Another report of sperm actually being grown in culture has been published. In the Journal Cell Stem Cell (Volume 18, Issue 3, p330–340, 3 March 2016), scientists in China report growing (mouse) sperm –like cells from (mouse) embryonic stem cells. Those cells were then able to be injected into (mouse) eggs and create normal adults that in turn were able to mate and produce healthy offspring.
The potential application of this new technology for people is for use in men who cannot produce sperm, either because they have a condition called sertoli cell only where there are no sperm making cells at all, or in the setting of maturation arrest, where sperm progenitors fail to mature into sperm. This condition can happen due to a genetic abnormality, due to exposure to toxic agents and or chemotherapy, as well as for unknown reasons. These types of problems affect at least one percent of men with fertility issues.
Authors Qi Zhou and Xiao-Yang Zhao of the Institute of Zoology at the Chinese Academy of Sciences to developed this stem cell-based method. The process to create these cells begins with generation of stem cells from mature somatic or body cells, in this case, skin cells. Stem cells are cells capable of differentiating into different tissue types. Those stem cell were induced to become immature (primordial) germ cells or sperm making cells. Sperm cells are normally derived in a maturation process starting with spermatogonia which then divide to produce to primary spermatocytes which divide again to produce secondary spermatocytes. Those cells then undergo maturational changes to form spermatids and then to mature further into sperm.
The researchers were able to mature the sperm making cells into what they call “Haploid spermatid-like cells”. According to the article, the process involved co-culture of primordial germ cells with neonatal testicular cells and sequential exposure to certain chemicals known as morphogens as well as sex hormones. The process culminated in the formation of the spermatid-like cells. These cells were then injected into mouse eggs or oocytes using in vitro fertilization techniques and those resulting embryos were able to mature into viable adults. Six healthy mice were produced and those mice went on to have mate and have offspring. Testing of this model will likely continue using a primate animal model.
In a related story, Creative Medical Technologies, Inc. (CMT)has announced the signing of a license agreement with LA BioMed for a US patent application covering the use of stem cells for treatment of male infertility.
In this patent application and subsequent publication,1 Dr. Ronald. Swerdloff, demonstrated that the administration of bone marrow cells into the testicles of mice with chemically induced damage to sperm producing cells led to the generation of new sperm-producing cells. The new sperm producing cells were shown to have been produced by the donor bone marrow cells.
Technologies such as these give new hope in the future to men who are unable to generate sperm. Given the acceleration of results in this area, it’s probably not unrealistic to anticipate human trials in the next five years. Caution does need to be taken to ensure safety, however. Use of immature sperm precursors known as ROSNI (round spermatid nuclear injection) to initiate pregnancies in people was performed a decade ago. It has been largely abandoned due to low success rates and a possible increase in risk of congenital abnormalities.
