BACKGROUND:The mechanism of programmed death receptor-1(PD-1)effect on osteogenic differentiation of bone marrow mesenchymal stem cells in high glucose environment remains unclear. OBJECTIVE:To explore the effect of PD-1 on osteogenic differentiation of rat bone marrow mesenchymal stem cells in high glucose environment and its regulatory mechanism. METHODS:Rat bone marrow mesenchymal stem cells were randomly divided into normal glucose group(5.6 mmol/L),high glucose group(30 mmol/L),PD-1 overexpression group,PD-1 overexpression no-load group,PD-1 knockdown group,PD-1 knockdown no-load group,and PI3K/AKT pathway inhibitor group(PD-1 knockdown+5 μmol/L LY294002).Rat bone marrow mesenchymal stem cells were cultured in high glucose to simulate the diabetic environment in vitro.The mRNA expression of PD-1 and ligand PD-L1 and the mRNA expression of osteogenic markers Runx2 and OSX in rat bone marrow mesenchymal stem cells were detected by qRT-PCR.The osteogenic differentiation ability was observed by alkaline phosphatase staining and alizarin red staining.Cell proliferation was detected by CCK-8 assay.The protein expressions of PD-1,PD-L1,p-PI3K,and p-AKT were detected by western blot assay. RESULTS AND CONCLUSION:(1)The levels of PD-1 and PD-L1 were significantly increased in the high glucose environment in vitro,and the osteogenic differentiation ability of bone marrow mesenchymal stem cells was inhibited in the high glucose environment.(2)Knockdown of PD-1 expression could promote osteogenic differentiation of bone marrow mesenchymal stem cells,increase cell proliferation activity,and activate the PI3K/AKT pathway.(3)After addition of PI3K/AKT pathway inhibitor LY294002,the ability of bone marrow mesenchymal stem cells to differentiate into osteoblasts decreased.The results show that PD-1 is dependent on the PI3K/AKT signaling pathway to inhibit osteogenic differentiation of rat bone marrow mesenchymal stem cells under high glucose environment.

【Objective】 To compare the clinical efficacy and sagittal parameters of oblique lateral interbody fusion （OLIF） combined with posterior percutaneous internal fixation and percutaneous transforaminal endoscope-assisted posterior lumbar interbody fusion （PT-Endo-TLIF） in treating degenerative lumbar spondylolisthesis. 【Methods】 A retrospective analysis was made on 43 patients with Meyerding Ⅰ and Ⅱ° degenerative lumbar spondylolisthesis treated in our hospital from September 2017 to January 2020. Among them 23 cases were treated by OLIF， and the other 20 cases were treated by PT-Endo-TLIF. We observed and recorded the operation time， average length of hospital stay， and intraoperative blood loss， and postoperative complications of the patients. The patients were followed up 3 day， 6 and 12 months after the operation. The lumbar sagittal parameters of the two groups were compared by X-ray， CT and MRI examinations. The patients’ lower back pain was recorded for visual analogue scale （VAS）， and Oswestry disability index （ODI） was used to evaluate the clinical efficacy. 【Results】 Both groups of patients successfully completed the operation and follow-up， with the average follow-up time of 12 months. The average amount of intraoperative blood loss and operation time were significantly lower in OLIF group than in PT-Endo-TLIF group （P<0.05）. Intervertebral height increased significantly in the two groups after operation compared with pre-operation （P<0.05）. Compared with pre-operation， lumbar lordosis angle， lower lumbar lordosis angle and lumbar lordosis distribution index increased in both groups （P<0.05）， with no significant difference between them （P>0.05）. The inclination angle of L4 vertebral body and the distance between L1 vertical line and S1 in both groups were decreased compared with those before surgery （P<0.05）， but there was no significant difference between the two groups （P>0.05）. The inclination angle of L5 vertebral body in the two groups was increased compared with that before surgery （P<0.05）， but there was no statistical significance between both groups （P>0.05）. 【Conclusion】 OLIF surgical technique has the comparative advantages of definite curative effect， less trauma， fewer surgical complications， shorter operation time， less bleeding， and good recovery of the height of intervertebral space， which is suitable for its application among clinicians.