iPSC-derived mesenchymal cells that support alveolar organoid development

肺胞オルガノイドをつくることができるヒトiPS細胞由来間葉細胞の作成. 京都大学プレスリリース. 2022-10-12.Mesenchymal cells are necessary for organ development. In the lung, distal tip fibroblasts contribute to alveolar and airway epithelial cell differentiation and homeostasis. Here, we report a method for generating human induced pluripotent stem cell (iPSC)-derived mesenchymal cells (iMESs) that can induce human iPSC-derived alveolar and airway epithelial lineages in organoids via epithelial-mesenchymal interaction, without the use of allogenic fetal lung fibroblasts. Through a transcriptome comparison of dermal and lung fibroblasts with their corresponding reprogrammed iPSC-derived iMESs, we found that iMESs had features of lung mesenchyme with the potential to induce alveolar type 2 (AT2) cells. Particularly, RSPO2 and RSPO3 expressed in iMESs directly contributed to AT2 cell induction during organoid formation. We demonstrated that the total iPSC-derived alveolar organoids were useful for characterizing responses to the influenza A (H1N1) virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, demonstrating their utility for disease modeling

Sanitizing efficacy and antimicrobial mechanism of peracetic acid against histamine-producing bacterium, Morganella psychrotolerans

In this study, we aimed to investigate the sanitizing effects of peracetic acid (PAA), and the underlying mechanism of its antimicrobial action against Morganella psychrotolerans. The exposure of M. psychrotolerans to 20 ppm PAA for 5 min led to its decrease below the detection level, indicating that PAA has a significant antibacterial effect against M. psychrotolerans in vitro. Moreover, the viable counts of M. psychrotolerans on saury (Cololabis saira) surface were showed a reduction of 1.40 and 2.23 log CFU/cm(2) upon treatment with 80 ppm PAA for 1 and 5 min, respectively. Further, PAA treatment delayed the growth of M. psychrotolerans on saury surface during storage at 4 degrees C. Next, the antimicrobial mechanism of PAA against M. psychrotolerans cells was investigated, and the damage to the cell membrane and cell surface upon PAA treatment was observed using scanning electron microscopy (SEM) and epifluorescence microscopy. The chromosomal DNA and the protein profiles after PAA treatment were also analyzed. Form our results, we hypothesized that the bactericidal effect of PAA treatment was mainly attributed to damage the bacterial cell membrane. These results indicate that PAA may be an efficient disinfectant against M. psychrotolerans and has applications in seafood processing and storage

Histamine Production Behaviors of a Psychrotolerant Histamine-Producer, Morganella psychrotolerans, in Various Environmental Conditions

Histamine food poisoning is a major safety concern related to seafood consumption worldwide. Morganella psychrotolerans is a novel psychrotolerant histamine-producer. In this study, the histamine production behaviors of M. psychrotolerans and two other major histamine-producers, mesophilic Morganella morganii and psychrotrophic Photobacterium phosphoreum, were compared in seafood products, and histamine accumulation by M. psychrotolerans was characterized at various pH and temperature levels in culture broth. The growth of M. psychrotolerans and P. phosphoreum increased similarly at 4 degrees C in canned tuna, but M. psychrotolerans produced much higher levels of histamine than P. phosphoreum. Histamine accumulation by M. psychrotolerans was induced at lower environmental pH condition at 4 and 20 degrees C. The optimal temperature and pH for producing histamine by crude histidine decarboxylase of M. psychrotolerans were 30 degrees C and pH 7, respectively. The activity of the crude HDC extracted from M. psychrotolerans cells at 10 degrees C retained 45% of the activity at 30 degrees C. Histidine decarboxylase gene expression of M. psychrotolerans was induced by low pH conditions. These results suggest that M. psychrotolerans are also a very important histamine-producer leading to histamine poisoning associated with seafood below the refrigeration temperature