Biological therapy for non-obstructive azoospermia

Introduction: Most male patients with non-obstructive azoospermia (NOA) have no therapeutic options outside of assisted reproductive techniques to conceive a biological child. If mature sperm cannot be obtained from the testes, these patients must rely on options of donor sperm or adoption. Several techniques are in the experimental stage to provide this patient population alternatives for conceiving. Areas covered: This review discusses three of the experimental techniques for restoring fertility in men with NOA: spermatogonial stem cell transplantation, the use of adult and embryonic stem cells to develop mature gametes and gene therapy. After this discussion, the authors give their expert opinion and provide the reader with their perspectives for the future. Expert opinion: Several limitations, both technical and ethical, exist for spermatogonial stem cell transplantation, the use of stem cells and gene therapy. Well-defined reproducible protocols are necessary. Furthermore, several technical barriers exist for all protocols. And while success has been achieved in animal models, future research is still required in human models.