Insulin expression and C-peptide in type 1 diabetes subjects implanted with stem cell-derived pancreatic endoderm cells in an encapsulation device

Abstract

These preliminary data from an ongoing first-in-human phase 1/2, open-label study provide proof-of-concept that pluripotent stem cell-derived pancreatic endoderm cells (PEC-01) engrafted in type 1 diabetes patients become islet cells releasing insulin in a physiologically regulated fashion. In this study of 17 subjects aged 22-57 with type 1 diabetes, PEC-01 cells were implanted subcutaneously in VC-02 macroencapsulation devices, allowing for direct vascularization of the cells. Engraftment and insulin expression were observed in 63% of VC-02 units explanted from subjects at 3-12 months post-implant. Six of 17 subjects (35.3%) demonstrated positive C-peptide as early as 6 months post-implant. Most reported adverse events were related to surgical implant or explant procedures (27.9%) or to side-effects of immunosuppression (33.7%). Initial data suggest that pluripotent stem cells, which can be propagated to the desired biomass and differentiated into pancreatic islet-like tissue, may offer a scalable, renewable alternative to pancreatic islet transplants.

Trial registration: ClinicalTrials.gov NCT03163511.

Graphical abstract

Figure 1

The two different types of units used in the present study (Upper photo) Sentinels (VC-02-20), which are smaller in size (1.5 cm x 1 cm) and have fewer cells, are explanted and examined periodically to evaluate status of the dose-finding units. For size comparison a US quarter is shown. (Lower photo) The larger dose-finding units (VC-02-300, 9 cm x 3 cm)) are used to develop the procedures and to assess the safety and efficacy of various quanta of cell doses.

Figure 2

Trial Design of Cohort 2

Figure 3

Histology of cross-sections of a sentinel explanted from “Subject D-001” with glucose-responsive C-peptide illustrates both the cellular and non-cellular regions of a mature graft (A–C) Three serial cross-sections (B) of approximately 4 mm apart within the explant stained with hematoxylin and eosin (H&E) reveal cellular regions (purple, hematoxylin-stained, enlarged in C) and non-cellular regions (pink, eosin-stained, enlarged in A). The non-cellular regions consist of collagenous fibers corresponding to regions of infiltrating host myofibroblasts observed at earlier time points (see Figure S2). (D–G) Panels (D)–(G) show immunohistochemistry of the cellular region identified in (C). Chromogranin A-staining shows the vast majority of the graft consists of endocrine cells (D). Staining for alpha smooth muscle actin (αSMA) identifies host-derived myofibroblasts (E), especially in the bottom left within the device lumen, and in larger blood vessels, but not or only weakly so smaller capillaries. Glucagon (brown) and insulin (magenta) staining account for the majority of graft-derived endocrine cells, glucagon being more abundant (F). Staining for CD34 identifies small capillaries as well as larger blood vessels (G). Note paucity of CD34 staining in the region devoid of graft-derived cells (bottom left within device lumen). Counterstain in all IHC panels is hematoxylin. Scale bars, 2.5 mm (top center) and 250 μm (all other images).

Figure 4

Histology of cross-sections from an explanted dose-finding unit at approximately 11 months from “Subject E-002” Several panels illustrate the histological features routinely observed in the cellular regions of VC-02 grafts. Shown are “nearly adjacent” sections. Gray strips seen at the top and bottom of each image are the delivery device membranes. (A) H&E staining reveals densely packed cells reminiscent of human endocrine islet morphologies, albeit without the macro-anatomical “islet” nature. (B) Nearly all graft-derived cells are endodermal in nature as demonstrated by nuclear staining to the transcription factors FOXA2 and CDX2. The open structure lined with endodermal cells, exemplified in the lower left of each image, is not a prominent feature but observed occasionally in the cellular regions of the grafts. (C) A subset of graft-derived cells coincident with insulin-expressing cells show nuclear immunoreactivity for NKX6-1, a transcription factor specific to β cells in mature human islets. (D) The cellular regions are well vascularized with microcapillary structure, demonstrated with the endothelial cell marker CD34 (magenta). CD3 staining (brown) marks T cells, not abundant but observed occasionally outside the device lumen, but rarely inside the lumen among graft-derived cells. (E) Many cells show glucagon (GCG) immunoreactivity. (F) Many cells show insulin (INS) immunoreactivity in regions coincident with NKX6-1 expression. Scale bars, 250 μm. Counterstain is hematoxylin.