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Abstract: FR-PO488

Phenotypic Switch Study in Cultured Arterial and Venous SMCs: Messages for the Future Development of Novel Therapies for Vascular Access Dysfunction

Session Information

  • Dialysis: Vascular Access
    November 03, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

  • 803 Dialysis: Vascular Access

Authors

  • Arteaga, Eyla C., The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States
  • Wai, Christine, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States
  • Uriyanghai, Unimunkh, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States
  • Sudarsanam, Vinay A., The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States
  • Roy-Chaudhury, Prabir, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States
  • Xi, Gang, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States
Background

Smooth muscle cell (SMC) dedifferentiation, proliferation, migration, and extracellular matrix protein secretion are key events in the progression of SMC phenotypic switch and the development of intimal hyperplasia (IH) as well as negative vascular remodeling, which is responsible for arteriovenous access (AVF and AVG) failure. Previous studies have demonstrated differences in proliferation between venous (vSMC) and arterial SMCs (aSMC) but have not attempted to characterize specific pathways in this process. We herein aim to characterize the role of IRS-1/KLF-4/p53 pathway and other dedifferentiation related pathways regulating SMC phenotypic switch in pig vSMCs and aSMCs.

Methods

To reach the SMC differentiation stage before applying phenotypic switch stimuli, confluent cells were exposed to differentiation medium (DM, containing 1%FBS, 1% P/S and 30ug/ml heparin) for different time periods. A hyperglycemic milieu was created through the addition of 20 mM glucose 24-48hr before harvesting/treatments. PDGFBB or IGF-1 was applied to create a dedifferentiation milieu for different durations. Cellular expression of proteins of interest were assessed using either immunofluorescence (IF) staining or Western blots.

Results

Hyperglycemia significantly suppressed myocardin expression and enhanced KLF-4 expression in both cell types. IRS-1 suppression in response to hyperglycemia, however, only occurred in aSMCs. Exposure to DM resulted in a suppression of proliferation and an increase in SMC differentiation marker expression (calponin and myocardin), in both cell types. IF staining demonstrated that Thrombospondin-1 was highly expressed over time in vSMCs under both hyperglycemic and normoglycemic conditions whereas, in aSMCs, this only occurred in the setting of hyperglycemia. Finally, PDGFBB was able to induce dedifferentiation under either normal or hyperglycemic conditions in both cell types while IGF-I was able to induce SMC dedifferentiation only under hyperglycemic conditions.

Conclusion

Arterial and venous SMC appear to have both similarities and differences regarding dedifferentiation/phenotypic switch pathways in response to hyperglycemia or growth factors. Hyperglycemia and PDGFBB are potent stimuli for SMC dedifferentiation.

Funding

  • NIDDK Support