated as neuron-specific occurs in human lens and cornea, and is maintained by hAbetaPP expressed in mouse tissues. These present data implicate AbetaPP in fiber cell formation and in early-onset cataracts in Down syndrome. Finally, our findings provide further support for our hypothesis that Alzheimer pathophysiology contributes to the cataract formation that is increasing in the aging population.