Student CHA UNIVERSITY CHA Advanced Research Institute, CHA University, Republic of Korea
Abstract: Mesenchymal stem cells (MSCs) have demonstrated significant therapeutic potential in renal injury models. However, the exact mechanism of their transport to the kidneys—whether as intact cells or extracellular vesicles (EVs)—remains debated. Additionally, immune cells that phagocytose MSCs may contribute to renal repair through anti-inflammatory effects. This study investigates how feline amniotic membrane-derived mesenchymal stem cells (fAM-MSCs) are delivered to the kidneys in a chemically induced renal injury mouse model, focusing on the timing and cellular forms of viable and apoptotic MSCs in the kidneys and bloodstream following intravenous (IV) and intraperitoneal (IP) administration. Renal injury was induced in male C57BL/6 or NSG mice via intraperitoneal injection of cisplatin (10 mg/kg) and lipopolysaccharide (LPS, 5 mg/kg). fAM-MSCs labeled with NIR815 or PKH26 were administered by IV or IP routes. Fluorescence imaging tracked MSC distribution over time, while PCR was employed to detect feline mitochondrial and nuclear DNA in the kidneys and bloodstream. Flow cytometry analyzed interactions between immune cells and transplanted MSCs. Fluorescence imaging revealed rapid migration of fAM-MSCs to the kidneys within 1 hour of injection. PCR detected feline mitochondrial DNA in the kidneys, but no nuclear DNA, suggesting the absence of intact MSCs. Mitochondrial DNA persisted in the bloodstream for up to 3 hours post-injection, whereas nuclear DNA was undetectable. Flow cytometric analysis showed that macrophages and other immune cells phagocytosed more than 42% of transplanted MSCs. IV-administered MSCs were more frequently observed in the bloodstream at 3 hours post-injection compared to IP-administered MSCs. These results indicate that the therapeutic effects of fAM-MSCs are mediated by their components, such as EVs, and by macrophage-mediated anti-inflammatory processes, rather than intact viable cells. IP administration appears to bypass the bloodstream, delivering MSCs directly to the kidneys. This study provides critical insights into the mechanisms of MSC-based renal therapies and highlights the importance of EVs and immune cell interactions in achieving therapeutic outcomes.
Funding Source: This research was supported by a grant of Korean Cell-Based Artificial Blood Project funded by the Korean government (grant number: RS-2023-KH140925).
