Promoting Vasa Vasorum Neovascularization of Vein Grafts Extenuates Hypoxia of the Wall and Its Subsequent Influence on Intimal Hyperplasia

Background： The autologous saphenous vein is the most common conduit for coronary artery bypass grafting, but the vein graft disease will occur. This study used Matrigel basement membrane matrix with many different growth factors to promote vasa vasorum neovascularization and extenuate the hypoxia to improve remodeling. Methods： This study observed the hypoxia and thickness of the vein grafts at different times. Normal veins and vein grafts with 15 min ofischemia one day postoperatively were harvested in the neck of rabbits. Paired vein grafts with 15 min ischemia bilaterally （control vs. Matrigel basement membrane matrix） were performed and harvested at 2, 6, and 12 weeks postoperatively. The rabbits were randomly divided into four postoperative groups （six rabbits in each group）： Group 1, one day postoperatively; Group 2, 2 weeks postoperatively; Group 3, 6 weeks postoperatively; and Group 4, 12 weeks postoperatively. The dimensions of vessel wall were captured, and the mean thicknesses of intima, media, and adventitia were measured. The hypoxia-inducible factor （HIF）- 1α and HIF-2ot labeling indices ofintima, media, and adventitia were also measured. Results： In Group 1, the labeling index of HIF-1α was high in the normal vein and decreased significantly in the vein grail one day postoperatively （intima： 80 4- 3% vs. 12 4- 1%, P = 0.01 ; media： 67 ±5% vs. 11 ± 1%, P = 0.01 ; adventitia： 40 ± 10% vs. 7 ±2%, P = 0.03）. The labeling index of HIF-2α had similar trend as HIF-1α （intima： 80 ± 10% vs. 10 ± 5%, P = 0.02; media： 60± 14% vs. 12 ± 2%, P = 0.01 ; adventitia： 45±20% vs. 10±4%, P = 0.03）. Compared with the control vein gratrol vein grafts with Matrigel basement membrane matrix had lower labeling indices of HIF-1α and HIF-2α in media and adventitia at Group 2 （HIF-1α： 34 ± 5% vs. 20 ±4%, P = 0.04 for media： 23 ± 3% vs. 11 ± 2%, P = 0.03 for adventitia; HIF-2α： 37 ± 6% vs. 21 ± 4%, P = 0.03 for media; 24 ±4% vs. 13 ± 2%, P = 0.04 for adventitia） and Group 3 （HIF-1α： 33 ± 4% vs. 7 ± 2%, P = 0.04 for media; 13 ± 3% vs. 3± 1%, P = 0.02 for adventitia; HIF-2α： 27 ± 4% vs. 12 ± 3%, P = 0.02 for media; 19 ± 2% vs. 6 ± 1%, P = 0.02 for adventitia）. There were no differences in mean thickness of intima, media, and adventitia between bilateral vein grafts at 2, 6, and 12 weeks postoperatively. Conclusions： This study indicated that promoting vasa vasorum neovascularization of vein grafts extenuated hypoxia, but did not influence the intimal hyperplasia of the wall,

Design, synthesis and systematic evaluation of all possible cyclic dinucleotides (CDNs) that activate human stimulator of interferon genes (STING) variants

Cyclic dinucleotides(CDNs) are known to activate stimulator of interferon genes(STING) and induce type I interferon responses, therefor possess great potentials to be of immunotherapeutic value for cancers and infectious diseases. However, the existence of different single nucleotide polymorphism(SNP) of human STING(hSTING) gene poses an obstacle to achieve broad-spectrum activation by CDNs. We reported here the design and synthesis of a total of 36 CDNs, representing all structural variations, that contain four bases(A, G, C, U) and two linkage directions(2′-5′-linked and 3′-5′-linked phosphodiester).Through systematic evaluation of IFN-β induction with a dual-luciferase reporter assay, we discovered that wild type hSTING and two isoforms(HAQ and AQ) showed strong response while hSTING-R232 H and R293 Q exhibited the relatively weak response to CDNs stimulation. For the first time, we found that the c[G(2′,5′)U(2′,5′)] showed excellent activity against all five hSTING variants even equivalent to the endogenous ligand c[G(2′,5′)A(3′,5′)]. Furthermore, we have also demonstrated that 3′-3′CDNs with two 3′-5′ phosphodiesters showed higher serum and hydrolase stability than 2′-2′ CDNs with two 2′-5′ phosphodiesters and 2′-3′ CDNs with one 2′-5′ and one 3′-5′ phosphodiester. It is very interesting to note that 2′-2′ CDNs has been found for the first time to show strong activity. These findings will stimulate our exploration for the new functional role of CDNs, and provide guidelines to design CDNs based hSTING targeted drugs.