Biology subjects

Li, Z.-Y.

Publications and source records attributed to Li, Z.-Y..

4 recordsLinked to original sources

bioRxiv2025

Putative long-range mossy fiber sprouting and regional hypermetabolic capacity in the hippocampus of patients with mesial temporal lobe epilepsy

Mesial temporal lobe epilepsy (MTLE) is pathologically characterized by neuronal loss in the dentate hilus, CA3 and CA1 regions, and mossy fiber (MF) sprouting into the inner molecular layer (iML). The latter forms aberrant excitatory circuities that are considered to facilitate recurrent seizures, with the subiculum also being related to epileptogenic activation. We recently identified a distinct expression of -smooth muscle actin (SMA) at the MF terminals in human hippocampus. This prompted us to explore MF sprouting in resected hippocampi (n=20) from patients with MTLE relative to postmortem control (n=20) using SMA along with reference markers for pathological cross-validation. Compared to control, neuronal loss assessed with neuron-specific nuclear antigen and sortilin immunolabeling reached CA1 in all resected hippocampi. SMA, zinc transporter 3 and {beta}-secretase 1 immunolabeling in the iML tended to be increased. The MF-related markers also revealed a preserved fibrous band extending across CA1 to subiculum. Cytochrome c oxidase immunolabeling also increased in iML and subiculum in the MTLE group. Taking together, the current findings point to the existence of long-range MF sprouting and a regional hypermetabolic compacity in the hippocampal formation of patients with drug resistant MTLE.

neuroscience↗

bioRxiv2024

Engineering tissue-mimetic hydrogels with continuous viscoelastic gradient for programmed cell migration

The dynamic, viscoelastic nature of the extracellular matrix (ECM), with variations in stiffness and viscosity, plays a key role in cellular behaviors like mechano-sensing, migration, and force generation. Viscoelastic hydrogels are important for mimicking the ECM to study cell migration and tissue engineering. However, creating hydrogels with continuous viscoelastic gradients is challenging due to issues with spatial resolution, reproducibility, and accurately replicating native tissue properties. Here we present a novel approach to generate hydrogels with precisely controllable viscoelastic gradients using drop-by-drop condensation. This approach allows fine-tuned replication of the tissue-specific local mechanical properties, resulting in hydrogels of heterogeneous viscoelasticity. Directed migration and separation of multiple cell lines are thus driven by local viscosity and elasticity rather than solely stiffness. By incorporating non-linear mechanical gradients, this technique provides insights into ECM viscoelasticitys role in cellular behavior and offers a versatile platform for advanced tissue engineering and regenerative medicine applications.

biophysics↗

bioRxiv2023

CD32 allows capturing blood cells emergence in slow motion during human embryonic development

During development, in the embryo proper blood cells emerge from a subset of specialized endothelial cells, named hemogenic endothelial cells (HECs), via a process known as endothelial-to-hematopoietic transition (EHT) driven by time-specific Notch signaling activation1. HECs represent an elusive cell population as they are rare and transient, rapidly generating blood cells, and specific markers are lacking. Therefore, it remains unclear how and when the hematopoietic fate is specified and how blood cell emergence is molecularly regulated. Notably, thorough characterization of this process is essential to guide the generation of therapeutic blood products in vitro from human pluripotent stem cells (hPSCs). To identify specific human HEC markers, we performed transcriptomic analysis of 28-32-day human embryos, a developmental stage characterized by active hematopoiesis. We observed that the expression of FCGR2B, encoding for the Fc receptor CD32, is highly enriched in the ACE+CD34+ endothelial cell population that contains HECs. Functional ex vivo analyses confirmed that multilineage hematopoietic potential is highly enriched in CD32+ endothelial cells isolated from human embryos. In addition, clonal analysis revealed that 90% of CD32+ hPSC-derived endothelial cells are bona fide HECs. We leveraged this specificity to study how HECs commit to the blood fate. Remarkably, our analyses indicated that HECs progress through different states culminating with the one identified by CD32 expression. Indeed CD32+ HECs no longer require Notch to generate hematopoietic progeny and display full commitment to hematopoiesis even before the expression of hematopoietic markers. These findings provide a precise method for isolating HECs primed to the blood fate from human embryos and hPSC cultures, thus allowing the efficient generation of hematopoietic cells in vitro.

developmental biology↗

bioRxiv2019

Numerical Investigation of Drug Transport from Blood Vessels to Tumor Tissue Using a Tumor-Vasculature-on-a-Chip

The delivery of adequate concentration of anticancer drugs to tumor site is critical to achieve effective therapeutic treatment, but it is challenging to experimentally observe drug transport and investigate the spatial distribution of the drug in tumor microenvironment. In this study, we investigated the drug transport from a blood vessel to tumor tissue, and explored the effect of tumor size, tumor numbers and positioning on drug concentration distribution using a numerical method in combination with a microfluidic Tumor-Vasculature-on-a-Chip (TVOC) model. The TVOC model is composed of a vessel channel, a tumor channel sandwiched with a porous membrane. A species transport model based on computational fluid dynamics was adapted to investigate drug transport. The numerical simulation was firstly validated using experimental data, and then used to analyse the spatial-temporal structure of the flow, and to investigate the effect of tumor size and positioning on drug transport and drug concentration heterogeneity. We found the drug concentration surrounding the tumor is highly heterogeneous, with the most downstream point the most difficult for drugs to transport and the nearest point to the blood vessel the easiest. Moreover, tumor size and positioning contribute significantly to this drug concentration heterogeneity on tumor surface, which is dramatically augmented in large and downstream-positioned tumors. These studies established the relationship between solid tumor size/positioning and drug concentration heterogeneity in the tumor microenvironment, which could help to understand heterogenous drug distribution in tumor microenvironment.

bioengineering↗