Effects of alginate/chondroitin sulfate-based hydrogels on bone defects healing.

Repairing bone defects remains challenging in orthopedics. Here, strontium (Sr) alginate hydrogels containing chondroitin sulfate (CS) were fabricated for enhancing bone defects repair. The effects of CS incorporation ratio on the morphology, structure, thermal stability, water uptake and mechanical performance of Sr-CS/alginate hydrogels were also evaluated. Increasing CS incorporation ratio, Sr-CS/alginate hydrogels exhibit decreasing mechanical properties and lower water retention capacity. In vitro results suggest that Sr-CS/alginate hydrogels with higher CS ratio facilitate the proliferation of osteoblasts. Additionally, the osteogenic genes expressions were investigated by real-time quantitative polymerase chain reaction (RT-qPCR). The results reveal that Sr-CS/alginate hydrogels should have positive effects on modulating the osteogenic factors. Moreover, by employing repair femoral cylindrical defects rabbit model, the efficiency of as-fabricated Sr-CS/alginate hydrogels in bone regeneration was evaluated. The animal study suggests that Sr-CS/alginate hydrogel could significantly facilitate bone defects repair and therefore should potentially be useful for osteochondral tissue engineering.

Strontium chondroitin sulfate/silk fibroin blend membrane containing microporous structure modulates macrophage responses for guided bone regeneration.

A membrane used for guided bone regeneration (GBR) serves as a bioactive compartment rather than a physical barrier. However, the pure membrane may not provide an optimal microenvironment for bone formation and remodeling. Here, a novel strontium chondroitin sulfate/silk fibroin (SrCS/SF) blend membrane containing microporous structure was fabricated. By increasing incorporation content of SrCS, SrCS/SF membranes exhibit better mechanical properties and higher water retention capacity. In vitro results reveal that higher content of SrCS membranes facilitate osteoblasts proliferation. The evaluation of the osteoimmunomodulatory effects of the membranes reveals that SrCS/SF membranes should have positive effects on modulating the osteoimmune response of macrophages, by downregulating the expression of pro-inflammatory cytokines and the expression of degradation related catabolic genes and upregulating osteogenic factors. It is therefore believed that the developed SrCS/SF membranes should be potentially used as multifunctional bioactive GBR membranes.