Transplantation of human embryonic stem cell-derived retinal pigment epithelial cells via injectable microfluidic-templated microgels for retinal regeneration

Retinal pigment epithelial (RPE) cells are specialized neural cells crucial for vision, while human embryonic stem cell-derived retinal pigment epithelial (hESC-RPE) cells hold great potential as a viable cell source for treating retinal degenerative diseases like retinitis pigmentosa (RP). However, the transplantation efficiency and viability of hESC-RPE cell suspensions are relatively low due to detrimental shear-force during operations and host immune-clearance. We herein develop an alternative transplantation strategy with the aid of a microfluidic-templating microgel cell carrier to achieve substantially enhanced loading and delivery efficiency of hESC-RPE cells, thereby promoting visual function recovery after subretinal injection in the RP model Royal College of Surgeons (RCS) rats. Specifically, injectable monodispersed microgels consisting of gelatin-methacryloyl/Hyaluronic acid-methacryloyl core coated with fibrin shell (denoted as Fib@GHMS) were fabricated in a high-throughput and controllable manner, facilitating the adhesion and proliferation of hESC-RPE cells. RCS rats treated with microcarriers showed significantly improved visual function, evidenced by increased B-wave amplitudes and the preservation of the inner nuclear layer at 8 weeks post-surgery. In conclusion, our innovative delivery system Fib@GHMS for hESC-RPE cell transplantation presents a potential therapeutic graft for retinal tissue engineering. It may open a new avenue for clinical transplantation of minimally invasive cell-based treatments in retinal degenerative diseases.