Clinical Exchange in Japan

From July to September 2025, I participated in a research program in the Department of Gastroenterology and Hepatology at Nagoya University Hospital under the supervision of Dr. Norihiro Imai. My work focused on the ultrastructural and functional investigation of liver tissue, which allowed me to gain a deeper understanding of hepatocyte biology and anatomy and further develop my technical laboratory skills.

During my research in Nagoya, I received training in transmission electron microscopy, which enabled me to acquire high-resolution images of human liver biopsy specimens from patients with various liver diseases. Our research work aims to integrate ultrastructural analysis of human hepatocyte organelles with clinical data and RNA sequencing to establish parameters for evaluating hepatocyte morphology and to facilitate the differentiation between the distinct liver disease phenotypes. Using the TEM images from 52 patients I obtained in Nagoya, I am able to currently train a machine learning program to identify different hepatocellular organelles and perform a comprehensive morphometric analysis of hepatocyte subcellular architecture.

In addition to imaging studies, I also conducted cell culture experiments using both human HepG2 and mouse Hepa 1-6 hepatocyte cell lines. To establish in vitro models of hepatic steatosis, I incubated cells with fatty acids, including oleic and palmitic acids. For functional analysis, I utilized the Seahorse XF Analyzer to measure parameters of mitochondrial respiration and glycolysis. Combined with fluorescence microscopic visualization and three-dimensional reconstruction of hepatocyte mitochondria and lipid droplets, our experiments sought to investigate the potential protective effects of pentagalloyl glucose, a polyphenolic compound naturally found in Japanese green tea leaves, and to evaluate its ability to mitigate lipotoxicity and oxidative stress in hepatocytes.

During my stay in Nagoya, we also submitted our manuscript, on which I am the first author, titled “Morphological Alterations of Peridroplet Mitochondria in Human Liver Biopsy,” which has been successfully accepted for publication in Scientific Reports. In this study, we analyzed morphological differences between two hepatic mitochondrial subpopulations using transmission electron microscopy and implemented deep learning methods for the automated detection and segmentation of mitochondria. Based on this work, we also prepared a poster that was selected as a Poster of Distinction for presentation at The Liver Meeting in Washington, D.C., as well as an oral presentation that I will deliver at the 4th Meeting Nazionale - The Concept of Obesity Translation Conference in Naples, Italy.

In summary, my time at the Hepatology Department was an incredibly fruitful, valuable, and rewarding experience. I learned advanced experimental techniques, participated in scientific discussions, contributed to manuscript revisions, and engaged in data analysis, all of which broadened both my scientific and personal perspectives. The data I collected in Nagoya is a key part of my ongoing research projects, and I am very excited to continue this work after my return to Poland. Beyond my training in the laboratory, daily life in Nagoya was equally enriching and highly inspiring. The Japanese emphasis on precision, dedication to excellence, and attention to detail are values that deeply impressed me and will definitely stay with me forever.

I am profoundly thankful to Dr. Imai for his continuous guidance, as well as the tremendous support I received from the other members of the department. I also wish to express my gratitude for the chance to study at Nagoya University and the inspiration this opportunity provided me, and I look forward with great anticipation to the future results of my work.