The amnion is the inner of two membranes surrounding the fetus. That it arises from embryonic epiblast cells prior to gastrulation suggests that it m

The monolayer of cells forming the human corneal endothelium is critical to the maintenance of corneal transparency and is not known to regenerate in vivo. Thus, dysfunction of these cells constitutes the most often cited reasons for the 150,000 or so corneal transplants performed yearly. Although current corneal transplantation is more than 90% successful at 1 year, longer term results are not as encouraging with approximately 70% success at 5 years. Nonimmunologic graft failure and allograft endothelial rejection are the main problems. Furthermore, the global shortage of donor corneas greatly restricts several corneal transplantations performed. With advances in understanding corneal endothelial cell biology, it is now possible to cultivate human corneal endothelial cells (HCECs) in vitro, thus providing new opportunities to develop novel tissue-engineered human corneal endothelium. This review will provide an overview of (a) the characteristics of human corneal endothelium; (b) past and present HCECs isolation and culture protocols; (c) various potential carriers for the generation of tissue-engineered corneal endothelium, together with some of the functional studies reported in various animal models; and (d) the current rapid advancements in surgical techniques for keratoplasty. A successful combination of tissue-engineered human corneal endothelium coupled with innovative and groundbreaking surgical procedures will bridge basic research involving cultured HCECs, bringing it from bench to bedside.

Corneal endothelium-associated corneal blindness is the most common indication for corneal transplantation. Restorative corneal transplant surgery is the only option to reverse the blindness, but a global shortage of donor material remains an issue. There are immense clinical interests in the development of alternative treatment strategies to alleviate current reliance on donor materials. For such endeavors, ex vivo propagation of human corneal endothelial cells (hCECs) is required, but current methodology lacks consistency, with expanded hCECs losing cellular morphology to a mesenchymal-like transformation. In this study, we describe a novel dual media culture approach for the in vitro expansion of primary hCECs. Initial characterization included analysis of growth dynamics of hCECs grown in either proliferative (M4) or maintenance (M5) medium. Subsequent comparisons were performed on isolated hCECs cultured in M4 alone against cells expanded using the dual media approach. Further characterizations were performed using immunocytochemistry, quantitative real-time PCR, and gene expression microarray. At the third passage, results showed that hCECs propagated using the dual media approach were homogeneous in appearance, retained their unique polygonal cellular morphology, and expressed higher levels of corneal endothelium-associated markers in comparison to hCECs cultured in M4 alone, which were heterogeneous and fibroblastic in appearance. Finally, for hCECs cultured using the dual media approach, global gene expression and pathway analysis between confluent hCECs before and after 7-day exposure to M5 exhibited differential gene expression associated predominately with cell proliferation and wound healing. These findings showed that the propagation of primary hCECs using the novel dual media approach presented in this study is a consistent method to obtain bona fide hCECs. This, in turn, will elicit greater confidence in facilitating downstream development of alternative corneal endothelium replacement using tissue-engineered graft materials or cell injection therapy.

STEM CELLS, a peer reviewed journal published monthly, provides a forum for prompt publication of original investigative papers and concise reviews. STEM CELLS is read and written by clinical and basic scientists whose expertise encompasses the rapidly expanding fields of stem and progenitor cell biology. STEM CELLS welcomes original articles and concise reviews describing basic laboratory investigations of stem cells and the translation of their clinical aspects of characterization and manipulation from the bench to patient care. The journal covers all aspects of stem cells embryonic stem cells/induced pluripotent stem cells; tissue-specific stem cells; stem cell technology: epigenetics, genomics, proteomics, and metabonomics; cancer stem cells; translational and clinical research; and regenerative medicine.