Beta cells of the pancreatic islets of Langerhans act as glucose sensors, adjusting insulin output in response to blood glucose
levels. A porous silicon capsule was engineered as a delivery vehicle for porcine pancreatic beta-islet cells. The pore size in the capsule wall was optimized to allow for transport of glucose and insulin in and out of * indicates a significant difference compared to all other groups SS SS-TMSi SS-PCSi Platelet Deposition (Platelets/mm2 ) 2000 4000 6000 8000 * Silanated Phosphorylcholine (PCSi) * the capsule while protecting the islet cells from the host immune system. Pilot in vitro studies demonstrated effective glucose monitoring and insulin production by encapsulated beta islet cells. Upon implantation in a rat diabetes model, it was found that glucose was not monitored consistently and insulin was secreted below therapeutic levels. Bioluminescence imaging revealed that the beta islet cells were 96% viable in the capsules. What is the likely reason for the impaired function of the islet cell-silicon implants in vivo
The host's immune response to the transplanted graft, which is commonly exhibited as pericapsular fibrotic overgrowth (PFO), is one of the key causes of defective encapsulated islets in (PFO).PFO creates a barrier upon this capsule surface that inhibits and impedes oxygen and nutrients from entering, resulting in islet cell deprivation, hypoxia, and/or death. This host immune response was missing under in vitro circumstances, which explains why glucose sensing and insulin release were more efficient than in vivo circumstances. Nonetheless, utilizing nanoporous encapsulation or modifying the microcapsular shape and geometry can solve these issues.
