Purpose: To restore fertility the current consensus suggests early orchiopexy for cryptorchidism. However, despite early orchiopexy it is reported that transformation of gonocytes into adult dark spermatogonia is already impaired at the time of surgery and consequently affects future fertility. To elucidate the biological processes occurring during germ cell maturation in the cryptorchid testis, we identified the genes affected by testicular maldescent using polymerase chain reaction based suppression subtractive hybridization, and investigated differentially expressed genes to determine whether they are related to cell differentiation and spermatogenesis.
Materials and methods: Testicular tissues were excised from 24 boys 12 to 59 months old who underwent orchiopexy or hydrocelectomy at our hospital. Two-way subtraction was performed to compare their tissue samples and those from age matched boys with ipsilateral cryptorchidism and a descended testis. Differential expression was validated by real-time reverse transcriptase polymerase chain reaction. To clarify the distribution of candidate genes, immunohistochemical and western blot analysis was performed.
Results: We obtained 84 clones corresponding to transcripts representing differential expression. Basic local alignment search tool searches revealed 32 different known genes with 98% to 100% similarity. Among these genes we further investigated 3 genes, TPT1, EEF1A1 and NuMA1, which were significantly more highly expressed in cryptorchidism than in descended testes and were detected in the spermatogonia from immature to adult testes.
Conclusions: TPT1, EEF1A1 and NuMA1 have cell growth related functions, suggesting that they have certain roles in germ cell differentiation and maintenance of stem cell potential. Changes in the expression levels of these genes in the testes might enable novel evaluation of spermatogenic failure caused by cryptorchidism.