The feasibility of using stored mouse blood vessels for mechanical testing
Download
1 / 27

The Feasibility of Using Stored Mouse Blood Vessels for Mechanical Testing - PowerPoint PPT Presentation


  • 75 Views
  • Uploaded on

The Feasibility of Using Stored Mouse Blood Vessels for Mechanical Testing. Amber Kunkel Advisor: Jessica Wagenseil , D.Sc. Department of Biomedical Engineering Saint Louis University. Radial cut. Opening angle (OA). What Are Blood Vessel Mechanics?.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'The Feasibility of Using Stored Mouse Blood Vessels for Mechanical Testing' - karik


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
The feasibility of using stored mouse blood vessels for mechanical testing

The Feasibility of Using Stored Mouse Blood Vessels for Mechanical Testing

Amber Kunkel

Advisor: Jessica Wagenseil, D.Sc.

Department of Biomedical Engineering

Saint Louis University


What are blood vessel mechanics

Radial cut Mechanical Testing

Opening angle (OA)

What Are Blood Vessel Mechanics?

  • How longitudinal force, diameter, compliance respond to inflation and longitudinal stretching

  • Unloaded dimensions

  • Opening angle (residual strain)

  • Stress and strain in response to stretches or inflations


Why blood vessel mechanics
Why Blood Vessel Mechanics? Mechanical Testing

  • Model in vivo conditions

  • Understand normal functions and any abnormalities

  • Mechanics of mouse aorta and carotid used to study:

    • Elastin +/- mice and Supravalvular Aortic Stenosis (Wagenseil lab)

    • Smoking

    • Aortic development

    • Muscular dystrophy and Marfan syndrome


Why storage
Why Storage? Mechanical Testing

  • Vessels usually tested within 1 day of dissection

  • But the carotid and aorta are large elastic arteries, could theoretically be stored longer

  • Applications of longer storage time:

    • Improved collaboration

    • Easier scheduling

    • Insurance against equipment failure or other unexpected circumstances


Study overview
Study Overview Mechanical Testing

  • 30 mice (8 week old) sacrificed over 1 month

  • Ascending aorta, left common carotid, and right common carotid removed

  • Five time points: refrigerated in physiologic saline for 1, 3, 7, 14, or 28 days


Mechanical testing

Vessel Bath Mechanical Testing

Translation

Stage

Microscope

Force

Transducer

Pressure

Transducer

D

Pressure

Controlled

Pump

L

Desktop

Computer

Stretch

z

d

Inflate

Mechanical Testing

  • Setup

  • Preconditioning


Mechanical testing ctd
Mechanical Testing Mechanical TestingCtd.

  • Inflation protocols

    • At 1, 1.1, and 1.2x in vivo length

    • 3 cycles, 0-175 mmHg, steps of 25, 12 sec/step

  • Stretch protocols

    • At 50, 100, and 150 mmHg

    • 3 cycles, 1-1.2x in vivo length


Dimensions
Dimensions Mechanical Testing

  • Three rings cut from left carotid and ascending aorta

  • Image under microscope

  • Measure inner diameter, outer diameter, thickness

  • Ascending aortas cut radially, used for opening angle measurements


Data analysis
Data Analysis Mechanical Testing

  • Pressure-force, pressure-diameter, and pressure-compliance curves from 1 cycle of first inflation protocol

  • Image J to compute thickness, inner and outer diameters

  • Circumferential stretch, circ stress, and axial stress

  • Matlab for opening angle

  • ANOVA and Scheffe post

    hoc test (P<.05)


Dimensions left carotid diameters
Dimensions: Left Carotid Diameters Mechanical Testing

  • No significant difference between time points

  • But there is a slight trend to each…


Left carotid thickness
Left Carotid Thickness Mechanical Testing

  • Slightly decreasing outer diameter and increasing inner diameter leads to steadily decreasing thickness

  • 1 day vessels are significantly different from 7 and 28 days


Ascending aorta diameters
Ascending Aorta Diameters Mechanical Testing

  • 1 day OD is significantly different from 7; 1 day ID is significantly different from 3, 7, and 28 days


Ascending aorta thickness
Ascending Aorta Thickness Mechanical Testing

  • This time, changes in diameter actually cancel each other out

  • 1 day is only significantly different from 28


Pressure diameter
Pressure-Diameter Mechanical Testing

  • At all pressures except 25, no difference between dates

  • At 25, only 7 day is different from 1 day


Pressure compliance
Pressure-Compliance Mechanical Testing

  • At 50, 75, and 100 mmHg, the 1 day compliance is significantly different from 14 and 28 days


Pressure force
Pressure-Force Mechanical Testing

  • 1 day is significantly different from 14 at all but the highest pressures

  • However, there is no clear pattern to the force differences


Pressure circumferential stretch ratio
Pressure- Circumferential Stretch Ratio Mechanical Testing

  • No significant differences between time points

  • Circumferential stretch ratio changes less the longer the vessels are stored


Pressure circumferential stress
Pressure-Circumferential Stress Mechanical Testing

  • 1 day is significantly different from 7 and 28 at P25 and P50, and from 28 at P75

  • Again, no clear pattern to differences between days


Pressure axial stress
Pressure- Axial Stress Mechanical Testing

  • Significant difference between 1 day and 14 day for P0-P100

  • Still lacks a clear pattern


Opening angle
Opening Angle Mechanical Testing

  • No significant difference between vessels


Discussion
Discussion Mechanical Testing

  • 1 and 3 day vessels the same except for ASC inner diameter

  • Every other time point shows several differences, so 3 days could be our limit

  • Where are these differences coming from?


Vessel degradation
Vessel Degradation? Mechanical Testing

  • Supported by decreases in LCC thickness and ASC inner diameter

  • Could explain why compliance decreases with storage time

  • But this doesn’t fit some of the other trends we’ve seen


Other explanations dimensions
Other Explanations: Dimensions Mechanical Testing

  • Measurements done by hand, not blindly

  • Could be influenced by order measured

  • Rings cut by 2 different people

  • Lighting, angle, and height of rings can also influence readings

1 day (6/9 lcc1)

28 day (7/6 lcc1)


Other explanations mechanical testing

Vessel Bath Mechanical Testing

Translation

Stage

Microscope

Force

Transducer

Pressure

Transducer

Pressure

Controlled

Pump

Desktop

Computer

Other Explanations: Mechanical Testing

  • Some variation between days is normal

  • More could be explained by abnormal myograph functions

    • Outflow pressure often lagging

    • Temporary solutions could have interfered with readings


Future work improvements
Future Work/ Improvements Mechanical Testing

  • Test more vessels

  • Protein content analysis and histology to understand changes in dimensions

  • Use data from additional protocols for modeling

  • Consistency in cutting rings, maybe blind measurements for dimension analysis

  • Fix leak in myograph


Acknowledgements
Acknowledgements Mechanical Testing

  • NSF

  • SLU BME

  • Dr. Wagenseil

  • Victoria Le

  • Dr. Willits

  • Neva Gillan


References
References Mechanical Testing

  • Huang, Y., Guo, X., & Kassab, G. S. (2005). Axial nonuniformity of geometric and mechanical properties of mouse aorta is increased during postnatal growth. American Journal of Physiology: Heart and Circulatory Physiology, 290, H657-H664.

  • Wagenseil, J. E., Ciliberto, C. H., Knutsen, R. H., Levy, M. A., Kovacs, A., & Mecham, R. P. (2009). Reduced vessel elasticity alters cardiovascular structure and function in newborn mice. Circulation Research, 104, 1217-1224.

  • Wagenseil, J. E., Nerurkar, N. L., Knutsen, R. H., Okamoto, R.J., Li, D. Y., Mecham, R.P. (2005). Effects of elastinhaploinsufficiency on the mechanical behavior of mouse arteries. American Journal of Physiology: Heart and Circulatory Physiology, 289, H1209-H1217.

  • Shifren, A., Durmowicz, A.G., Knusten, R.H., Faury, G., & Mecham, R.P. (2008). Elastin insufficiency prediscposes to elevated pumonary circulatory pressures through changes in elastic artery structure. Journal of Applied Physiology, 105, 1610-1619.

  • Guo, X., Oldham, M. J., Kleinman, M.T., Phalen, R.F. & Kassab, G.S. (2006). Effects of cigarette smoking on nitric oxide, strucutral, and mechanical properties of mouse arteries. American Journal of Physiology: Heart and Circulatory Physiology, 291, H2354-H2361.

  • Dye, W.W., Gleason, R.L., Wilson, E., & Humphrey, J.D. (2007). Altered biomechanical properties of carotid arteries in two mouse models of muscular dystrophy. Journal of Applied Physiology, 103, 664-672.

  • Fung, Y.C., & Liu, S.Q. (1989). Change of residual strains in arteries due to hypertrophy caused by aortic constriction. Circulation Research, 65, 1340-1349.

  • Chung, A.W.Y., Au Yeung, K., Sandor, G.G.S., Judge, D.P., Dietz, H.C., & van Breemen, C. (2007). Loss of elastic fiber integrity and reduction of vascular smooth muscle contraction resulting from the upregulated activities of matrix metalloproteinase-2 and -9 in the thoracic aortic aneurysm in Marfan Syndrome. Circulation Research, 101, 512-522.

  • Guo, X., Lanir, Y., & Kassab, G.S. (2007). Effect of osmolarity on the zero-stress state and mechanical properties of aorta. American Journal of Physiology: Heart and Circulatory Physiology, 293, H2328-H2334.

  • Mercier, N., Osborne-Pellegrin, M., El Hadri, K., Kakou, A., Labat, C., Loufrani, L., Henrion, D., Challande, P., Jalkanen, S., Feve, B., & Lacolley, P. (2006). Carotid arterial stiffness, elastic fibre network and vasoreactivity in semicarbazide-sensitive amine-oxidase null mouse. Cardiovascular Research, 72(2), 349-357.

  • Gleason, R.L., Dye, W.W., Wilson, E., & Humphrey, J.D. (2008). Quantification of the mechanical behavior of carotid arteries from wild-type, dystrophin-deficient, and sarcoglycan-delta knockout mice. Journal of Biomechanics, 41, 3213-3218.