On-chip physiological mimicry of neurovascular unit: challenges and perspectives

Neurological disorders including neurodegenerative diseases,brain tumors,and stroke are the second leading cause of death and the greatest cause of disability worldwide.However,it remains challenging to achieve effective drug delivery to the central nervous system for treatments of neurological diseases due to the blood-brain barrier(BBB).The function of the BBB is regulated by the physiological interactions between various types of cells in the neurovascular unit(NVU).In the NVU,the brain vasculature of the BBB is surrounded by brain pericytes,brain astrocytes,neurons,and microglia(Figure 1).Moreover,the NVU at the levels of arteries and veins includes contractile smooth muscle cells(Schaeffer and Iadecola,2021).

High-density lipoprotein mimetic nanotherapeutics for cardiovascular and neurodegenerative diseases

High-density lipoprotein （HDL） serves as a natural nanoparticle with compositional and functional heterogeneity and contributes to the maintenance of lipid metabolism and various biological functions. HDL also transports endogenous microRNAs, vitamins, hormones, and proteins through blood and interstitial fluids to various organs. These unique and diverse features of HDL have encouraged its applications for the transport of therapeutics and diagnostic reagents in the last decade. In this review, we describe the heterogeneous characteristics and biological functions of HDL and highlight HDL mimetic approaches, including apolipoprotein mimetic peptides and reconstituted HDL nanoparticles. Given the potential of HDL as a nanocarrier delivering various therapeutic agents, we discuss the current representative studies of HDL mimetic nanotherapeutics for cardiovascular and neurodegenerative diseases and analyze the current challenges and future perspective.

Advances in sensor developments for cell culture monitoring

Cell culture encompasses procedures for extracting cells from their natural tissue and cultivating them under controlled artificial conditions. During this process, various factors, including cell physiological/morphological properties, culture environments, metabolites, and contaminants, have to be precisely controlled and monitored for the survival of cells and the pursuit of the desired properties of the cells. This review summarizes recent advances in sensor technologies and manufacturing strategies for various cell culture platforms using traditional plastics, microfluidic chips, and scalable bioreactors. We share the details of newly developed biological sensors, chemical sensors, optical sensors, electronic chip technologies, and material integration methods. The precise control of parameters based on the feedback by these sensors and electronics enhances cell culture quality and throughput.

Extracellular matrix-based intracortical microelectrodes:Toward a microfabricated neural interface based on natural materials

Extracellular matrix(ECM)-based implantable neural electrodes(NEs)were achieved using a microfabrication strategy on naturalsubstrate-based organic materials.The ECM-based design minimized the introduction of non-natural products into the brain.Further,it rendered the implants sufficiently rigid for penetration into the target brain region and allowed them subsequently to soften to match the elastic modulus of brain tissue upon exposure to physiological conditions,thereby reducing inflammatory strain fields in the tissue.Preliminary studies suggested that ECM-NEs produce a reduced inflammatory response compared with inorganic rigid and flexible approaches.In vivo intracortical recordings from the rat motor cortex illustrate one mode of use for these ECM-NEs.