Kidney Week

Abstract: FR-PO497

Uremic Serum Results in an Activation and Phenotypic Switch of Pig Venous and Arterial Smooth Muscle Cells (SMCs)

Session Information

• Dialysis Vascular Access
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

• 803 Dialysis: Vascular Access

Authors

• Su, Huanjuan, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Huanjuan Su

• Arteaga, Eyla C., The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Eyla C. Arteaga

• Wai, Christine, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Christine Wai

• Uriyanghai, Unimunkh, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Unimunkh Uriyanghai, MD, PhD

• Sudarsanam, Vinay A., The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Vinay A. Sudarsanam

• Haddad, Samuel, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Samuel Haddad

• Bahnson, Edward Moreira, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States

Edward Moreira Bahnson, PhD

• Roy-Chaudhury, Prabir, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Prabir Roy-Chaudhury, MD, PhD, FASN

• Xi, Gang, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Gang Xi, PhD

Background

ESKD patients suffer from both an aggressive vascular access stenosis in the venous segment of AVFs and AVGs and widespread peripheral arterial disease (PAD). Both disease states respond poorly to conventional endovascular and surgical interventions. Despite the magnitude of the clinical problem, the exact pathogenetic role of the uremic state in both these conditions remains unclear.

Methods

Uremic serum was obtained from our previously described pig model of uremia (documented creatinine of >8mg/dL for over 3 weeks). Control serum was obtained from an age matched non-uremic pig. The MTT assay was used to assess cell proliferation and a cell-scratch assay was utilized to assess cell migration. Western blot expression was used to assess markers of cellular proliferation (PCNA and p53), phenotypic switch (myocardin and calponin), extracellular matrix (ECM) production (vitronectin and fibronectin) and calcification (Runx2).

Results

The MTT assay demonstrated that 30% uremic serum was able to stimulate the proliferation of both arterial (1.25±0.14 fold increase) and venous (1.17±0.13 fold increase) SMCs. Uremic serum also consistently enhanced PCNA and p53 expression in both cell types. The production of ECM proteins such as vitronectin and fibronectin was also increased when cells were exposed to uremic serum (ApSMC > VpSMC). SMC migration showed that uremic serum increased the migration of ApSMC (1.21±0.14 fold increase) and VpSMC (1.23±0.12 fold increase). Uremia also induced a phenotypic switch in both cell types (greater in ApSMC), with a suppression of myocardin and calponin expression (indicating a switch to a more activated, dedifferentiated and synthetic phenotype). Uremic serum also significantly stimulated cellular calcification (Runx2) particularly in ApSMC.

Conclusion

Uremia results in phenotypic switch of both venous and arterial SMCs in vitro with an increase in proliferation and migration, ECM production and expression of cell calcification markers. These changes were often exaggerated in ApSMCs as compared to VpSMCs. Our findings suggest that uremia per se could play an important role in both the aggressive arteriovenous stenosis and PAD in hemodialysis patients.

Funding

• NIDDK Support