In Vivo Evaluation of Injected and Bioprinted Hyaluronic Acid-Based Bioink in Corneal Stromal Pocket

The corneal stroma contains specialized stromal keratocytes (CSKs) that preserve corneal transparency and homogeneity. Stromal scarring and opacities lead to vision loss in millions globally. While corneal transplantation remains the gold standard, it is constrained by donor shortages. Cell-based therapies using primary stromal cells show promise but still depend on donor tissue. Human adipose tissue-derived stem cells (hASCs) offer an abundant alternative, capable of differentiating into CSKs. A three-dimensional (3D) tissue matrix is essential for mimicking native tissue and supporting stromal regeneration. Hyaluronic acid (HA)-based matrices emerge as promising stromal substitutes. In this study, we aim to investigate the biocompatibility of HA-based bioink, both as injectable formulations and bioprinted constructs containing hASC-CSKs. In vitro, bioprinted HA-based constructs containing hASC-CSKs exhibit high cell viability, an organized structure, and maintained transparency. In vivo, the bioink integrates progressively into the corneal stroma, considerably reducing stromal thickness within two weeks. It supports the hASC-CSK phenotype post-transplantation, as indicated by lumican expression. Although inflammatory responses are observed, the bioink shields transplanted cells from immune rejection, promoting graft survival and integration. These findings demonstrate that HA-based bioink serves as a biocompatible scaffold for cell delivery, supporting stromal regeneration and highlighting its potential for future corneal therapies.