An inflammatory vascular endothelium-mimicking microfluidic device to enable leukocyte rolling and adhesion for rapid infection diagnosis

A non-human primate derived anti-P-selectin glycoprotein ligand-1 antibody curtails acute pancreatitis by alleviating the inflammatory responses

Acute pancreatitis (AP) is a devastating disease characterized by an inflammatory disorder of the pancreas. P-selectin glycoprotein ligand-1 (PSGL-1) plays a crucial role in the initial steps of the adhesive at process to inflammatory sites, blockade of PSGL-1 might confer potent anti-inflammatory effects. In this study, we generated two non-human primate derived monoclonal antibodies capable of efficiently targeting human PSGL-1, RH001-6 and RH001-22, which were screened from immunized rhesus macaques. We found that RH001-6, can effectively block the binding of P-selectin to PSGL-1, and abolish the adhesion of leukocytes to endothelial cells in vitro. In vivo, we verified that RH001-6 relieved inflammatory responses and pancreatic injury in both caerulein and l-arginine induced AP models. We also evaluated the safety profile after RH001-6 treatment in mice, and verified that RH001-6 did not cause any significant pathological damages in vivo. Taken together, we developed a novel non-human primate derived PSGL-1 blocking antibody with high-specificity, named RH001-6, which can interrupt the binding of PSGL-1 and P-selectin and attenuate inflammatory responses during AP. Therefore, RH001-6 is highly potential to be further developed into therapeutics against acute inflammatory diseases, such as AP.

Nanoscopic Characterization of Cell Migration under Flow Using Optical and Electron Microscopy

Hematopoietic stem/progenitor cell (HSPC) and leukemic cell homing is an important biological phenomenon that takes place through essential interactions with adhesion molecules on an endothelial cell layer. The homing process of HSPCs begins with the tethering and rolling of the cells on the endothelial layer, which is achieved by the interaction between selectins on the endothelium to the ligands on HSPC/leukemic cells under shear stress of the blood flow. Although many studies have been based on in vitro conditions of the cells rolling over recombinant proteins, significant challenges remain when imaging HSPC/leukemic cells on the endothelium, a necessity when considering characterizing cell-to-cell interaction and rolling dynamics during cell migration. Here, we report a new methodology that enables imaging of stem-cell-intrinsic spatiotemporal details during its migration on an endothelium-like cell monolayer. We developed optimized protocols that preserve transiently appearing structures on HSPCs/leukemic cells during its rolling under shear stress for fluorescence and scanning electron microscopy characterization. Our new experimental platform is closer to in vivo conditions and will contribute to indepth understanding of stem-cell behavior during its migration and cell-to-cell interaction during the process of homing.

Modeled vascular microenvironments: immune-endothelial cell interactions in vitro

The advancement of in vitro techniques enables a better understanding of biological processes and improves drug screening platforms. In vitro studies allow for enhanced observation of cell behavior, control over the mimicked microenvironment, and the ability to use human cells. In particular, advances in vascular microenvironment recapitulation are of interest given vasculature influence in cardiovascular vascular diseases and cancer. These investigate alterations in endothelial cell behavior and immune cell interactions with endothelial cells. Specific immune cells such as monocytes, macrophages, neutrophils, and T cells influence endothelial cell behavior by promoting or inhibiting vasculogenesis through cell-cell interaction or soluble signaling. Results from these studies showcase cell behavior in vascular diseases and in the context of tumor metastasis. In this review, we discuss examples of in vitro studies modeling immune cell-endothelial cell interactions to present methods and recent findings in the field. Schematic showcasing common methods of in vitro experimentation of endothelial-immune cell interactions, including interactions with flow, static culture, or in-direct contact.

Microfluidic models of the human circulatory system: versatile platforms for exploring mechanobiology and disease modeling

The human circulatory system is a marvelous fluidic system, which is very sensitive to biophysical and biochemical cues. The current animal and cell culture models do not recapitulate the functional properties of the human circulatory system, limiting our ability to fully understand the complex biological processes underlying the dysfunction of this multifaceted system. In this review, we discuss the unique ability of microfluidic systems to recapitulate the biophysical, biochemical, and functional properties of the human circulatory system. We also describe the remarkable capacity of microfluidic technologies for exploring the complex mechanobiology of the cardiovascular system, mechanistic studying of cardiovascular diseases, and screening cardiovascular drugs with the additional benefit of reducing the need for animal models. We also discuss opportunities for further advancement in this exciting field.

Host Diagnostic Biomarkers of Infection in the ICU: Where Are We and Where Are We Going?

Purpose of Review

Early identification of infection in the critically ill patient and initiation of appropriate treatment is key to reducing morbidity and mortality. On the other hand, the indiscriminate use of antimicrobials leads to harms, many of which may be exaggerated in the critically ill population. The current method of diagnosing infection in the intensive care unit relies heavily on clinical gestalt; however, this approach is plagued by biases. Therefore, a reliable, independent biomarker holds promise in the accurate determination of infection. We discuss currently used host biomarkers used in the intensive care unit and review new and emerging approaches to biomarker discovery.

Recent Findings

White cell count (including total white cell count, left shift, and the neutrophil-leucocyte ratio), C-reactive protein, and procalcitonin are the most common host diagnostic biomarkers for sepsis used in current clinical practice. However, their utility in the initial diagnosis of infection, and their role in the subsequent decision to commence treatment, remains limited. Novel approaches to biomarker discovery that are currently being investigated include combination biomarkers, host 'sepsis signatures' based on differential gene expression, site-specific biomarkers, biomechanical assays, and incorporation of new and pre-existing host biomarkers into machine learning algorithms.

Summary

To date, no single reliable independent biomarker of infection exists. Whilst new approaches to biomarker discovery hold promise, their clinical utility may be limited if previous mistakes that have afflicted sepsis biomarker research continue to be repeated.