Organogenesis of kidney and endocrine pancreas: the window opens

Abstract

Growing new organs in situ by implanting developing animal organ primordia (organogenesis) represents a novel solution to the problem of limited supply for human donor organs that offers advantages relative to transplanting embryonic stem (ES) cells or xenotransplantation of developed organs. Successful transplantation of organ primordia depends on obtaining them at defined windows during embryonic development within which the risk of teratogenicity is eliminated, growth potential is maximized, and immunogenicity is reduced. We and others have shown that renal primordia transplanted into the mesentery undergo differentiation and growth, become vascularized by blood vessels of host origin, exhibit excretory function and support life in otherwise anephric hosts. Renal primordia can be transplanted across isogeneic, allogeneic or xenogeneic barriers. Pancreatic primordia can be transplanted across the same barriers undergo growth, and differentiation of endocrine components only and secrete insulin in a physiological manner following mesenteric placement. Insulin-secreting cells originating from embryonic day (E) 28 (E28) pig pancreatic primordia transplanted into the mesentery of streptozotocin-diabetic (type 1) Lewis rats or ZDF diabetic (type 2) rats or STZ-diabetic rhesus macaques engraft without the need for host immune-suppression. Our findings in diabetic macaques represent the first steps in the opening of a window for a novel treatment of diabetes in humans.

Keywords: chronic kidney disease; diabetes mellitus; non-human primates; transplantation; xenotransplantation; β-cell.

Figure 1

Organ replacement therapies of the future.

Figure 2

Photomicrographs (A, C and D) and photographs (B, E and F) of pig renal primordia. (A and B) E28 primordia (s, stroma; ub, ureteric bud); (C–F) Pig renal primordia seven weeks post transplantation in a rat mesentery (C) Developed primordium in situ; (D) Primordium after removal from the mesentery (u, ureter) (E) cortex with a glomerulus (g) proximal tubule (pt) and distal tubule (dt) labeled. (F) Medulla with collecting ducts (cd) labeled. Magnifications are shown for (A and B) in (A); (C and D) in (D); for (E and F) in (E) Reproduced with permission (ref. 40).

Figure 3

Photomicrographs of mesenteric lymph node from a STZ-diabetic rhesus macaque, 78 days post-transplantation of E28 pig pancreatic primordia. (A, C and E) are stained with an anti-insulin antibody. (B, E and F) are stained using a control serum. Sections of medullary sinus are delineated by arrows (A–D). Individual cells with beta cell morphology are delineated by arrowheads (E and F). Scale bars 120 µm (A and B); 80 µm (C and D); and 20 µm (E and F). Reproduced with permission (ref. 2).

Figure 4

In situ hybridization was performed using pig proinsulin antisense (A and C) or sense probes (B and D) on sections of mesenteric lymph node originating from a STZ-diabetic rhesus macaque 407 days post-transplantation of E28 pig pancreatic primordia. Scale bars 80 µm (A and B) and 30 µm (C and D). Reproduced with permission (ref. 2).

Figure 5

Chromatogram (A) and product ion mass spectrum (B) of porcine insulin (precursor ion [M+5H]5+ m/z 1156.3) extracted from 2 ml plasma obtained five minutes after IV glucose administration to a STZ-diabetic transplanted rhesus macaque. The retention time and diagnostic product ions derived from the five-fold charged precursor ion unambiguously identify porcine insulin. chromatogram (C) and product ion mass spectrum (D) of human/macaque insulin (precursor ion [M+5H]5+ m/z 1162.3) extracted from 1 ml of non-diabetic rhesus macaque plasma. The retention time and diagnostic product ions derived from the five-fold charged precursor ion unambiguously identify human/macaque insulin. Reproduced with permission (ref. 2).

Figure 6

Advantages of organogenesis.