Enzymatically crosslinked silk-nanosilicate reinforced hydrogel with dual-lineage bioactivity for osteochondral tissue engineering

Multifunctional polyphenol-based silk hydrogel alleviates oxidative stress and enhances endogenous regeneration of osteochondral defects

“…The large amount of phenolic hydroxyl groups in TA form strong hydrogen bonds with water, thereby increasing the hydrophilicity of SF-TA hydrogel [ 46 ]. Such enhanced hydrophilicity of hydrogel is beneficial for the absorption of bone marrow blood in the initial stage of osteochondral defect repair, which may improve the infiltration of BMSCs and growth factors into the hydrogel, and ultimately promote osteochondral regeneration [ 5 ].…”

“…Where indicated, 1 ​ng/ml IL-1β (Genscript, Nanjing, China) or 400 ​μM ​H 2 O 2 (Yuanle, Shanghai, China) was added to the media to stimulate cells. Cell viability was measured with the Calcein-AM/PI Double Staining Kit (Dojindo, Japan), and cell proliferation was measured with Cell Counting Kit-8 (CCK8, APExBIO, Houston, TX), as described previously [ 5 ].…”

“…Osteogenic and chondrogenic induction of BMSCs was performed according to our previous protocol [ 5 ]. Positive induction of osteogenesis was confirmed using BCIP/NBT Alkaline Phosphatase (ALP) Color Development Kit (Beyotime, China).…”

“…Samples were scanned using a Micro-CT scanner (Bruker SkyScan1176, Billerica, MA), and high-resolution micro-CT images were collected. Reconstruction and analysis of bone volume/total volume (BV/TV), and trabecular numbers (Tb.N) were carried out by concentrically placing a cylindrical region of interest (ROI, diameter: 5 ​mm, height: 5 ​mm) in the center of the original defect region with the threshold of 350–1080 for cartilage analysis, and >1080 for bone analysis [ 5 ].…”

“…Physiologically, when an osteochondral defect occurs and the subchondral bone plate is penetrated, a large number of endogenous bone marrow-derived mesenchymal stem cells (BMSCs) are released from the bone marrow and migrate into the chondral and subchondral areas to participate in the self-repair process [ 4 ]. However, the spontaneous repair process following trauma or microfracture surgery often results in the formation of fibrotic tissue, which is mechanically- and functionally-inferior to normal hyaline cartilage and subchondral bone [ 5 , 6 ].…”