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Biology subjects

Griffith, B.

Publications and source records attributed to Griffith, B..

3 recordsLinked to original sources

A Combined Computational Fluid Dynamics Modeling and Geometric Morphometrics Methods Approach to Quantifying Hemodynamic and Anatomical Features of Embryonic Chick Heart Anatomies Reconstructed from Light Sheet Fluorescence Microscopy Imaging

Although congenital heart defects occur in approximately 1% of newborns in the US annually, their pathogenesis remains largely unknown. Less than a third of congenital heart defects are traced a known genetic or environmental cause. It has been demonstrated that hemodynamic forces such as wall shear stress are critical for heart development. However, measuring these hemodynamic factors in vivo is infeasible due to physical limitations, such as the small size and constant motion of the embryonic heart. An alternative approach is to recapitulate the hemodynamic environment by simulating blood flow and calculating the resulting hemodynamic forces through computational fluid dynamics modeling. We use computational fluid dynamics modeling to quantify hemodynamics in a cohort of cell-accurate embryonic chick heart anatomies reconstructed using light sheet fluorescent microscopy. Additionally, we perform a quantitative analysis on geometric features using geometric morphometric methods. Together, the high-resolution but accessible imaging technique of light sheet fluorescence microscopy to reconstruct the anatomies paired with computational fluid dynamics modeling and geometric morphometrics methods produces a fast and accessible pipeline for quantitative hemodynamic and anatomical analysis in embryonic heart development.

developmental biology↗

Analysis of donor pancreata defines the transcriptomic signature and microenvironment of early pre-neoplastic pancreatic lesions

The adult healthy human pancreas has been poorly studied given lack of indication to obtain tissue from the pancreas in the absence of disease and rapid postmortem degradation. We obtained pancreata from brain dead donors thus avoiding any warm ischemia time. The 30 donors were diverse in age and race and had no known pancreas disease. Histopathological analysis of the samples revealed PanIN lesions in most individuals irrespective of age. Using a combination of multiplex immunohistochemistry, single cell RNA sequencing, and spatial transcriptomics, we provide the first ever characterization of the unique microenvironment of the adult human pancreas and of sporadic PanIN lesions. We compared healthy pancreata to pancreatic cancer and peritumoral tissue and observed distinct transcriptomic signatures in fibroblasts, and, to a lesser extent, macrophages. PanIN epithelial cells from healthy pancreata were remarkably transcriptionally similar to cancer cells, suggesting that neoplastic pathways are initiated early in tumorigenesis. Statement of significanceThe causes underlying the onset of pancreatic cancer remain largely unknown, hampering early detection and prevention strategies. Here, we show that PanIN are abundant in healthy individuals and present at a much higher rate than the incidence of pancreatic cancer, setting the stage for efforts to elucidate the microenvironmental and cell intrinsic factors that restrain, or, conversely, promote, malignant progression.

cancer biology↗

Microphysiological vascular malformation model reveals a role of dysregulated Rac1 and mTORC1/2 in lesion formation.

Somatic activating mutations of PIK3CA are associated with the development of vascular malformations (VMs). Here, we describe a microfluidic model of PIK3CA-driven VMs consisting of human umbilical vein endothelial cells (HUVECs) expressing PIK3CA activating mutations embedded in 3D hydrogels. We observed enlarged and irregular vessel phenotypes, consistent with clinical signatures and concomitant with PI3K-driven upregulation of Rac1/PAK, MEK/ERK, and mTORC1/2 signaling. We observed differential effects between Alpelisib, a PIK3CA inhibitor, and Rapamycin, an mTORC1 inhibitor, in mitigating matrix degradation and vascular network topology. While both drugs are effective in preventing vessel enlargement, Alpelisib suppressed mTORC2-dependent AKT1 phosphorylation and MEK/ERK signaling. Rapamycin failed to reduce MEK/ERK and mTORC2 activity and resulted in vascular hyperbranching, while inhibiting PAK, MEK1/2, and mTORC1/2 signaling mitigates abnormal growth and vascular dilation. Collectively, these findings establish an in vitro platform for modeling VMs and confirm a role of dysregulated Rac1/PAK and mTORC1/2 signaling in PIK3CA-driven VMs.

bioengineering↗