Different mechanisms mediate the rejection of porcine neurons and endothelial cells transplanted into the rat brain

Abstract

In order to investigate the early cellular responses mediating xenograft rejection in the brain, porcine aortic endothelial cells (PAEC) or porcine fetal mesencephalic neurons (PNEU) were transplanted into the striatum of LEW.1A rats. PAEC were detected with a specific anti-beta1 integrin antibody, and PNEU with an anti-porcine neurofilament antibody, or an antibody recognizing the NeuN antigen. PAEC grafts were massively infiltrated within 24 h by OX42-positive cells, which may correspond to polymorphonuclear (PMN) cells or macrophages. At that moment, the graft contained numerous cells expressing the inducible isoform of NO-synthase (iNOS). Infiltration by ED1-positive macrophages was effective after three days. The beta1-integrin labeling decreased from that time-point to day 7 post-implantation, and vanished after 11 days. Although some OX8-positive cells were present around the graft as soon as 3 days after transplantation, cells expressing the T-cell receptor (TCR)-beta chain infiltrated the graft after 7 days and their number remained low. A strong, diffuse OX8-and ED1-positive immunoreactive material remained in the scar up to the third week. In striking contrast, PNEU grafts remained poorly infiltrated by OX42- or ED1-positive cells during the first two weeks. A massive infiltration by macrophages and TCRbeta-positive lymphocytes occurred after 3 weeks. Natural killer (NK) cells were more scarce. The inflammation territory enlarged, and blood vessels were overloaded with macrophages or lymphocytes. Nevertheless, the graft contained NeuN-positive nuclei and neurites harbouring the porcine neurofilament protein. Hence, rejection was not completed at this time-point. These results suggest that the rapid rejection of PAEC is mainly driven by macrophages and possibly PMN cells, unlike PNEU, whose rejection is delayed and also involves lymphocytes. Differences in immunogenicity of grafted cells and/or patterns of production of pro-inflammatory cytokines may account for these contrasted rejection kinetics.

Mesenchymal stem cells induce a weak immune response in the rat striatum after allo or xenotransplantation

“…Xenotransplantation of porcine foetal neuroblasts to overcome striatal dopamine or GABA decreases in patients with Parkinson's or Huntington's disease, respectively, seems a viable alternative to allotransplantion of human foetal donor tissue, especially because the latter is complicated by both practical and ethical issues [55]. However, it has been shown that xenotransplantation induces a severe immune response leading to the graft rejection [35,36,55]. For example, foetal porcine xenoneuroblasts can trigger a severe lymphocyte response [35,36] which might be mitigated with co-transplantation of MSCs.…”

“…However, it has been shown that xenotransplantation induces a severe immune response leading to the graft rejection [35,36,55]. For example, foetal porcine xenoneuroblasts can trigger a severe lymphocyte response [35,36] which might be mitigated with co-transplantation of MSCs. Therefore, MSCs, as being hypoimmunogenic, could increase graft survival without the use of immunosupressors when co-transplanted with pig brain tissue.…”

“…After being anesthetized with an intraperitoneal (i.p.) injection of xylazine (10 mg/kg)/ketamine (75 mg/kg), the animals were transplanted (2 l) with 400,000 eGFP rat MSCs [33], or Hoechst labelled [34], human MSCs (xenotransplantation) or rat MSCs (allotransplantation) into the left striatum, using a 10 l Hamilton microsyringe placed, at the following coordinates, relative to Bregma: ϩ0.7 mm AP; ϩ2.8 mm ML; -5.8 mm and Ϫ5.4 mm DV (with tooth bar at Ϫ3.3 mm) [35]. Rats were sacrificed at 5, 14, 21 or 63 days after transplantation.…”

Migration, fate and in vivo imaging of adult stem cells in the CNS

“…In addition to information about grafted cells, MRI can provide information about the surrounding tissue (i.e., lesion size, edema or inflammation), which may have an effect on graft survival or the functional recovery of the tissue. [27][28][29][30] …”

Porcine Fetal Ventral Mesencephalic Cells are Targets for Primed Xenoreactive Human T Cells

“…The cryopreservation mevide further evidence of cellular mechanisms playing an dium used was 0.9% saline, 0.6% glucose, and 10% diimportant role in the rejection of intracerebral xenotransmethyl sulfoxide (DMSO) (AIM-V medium, Gibco). plantation (13,39).…”