The efficient induction of human retinal ganglion-like cells provides a platform for studying optic neuropathies

HMGB2 knockdown ameliorates retinal ganglion cell injury by inhibiting NLRP3 inflammasome activation after retinal ischemia

AIM

To explore the neuroprotective effects of high mobility group box 2 (HMGB2) knockdown on retinal ganglion cells (RGCs) in the retinal ischemia-reperfusion injury (RIRI).

METHODS

Oxygen-glucose deprivation (OGD)-injured RGCs from postnatal three-day C57BL/6 mice pups and high intraocular pressure (IOP)-induced RIRI mice were used as cellular and animal models of RIRI. The expression of HMGB2 in the retina of RIRI mice and OGD-injured RGCs was detected through reverse transcription-polymerase chain reaction (RT-qPCR) and Western blotting. The effects of HMGB2 silencing on the morphological changes, RGCs survival, and cell apoptosis in mouse retinal tissues were observed through H&E staining, immunofluorescence staining with RNA-binding protein with multiple splicing (RBPMS) antibody, and TUNEL staining, respectively. RGC viability and apoptosis were examined by CCK-8 and flow cytometry assays. The levels of proteins associated with NOD-like receptor thermal protein domain associated protein 3 (NLRP3)-mediated pyroptosis [NLRP3, Caspase-1, GSDMD-N, interleukin (IL)-1β, IL-18] in vivo and in vitro were measured by Western blotting.

RESULTS

HMGB2 protein and NLRP3 were upregulated in the retina of RIRI mice and OGD-injured RGCs (P<0.001). The retina was edematous, accompanied by disorganized cell arrangement and decreased thickness of all layers, and obvious vacuoles in ganglion cell layer. HMGB2 silencing alleviated the reduction in total retinal thickness and the severity of retinal tissue damage as well as suppressed RGC loss and retinal cell apoptosis in RIRI mice. OGD-induced RGC apoptosis was ameliorated after downregulation of HMGB2 in vitro. Intravitreal injection of the AAV-sh-HMGB2 and si-HMGB2 resulted in significantly decrease of NLRP3, Caspase-1, GSDMD-N, IL-1β, and IL-18 protein levels in the retinal tissues of RIRI mice and OGD-injured RGCs, respectively (all P<0.001).

CONCLUSION

HMGB2 knockdown protects against RGC apoptosis and pyroptosis after RIRI through suppressing NLRP3 inflammasome activation.

Enriching new transplantable RGC-like cells from retinal organoids for RGC replacement therapy

Optic neuropathies, such as glaucoma, are due to progressive retinal ganglion cells (RGCs) degeneration, result in irreversible vision loss. The promising RGCs replacement therapy for restoring vision are impeded by insufficient RGC-like cells sources. The present work was enriched one new type RGC-like cells using two surface markers CD184 and CD171 from human induced pluripotent stem cells (hiPSCs) by FACS sorting firstly. These new kind cells have well proliferation ability and possessed passage tolerance in vitro 2D or 3D spheroids culture, which kept expressing Pax6, Brn3b and βIII-Tubulin and so on. The transplanted CD184+CD171+ RGC-like cells could survive and integrate into the normal and optic nerve crush (ONC) mice retina, especially they were more inclined to across the optic nerve head and extend to the damaged optic nerve. These data support the feasible application for cell replacement therapy in RGC degenerative diseases, as well as help to develop new commercial cells sorting reagents and establish good manufacturing practice (GMP) grade RGC-like donor cells for further clinical application.