Author Contributions G.M. designed and performed the experiments, analyzed and interpreted the data, and wrote the manuscript. M.A.M. designed and supervised the research, analyzed and interpreted the data, and wrote the manuscript. C.V.C. co-designed and assisted with high spatiotemporal resolution microscopy experiments. E.J.H. and J.R.P. co-designed and assisted with zebrafish experiments. N.M. and T.P. co-designed and performed the BBB-on-a-chip experiments. C.C.D. assisted with some of the experiments. L.I.Z. and D.E.I. provided zebrafish and BBB-on-a-chip models, respectively.

Specific leukocyte/endothelial interactions are critical for immunity and inflammation, yet the molecular details of this interaction interface remain poorly understood. Thus, we investigated, with confocal microscopy, the distribution dynamics of the central adhesion molecules ICAM-1 and LFA-1 in this context. Monolayers of activated HUVECs stained with fluorescent anti-ICAM-1 Fabs or Chinese hamster ovary-K1 cells expressing ICAM-1-green fluorescent protein were allowed to bind LFA-1-bearing monocytes, neutrophils, or K562 LFA-1 transfectants. ICAM-1 was rapidly relocalized to newly formed microvilli-like membrane projections in response to binding LFA-1 on leukocytes. These ICAM-1-enriched projections encircled the leukocytes extending up their sides and clustered LFA-1 underneath into linear tracks. Projections formed independently of VCAM-1/very late Ag 4 interactions, shear, and proactive contributions from the LFA-1-bearing cells. In the ICAM-1-bearing endothelial cells, projections were enriched in actin but not microtubules, required intracellular calcium, and intact microfilament and microtubule cytoskeletons and were independent of Rho/Rho kinase signaling. Disruption of these projections with cytochalasin D, colchicine, or BAPTA-AM had no affect on firm adhesion. These data show that in response to LFA-1 engagement the endothelium proactively forms an ICAM-1-enriched cup-like structure that surrounds adherent leukocytes but is not important for firm adhesion. This finding leaves open a possible role in leukocyte transendothelial migration, which would be consistent with the geometry and kinetics of formation of the cup-like structure.

Antigen-specific immunity requires regulated trafficking of T cells in and out of diverse tissues in order to orchestrate lymphocyte development, immune surveillance, responses, and memory. The endothelium serves as a unique barrier, as well as a sentinel, between the blood and the tissues, and as such it plays an essential locally tuned role in regulating T cell migration and information exchange. While it is well established that chemoattractants and adhesion molecules are major determinants of T cell trafficking, emerging studies have now enumerated a large number of molecular players as well as a range of discrete cellular remodeling activities (e.g., transmigratory cups and invadosome-like protrusions) that participate in directed migration and pathfinding by T cells. In addition to providing trafficking cues, intimate cell–cell interaction between lymphocytes and endothelial cells provide instruction to T cells that influence their activation and differentiation states. Perhaps the most intriguing and underappreciated of these “sentinel” roles is the ability of the endothelium to act as a non-hematopoietic “semiprofessional” antigen-presenting cell. Close contacts between circulating T cells and antigen-presenting endothelium may play unique non-redundant roles in shaping adaptive immune responses within the periphery. A better understanding of the mechanisms directing T cell trafficking and the antigen-presenting role of the endothelium may not only increase our knowledge of the adaptive immune response but also empower the utility of emerging immunomodulatory therapeutics.

Background Conventional preclinical models often miss drug toxicities, meaning the harm these drugs pose to humans is only realized in clinical trials or when they make it to market. This has caused the pharmaceutical industry to waste considerable time and resources developing drugs destined to fail. Organ-on-a-Chip technology has the potential improve success in drug development pipelines, as it can recapitulate organ-level pathophysiology and clinical responses; however, systematic and quantitative evaluations of Organ-Chips’ predictive value have not yet been reported. Methods 870 Liver-Chips were analyzed to determine their ability to predict drug-induced liver injury caused by small molecules identified as benchmarks by the Innovation and Quality consortium, who has published guidelines defining criteria for qualifying preclinical models. An economic analysis was also performed to measure the value Liver-Chips could offer if they were broadly adopted in supporting toxicity-related decisions as part of preclinical development workflows. Results Here, we show that the Liver-Chip met the qualification guidelines across a blinded set of 27 known hepatotoxic and non-toxic drugs with a sensitivity of 87% and a specificity of 100%. We also show that this level of performance could generate over $3 billion annually for the pharmaceutical industry through increased small-molecule R&D productivity. Conclusions The results of this study show how incorporating predictive Organ-Chips into drug development workflows could substantially improve drug discovery and development, allowing manufacturers to bring safer, more effective medicines to market in less time and at lower costs.

Human organ-on-a-chip (Organ-Chip) technology has the potential to disrupt preclinical drug discovery and improve success in drug development pipelines as it can recapitulate organ-level pathophysiology and clinical responses. The Innovation and Quality (IQ) consortium, formed by multiple pharmaceutical and biotechnology companies, has published guidelines that define criteria for qualifying preclinical models, however, systematic and quantitative evaluation of the predictive value of Organ-Chips has not yet been reported. Here, 780 Liver-Chips were analyzed to determine their ability to predict drug-induced liver injury (DILI) caused by small molecules identified as benchmarks by the IQ consortium. The Liver-Chip met the qualification guidelines across a blinded set of 27 known hepatotoxic and non-toxic drugs with a sensitivity of 80% and a specificity of 100%. A computational economic value analysis suggests that with this performance the Liver-Chip could generate $3 billion annually for the pharmaceutical industry due to increased R&D productivity.

This study was designed to compare the relationship of measured and estimated indices of adiposity with the spontaneous GH secretion (SGHS) in 37 normal short stature children. Fifteen of the 37 patients (10 males and 5 females) were pubertal, and 22 (17 males and 5 females) were prepubertal. All patients underwent a review of their medical history, a physical exam, laboratory tests, and a nutritional assessment that included anthropometry and evaluation of body composition by bioelectric impedance. The percentage of body fat and body fat mass index were used as measured indices of adiposity. The weight for height ratio, body mass index, and body mass index z-scores were calculated and used as estimated indices of adiposity. Our results showed that SGHS is greatly influenced by variations in adiposity in normal short stature children, and measured indices of adiposity demonstrated the strongest negative correlation with SGHS. Gender differences were apparent in the degree of adiposity that modified SGHS, and it appears that adiposity altered the amplitude of GH pulses in pubertal patients and the number of pulses in prepubertal children. These results suggest that interpretation of SGHS must take into account body composition and gender in addition to pubertal status.

Loss of function of the tumor suppressor p53 is known to increase the rate of migration of cells transiting the narrow pores of the traditional Boyden chamber assay. Here by contrast we investigate how p53 impacts the rate of cellular migration within a 2D confluent cell layer and a 3D collagen-embedded multicellular spheroid. We use two human carcinoma cell lines, the bladder carcinoma EJ and the colorectal carcinoma HCT116. In the confluent 2-D cell layer, for both EJ and HCT cells the migratory speeds and effective diffusion coefficients for the p53 null cells were significantly smaller than in p53-expressing cells. Compared to p53 expressers, p53-null cells exhibited more organized cortical actin rings together with reduced front-rear cell polarity. Furthermore, loss of p53 caused cells to exert smaller traction forces upon their substrates, and reduced formation of cryptic lamellipodia. In the 3D multicellular spheroid, loss of p53 consistently reduced collective cellular migration into surrounding collagen matrix. As regards the role of p53 in cellular migration, extrapolation from the Boyden chamber assay to other cellular microenvironments is seen to be fraught even in terms of the sign of the effect. Together, these paradoxical results show that the effects of p53 on cellular migration are context-dependent.

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