Long-term stability, functional competence, and safety of microencapsulated specific pathogen-free neonatal porcine Sertoli cells: a potential product for cell transplant therapy

Background: Porcine Sertoli cells (pSCs) have been employed for cell therapy in pre-clinical studies for several chronic/immune dis- eases as they deliver molecules associated with trophic and anti-inflam- matory effects. To be employed for human xenografts, pSCs products need to comply with safety and stability. To fulfill such requirements, we employed a microencapsulation technology to increase pre-trans- plant storage stability of specific pathogen-free pSCs (SPF-pSCs) and evaluated the in vivo long-term viability and safety of grafts. Methods: Specific pathogen free neonatal pigs underwent testis excision under sterility. pSCs were isolated, characterized by immunofluores- cence (IF) and cytofluorimetric analysis (CA) and examined in terms of viability and function (namely, production of anti-m€ hormone (AMH), inhibin B, and transforming growth factor beta-1 (TFGb-1)). After microencapsulation in barium alginate microcapsules (Ba-MC), long-term SPF-pSCs (Ba-MCpSCs) viability and barium concentrations were evaluated at 1, 24 throughout 40 h to establish pre-transplant stor- age conditions. Results: The purity of isolated pSCs was about 95% with negligible contaminating cells. Cultured pSCs monolayers, both prior to and after microencapsulation, maintained high function and full viability up to 24 h of storage. At 40 h post-encapsulation, pSCs viability decreased to 80%. Barium concentration in Ba-MCpSCs lagged below the normal maximum daily allowance and was stable for 4 months in mice with no evident side effects. Conclusions: Such results suggest that this protocol for the isolation and microencapsulation of pSCs is compatible with long-haul transpor- tation and that Ba-MCpSCs could be potentially employable for xeno- transplantation.