ABSTRACT
BACKGROUND: Local endothelial progenitor cells (EPCs) have been reported to promote migration and homing of EPCs by releasing stromal cell-derived factor-1 (SDF-1) under hypoxia environment. OBJECTIVE: To investigate the effect of different hypoxia periods on the expression of SDF-1 protein in EPCs and the migration of EPCs, thus providing new ideas for the treatment of ischemic diseases. METHODS: The bone marrow of the long bone was removed from Sprague-Dawley rats used for isolate EPCs. After culture and identification, EPCs were divided into four groups: control (normoxia), 6-, 12- and 24-hour hypoxia groups. The expression level of SDF-1 in the supernatant of EPCs in each group was detected by ELISA and immunofluorescence. The mRNA and protein levels of SDF-1 were detected by RT-PCR and western blot assay. The effect of hypoxia on the migration of EPCs was tested by Transwell assay. RESULTS AND CONCLUSION: The obtained cells were identified as EPCs. ELISA and immunofluorescence results showed that compared with the control group, the expression level of SDF-1 began to increase at 6 hours of hypoxia, peaked at 12 hours of hypoxia, and then decreased at 24 hours of hypoxia. RT-PCR and western blot assay results found that the mRNA and protein expression levels of SDF-1 were the highest in the 12-hour hypoxia group, followed by 6- and 24-hour hypoxia groups, and the lowest in the control group (P < 0.01). The number of EPCs penetrating the membrane in the 12-hour hypoxia group was significantly more than that in the 6- and 24-hour hypoxia groups, and the number in the 24-hour hypoxia group was significantly more than that in the control group (P < 0.05). In summary, hypoxia can promote the secretion of SDF-1 and induce the migration of EPCs.
ABSTRACT
Objective To introduce the technique and experience in reconstruction of posterior crueiate ligament-posterolateral comer(PCL-PLC)injuries with only one allograft of Achilles tendon. Methods The instable knees in 12 cases with PCL injury combined with three degree chronic PLC injury were treated with PCL reconstruction under arthroscope and PLC reconstruction through posterolateral arc incision.Single bundle grafts of PCL reconstructions in tibial and femoral tunnels were fixed by resorption screws.Fibular collateral ligament(FCL)and popliteofibular ligament(PFL)were reconstructed with reforming Larson(?)method.All reconstruction grafts only needed one Achilles tendon as donator.Total op- eration time was 130 minutes including 90 minutes of PCL reconstruction and 40 minutes of PLC recon- struction.Gradual weight loading was allowed after six weeks of bracing.Results Follow-up for mean 12 months(5-24 months)indicated that tibial“step off”reduction was 83%(10/12)and posterior drawer test of 0-1~+ 75%(9/12).Dial sign evaluated that normal external rotation angle was 75%(8/12).Nor- real varus stress test at 30?knee flexion accounted for 83%(10/12).Scores of Lysholm,Tegner and HSS were 90.5,5.1 and 84.5,respectively(P＜0.01=.Conclusion Synchronized reconstruction of PCL and PLC injuries with only one Achilles tendon can obtain satisfactory clinical result,with less expense and shorter operation time.