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Biomechanics

Biomechanics - Poster Session E

Poster Q6 - The effect of perivascular adipose tissue on the piezoelectric property of the thoracic aorta

Saturday, October 26, 2024
10:00 AM – 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  Perivascular adipose tissue (PVAT) surrounds most blood vessels and is critical in regulating vascular function through mechanisms such as the secretion of vasoactive substances that modify vascular tone. There has been increasing focus on how PVAT interacts with aortic tissue, particularly in the context of cardiovascular diseases. Here, we sought to explore the electromechanical property of piezoelectricity in the aorta. Piezoelectric materials respond to deformation by producing an electrical signal and in native tissues, piezoelectricity is thought to play a role in tissue homeostasis and repair. Aortic tissue may have measurable piezoelectric properties since collagen, which has well-known piezoelectric characteristics, is a key structural component of aortic tissue. Our hypothesis is that the aorta and PVAT have piezoelectric activity. This study determined the piezoelectric properties of the aorta, including the PVAT layer, to better understand its contribution to the piezoelectric properties of the aorta. The piezoelectric coefficient, d33, was measured in the rat thoracic aorta. d33 is a material property of piezoelectric materials that measures the charge generated when force is applied. The aorta were tested with or without the PVAT. The PVAT layer was also tested alone. Findings demonstrated an additive effect of the PVAT on the piezoelectric property of d33 suggesting the PVAT plays an electromechanical role in the function of the aorta.

Materials and

Methods:  The thoracic aorta from Dahl SS rats were dissected as previously described (Watts et al., 2020). The aorta either remained intact (Aorta w/ PVAT) or PVATs were removed (Aorta w/o PVAT). The removed PVAT was also tested (PVAT). Samples were stored at -20oC until use. The samples were thawed and from each full-length sample, two 5 mm sections were cut. Each 5 mm section was then cut longitudinally and opened for testing (Figure 1). Samples were rinsed in DI water and the d33 coefficients were measured using a Piezometer (Piezotest, Inc.). Sample size of n=5 was used. The inner (tunica intima) and outer (tunica adventitia) sides of the Aorta w/ PVAT and Aorta w/o PVAT were tested. The PVAT does not have a side since it’s adipose tissue. For statistical testing, a one-way ANOVA and post hoc Tukey-Kramer for multiple comparisons were performed with level of significance at p-value < 0.05.

Results, Conclusions, and Discussions: 

Results: All groups had measurable d33 values (Figure 2). The negative and positive signs of d33 indicate a change in polarity of the charge, which was detected for the inner and outer layers of both the Aorta w/ PVAT and Aorta w/o PVAT groups. Statistical differences in d33 were detected between the inner and outer sides of both the Aorta w/PVAT and Aorta w/o PVAT where the inner sides of these tissues had lower and negative d33 values as compared to their outer counterparts. The PVAT alone had a positive d33 comparable to the outer side of the Aorta w/o PVAT. The outer side of the Aorta w/ PVAT had the highest d33 (0.436 + 0.099 pC/N), where adding the average d33 values for PVAT alone (0.159 + 0.1.09 pC/N) and the Aorta w/o PVAT (0.196 + 0.172 pC/N) results in a similar d33 as the Aorta w/ PVAT.

Discussion: The results from this study demonstrate the aorta with or without PVAT have piezoelectric properties where the highest piezoelectric coefficient was obtained for the outside layer (tunica adventitia) of the aorta with PVAT. The PVAT appears to have an additive effect on the piezoelectric coefficient since the PVAT alone and the Aorta w/o PVAT had lower and similar d33. as compared to the aorta with PVAT. Findings also demonstrated polarity differences between the inner and outer sides of the aorta with or without the PVAT, which may result from the types and organization of the extracellular matrix molecules present (Watts et al., 2020). These findings suggest that the PVAT contributes to the aorta’s piezoelectric properties.

Conclusions: Present literature has primarily characterized the mechanical properties of the aortas with recent work demonstrating that PVAT contributes to stress relaxation. For the first time, the present studies demonstrate that PVAT enhances the piezoelectric properties of the aorta which may have implications in its overall function. Future tests will measure the voltage output when subjected to compression and tensile testing. Additionally, a closer examination of the organization of the ECM proteins, collagen and elastin, which have well-known piezoelectric activity, are also needed.

Acknowledgements (Optional):