P-246

Pre-vascularization of a subcutaneous biohybrid device for cellular grafts

A.-C. Brady¹, M. Lopez-Cabezas¹, R.Damaris Molano¹, E. Zahr-Akrawi², D. Bates³, C. Ricordi¹, P. Buchwald¹, A. Pileggi^1
1 The Miami JDRFI Accelerator for Human Beta Cell Replacement and Tolerance Induction. Diabetes Research Institute, University of Miami, Miami, USA; ² University of Miami / Diabetes Research Institute, Departments of Surgery, Microbiology & Immunology, Miami, USA; ³ VisualSonics, Toronto, Canada

Objectives: Subcutaneous, pre-vascularized devices provide sustained function of islet cell grafts in rodents. We evaluated the kinetics of neo-vascularization of a cylindrical subcutaneous device in rats .

Methods: The biohybrid devices (Converge Biotech) were preimplanted subcutaneously in Lewis rats 3 days, 1-, 2- and 3-wks prior to vascularization assessment. Live microscopy of intraluminal device vasculature was evaluated using one-channel fluorescent fiber-optic microscope probes (Cellvizio^®) following FITC-dextran intravenous bolus (green fluorescence). Confocal fluorescent microscopy was done on sections of devices explanted after intravenous bolus of the lipophylic dye DiI (red fluorescence). Reversal of diabetes after transplantation of a suboptimal syngeneic islet mass in devices prevascularized for 3 days, 1, 2, 3, and 6 weeks was assessed in streptozotocin-induced diabetic rats.

Results: Vascular structures were detected on the inner devices' walls by live microscopy starting 2 and 3 wks after implantation, with higher complexity of vascular structures and numbers at the later time points tested. A statistically significant increase in vessel length (p=9.26x10^-13) and vessel area (p=2.03x10^-17) was observed when comparing 3-wks to 2-wks devices. Evaluation of tissue sections showed vascular structures in the surrounding of the device’s at 2 and 3 weeks post-implantation,while the degree of vascularization was much lower or absent at earlier time points. Primary non-function was observed in all rats receiving islets 3 days after device implantation, while diabetes was corrected in a proportion of the recipients after at least a week from its implantation.

Conclusions: Our data indicates that neo-vascularization of the device of at least a week may contribute creating a favorable environment for islet engraftment.

Disclosure: CR, PB and AP are on the Scientific Advisory Board of Converge Biotech, Inc.

P-246

Pre-vascularization of a subcutaneous biohybrid device for cellular grafts

A.-C. Brady¹, M. Lopez-Cabezas¹, R.Damaris Molano¹, E. Zahr-Akrawi², D. Bates³, C. Ricordi¹, P. Buchwald¹, A. Pileggi^1
1 The Miami JDRFI Accelerator for Human Beta Cell Replacement and Tolerance Induction. Diabetes Research Institute, University of Miami, Miami, USA; ² University of Miami / Diabetes Research Institute, Departments of Surgery, Microbiology & Immunology, Miami, USA; ³ VisualSonics, Toronto, Canada

Objectives: Subcutaneous, pre-vascularized devices provide sustained function of islet cell grafts in rodents. We evaluated the kinetics of neo-vascularization of a cylindrical subcutaneous device in rats .

Methods: The biohybrid devices (Converge Biotech) were preimplanted subcutaneously in Lewis rats 3 days, 1-, 2- and 3-wks prior to vascularization assessment. Live microscopy of intraluminal device vasculature was evaluated using one-channel fluorescent fiber-optic microscope probes (Cellvizio^®) following FITC-dextran intravenous bolus (green fluorescence). Confocal fluorescent microscopy was done on sections of devices explanted after intravenous bolus of the lipophylic dye DiI (red fluorescence). Reversal of diabetes after transplantation of a suboptimal syngeneic islet mass in devices prevascularized for 3 days, 1, 2, 3, and 6 weeks was assessed in streptozotocin-induced diabetic rats.

Results: Vascular structures were detected on the inner devices' walls by live microscopy starting 2 and 3 wks after implantation, with higher complexity of vascular structures and numbers at the later time points tested. A statistically significant increase in vessel length (p=9.26x10^-13) and vessel area (p=2.03x10^-17) was observed when comparing 3-wks to 2-wks devices. Evaluation of tissue sections showed vascular structures in the surrounding of the device’s at 2 and 3 weeks post-implantation,while the degree of vascularization was much lower or absent at earlier time points. Primary non-function was observed in all rats receiving islets 3 days after device implantation, while diabetes was corrected in a proportion of the recipients after at least a week from its implantation.

Conclusions: Our data indicates that neo-vascularization of the device of at least a week may contribute creating a favorable environment for islet engraftment.

Disclosure: CR, PB and AP are on the Scientific Advisory Board of Converge Biotech, Inc.