Abstract
Cartilage defects can result in pain, disability, and osteoarthritis.
Hydrogels providing a chondroregeneration-permissive environment are often
mechanically weak and display poor lateral integration into the surrounding
cartilage. This study develops a visible-light responsive gelatin ink with
enhanced interactions with the native tissue, and potential for intraoperative
bioprinting. A dual-functionalized tyramine and methacryloyl gelatin (GelMA-Tyr)
is synthesized. Photo-crosslinking of both groups is triggered in a single
photoexposure by cell-compatible visible light in presence of
tris(2,2'-bipyridyl)dichlororuthenium(II) and sodium persulfate as initiators.
Neo-cartilage formation from embedded chondroprogenitor cells is demonstrated in
vitro, and the hydrogel is successfully applied as bioink for
extrusion-printing. Visible light in situ crosslinking in cartilage defects
results in no damage to the surrounding tissue, in contrast to the native
chondrocyte death caused by UV light (365–400 nm range), commonly used in
biofabrication. Tyramine-binding to proteins in native cartilage leads to a
15-fold increment in the adhesive strength of the bioglue compared to pristine
GelMA. Enhanced adhesion is observed also when the ink is extruded as printable
filaments into the defect. Visible-light reactive GelMA-Tyr bioinks can act as
orthobiologic carriers for in situ cartilage repair, providing a permissive
environment for chondrogenesis, and establishing safe lateral integration into
chondral defects.