Topical delivery of cultivated limbal stem cells via porous photocurable hydrogel: A noninvasive, convenient, and efficient stem cells delivery strategy for limbal stem cell deficiency.

Topical administration of stem cells is one of the simplest approaches to stem cell-based therapy for limbal stem cell deficiency (LSCD). Without timely supplementation of deficient stem cells, LSCD may worsen, carrying a high risk of blindness in severe cases. However, challenges such as stem cell loss, poor cell attachment, short retention time, and phenotypic transformation of stem cells limit the efficiency of direct stem cell delivery. To address these problems, this study conducted in vitro and in vivo screenings of photocurable hydrogels and identified a porous Gelatin Methacryloyl (PG) hydrogel with larger pore sizes prepared by phase separation technology that satisfies four critical conditions: (i) encapsulating stem cells before delivery, (ii) maintaining the viability and self-renewal of stem cells via activation of the non-canonical Wnt signaling pathway, (iii) adhering uniformly to the ocular surface, and (iv) supporting stem cell proliferation, migration, and adhesion to the target interfaces. In a rabbit model of LSCD, the PG hydrogel loaded with cultivated limbal stem cells was applied to the ocular surface in combination with corneal bandage lenses, enabling a sutureless, non-invasive, convenient, and efficient stem cell delivery system. This innovative delivery strategy not only greatly simplified the existing process of limbal stem cell transplantation and significantly reduced surgery time, but also successfully overcame the challenges associated with direct stem cell eye drops. Most importantly, it promoted corneal injury repair, achieving avascular and scar-free corneal regeneration.