Another important combination is BMP-2 with triptolide incorporated into a hydrogel and the inhibition of pro-inflammatory cytokine expression like interleukin (IL)-1β and tumor necrosis factor (TNF)-α as these factors on osteogenic differentiation was studied by the research group of Lacey et al. The results revealed that these interleukins play a great role in bone loss and inflammatory conditions like rheumatoid arthritis (Lacey et al., 2009; Kim and Tabata, 2015). Here, TNF is linked to rheumatoid arthritis.