Age-dependent expression of immune-privilege and proliferation-related molecules on porcine Sertoli cells

Sertoli cell transplantation attenuates microglial activation and inhibits TRPC6 expression in neuropathic pain induced by spinal cord injury

BACKGROUND

Cell therapy is a promising treatment method for relieving neuropathic pain caused by spinal cord injuries (SCI). Sertoli cells (SCs) are an attractive choice given their demonstrated secretion of growth factors and immunosuppressant effect. This study mechanistically characterizes the analgesic effect of SCs transplantation.

METHODS

The clip compression SCI model was carried out on the T12-T13 level in male Wistar rats. One-week post-SCI, SCs were transplanted into the site of injury. Animals underwent Basso, Beattie, and Bresnahan locomotor scoring, mechanical allodynia, and thermal hyperalgesia on a weekly basis for a duration of six weeks. Histological examination of the spinal cord and molecular evaluation of Iba-1, P2Y4, TRPC6, and P-mTOR were performed. SCs survival, measured by anti-Müllerian hormone expression in the spinal cord.

RESULTS

Animals that received SCs transplantation showed improvement in motor function recovery and pain relief. Furthermore, a cavity was significantly decreased in the transplanted animals (p = 0.0024), the expression level of TRPC6 and caspase3 and the number of activated microglia decreased compared to the SCI animals, and p-mTOR and P2Y4R expression remarkably increased compared to the SCI group.

CONCLUSION

SCs transplantation produces an analgesic effect which may represent a promising treatment for SCI-induced chronic pain.

Xenotransplanted Pig Sertoli Cells Inhibit Both the Alternative and Classical Pathways of Complement-Mediated Cell Lysis While Pig Islets Are Killed

Xenotransplantation has vast clinical potential but is limited by the potent immune responses generated against xenogeneic tissue. Immune-privileged Sertoli cells (SCs) survive xenotransplantation long term (≥90 days) without immunosuppression, making SCs an ideal model to identify xenograft survival mechanisms. Xenograft rejection includes the binding of natural and induced antibodies and the activation of the complement cascade. Using an in vitro cytotoxicity assay, wherein cells were cultured with human serum and complement, we demonstrated that neonatal pig SCs (NPSCs) are resistant to complement-mediated cell lysis and express complement inhibitory factors, membrane cofactor protein (MCP; CD46), and decay- accelerating factor (DAF; CD55) at significantly higher levels than neonatal pig islets (NPIs), which served as non-immune-privileged controls. After xenotransplantation into naive Lewis rats, NPSCs survived throughout the study, while NPIs were rejected within 9 days. Serum antibodies, and antibody and complement deposition within the grafts were analyzed. Compared to preformed circulating anti-pig IgM antibodies, no significant increase in IgM production against NPSCs or NPIs was observed, while IgM deposition was detected from day 6 onward in both sets of grafts. A late serum IgG response was detected in NPSC (days 13 and 20) and NPI (day 20) recipients. Consistently, IgG deposition was first detected at days 9 and 13 in NPSC and NPI grafts, respectively. Interestingly, C3 was deposited at days 1 and 3 in NPI grafts and only at day 1 in NPSC grafts, while membrane attack complex (MAC) deposition was only detected in NPI grafts (at days 1-4). Collectively, these data suggest NPSCs actively inhibit both the alternative and classical pathways of complement-mediated cell lysis, while the alternative pathway plays a role in rejecting NPIs. Ultimately, inhibiting the alternative pathway along with transplanting xenogeneic tissue from transgenic pigs (expressing human complement inhibitory factors) could prolong the survival of xenogeneic cells without immunosuppression.

Resistance of neonatal porcine Sertoli cells to human xenoantibody and complement-mediated lysis is associated with low expression of alpha-Gal and high production of clusterin and CD59

BACKGROUND

Porcine Sertoli cells have an inherent resistance to human xenoreactive antibody and complement-mediated lysis, however, the mechanisms of protection are still unclear.

METHODS

Neonatal porcine Sertoli cells (NPSCs) were isolated from testes of 10 to 15-day-old piglets. Immortalized porcine aortic endothelial cells (iPECs) were used as control cells. An in vitro humoral injury model was used to assess whether NPSCs could resist human xenoantibody and complement-mediated lysis. Expressions of alpha-Gal, clusterin, CD59, CD46, and CD55 were examined to investigate the possible mechanisms of the immunoprotection of NPSCs.

RESULTS

Compared with iPECs, NPSCs significantly resisted human natural antibody and complement-mediated lysis when incubated with 20% normal human serum (NHS) in vitro (24.38 +/- 0.50 vs. 53.13 +/- 14.53%, P < 0.01). Mechanistically, NPSCs expressed lower level of alpha-Gal (Gmean: 41.78 +/- 2.39 vs. 95.17 +/- 2.39, P < 0.01), which was correlated with decreased binding of human xenoreactive IgG and IgM. Additionally, NPSCs expressed higher level of clusterin measured by both Western blot and fluorescence-activated cell sorter analysis and expressed more CD59 mRNA detected by reverse-transcription polymerase chain reaction.

CONCLUSIONS

These data demonstrate that the resistance of NPSCs to human xenoantibody and complement-mediated lysis is associated with low expression of xenoantigen alpha-Gal and high production of the complement inhibitors clusterin and CD59.

Establishment and characterization of porcine Sertoli cell line for the study of xenotransplantation

BACKGROUND

An understanding of the main mechanism that determines the ability of immune privilege related to Sertoli cells (SC) will provide clues for promoting a local tolerogenic environment. In this report, we established neonatal porcine SC line and evaluated their characteristics.

METHODS

SC line was established following the transfection of primary SC (NPSC) from the testis of neonatal pig with plasmid pRNS-1 carrying genes for neomycin resistance and the SV40 large T antigen. Immunohistochemistry and RT-PCR were performed to evaluate the character of immortalized SC lines.

RESULTS

Our immortalized SC line (iPS) proliferated stably and had a phenotype similar to NPSC, as indicated by the immunoexpression of follicle stimulating hormone receptor (FSHR), and mRNA expression of androgen receptor (AR), and Wilms' tumor antigen (WT1). Interestingly, NPSC and iPS expressed mRNA of complement regulatory proteins (CRP) such as membrane cofactor protein (CD46), decay accelerating factor (DAF or CD55), and protectin (CD59), but CD59 mRNA expression was negligible in iPS.

CONCLUSION

These results suggest that iPS, immortalized by the introduction of SV40 T, retain their original characteristics, except for the relatively low expression of CD59, and that they may be useful for future in vitro and in vivo studies of immune privilege mechanisms related to SC.