2.9. Construction of IVDD rat model and intradiscal injection of lentivirus

A total number of 24 adult male Sprague–Dawley (SD, SPF and 250–300g), aged 3 months, were supplied by Shanghai Slac Laboratory Animal Co. Ltd. The SD rats were randomly divided into four groups (Control, IVDD, IVDD+KLF10, and IVDD+NC). The IVDD rat model was constructed as described previously [22,23]. Briefly, the rats were anaesthetized by intraperitoneal injection of 5% chloral hydrate (6 ​mL/kg) and Co7/8 of rat discs were punctured using 21-gauge needle. The punctured depth was 5 ​mm from the AF to the NP in the center of the disc and the needle was rotated 180° and then held for 30s. After that, a total of 10 ​μl construct of Lenti-KLF10 and Lenti-NC (approximately 5 ​× ​10⁸ TU/mL) were slowly injected into the punctured discs. No further treatment was carried out in control and IVDD groups. After injection, the rats were placed in their respective cages. Our animal protocol was authorized by the Ethics Committee of Shanghai East Hospital.