Research Highlight

Injectable hydrogels for healing bone defects

doi:10.1038/nindia.2019.11 Published online 30 January 2019

Researchers have synthesised a new type of composite hydrogel that, when loaded with specific bone-forming cells, can heal bone defects by triggering the bone-regenerating process1. These hydrogels could be used to treat bone defects caused by disease and trauma. 

Hydrogels are excellent materials for delivering cells such as bone-forming cells and drugs to specific target tissues. However, most of them lack efficiency in promoting the formation of new tissue. 

An international team including scientists from the Symbiosis International University in Pune, India, made the hydrogels using specific natural polymers and biomineralised microspheres. They then loaded the hydrogels with mesenchymal stromal cells, specific bone-forming cells found in the bone marrow of sheep.   

The researchers tested the efficiency of the cell-loaded hydrogels in promoting growth of new bone tissue and healing surgically created bone defects in female adult sheep. The hydrogels, when maintained on a nutrient broth for three weeks, allowed the stromal cells to form a collagen-rich gelatinous substance and bone tissues. The cell-loaded gels also secreted high amounts of calcium after three weeks. 

The cells didn’t die and spread inside the gels, indicating that the gels are biocompatible. The researchers subsequently injected the cell-loaded hydrogels into the bone-defect sites of the sheep. 

The defect sites showed new bone formation in all the animals. The untreated sheep, however, showed minimal bone formation within the defect sites while the defect sites in the sheep treated with the cell-loaded gels formed higher volumes of new bone tissue. 


1. Ingavle, G. C. et al. Injectable mineralized microsphere-loaded composite hydrogels for bone repair in a sheep bone defect model. Biomaterials. 197, 119-128 (2019)