The effects of di(n-butyl) phthalate (DBP) exposure on testis cell development/function in human fetal testis xenografts
Rod Mitchell1,2, Andrew Childs1, Richard Anderson1, Sander van den Driesche1, Chris McKinnell1, Sheila MacPherson1, W Wallace2, Chris Kelnar2, Philippa Saunders1 & Richard Sharpe1
Background: Endocrine disruption in the human fetal testis by environmental agents has been proposed as a possible cause of testicular dysgenesis syndrome (TDS) comprising male reproductive disorders such as testicular germ cell tumours (TGCT), cryptorchidism, hypospadias and low sperm counts. Exposure of fetal rats to the widely used plasticizer di(n-butyl) phthalate (DBP) results in a TDS-like syndrome due to a reduction in testosterone production. Whether such effects also occur on the human fetal testis is difficult to determine. We have recently demonstrated that xenografting of human fetal testis tissue results in normal seminiferous cord formation and cellular development/function. Objective and hypotheses: To develop models of ex-situ human fetal testicular development and to determine the effects of proposed endocrine disruptors (e.g. DBP).
Methods: We xenografted testis tissue from fetal rat (e17.5, n=39) or human (1420 weeks gestation, n=13), either as whole tissue or isolated cell suspensions into nude mice. We treated the host mice with DBP or vehicle for part of the grafting period (up to 6 weeks). Testosterone production by the grafts was determined. Morphological and immunohistochemical analysis was performed to investigate seminiferous cord formation and cellular development using a range of markers.
Results: Xenografts of isolated fetal rat cell suspensions re-formed seminiferous cords. In rats, exposure of whole tissue or isolated cell suspension to DBP significantly reduced testosterone production and steroidogenesis. However steroidogenesis in human fetal testis xenografts was unaffected by DBP. Testosterone independent effects that altered germ cell numbers or aggregation were found in the DBP exposed xenografts from human and rat but not in the vehicle treated controls.
Conclusions: These results suggest that phthalates may not impair steroidogenesis in human fetal testis as indicated by animal models. Xenografting (tissue/cell suspensions) opens new possibilities to study testicular development and endocrine disruption in the human fetal testis.
Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.