Investigation of the effectiveness of gelatin hydrolysate in human iPS-RPE cell suspension transplantation.

Introduction: The retinal pigment epithelium (RPE) plays essential roles in maintaining retinal functions as well as choroidal capillaries and can lead to visual disorders if dysfunctional. Transplantation of human-induced pluripotent stem cell-derived RPE (hiPSC-RPE) is a promising therapy for such RPE impaired conditions including age-related macular degeneration. The challenge with cell suspension transplantation is targeted delivery of graft cells and undesired cell reflux. Gelatin hydrolysate, a soluble variant with specific molecular weight distribution, is examined in this study for its potential use in hiPSC-RPE suspension transplantation, particularly in reducing cell reflux and enhancing RPE engraftment. Methods: A retinal bleb model was created using polydimethylsiloxane (PDMS) soft lithography to quantify cellular reflux. We examined the effects of gelatin hydrolysate on the hiPSC-RPE of various aspects of cell behavior and performance such as cell viability, hypoxia reaction, morphology, induction of inflammation and immune responses. Results: Gelatin hydrolysate at 5 % concentration effectively mitigated cell reflux in vitro mimic, improved cell viability, reduced cell aggregation, and had an inhibitory effect on hypoxic reactions due to cell deposition with hiPSC-RPE. Additionally, gelatin hydrolysate did not affect cell adhesion and morphology, and decreased the expression of major histocompatibility complex class II molecules, which suggests reduced immunogenicity of hiPSC-RPE. Conclusion: Gelatin hydrolysate is considered a valuable and useful candidate for future regenerative therapies in hiPSC-RPE suspension transplantation.

Integration Capacity of Human Induced Pluripotent Stem Cell-Derived Cartilage.

IMPACT STATEMENT: Cartilage particles derived from human induced pluripotent stem cells (hiPS-Carts) are one candidate source for transplants for treatment of articular cartilage damage. This study shows that hiPS-Carts integrate with each other in an in vitro model and analyzed the course of the integration. The integration starts at the perichondrium-like membrane at around 1 week and then progresses to the central cartilage within 4-8 weeks. The results indicate that FGF18 secreted from the perichondrium-like membrane accelerates the initial step of integration. The findings contribute to understanding how hiPS-Carts form repair tissue and provide clue to accelerate healing after transplantation.