Background and Purpose: Research into groundbreaking therapeutic approaches like cell transplantation and gene therapy is progressing, offering the potential to overcome intractable diseases previously considered incurable. These treatments often rely on local injection of active components (e.g., transplanted cells, viral vectors, nucleic acids) to exert their effects. However, a significant challenge is the frequent leakage of the injected material immediately after administration. This study investigated whether medical-grade gelatin could be used as a simple method to effectively suppress this immediate post-injection leakage.

Methods: We prepared various gelatin formulations, including solutions and fine particle suspensions, by mixing them with phosphate-buffered saline (PBS). These samples were injected into a surgical training simulator, which mimics the physical properties of living tissue, using a 1 mL syringe equipped with various needle gauges (23, 25, 27, 30, and 33G). After needle withdrawal, the weight of the leaked fluid was measured.

Results and Discussion: The addition of gelatin significantly reduced leakage from the simulated organ compared to PBS alone. The leakage suppression effect and injectability varied depending on the gelatin formulation, suggesting their potential applicability across a wide range of uses.

Currently, we are primarily focusing on applications in cell transplantation, having achieved promising results in subretinal and myocardial injections in small animal models. For fields where post-injection leakage is a critical issue, simply incorporating gelatin offers a simple and safe way to control the localization of injected substances. This approach is expected to enhance therapeutic efficacy and prevent complications.