Xenotransplanted Embryonic Kidney Provides a Niche for Endogenous Mesenchymal Stem Cell Differentiation into Erythropoietin-Producing Tissue

Abstract

Recent findings have demonstrated that stem cells can differentiate into mature tissue when supplied with a niche containing factors identical to those in the normal developmental program. A niche for the development of an organ can be provided by xenotransplantation of a similar developing organ. However, this process has many technical, safety, and ethical concerns. Here, we established xenotransplantation models that control endogenous mesenchymal stem cell (MSC) differentiation into mature erythropoietin (EPO)-producing tissue in a niche provided by a developing xenometanephros. Transplantation of rat metanephroi into mouse omentum, and similarly pig metanephroi into cat omentum, led to the recruitment of host cells and EPO production. EPO-expressing cells were not differentiated from integrating vessels because they did not coexpress endothelial markers (Tie-2 and VE-cadherin). Instead, EPOexpressing cells were shown to be derived from circulating host cells, as shown by enhanced green fluorescent protein (EGFP) expression in the grown transplants of chimeric mice bearing bone marrow from a transgenic mouse expressing EGFP under the control of the EPO promoter. These results suggest that donor cell recruitment and differentiation in a xenotransplanted developing organ may be consistent between species. The cells responsible for EPO expression were identified as MSCs by injecting human bone marrow-derived MSCs and endothelial progenitor cells into NOD/SCID mice. Furthermore, using metanephroi from transgenic ER-E2F1 suicide-inducible mice, the xenotissue component could be eliminated, leaving autologous EPO-producing tissue. Our findings may alleviate adverse effects due to long-lasting immunosuppression and help mitigate ethical concerns.

Erythropoietin Gene Expression: Developmental-Stage Specificity, Cell-Type Specificity, and Hypoxia Inducibility

“…This idea is supported by the observation that kidney progenitor cells produce renal tubules and glomeruli but not blood vessels or interstitial tissues, which contain REP cells (Matsumoto et al 2012;Taguchi et al 2014).…”

Urine excretion strategy for stem cell-generated embryonic kidneys

“…Pig metanephroi were cryopreserved using the previously reported vitrification method (8,20), with slight modifications. Briefly, metanephroi were initially equilibrated with 7.5% (vol/vol) ethylene glycol (EG) and 7.5% (vol/vol) DMSO in handling medium [HM; 20 mM Hepes-buffered tissue culture medium 199 + 20% (vol/vol) calf serum] for 25 min, followed by a second equilibration in vitrification solution (VS), consisting of 15% (vol/vol) EG and 15% (vol/vol) DMSO in HM, for 20-50 min, on ice.…”

Reforming the Kidney Starting from a Single-Cell Suspension

“…Matsumoto et al [6] recently showed that xenotransplanted metanephros could supply endogenous mesenchymal stem cells with a niche for differentiation into renal tissue. PCR using species-specific primers and sequence analysis revealed that xenotransplanted metanephros, from rat to mouse and similarly from pig to cat, expresses erythropoietin (EPO) of host animal origin.…”

“…Embryonic kidney rudiments implanted beneath the renal capsule [4,5], within the omentum [5,6] or into tunnels in the cortices of host kidneys [7] become integrated into living animals. Cultured fetal kidneys [8] also become vascularized and form mature glomeruli upon in vivo transplantation.…”