Effectiveness of intraglandular allogeneic mesenchymal stem cell administration for treating chronic vesicular adenitis in bulls

This study aimed to evaluate the effects of the application of allogeneic mesenchymal stem cells (MSCs) bilaterally and intraglandularly in the vesicular glands of bulls affected by seminal vesiculitis. Twelve bulls that presented chronic vesiculitis with two or more recurrences were selected at Semen Collection and Processing Centres, based on the presence of pus in the semen, leukocytes on the motility and vigour evaluation slide, reactive to the California Mastitis Test - CMT (one cross or more) and the presence of leukocytes on a slide stained by Diff Quik staining with more than 5 polymorphonuclear cells (PMN) per field. Ultrasound examination of the vesicular glands was performed, and the clinical signs were definitive for the diagnosis. The proposed method of the intraglandular injection of MSCs involved application through the ischiorectal fossa with a long needle measuring 30–35 cm and a guide measuring 25–30 cm in length directly into the affected vesicular glands. The MSCs were cultured and frozen in the Bio Cell Cellular Therapy® laboratory (Brasilia, Brazil) and prepared by washing and centrifugation for intraglandular injection on the day of application. In total, 3x10⁶ MSCs were injected into each vesicular gland. Data were evaluated for normality of residuals using the Shapiro-Wilk test. When the normality of the test was significant (P < 0.05), the data were transformed or outliers were removed and reevaluated. The “T-Test” was applied to identify statistical differences between variables before and after treatment. The probability of P ≤ 0.05 was considered a significant difference. Data were presented as the mean ± standard error of the mean (S.E.M.). Improvements were observed in the initial percent motility from 60.09 ± 4.8 to 69.89 ± 4.6 (P < 0.05), as well as in the post-thawing percent motility from 26.26 ± 6.77 to 42.5 ± 5 0.99 (P < 0.05). The number of doses produced increased significantly after treatment with MSCs, from 95.61 ± 23.31 units to 337.84 ± 67.75 units (P < 0.05) per ejaculate. The number of leukocytes observed per field decreased from 5.83 ± 0.48 to zero, demonstrating the recovery of the inflamed vesicular glands. Based on the results presented, it was concluded that the application of 3x10⁶ MSCs in the vesicular glands of bulls with vesiculitis is safe and efficient, as it improved several parameters evaluated in this research, mainly the production of semen doses per ejaculate.