3D Corneal Shape After Implantation of a Biosynthetic Corneal Stromal Substitute.

PURPOSE: The current and projected shortage of transplantable human donor corneas has prompted the development of long-term alternatives to human donor tissue for corneal replacement. The biosynthetic stromal substitutes (BSS) characterized herein represent a potentially safe alternative to donor organ transplantation for anterior corneal stromal diseases. The goal of this phase 1 safety study was to characterize the three-dimensional (3D) corneal shape of the first 10 human patients implanted with a BSS and assess its stability over time. METHODS: Ten patients underwent anterior lamellar keratoplasty using a biosynthetic corneal stromal implant for either advanced keratoconus or central corneal scarring. Surgeries were performed at Linköping University Hospital, between October and November 2007. Serial corneal topographies were performed on all eyes up to a 4-year follow-up when possible. Three-dimensional shape average maps were constructed for the 10 BSS corneas and for 10 healthy controls. Average 3D shape corneal elevation maps, difference maps, and statistics maps were generated. RESULTS: The biosynthetic stromal substitutes implants remained stably integrated into the host corneas over the 4-year follow-up period, without signs of wound dehiscence or implant extrusion. The biosynthetic stromal substitutes corneas showed steeper surface curvatures and were more irregular than the healthy controls. CONCLUSIONS: Corneal astigmatism and surface steepness were observed 4 years after BSS implantation, while the implants remained stably integrated in the host corneas. Future studies will indicate if biomaterials technology will allow for the optimization of postoperative surface irregularity after anterior stromal replacement, a new window of opportunity that is not available with traditional corneal transplantation techniques.

In Vivo Functionality of a Corneal Endothelium Transplanted by Cell-Injection Therapy in a Feline Model.

PURPOSE: To evaluate the functionality of a corneal endothelium reconstituted by injection of corneal endothelial cells (CEC) in the anterior chamber of a feline model. METHODS: We operated the right eyes of 16 animals. Eight underwent central endothelial scraping and injection with 2 × 10(5) (n = 4) or 1 × 10(6) (n = 4) feline CEC supplemented with Y-27632 and labeled with 3,3'-Dioctadecyl-5,5'-Di(4-Sulfophenyl)Oxacarbocyanine (SP-DiOC18[3] or DiOC). After total endothelial scraping, two eyes were injected with 1 × 10(6) labeled CEC and Y-27632. The central (n = 3) or entire (n = 3) endothelium was scraped in six eyes followed by Y-27632 injection without CEC. Subjects were positioned eyes down for 3 hours. Outcomes included graft transparency, pachymetry, CEC morphometry, histology, electron microscopy, and function and wound healing-related protein immunostaining. RESULTS: Postoperatively, corneas grafted with 2 × 10(5) CEC and centrally scraped controls displayed the best transparency and pachymetry. Corneas grafted with 1 × 10(6) CEC yielded intermediate results. Entirely scraped controls remained hazy and thick. Histopathology revealed a confluent endothelial monolayer expressing sodium-potassium adenosine triphosphatase (Na(+)/K(+)-ATPase) and zonula occludens-1 (ZO-1) in corneas grafted with 2 × 10(5) CEC and centrally scraped controls, a nonuniform endothelial multilayer without expression of functional proteins in centrally scraped corneas grafted with 1 × 10(6) CEC, and a nonfunctional fibrotic endothelium in entirely scraped grafts and controls. Expression of DiOC in grafts was scarce. CONCLUSIONS: Injected CEC contributed little to the incompletely functional endothelium of grafted corneas. Y-27632 injection without CEC following scraping reconstituted the healthiest endothelium. Further studies investigating the therapeutic effect of Y-27632 alone are needed to validate these conclusions.

p53 Aggregates penetrate cells and induce the co-aggregation of intracellular p53.

Prion diseases are unique pathologies in which the infectious particles are prions, a protein aggregate. The prion protein has many particular features, such as spontaneous aggregation, conformation transmission to other native PrP proteins and transmission from an individual to another. Protein aggregation is now frequently associated to many human diseases, for example Alzheimer's disease, Parkinson's disease or type 2 diabetes. A few proteins associated to these conformational diseases are part of a new category of proteins, called prionoids: proteins that share some, but not all, of the characteristics associated with prions. The p53 protein, a transcription factor that plays a major role in cancer, has recently been suggested to be a possible prionoid. The protein has been shown to accumulate in multiple cancer cell types, and its aggregation has also been reproduced in vitro by many independent groups. These observations suggest a role for p53 aggregates in cancer development. This study aims to test the «prion-like¼ features of p53. Our results show in vitro aggregation of the full length and N-terminally truncated protein (p53C), and penetration of these aggregates into cells. According to our findings, the aggregates enter cells using macropinocytosis, a non-specific pathway of entry. Lastly, we also show that once internalized by the cell, p53C aggregates can co-aggregate with endogenous p53 protein. Together, these findings suggest prion-like characteristics for p53 protein, based on the fact that p53 can spontaneously aggregate, these aggregates can penetrate cells and co-aggregate with cellular p53.