In search of an efficient injection technique for future clinical application of spermatogonial stem cell transplantation: infusion of contrast dyes in isolated cadaveric human testes.

Objective: To develop an efficient infusion technique for human spermatogonial stem cell transplantation.

Design: A mixture with ultrasonic contrast, computerized tomography (CT) contrast, and Chinese ink was injected into isolated human testes through different sites (the rete testis, the head of the epididymis, the deferent duct, and blind testicular infusion). Ultrasound transducer was used to visualize the injection site and to observe the flow of the mixture injected in the testes. Then, micro-CT scan was used to construct three-dimensional images, allowing the calculation of the testicular volume filled by the mixture. Finally the efficiency of the infusion was evaluated on histologic sections.

Setting: Research laboratory.

Patient(s): Cadaver testes obtained from autopsied bodies at the department of pathology.

Intervention(s): Ultrasound-guided infusion of contrast liquid.

Main Outcome Measure(s): Contrast liquid-filled testis volume and presence of ink in seminiferous tubules.

Result(s): Ultrasonography clearly visualized the flow when seminiferous tubules were injected from the rete testis. No flow was observed when infusions were made either blindly, into the deferent duct, or into the head of the epididymis. On micro-CT no significant differences were observed between the different volumes. After rete testis infusion, ink particles were found in the lumen of the rete testis and in tubules, close and distant from the rete testis.

Conclusion(s): A single ultrasound-guided injection of 800 μL in the rete testis may provide a promising method to transplant human spermatogonial stem cells in a clinical setting.