Layered PLG scaffolds for in vivo plasmid delivery.

Gene delivery from tissue engineering scaffolds can induce localized expression of tissue inductive factors to direct the function of progenitor cells, either endogenous or transplanted. In this report, we developed a layering approach for fabricating scaffolds with encapsulated plasmid, and investigated in vivo gene transfer following implantation into intraperitoneal fat, a widely used site for cell transplantation. Porous poly(lactide-co-glycolide) (PLG) scaffolds were fabricated using a gas foaming method, in which a non-porous layer containing plasmid was inserted between two porous polymer layers.

Extracellular matrix protein-coated scaffolds promote the reversal of diabetes after extrahepatic islet transplantation.

Background: The survival and function of transplanted pancreatic islets is limited, owing in part to disruption of islet-matrix attachments during the isolation procedure. Using polymer scaffolds as a platform for islet transplantation, we investigated the hypothesis that replacement of key extracellular matrix components known to surround islets in vivo would improve graft function at an extrahepatic implantation site.

Methods: Microporous polymer scaffolds fabricated from copolymers of lactide and glycolide were adsorbed with collagen IV, fibronectin, laminin-332 or serum proteins before seeding with 125 mouse islets.

Polymer scaffolds as synthetic microenvironments for extrahepatic islet transplantation.

Background: Problems associated with the hepatic transplantation of islets may preclude the broad application of islet transplantation. Thus, we sought to develop an approach to the extrahepatic transplantation of islets using a synthetic biodegradable polymer scaffold.

Methods: Microporous polymer scaffolds that allow vascular ingrowth and nutrient diffusion from host tissues were fabricated from copolymers of lactide and glycolide.

Plasmid delivery in vivo from porous tissue-engineering scaffolds: transgene expression and cellular transfection.

Tissue engineering scaffolds capable of sustained plasmid release can promote gene transfer locally and stimulate new tissue formation. We have investigated the scaffold design parameters that influence the extent and duration of transgene expression and have characterized the distribution of transfected cells. Porous scaffolds with encapsulated plasmid were fabricated from poly(lactide-co-glycolide) with a gas foaming procedure, with wet granulation employed to mix the components homogeneously prior to foaming.

Neurotrophin releasing single and multiple lumen nerve conduits.

Tissue engineering strategies for nerve repair employ polymer conduits termed guidance channels and bridges to promote regeneration for peripheral nerve injury and spinal cord injury, respectively. An approach for fabrication of nerve conduits with single and multiple lumens capable of controlled release of neurotrophic factors was developed. These conduits were fabricated from a mixture of poly(lactide-co-glycolide) (PLG) microspheres and porogen (NaCl) that was loaded into a mold and processed by gas foaming.