Comparative biodistribution analysis of umbilical cord mesenchymal stromal cells <i>via</i> different administration routes in rabbit models

Umbilical cord mesenchymal stem cells (UC-MSCs) have shown therapeutic potential in renal diseases due to their homing ability. This study compared the effects of three administration routes (intravenous, local renal injection, and interventional injection) on UC-MSC distribution in kidney tissue. Eighteen New Zealand rabbits were assigned to the three groups (<i>n</i> = 6 each), and DiI-labelled UC-MSCs were tracked using confocal microscopy to evaluate their distribution in the kidney, lung, and brain. Local renal injection led to high MSC concentrations at the injection site, but distribution to the contralateral kidney was minimal and comparable to that of intravenous injection. Intravenous delivery <i>via</i> the marginal ear vein was simple and convenient but resulted in limited renal homing (< 1 %) and no significant difference between kidneys. Interventional injection achieved the highest delivery efficiency (12.4 %) and a more uniform renal distribution. Notably, inflammatory cytokine levels (IL-6, TNF-α, IL-10) were significantly elevated in the local injection group (<i>p</i> < 0.05). These results indicated that the choice of administration route critically affects MSC targeting and therapeutic potential, and interventional injection may offer the most effective strategy for precise UC-MSC delivery in renal therapy.