Studies on intraocular transplantation of pancreatic cells in a large‐eyed preclinical animal model

Abstract

AbstractPurpose: Pancreatic islet transplantation (PIT) to the anterior chamber of the eye (ACE) has been shown to correct hyperglycemia and restore/improve glycemic control in rodents and non‐human primates. These studies also suggested that the eye may be in several ways a superior host site compared to the conventional hepatic portal system. In order to bring this technology to the clinic, it is essential to establish a large‐eyed non‐primate transplantation model. This proposal aims at establishing a rabbit ACE model of allogeneic PIT. We expect to gain insight into isolated islets function as well as ACE grafting efficiency and histological morphology in the large‐eyed rabbit model.Methods: Pancreatic islets (PI) were isolated from Dutch Belted rabbits by injection of collagenase A into the pancreatic interstitium, digestion and hand picking under a stereo microscope. PI were cultured in RPMI medium overnight in a standard tissue culture incubator prior to assessment of purity. In vitro functional capacity of rabbit PI was assessed by glucose‐stimulated insulin release and intracellular Ca2+ imaging assays. PI were injected into the ACE an allogenic Dutch Belted rabbit using surgical procedures routinely applied in ophthalmology. PI engraftment and cellular content was analysed by anterior segment optical coherence tomography (ASOCT) and immunohistofluorescence (IHF).Results: Isolated PI were of high purity with an approximate yield of 600–800 islets per pancreas. Preliminary results of functional capacity demonstrate that islets are responsive to high glucose stimulus, despite some variability. Allogeneic transplantation of isolated PI into the ACE of a Dutch Belted rabbit was followed by ASOCT. Engraftment was confirmed by IHF for vimentin. IHF suggests ACE engrafted islets are viable and maintain alpha, beta and delta cells.Conclusions: The presented isolation method renders high purity and functional rabbit PI. Allogeneic transplantation of PI into the ACE was successful using clinically relevant procedures and resulted in islets engraftment and long‐term survival. These results may have implications for the clinical treatment of diabetes mellitus, particularly regarding patients with indications for PIT.