使用机器人注射装置在小鼠中进行高通量且精确的脾内注射用于转移性癌症建模

Intrasplenic injections represent a critical technique for establishing metastatic cancer models, particularly for hepatic metastases from colorectal, pancreatic, and gastric cancers. However, traditional intrasplenic injection methods have distinct challenges: blind percutaneous approaches suffer from targeting inaccuracy and variable outcomes, while surgical methods, though more precise, significantly increase procedural complexity and limit experimental throughput. Ultrasound-guided percutaneous injection combines the reproducibility of surgical visualization with the efficiency of minimally invasive delivery. To this end, we have developed a standardized protocol using the Revvity VivoJect (VJ) instrument to enable precise, high-throughput intrasplenic cell delivery in mice. The VJ platform combines real-time ultrasound imaging with motor-controlled needle positioning for accurate target identification and injection. To demonstrate feasibility of spleen injection with VJ, a pilot study was conducted comparing percutaneous (N=7) and surgical (N=5) spleen injections in nude mice. For the percutaneous group, mice were sedated with isoflurane, positioned in right lateral recumbency, coupled to the VJ transducer with ultrasound gel, and injected using ultrasound guidance to identify the spleen. Mice received 50 μL injections of HT-29-RedF-Luc human colorectal adenocarcinoma cells (1×10⁶ cells) mixed with IVISense 750 fluorescent tracer. The FLI tracer was used for ex vivo confirmation of injection delivery, while Luc-tagged cells were used for in-vivo tracking of metastasis. For traditional surgical group, anesthetized mice underwent mini-laparotomy to expose the spleen for direct injection of the same cancer cell suspension, followed by surgical staple closure and standard post-operative monitoring. Injection accuracy was confirmed through immediate ex vivo fluorescent imaging (FLI) in a small subset of mice (N=2) and subsequent bioluminescence (BLI) monitoring. VJ achieved 100% successful percutaneous intrasplenic delivery across all test animals, as confirmed by FLI tracer localization and absence of peritoneal spillage. Day 4 in vivo BLI demonstrated successful establishment of hepatic metastases in all injected mice, with consistent tumor burden distribution to the surgical group. VJ reduced procedure time to under 5 minutes per animal with immediate animal recovery and no adverse effects. These results suggest VJ can transform intrasplenic injection from a technically challenging, low-throughput invasive surgical procedure into a reproducible, high-efficiency method suitable for large-scale metastasis studies. This advancement enables more robust preclinical evaluation of anti-metastatic therapies and biomarker validation in clinically relevant models of hepatic metastasis from gastrointestinal cancers.