Eliminating malignant contamination from therapeutic human spermatogonial stem cells

Area of Science:

• Reproductive Biology
• Cancer Biology
• Cell Biology

Background:

• Spermatogonial stem cell (SSC) transplantation offers potential for restoring fertility, particularly after cancer treatments causing male infertility.
• Ensuring the safety of SSC transplantation requires methods to isolate pure SSCs and eliminate malignant cells from human testicular samples.

Purpose of the Study:

• To develop and validate a flow cytometry-based method for isolating human spermatogonia.
• To simultaneously remove contaminating leukemia cells from human testicular cell suspensions for safe fertility preservation.

Main Methods:

• Utilized multi-parameter flow cytometry (FACS) to analyze cell surface antigen expression on human testicular cells and leukemia cell lines (MOLT-4, TF-1a).
• Identified differential expression of EpCAM, HLA-ABC, and CD49e on spermatogonia versus leukemia cells.
• Performed cell sorting to isolate EpCAM+/HLA-ABC-/CD49e- (putative spermatogonia) and EpCAM-/HLA-ABC+/CD49e+ (putative leukemia) fractions.

Main Results:

• EpCAM expression was detected on human spermatogonia but not on MOLT-4 cells.
• HLA-ABC and CD49e were highly expressed on MOLT-4 cells but absent on spermatogonia.
• The EpCAM+/HLA-ABC-/CD49e- fraction showed spermatogonial activity and did not form tumors in xenotransplantation.
• The EpCAM-/HLA-ABC+/CD49e+ fraction formed tumors, confirming its malignant nature.

Conclusions:

• Flow cytometry, by exploiting distinct cell surface antigen profiles, enables the isolation and enrichment of human spermatogonia.
• This FACS-based approach effectively removes malignant contamination, enhancing the safety of SSC-based fertility preservation strategies.
• The method is adaptable for removing other leukemia cell types, such as TF-1a, broadening its clinical applicability.