Corneal bioprinting utilizing collagen‐based bioinks and primary human keratocytes

Abstract

Corneal transplantation is the treatment of choice for patients with advanced corneal diseases. However, the outcome may be affected by graft rejection, high associated costs, surgical expertise, and most importantly the worldwide donor shortage. In recent years, bioprinting has emerged as an alternative method for fabricating tissue equivalents using autologous cells with architecture resembling the native tissue. In this study, we propose a freeform and cell‐friendly drop‐on‐demand bioprinting strategy for creating corneal stromal 3D models as suitable implants. Corneal stromal keratocytes (CSK) were bioprinted in collagen‐based bioinks as 3D biomimetic models and the geometrical outcome as well as the functionality of the bioprinted specimens were evaluated after in vitro culture. We showed that our bioprinting method is feasible to fabricate translucent corneal stromal equivalents with optical properties similar to native corneal stromal tissue, as proved by optical coherence tomography. Moreover, the bioprinted CSK were viable after the bioprinting process and maintained their native keratocyte phenotypes after 7 days in in vitro culture, as shown by immunocytochemistry. The proposed bioprinted human 3D corneal models can potentially be used clinically for patients with corneal stromal diseases.

Tissue mimetic hyaluronan bioink containing collagen fibers with controlled orientation modulating cell morphology and alignment

“…At the low concentration used in this study (≤ 0.5% w/v), printability was rescued by the shear thinning THA. A similar approach was presented by Duarte Capos et al using agarose as shear thinning component [32]. On the other hand, printing properties of THA previously investigated in our group were preserved upon mixing with Col [33].…”

Prospects and Challenges of Translational Corneal Bioprinting

“…Several bioprinting approaches for corneal tissue engineering have been investigated [84][85][86]. Sorkio et al [86] introduced a laser-based bioprinting technique to create corneal mimicking structures ( Figure 3D).…”

“…Isolation and propagation of CSKs is challenging, as this delicate cell type easily transforms to scar inducing SFs. This challenging aspect was later improved in a recent study, that employed drop-on-demand bioprinting, [86] which is a more cell-friendly printing method relative to extrusion and laser-based bioprinting. In this study, CSKs were encapsulated in agarose-collagen type I bioinks and printed through a microvalve that was coupled to a pressurized air supply.…”

“…To summarize the results presented thus far, none of the bioprinting approaches has been able to satisfy all demands. Some studies show high survival rates and elongation of human CSKs but suboptimal mechanical properties [86]. Others were able to produce constructs with a high light transmission, yet low biomechanical stability and lack of cell-cell interactions [88].…”

The progress in corneal translational medicine

“…Some studies show high survival rates and elongation of human CSKs, but suboptimal mechanical properties. 203 Others were able to produce constructs with a high light transmission, but with low biomechanical stability and lack of cellcell interactions. 93 Future developments in 3D bioprinting have to optimize the technology and components to match the complexity of the human corneal stroma.…”