Ultrathin Polyimide Membrane as Cell Carrier for Subretinal Transplantation of Human Embryonic Stem Cell Derived Retinal Pigment Epithelium

Abstract

In this study, we investigated the suitability of ultrathin and porous polyimide (PI) membrane as a carrier for subretinal transplantation of human embryonic stem cell (hESC) -derived retinal pigment epithelial (RPE) cells in rabbits. The in vivo effects of hESC-RPE cells were analyzed by subretinal suspension injection into Royal College of Surgeons (RCS) rats. Rat eyes were analyzed with electroretinography (ERG) and histology. After analyzing the surface and permeability properties of PI, subretinal PI membrane transplantations with and without hESC-RPE were performed in rabbits. The rabbits were followed for three months and eyes analyzed with fundus photography, ERG, optical coherence tomography (OCT), and histology. Animals were immunosuppressed with cyclosporine the entire follow-up time. In dystrophic RCS rats, ERG and outer nuclear layer (ONL) thickness showed some rescue after hESC-RPE injection. Cells positive for human antigen were found in clusters under the retina 41 days post-injection but not anymore after 105 days. In rabbits, OCT showed good placement of the PI. However, there was loss of pigmentation on the hESC-RPE-PI over time. In the eyes with PI alone, no obvious signs of inflammation or retinal atrophy were observed. In the presence of hESC-RPE, mononuclear cell infiltration and retinal atrophy were observed around the membranes. The porous ultrathin PI membrane was well-tolerated in the subretinal space and is a promising scaffold for RPE transplantation. However, the rejection of the transplanted cells seems to be a major problem and the given immunosuppression was insufficient for reduction of xenograft induced inflammation.

The formation of a functional retinal pigment epithelium occurs on porous polytetrafluoroethylene substrates independently of the surface chemistry

“…Studies of the mechanical properties of Bruch’s membrane are limited in number, study different layers and use a range of techniques to obtain data, however the elastic modulus appears to be around 2–4 MPa [38]. The substrates used in this study were several orders of magnitude higher than that of Bruch’s membrane, although similar to those used in other studies [7, 35] and in the same order of magnitude as that reported for non-porous PTFE [39]. Furthermore, the differences in surface stiffness resulting from the different surface treatments were relatively small, even across multiple regions on different samples.…”

Integration of Subretinal Suspension Transplants of Human Embryonic Stem Cell-Derived Retinal Pigment Epithelial Cells in a Large-Eyed Model of Geographic Atrophy

“…Despite the surgical difficulties and putative immunologic response to the transplant, implantation of sheets of hESC-RPE with or without a supportive biomatrix may be more efficient in repopulating areas with more extensive damage to the outer neuroretina/RPE/Bruch's membrane complex. 9,27,28 However, preclinical results in large-eyed animals suggest that caution is warranted, as such constructs may cause outer retinal atrophy. 10,28 Therefore, it would be important to optimize this technology, if successful integration of hESC-RPE is to be achieved in areas of extensive atrophy.…”

“…9,27,28 However, preclinical results in large-eyed animals suggest that caution is warranted, as such constructs may cause outer retinal atrophy. 10,28 Therefore, it would be important to optimize this technology, if successful integration of hESC-RPE is to be achieved in areas of extensive atrophy.…”

Microfluidic‐Printed Microcarrier for In Vitro Expansion of Adherent Stem Cells in 3D Culture Platform

“…Autologous stem cells require individual cell isolation and characterization, whereas allogeneic stem cells can be produced in a time‐ and cost‐effective way. Allogeneic stem cells are advantageous in the sense that a sufficient number of cells with a high biological activity can be secured from a healthy donor over a short time period for the storage and production of therapeutic agents . Therefore, they can be effectively used to treat acute diseases, such as stroke or acute GVHD …”