Figure 4. BP device transplantation and cell refilling in a dog.

(a) Schematics illustrating the design evolution of the resin-based BP device; the first design (left) was upgraded to include a porous structure for tissue integration and was elongated to expose the cell encapsulation module to the deeper subcutaneous space; the second design (center) was upgraded to the final design (right) by including a hexagon depression for frame cap removal by a hex wrench and a trimmed rim diameter of the top of the frame base to reduce skin coverage. (b) Digital image of the final BP device design. (c) Schematic and dimensions of the BP device components including a (top to bottom) PFC-infused PTFE nanomembrane, frame cap with a PDMS washer, cell encapsulation module, frame base with a porous exterior, anchor rings, and threading, and the alginate-impregnated nylon mesh. (d) Digital image of the device in a dog at 1-month post-implantation. (e) Digital image during the non-surgical refilling procedure: a hex wrench was placed in hexagon depression and twisted as the base was stabilized with forceps. (f) Digital image of the device in a transcutaneous position after the frame cap (including the cell encapsulation module) has been removed. (g) Digital image of the frame cap with the cell encapsulation module following retrieval at 1-month. (h) Digital image of the BP device with the replaced cap containing encapsulated rat islets. (i) Digital image of the BP device at 1-month post cell refilling. (j) Digital image of the retrieved cell encapsulation module at 1-month post cell replacement. (k) H&E staining of rat islets from the retrieved BP device. (l) Immunohistochemical staining of islets in the retrieved BP device. (m) Schematic highlighting the porous structure on the exterior of the frame base. (n) H&E staining of the device and surrounding subcutaneous tissue showing tissue integration into the porous structure.