Aim: To investigate the application of Scrotal Heat Stress (SHS) and Pulsed Unfocused Ultrasound
(PuFUS) to explore Blood-Testis Barrier (BTB) permeability in adult mice.
Background: The BTB provides a stable microenvironment and a unique immune barrier for spermatogenesis.
Meanwhile, it blocks macromolecular substances access, including therapeutic agents and antibodies,
thereby it decreases the therapeutic or immunocontraception effects.
Objectives: To determine the viability of these physical approaches in delivering macromolecular substances
into seminiferous tubules.
Materials & Methods: Mice were subjected to receive single SHS intervention at 39°C, 41°C, or 43°C
for 30 min. Whereas, mice received the PuFUS intervention at 1.75w/cm2, 1.25w/cm2, and 2.5w/cm2 for
2 min, 5 min, and 10 min, respectively. The Biotin and macromolecular substances (IgG, IgM, and
exosomes) were separately injected into the testicular interstitium at different times following SHS or
PuFUS interventions, to observe their penetration through BTB into seminiferous tubules.
Results: As detected by Biotin tracer, the BTB opening started from day-2 following the SHS and lasted
for more than three days, whereas the BTB opening started from 1.5h following PuFUS and lasted up to
24h. Apparent penetration of IgG, IgM, and exosomes into seminiferous tubules was observed after five
days of the SHS at 43°C, but none at 39°C, or any conditions tested with PuFUS.
Conclusion: The current results indicate that SHS at 43°C comparatively has the potential for delivering
macromolecular substances into seminiferous tubules, whereas the PuFUS could be a novel, quick, and
mild approach to open the BTB. These strategies might be useful for targeted drug delivery into testicular
seminiferous tubules. However, further studies are warranted to validate our findings.