Biology subjects

Pace, J.

Publications and source records attributed to Pace, J..

3 recordsLinked to original sources

bioRxiv2024

YAP/TAZ signaling in allantois-derived cells is required for placental vascularization

Normal placental development and angiogenesis are crucial for fetal growth and maternal health during pregnancy. However, molecular regulation of placental angiogenesis has been difficult to study due to a lack of specific genetic tools that isolate the placenta from the embryo and yolk sac. To address this gap in knowledge we recently developed Hoxa13Cre mice in which Cre is expressed in allantois-derived cells, including placental endothelial and stromal cells. Mice lacking the transcriptional regulators Yes-associated protein (YAP) and PDZ-binding motif (TAZ) in allantois-derived cells exhibit embryonic lethality at midgestation with compromised placental vasculature. snRNA-seq analysis revealed transcriptional changes in placental stromal cells and endothelial cells. YAP/TAZ mutants exhibited significantly reduced placental stromal cells prior to the endothelial architectural change, highlighting the role of these cells in placental vascular growth. These results reveal a central role for YAP/TAZ signaling during placental vascular growth and implicate Hoxa13-derived placental stromal cells as a critical component of placental vascularization.

developmental biology↗

bioRxiv2022

Near-Infrared Diffuse In Vivo Flow Cytometry

SignificanceDiffuse in vivo Flow Cytometry (DiFC) is an emerging technique for enumerating rare fluorescently labeled circulating cells non-invasively in the bloodstream. Thus far we have reported red and blue-green versions of DiFC. Use of near-infrared (NIR) fluorescent light would in principle allow use of DiFC in deeper tissues and would be compatible with emerging NIR fluorescence molecular contrast agents. AimIn this work, we describe the design of a NIR-DiFC instrument and demonstrate its use in optical flow phantoms in vitro and in mice in vivo. ApproachWe developed an improved optical fiber probe design for efficient collection of fluorescence from individual circulating cells, and efficient rejection of instrument autofluorescence. We built a NIR-DiFC instrument. We tested this with NIR fluorescent microspheres and cell lines labeled with OTL38 fluorescence contrast agent in a flow phantom model. We also tested NIR-DiFC in nude mice injected intravenously with OTL38-labeled L1210A cells. ResultsNIR-DiFC allowed detection of CTCs in flow phantoms with mean signal to noise ratios (SNRs) of 19 to 32 dB. In mice, fluorescently-labeled CTCs were detectable with mean SNR of 26 dB. NIR-DiFC also exhibited orders significantly lower autofluorescence and false-alarm rates than blue-green DiFC. ConclusionsNIR-DiFC allows use of emerging NIR contrast agents. This work could pave the way for future use of NIR-DiFC in humans.

bioengineering↗

bioRxiv2022

Signal and Measurement Considerations for Human Translation of Diffuse in vivo Flow Cytometry

SignificanceDiffuse in vivo flow cytometry (DiFC) is an emerging technology for fluorescence detection of rare circulating cells directly in large deep-seated blood vessels in mice. Because DiFC uses highly scattered light, in principle it could be translated to human use. However, an open question is whether fluorescent signals from single cells would be detectable in human-scale anatomies. AimSuitable blood vessels in a human wrist or forearm are at a depth of approximately 2-4 mm. The aim of this work was to study the impact of DiFC instrument geometry and wavelength on the detected DiFC signal and on the maximum depth of detection of a moving cell. ApproachWe used Monte Carlo simulations to compute Jacobian (sensitivity) matrices for a range of source-detector separations and tissue optical properties over the visible and near infrared (NIR) spectrum. We performed experimental measurements with three available versions of DiFC (488 nm, 640 nm, and 780 nm), fluorescent microspheres, and tissue mimicking optical flow phantoms. We used both computational and experimental data to estimate the maximum depth of detection at each combination of settings. Results and ConclusionsFor the DiFC detection problem, our analysis showed that for deep-seated blood vessels, the maximum sensitivity was obtained with NIR light (780 nm) and 3 mm source-and-detector separation. These results suggest that - in combination with a suitable molecularly targeted fluorescent probes - circulating cells and nanosensors could in principle be detectable in circulation in humans.

bioengineering↗