Preliminary observations on whole-ovary xenotransplantation as an experimental model for fertility preservation.

Ovarian tissue preservation and retransplantation is a promising strategy to restore fertility in cancer survivors. Ischaemia accompanying ovarian tissue grafting, however, can lead to significant follicle loss. Transplantation of the whole ovary by vascular anastomosis has been considered as an alternative to prevent widespread ischaemic damage. In this study, the feasibility and function of transplanting whole ovary with intact vasculature were evaluated, with the goal of developing a xenograft model for studies using donated human ovaries. Whole-swine ovaries with vascular pedicles were perfused and transplanted as intact ovaries by anastomosis into irradiated ovariectomized nude rats (n = 10). The observation period was between 1 and 4 weeks. Fresh swine ovaries served as controls (n = 10). Ovarian stroma and follicle populations were assessed through histological examination in both transplanted and control ovaries. Most of the transplanted whole ovaries (n = 6) maintained stromal quality and all preantral follicle classes were represented, although follicle numbers decreased compared with fresh control. Four transplanted ovaries were fibrotic after 1-4 weeks within the nude rat. Our results demonstrate transplantation of whole-pig ovary into nude rats is possible and support development of this xenograft model system for human studies.

Soluble DPP4 originates in part from bone marrow cells and not from the kidney.

Dipeptidyl peptidase 4 (DPP4) is known to inactivate incretins as well as important chemokines and neuropeptides. DPP4 is expressed as a transmembrane protein but also occurs as a soluble enzyme circulating in the blood. However, the origin of the soluble DPP4 (sDPP4) is still unknown. In this study, DPP4 activity was quantified in plasma and extracted from different rat organs. Then, in order to see if the kidney or the bone marrow was the source of sDPP4, kidney or bone marrow transplantation was performed between wildtype (wt) Dark Agouti (DA) and DPP4 deficient congenic rats (n=6-9). Kidney was verified to have the highest DPP4 activity, followed by spleen and lung. In the following three weeks after successful kidney transplantation only transient trace plasma DPP4 activity was detected in DPP4 deficient rats receiving wt kidneys. In addition, DPP4 activity was not diminished in DA wt rats receiving DPP4 deficient kidneys. Both findings indicated that sDPP4 did not originate from the kidney. In contrast, 43±14% (compared to wt) sDPP4 activity was detected in the plasma of DPP4 deficient DA rats that were reconstituted with wt bone marrow cells. Not only leukocyte but also macrophage subpopulations express DPP4 in bone marrow as well as in blood as assessed by flow cytometry. Thus, bone marrow derived cells but not the kidney represent at least one source of sDPP4. And leukocyte or macrophage subpopulations could be potential candidates.

Long-term gene therapy with thrombospondin 2 inhibits TGF-ß activation, inflammation and angiogenesis in chronic allograft nephropathy.

We recently identified Thrombospondin-2 (TSP-2) as a regulator of matrix remodelling and inflammation in experimental kidney disease by using TSP-2 null mice and successfully proved TSP-2 overexpression as a therapeutic concept in a short term glomerulonephritis model in the rat. In this current study, we investigated if long-term TSP-2 overexpression is also capable to ameliorate the progression of chronic kidney disease in the setting of the chronic allograft nephropathy F344-Lewis model in the rat. Two weeks after renal transplantation, two rat thigh muscles were transfected once only with either a TSP-2 overexpressing plasmid (n = 8) or a luciferase-expressing plasmid as control (n = 8). Rats were monitored for renal function, histological changes and gene expression in the graft for up to 30 weeks after transplantation. Unexpectedly, only in the TSP-2 treated group 2 rats died before the end of the experiment and renal function tended to be worsened in the TSP-2 group compared to the luciferase-treated controls. In addition, glomerular sclerosis and tubular interstitial injury as well as cortical fibronectin deposition was significantly increased in the TSP-2 treated kidneys despite reduced TGF-ß activation and marked anti-inflammatory (macrophages, T-cells and B-cells) effects in this group. Long-term TSP-2 therapy impaired repair of renal endothelium, as demonstrated by significant higher glomerular and peritubular endothelial rarefaction and reduced endothelial cell proliferation in the transplanted kidneys from TSP-2 treated rats compared to controls. This TSP-2 effect was associated with decreased levels of renal VEGF but not VEGF1 receptor. In conclusion, despite its anti-inflammatory and TGF-ß activation blocking effects, TSP-2 gene therapy did not ameliorate but rather worsened experimental chronic allograft nephropathy most likely via its anti-angiogenic properties on the renal microvasculature.