3-D Printed Testicular Cells Show Promise as Possible Infertility Treatment

By Marilynn Larkin

March 31, 2022

NEW YORK (Reuters Health) - For the first time, researchers have 3-D printed human testicular cells and identified early signs of sperm-producing capabilities.

"Regenerative approaches have the potential to transform how we treat severe male infertility and other diseases in the future," Dr. Ryan Flannigan of the University of British Columbia in Vancouver told Reuters Health by email. "A lot of work remains to understand critical drivers of normal human spermatogenesis and identify critical cell-specific deficiencies contributing to deficient spermatogenesis."

As reported in Fertility and Sterility Science, Dr. Flannigan and colleagues performed a biopsy to collect stem cells from the testicles of a 31-year-old male with non-obstructive azoospermia (NOA). They grew the cells in vitro and 3-D bioprinted them into tubular structures similar to sperm-producing seminiferous tubules; 3-D organoid cultures were used as a non-bioprinted in vitro control.

Close to 94% of the 3-D-printed cells were viable 24 hours after printing.

After 12 days, immunofluorescence staining was positive for phenotype markers confirming the presence of Sertoli, Leydig, peritubular myoid, and meiotic germ cells.

Further, quantitative reverse transcription PCR analysis showed that after 12 days in spermatogenic media, the bioprints substantially upregulated spermatogenic gene expression on par with non-bioprinted controls, and showed a particularly significant improvement in genes involved in spermatogonial stem cell maintenance.

Summing up, the authors write, "This study demonstrates for the first time the feasibility of 3-D bioprinting adult human testicular cells. We show that the bioprinting process is compatible with high testicular cell viability and without loss of the main somatic phenotypes within the testis tissue. We demonstrate an increase in germ cell markers in the 3-D bioprinted tubules after 12 days of in vitro culture. This platform may carry future potential for disease modelling and regenerative opportunities in a personalized medicine framework."

Dr. Flannigan said, "Our approach requires development on two fronts. First, we are working to optimize the physical 3-D printing to better position the cells, and to choose and develop bioinks to facilitate cell growth and development."

"Secondly, we need to understand cell needs and molecular signaling as the stem cells differentiate through various states as they progress to sperm," he said. "To accomplish this, we are using various modalities of single cell sequencing to understand how cells are supporting the process of spermatogenesis, as well as the molecular events that are changing as stem cells differentiate through various cell states in spermatogenesis."

In addition, he said, "We are also comparing how these processes differ from cells derived among those with NOA where a problem in sperm production is occurring. Identifying these gaps may allow us to identify strategies to overcome these problems in a controlled laboratory setting where we could supplement the cells with unique growth factors at specific time points."

"The largest hurdle will be to unlock the keys to understanding the cell requirements to complete spermatogenesis," he acknowledged. "Following this, we have to ensure that our process is reproducible, and adaptable by other centers, and that the sperm produced are genetically stable and safe for clinical use."

Dr. Ranjith Ramasamy, Director, Reproductive Urology at the University of Miami Miller School of Medicine in Florida, commented on the study in an email to Reuters Health. "Currently, in certain male patients, we are unable to identify any mature sperm, whether via ejaculation or through surgery, to use in in vitro fertilization. (The authors are) attempting to create an environment outside the body that allows immature sperm cells... to grow and potentially develop sperm, and this is a promising approach."

However, he said, "There are complexities to reproducing the exact human cellular environment in a laboratory, so it remains to be seen if this approach will successfully allow us to mature sperm."

"Clinicians should appropriately counsel current infertile patients that we may have the potential to mature preliminary sperm cells in the future," he said. "Discussion can be held with patients whether they would like to cryopreserve tissue for future research advances."

SOURCE: https://bit.ly/3wXIDH4 Fertility and Sterility Science, online February 16, 2022.

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