Cartilage is difficult to self‐repair and it is more challenging to repair an osteochondral defects concerning both cartilage and subchondral bone. Herein, it is hypothesized that a bilayered porous scaffold composed of a biomimetic gelatin hydrogel may, despite no external seeding cells, induce osteochondral regeneration in vivo after being implanted into mammal joints. This idea is confirmed based on the successful continuous 3D‐printing of the bilayered scaffolds combined with the sol‐gel transition of the aqueous solution of a gelatin derivative (physical gelation) and photocrosslinking of the gelatin methacryloyl (gelMA) macromonomers (chemical gelation). At the direct printing step, a nascent physical hydrogel is extruded, taking advantage of non‐Newtonian and thermoresponsive rheological properties of this 3D‐printing ink. In particular, a series of crosslinked gelMA (GelMA) and GelMA‐hydroxyapatite bilayered hydrogel scaffolds are fabricated to evaluate the influence of the spacing of 3D‐printed filaments on osteochondral regeneration in a rabbit model. The moderately spaced scaffolds output excellent regeneration of cartilage with cartilaginous lacunae and formation of subchondral bone. Thus, tricky rheological behaviors of soft matter can be employed to improve 3D‐printing, and the bilayered hybrid scaffold resulting from the continuous 3D‐printing is promising as a biomaterial to regenerate articular cartilage.
The
treatment of cartilage injury and osteoarthritis has been a
classic problem for many years. The idea of in situ tissue regeneration paves a way for osteochondral repair in vivo. Herein, a hydrogel scaffold linked with bioactive
peptides that can selectively adsorb transforming
growth factor β1 (TGF-β1) was hypothesized to not only
afford cell ingrowth space but also induce the endogenous TGF-β1
recruitment for chondrogenesis promotion. In this study, bilayered
porous scaffolds with gelatin methacryloyl (GelMA) hydrogels as a
matrix were constructed via three-dimensional (3D)
printing, of which the upper layer was covalently bound with bioactive
peptides that can adsorb TGF-β1 for cartilage repair and the
lower layer was blended with hydroxyapatite for subchondral regeneration.
The scaffolds showed promising therapeutic efficacy proved by cartilage
and osteogenic induction in vitro and osteochondral
repair of rats in vivo. In particular, the animal
gait behavior was recovered after the in situ tissue
regeneration, and the corresponding gait analysis demonstrated the
promotion of tissue regeneration induced by the porous hydrogels with
the binding peptides.
The intramyocardial injection of colchicine-loaded hydrogel system effectively promoted myocardial repair after infarction while minimizing the systemic toxicity of colchicine.
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