P-256

Bioengineering a highly vascularized matrix for the ectopic transplantation of islets

C. Ellis¹, B. Vulsevic², K. McEwan², E. Suuronen², G. Korbutt^1
1 University of Alberta, Surgery, Edmonton, Canada; ² University of Ottawa, Ottawa, Canada

Objective: Islet transplantation is a promising cure for Type 1 diabetes; however limitations of the intra-portal site and poor revascularization of islets must be overcome. We hypothesize that engineering a highly vascularized collagen-based construct subcutaneously, intra-muscularly, or within the omentum would allow for islet graft survival and function in these alternative sites. In this study we developed a collagen based biomaterial to support islet survival both in vitro and in vivo.

Methods: Neonatal porcine islets (NPIs) were embedded in collagen matrices crosslinked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide containing combinations of chondroitin-6-sulphate, chitosan, and laminin, and compared to controls cultured in standard media. Islets were examined for insulin secretory activity after 24 hours, 4 days, and 7 days in vitro. These same NPI collagen constructs were transplanted subcutaneously in B6/Rag mice and then assessed for islet survival and vascularization.

Results: At all time points assessed during in vitro culture there were no significant differences in insulin secretory activity between control islets and those embedded in the collagen constructs – thereby indicating that the collagen matrix had no adverse effect on islet function. At various time points post-transplant (up to 56 days) immunohistochemical analysis of the grafts confirmed the presence of intact insulin-positive islets. The grafts were also shown to be vascularized by Masson-Trichrome staining, which was confirmed by von Willebrand factor staining.

Conclusions: This study demonstrates that a collagen, chondroitin-6-sulphate, chitosan, and laminin matrix supports islet function in vitro and moreover allows islet survival and vascularization post-transplantation; therefore, this bio-engineered vascularized construct is capable of supporting islet survival.

P-256

Bioengineering a highly vascularized matrix for the ectopic transplantation of islets

C. Ellis¹, B. Vulsevic², K. McEwan², E. Suuronen², G. Korbutt^1
1 University of Alberta, Surgery, Edmonton, Canada; ² University of Ottawa, Ottawa, Canada

Objective: Islet transplantation is a promising cure for Type 1 diabetes; however limitations of the intra-portal site and poor revascularization of islets must be overcome. We hypothesize that engineering a highly vascularized collagen-based construct subcutaneously, intra-muscularly, or within the omentum would allow for islet graft survival and function in these alternative sites. In this study we developed a collagen based biomaterial to support islet survival both in vitro and in vivo.

Methods: Neonatal porcine islets (NPIs) were embedded in collagen matrices crosslinked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide containing combinations of chondroitin-6-sulphate, chitosan, and laminin, and compared to controls cultured in standard media. Islets were examined for insulin secretory activity after 24 hours, 4 days, and 7 days in vitro. These same NPI collagen constructs were transplanted subcutaneously in B6/Rag mice and then assessed for islet survival and vascularization.

Results: At all time points assessed during in vitro culture there were no significant differences in insulin secretory activity between control islets and those embedded in the collagen constructs – thereby indicating that the collagen matrix had no adverse effect on islet function. At various time points post-transplant (up to 56 days) immunohistochemical analysis of the grafts confirmed the presence of intact insulin-positive islets. The grafts were also shown to be vascularized by Masson-Trichrome staining, which was confirmed by von Willebrand factor staining.

Conclusions: This study demonstrates that a collagen, chondroitin-6-sulphate, chitosan, and laminin matrix supports islet function in vitro and moreover allows islet survival and vascularization post-transplantation; therefore, this bio-engineered vascularized construct is capable of supporting islet survival.