To evaluate the regenerative effect of pDNA‐BMP2 when added to CS–CSn–GP, in the study by Li, Ji, et al. (2017), rat calvarial defects and periodontitis model of beagle dog were implanted with CS–GP and CS–CSn (pDNA‐BMP2)–GP and compared with control groups without hydrogels. This evidence concerns the gene BMP2 and periodontitis.