Whole-Cell Patch-Clamp Electrophysiology to Study Ionotropic Glutamatergic Receptors and Their Roles in Addiction

Cryopreservation and post-thaw characterization of dissociated human islet cells

The objective of this study is to optimize the cryopreservation of dissociated islet cells and obtain functional cells that can be used in single-cell transcriptome studies on the pathology and treatment of diabetes. Using an iterative graded freezing approach we obtained viable cells after cooling in 10% dimethyl sulfoxide and 6% hydroxyethyl starch at 1°C/min to -40°C, storage in liquid nitrogen, rapid thaw, and removal of cryoprotectants by serial dilution. The expression of epithelial cell adhesion molecule declined immediately after thaw, but recovered after overnight incubation, while that of an endocrine cell marker (HPi2) remained high after cryopreservation. Patch-clamp electrophysiology revealed differences in channel activities and exocytosis of various islet cell types; however, exocytotic responses, and the biophysical properties of voltage-gated Na+ and Ca2+ channels, are sustained after cryopreservation. Single-cell RNA sequencing indicates that overall transcriptome and crucial exocytosis genes are comparable between fresh and cryopreserved dispersed human islet cells. Thus, we report an optimized procedure for cryopreserving dispersed islet cells that maintained their membrane integrity, along with their molecular and functional phenotypes. Our findings will not only provide a ready source of cells for investigating cellular mechanisms in diabetes but also for bio-engineering pseudo-islets and islet sheets for modeling studies and potential transplant applications.

Multimodal Imaging Mass Spectrometry: Next Generation Molecular Mapping in Biology and Medicine

Imaging mass spectrometry has become a mature molecular mapping technology that is used for molecular discovery in many medical and biological systems. While powerful by itself, imaging mass spectrometry can be complemented by the addition of other orthogonal, chemically informative imaging technologies to maximize the information gained from a single experiment and enable deeper understanding of biological processes. Within this review, we describe MALDI, SIMS, and DESI imaging mass spectrometric technologies and how these have been integrated with other analytical modalities such as microscopy, transcriptomics, spectroscopy, and electrochemistry in a field termed multimodal imaging. We explore the future of this field and discuss forthcoming developments that will bring new insights to help unravel the molecular complexities of biological systems, from single cells to functional tissue structures and organs.

Ex vivo construction of rabbit corneal endothelial cell sheets on a porcine descemet membrane graft

The aim of the present study was to investigate the feasibility of a new graft construction method using rabbit corneal endothelial cells (RCECs) and a porcine descemet membrane (DM) carrier. RCECs were isolated and the experimental group was treated with Y-27632, whereas the control group were cultured in medium without Y-27632. RCEC morphology was observed using an inverted microscope, and cell proliferation and apoptosis were detected by flow cytometry. To confirm the presence of RCECs, reverse transcription-quantitative PCR was used to detect gene expression levels of Na+-K+-ATPase, aquaporin 1, collagen α₂ (IV), collagen α₁ (VIII) and keratin-12. Histocompatibility testing was used to detect porcine DM antigenicity. A DM-RCEC graft was constructed, and morphology was observed using alizarin red-trypan blue and haematoxylin and eosin staining. Cell membrane potential was measured to evaluate the physical function of the DM-RCEC graft. Complex graft tension was measured using a modified tension detector and compared with fresh porcine DM-endothelium complex. In vitro-cultured RCECs formed a monolayer with a polygon morphology and cobblestone-like arrangement. In vitro-cultured RCECs exhibited typical RCEC characteristics before and after transplantation. The proliferation rates of the experimental and control groups were 62.68 and 34.50%, respectively (P<0.05); the apoptosis rates of the experimental and control groups were 8.99 and 35.68%, respectively (P<0.05). There was no antigenicity observed with the porcine DM. The action potential amplitude of the experimental and control groups was over −80 mV, reflecting normal RCEC physiological function. The tension measurements of the experimental and control groups were 20.0248±1.048 and 20.5013±0.657 g, respectively (P>0.05). Taken together, the results of the present study demonstrated that Y-27632 enhanced RCEC proliferation. In addition, the findings revealed the successful ex vivo construction of a RCEC sheet on a porcine DM graft.