Comparison of subcutaneous and intraperitoneal injection of d-luciferin for in vivo bioluminescence imaging

We compared subcutaneous (SC) injection and intraperitoneal (IP) injection of d-luciferin for in vivo bioluminescence imaging (BLI) to determine the utility of SC injection. Mice bearing SC tumours stably expressing firefly luciferase underwent in vivo BLI using SC and IP injection of d-luciferin. BLI studies were repeated at an interval of 3 h using a given injection route to assess repeatability and using different injection routes to assess correlation. In mice bearing both SC and IP tumours, BLI was performed successively using intravenous (IV), SC, and IP injection of d-luciferin. Haematological malignancy model mice underwent BLI using SC and IP injection. In SC tumours, the peak time was slightly shorter and the peak signal was greater using SC injection than using IP injection. The repeatability of determining peak signals was comparable between the two injection routes, and a good correlation was observed between them. In mice bearing both SC and IP tumours, signals from IP tumours relative to those from SC tumours were much greater using IP injection than using IV or SC injection. In the haematological malignancy model, signals from the spleen relative to those from the bone marrow were greater using IP injection than using SC injection. In addition to rare injection failure, the IP injection of d-luciferin led to the overestimation of signals from IP tissues. For BLI, SC injection was shown to be a convenient alternative to IP injection.