Organoids are 3D systems derived from stem cells that recapitulate human tissue microenvironments, offering a useful tool for a wide range of investigations, including developmental biology, drug screening and disease modelling. As the vasculature is critical in biological processes within the human body, both in health and disease, recent efforts in the field have focused on developing vascularised organoids. In this At a Glance article, we discuss a number of currently available vasculature fabrication approaches, including co-culture with vascular endothelial cells, assembloids, co-differentiation, genetic engineering, 3D bioprinting and organ-on-a-chip systems, along with their advantages and limitations. We also provide a comparison of these fabrication approaches and their use for modelling diseases. Finally, we discuss current challenges and future directions regarding the use of vascularised organoids to mimic human physiological conditions and as clinically relevant models of human diseases.

GABAA receptors are channel proteins crucial to mediating neuronal balance in the CNS. The structure of GABAA receptors allows for multiple binding sites and is key to drug development. Yet, the formation mechanism of the receptor’s distinctive pentameric structure is still unknown. This study aims to investigate the role of three predominant subunits of the human GABAA receptor in the formation of protein pentamers. Through purifying and refolding the protein fragments of the GABAA receptor α1, β2, and γ2 subunits, homopentamers were visualised with negative staining and Cryo-EM. To aid the analysis, AlphaFold2 was used to compare the structures. Results show that α1 and β2 subunit fragments successfully formed homo-oligomers, particularly homopentameric structures, while the predominant heteropentameric GABAA receptor was also replicated through the combination of the three subunits. However, it is still unclear whether γ2 subunits can form homopentamers or their main purpose is to bring together the α1 and β2 subunits to form GABAA receptors. Nevertheless, this study will lead to a deeper understanding of the atomic structure of GABAA receptors, especially in the formation mechanism of complex protein structures, and hopefully pave the way to the development of novel therapeutics for neuropsychiatric diseases.

Type-A γ-aminobutyric acid (GABA_A) receptors are channel proteins crucial to mediating neuronal balance in the central nervous system (CNS). The structure of GABA_A receptors allows for multiple binding sites and is key to drug development. Yet the formation mechanism of the receptor’s distinctive pentameric structure is still unknown. This study aims to investigate the role of three predominant subunits of the human GABA_A receptor in the formation of protein pentamers. Through purifying and refolding the protein fragments of the GABA_A receptor α1, β2, and γ2 subunits, the particle structures were visualised with negative staining electron microscopy (EM). To aid the analysis, AlphaFold2 was used to compare the structures. Results show that α1 and β2 subunit fragments successfully formed homo-oligomers, particularly homopentameric structures, while the predominant heteropentameric GABA_A receptor was also replicated through the combination of the three subunits. However, homopentameric structures were not observed with the γ2 subunit proteins. A comparison of the AlphaFold2 predictions and the previously obtained cryo-EM structures presents new insights into the subunits’ modular structure and polymerization status. By performing experimental and computational studies, a deeper understanding of the complex structure of GABA_A receptors is provided. Hopefully, this study can pave the way to developing novel therapeutics for neuropsychiatric diseases.