3D printing of a lithium-calcium-silicate crystal bioscaffold with dual bioactivities for osteochondral interface reconstruction

It is difficult to achieve self-healing outcoming for the osteochondral defects caused by degenerative diseases. The simultaneous regeneration of both cartilage and subchondral bone tissues is an effective therapeutic strategy for osteochondral defects. However, it is challenging to design a single type of bioscaffold with suitable ionic components and beneficial osteo/chondral-stimulation ability for regeneration of osteochondral defects. In this study, we successfully synthesized a pure-phase lithium calcium silicate (Li2Ca4Si4O13, L2C4S4) bioceramic by a sol-gel method, and further prepared L2C4S4 scaffolds by using a 3D-printing method. The compressive strength of L2C4S4 scaffolds could be well controlled in the range of 15-40 MPa when pore size varied from 170 to 400 μm. L2C4S4 scaffolds have been demonstrated to possess controlled biodegradability and good apatite-mineralization ability. At a certain concentration range, the ionic products from L2C4S4 significantly stimulated the proliferation and maturation of chondrocytes, as well as promoted the osteogenic differentiation of rBMSCs. L2C4S4 scaffolds simultaneously promoted the regeneration of both cartilage and subchondral bone as compared to pure β-TCP scaffolds in rabbit osteochondral defects. These findings suggest that 3D-printed L2C4S4 scaffolds with such specific ionic combination, high mechanical strength and good degradability as well as dual bioactivities, represent a promising biomaterial for osteochondral interface reconstruction.