Fiber-reinforced hydrogel combined with 3D printed scaffolds for regeneration of osteochondral defects

Osteochondral defects present a formidable challenge within the realm of orthopedic medicine. The burgeoning field of tissue engineering holds potential for the amelioration of these injuries. In this vein, we meticulously engineered an integrated osteochondral repair scaffold by combining a short-cut fiber-reinforced hydrogel as a cartilaginous layer with 3D printed scaffold as bone layer. The cartilaginous layer hydrogel is composed of sodium alginate (Alg) and hyaluronic acid (HA), which are similar to the extracellular matrix of chondrocytes. The incorporation of 25 wt% short-cut fibers into the hydrogel substantially enhanced its mechanical integrity and fostered in vitro proliferation and adhesion of bone marrow stromal cells (BMSCs). The bone layer of polylactic glycolic acid copolymer (PLGA)/nano-hydroxyapatite (n-HA)/gelatin (Gel) gradient scaffold (PHG) was successfully prepared by constructing Gel network in 3D printed PLGA/n-HA framework. A PHG scaffold semi-immersed in hydrogel forms a comb-toothed interlocking structure with the hydrogel to simulate the bone-cartilage interface at the natural knee joint of the human body. In vivo examinations of osteochondral defect repair corroborate that the integrated scaffold, enriched with 25 % short-cut fibers, efficaciously promotes simultaneous regeneration of cartilage and subchondral bone. Collectively, our findings advocate that the combination of 3D-printed scaffolds and hydrogels could be a promising candidate for functional osteochondral regeneration.