Injectable microcarriers enhance stem cell delivery and promote corneal regeneration for alkali burn

Corneal alkali burns represent severe ocular injuries characterized by acute inflammation and long-term stromal fibrosis, potentially causing irreversible vision loss. Stem cell therapy has emerged as a promising treatment due to its regenerative and immunomodulatory properties. However, conventional cell injection methods are limited by poor cell viability, low retention rates, and injection-induced mechanical trauma, significantly impairing therapeutic outcomes. Here, we present collagen-modified chitosan porous microspheres (ColMS) as a cell-laden porous microcarrier system to enhance adipose-derived stem cells (ADSCs) delivery efficiency for corneal repair following alkali burns. The ColMS possess tunable pore sizes (~6–18 μm) and particle diameters (~163–313 μm), providing a three-dimensional scaffold to support ADSC adhesion, proliferation, and enhanced cell viability during injection. In vitro experiments confirmed that ADSC-loaded ColMS (ColMS-ADSCs) exhibits robust immunomodulatory capacity and epithelial regenerative capabilities. Using a rat corneal alkali burn model, subconjunctival injection of ColMS-ADSCs suppressed acute inflammation in the early stage and effectively reduced corneal fibrosis in the late stage, leading to substantial restoration of corneal transparency. The treatment promoted epithelial regeneration, with epithelial thickness restored to near-normal levels and decreased myofibroblast activation, as evidenced by a 1.5-fold reduction in α-SMA fluorescence intensity compared to the alkali burn group. This work demonstrate that ColMS effectively enhance stem cell delivery efficiency, offering a promising clinical strategy for the treatment of corneal alkali burns, potentially opening new avenues toward improved vision restoration.