Stem Cells to Produce Testes for Sterile Men

Statistics show that couple infertility is due equally to men as to women.

Male sterility is triggered by impairment in the multiplication and development of the germ cells (that generate sperm cells) or of their supporting tissues.

A new investigation pointed out that bone marrow stem cells could be employed in treating male infertility. The stem cells could replace nonfunctioning or impaired cells. The research, made by a team led by Dr. Ronald S. Swerdloff of the Harbor-UCLA Medical Center on mice, employed a technique based on the green fluorescent protein (GFP). Green bone marrow stem cells, easy to detect in live mice, were put into the testes of mice reduced by chemicals or genetic engineering (mutations in a gene involved in sperm production) to sterility.

The donor GFP-expressing cells were detected thriving in the recipient mice for the whole duration of the study, 12-weeks. The donor stem cells differentiated on either germ cells or supporting cells. The new differentiated donor (green) cells were located near the native recipient counterparts, thus the local tissue environment might have tuned the development of the donor stem cells.

To be sure that the morphological differentiation was correlated with a functional one, the expression of specific proteins on the cell membrane was investigated. Both types of freshly differentiated cells presented marker proteins which develop only on the differentiated cells, but are absent on stem cells.

Thus, bone marrow stem cells are able to differentiate into fully functional testes cells in the testes.

The team also found that not all the germ cells did differentiate into specific testis tissue, thus more factors or cellular signals are necessary, like hormones, to fully complete the differentiation, a task for future research.

As this research used a mix of bone marrow stem cells, more researchers have to identify specific suited stem cell type to differentiate in the testes, with high implications for treating sperm impairment or low testosterone synthesis.