New Study Advances Laboratory-Grown Human Germ Cells Toward Sperm Development
A new study successfully advances laboratory-grown human germ cells using mouse tissue grafts, marking a step toward overcoming male infertility.
For many people, the desire to have children is accompanied by the hope that the natural meeting of a tiny egg and a sperm cell will occur effortlessly. However, for some men, sperm cells are not produced, potentially blocking the path to biological parenthood. A new study has brought science a step closer to the possibility of growing human sperm cells in a laboratory environment.
Every cell in our body contains the same DNA, acting as an instruction manual for building and operating the body. Yet, different cell types use different parts of these instructions. Scientists once believed that once a cell specialized, it could not revert to a different role. However, researchers discovered that adult cells can be reprogrammed into a flexible, stem cell-like state, capable of developing into various cell types.
Laboratory-Grown Germ Cells
In the current study, researchers used reprogrammed cells to direct blood-derived cells from a male donor into germ cells—early-stage cells that can develop into sperm. Since creating sperm is a complex process, earlier research had stalled at the initial stages. To overcome this, scientists realized they needed to mimic the environment of a testis.
Researchers combined human germ cells with support cells extracted from developing mouse testes. These cells organized into a tissue-like structure and were grafted under the kidney capsule of immunocompromised mice. The tissue survived for months, organizing into structures resembling human testicles where human cells continued developing.
Progress and Limitations
After several months, the human germ cells progressed significantly through the stages toward sperm creation. Gene expression analysis showed they followed a developmental sequence similar to natural bodily processes. However, the process eventually stalled, and mature sperm cells were not produced even after eight to nine months.
To address limitations in testing human cells, researchers developed a similar system using rhesus macaque stem cells. While monkey cells advanced through early developmental stages, they also halted before becoming mature sperm. Although these laboratory-grown cells are still far from participating in human fertilization, the system provides a vital new platform to study early male germ cell development and male infertility.
