PLX3397, a CSF1 receptor inhibitor, limits allotransplantation-induced vascular remodelling

AIMS

Graft vascular disease (GVD), a clinically important and highly complex vascular occlusive disease, arises from the interplay of multiple cellular and molecular pathways. While occlusive intimal lesions are composed predominantly of smooth-muscle-like cells (SMLCs), the origin of these cells and the stimuli leading to their accumulation in GVD are uncertain. Macrophages have recently been identified as both potential drivers of intimal hyperplasia and precursors that undergo transdifferentiation to become SMLCs in non-transplant settings. Colony-stimulating factor-1 (CSF1) is a well-known regulator of macrophage development and differentiation, and prior preclinical studies have shown that lack of CSF1 limits GVD. We sought to identify the origins of SMLCs and of cells expressing the CSF1 receptor (CSF1R) in GVD, and to test the hypothesis that pharmacologic inhibition of CSF1 signalling would curtail both macrophage and SMLC activities and decrease vascular occlusion.

METHODS AND RESULTS

We used genetically modified mice and a vascular transplant model with minor antigen mismatch to assess cell origins. We found that neointimal SMLCs derive from both donor and recipient, and that transdifferentiation of macrophages to SMLC phenotype is minimal in this model. Cells expressing CSF1R in grafts were identified as recipient-derived myeloid cells of Cx3cr1 lineage, and these cells rarely expressed smooth muscle marker proteins. Blockade of CSF1R activity using the tyrosine kinase inhibitor PLX3397 limited the expression of genes associated with innate immunity and decreased levels of circulating monocytes and intimal macrophages. Importantly, PLX3397 attenuated the development of GVD in arterial allografts.

CONCLUSION

These studies provide proof of concept for pharmacologic inhibition of the CSF1/CSF1R signalling pathway as a therapeutic strategy in GVD. Further preclinical testing of this pathway in GVD is warranted.

Sleeve Technique is Superior to End-to-End Anastomosis and Cuff Technology in Mouse Model of Graft Vascular Disease

BACKGROUND

Graft vascular disease (GVD) is the main reason of late transplanted organ failure, which limits the long-term survival of patients. Murine aortic transplant is widely used in the field to understand the mechanisms leading to GVD. Currently, 3 major techniques, end-to-end anastomosis, sleeve suture and cuff technology, have been used to study the mechanism of GVD. However, which method is more suitable in mouse model of GVD? Herein, we compared these 3 surgical techniques in a mouse allograft arteriosclerosis model to determine the technique with the most appreciable outcomes.

METHODS

Male C57Bl/6 (H-2b) and BALB/c (H-2d) mice were used for aorta transplantation with these 3 techniques. These 3 techniques were compared with regard to donor artery acquisition time, artery anastomosis time, overall surgical time, the amount of bleeding of each technique and the success rate of surgery. Hematoxylin and eosin (H&E) and Masson staining were used to examine the pathological changes of grafted vessels. The protein expression of phospho-NF-κb P65 and PCNA were determined to validate laminar flow and proliferative capacity of neointima obtained from different surgical and control groups.

RESULTS

Sleeve suture had a shorter vascular anastomosis time and total operation time than end-to-end anastomosis and cuff technique. Sleeve suture and cuff technique had significantly fewer amount of bleeding from the site of vascular anastomosis than end-to-end anastomosis. Moreover, sleeve suture had the highest success rate among these 3 techniques. There was no difference in the degree of graft stenosis and collagen deposition between these 3 techniques. In addition, there was no significant difference in the expression of phospho-NF-κb P65and PCNA between the experimental group.

CONCLUSIONS

Sleeve suture is superior to end-to-end anastomosis and cuff technique with regard to vascular grafting in the murine model.