Vascular Calcification

1. Vascular Calcification Kristina Boström, MD, PhD Cardiology, UCLA

2. Case Presentation 74 y o Caucasian female, with hypertension and critical aortic stenosis. One year prior to presentation, aortic valve replacement had been attempted but was aborted due to severe aortic calcification, so called “porcelain aorta”. Now increasing symptoms of shortness of breath with exertion and chest pain, with recurrent hospital admissions for congestive heart failure.

3. Echocardiogram: LVEF >60% with concentric left ventricular hypertrophy and diastolic dysfunction. Mild mitral regurgitation. Moderate tricuspid regurgitation. Cardiac Catheterization: Normal systolic function. Non-obstructive coronary disease. CT Chest: “Uniform, smooth calcification of the ascending aorta extending from the root to the origin of great vessels, with trivial atherosclerotic calcifications of the descending aorta. The appearance of the ascending aorta is reminiscent of aortic graft.” Extensive aortic valve calcification and moderate mitral valve calcification.

4. Circumferential Calcification in the Ascending Aorta

5. Left Ventricular Apical Conduit to Descending Thoracic Aorta

6. This Case Illustrates …. • Calcification can be characterized by the • anatomical location. • There are more than one type of vascular • calcification. • We are unable to efficiently treat vascular • calcification. • Vascular calcification may cause clinical • complications.

7. Vascular Calcification Differs in: Anatomical location Aortic Coronary Peripheral arteries Heart valve Vascular layer Intima Media Adventitia Heart valve Association with disease Atherosclerosis Mönckeberg’s (Media Sclerosis) Diabetes Renal Failure

8. Vascular Calcification Is Associated with Vascular Disease: Intima Atherosclerosis Renal Failure Diabetes Mönckeberg’s (Media sclerosis) Renal Failure Diabetes Media Adventitia Diabetes Heart valves Atherosclerosis

9. Intimal Calcification - Atherosclerosis Sangiorgi et al. JACC 1998

10. Media Intima Calcification CLINICAL IMPLICATIONS OF INTIMAL CALCIFICATION Coronary Arteries • Correlated with Coronary Artery Disease and atherosclerotic plaque burden. • Associated with Sudden Cardiac Death • Promotes dissection following angioplasty Calcified, Atherosclerotic Coronary Artery Webpath

11. Rupture at Edge of Calcified Lesion In Vitro In Vivo - after angioplasty Mechanical stress analysis of a rigid inclusion in distensible material: a model of atherosclerotic calcification and plaque vulnerability. Hoshino et al. Am J Physiol 2009

12. Coronary Calcification Detected by Electron Beam CT (EBCT) - “Heart Scans”

13. Coronary Calcification - EBCT A negative EBCT test is associated with a low risk of a cardiovascular event in the next 2 to 5 years. A positive EBCT confirms the presence of a coronary atherosclerotic plaque. The greater the amount of calcium, the greater the likelihood of occlusive CAD, but there is not a 1-to-1 relationship, and findings may not be site specific. Thetotal amount of calcium correlates best with the total amount of atherosclerotic plaque, although the true "plaque burden" is underestimated

14. Atherosclerotic Plaques Medial Calcification

15. VASCULAR MEDIAL CALCIFICATION (Mönckeberg’s media sclerosis, elastocalcinosis) Arteriosclerosis associated with aging, diabetes, and end stage renal disease Webpath Price et al. ATVB 2000

16. CLINICAL IMPLICATIONS OF VASCULAR MEDIAL CALCIFICATION Aorta • Correlates with increased ischemic episodes in peripheral vascular disease (PVD) Peripheral Arteries • Strong marker for future cardiac events, PVD, and lower extremity amputations in diabetics • Prognostic marker for all-cause and cardiovascular mortality in dialysis patients Causes increased aortic stiffness, pulse pressure, left ventricular hypertrophy and cardiovascular mortality

17. Medial Calcification in Arteries of Dialysis Patients 30-700 fold increase in cardiovascular mortality risk in dialysis patients compared to the general population. Decreased survival in end stage renal disease patient with intimal and medial vascular calcification Moe et al. Kidney Int. 2002

18. Heart Valve Calcification Normal Aortic Valve Calcified Bioprosthetic Valve Senile Aortic Stenosis

19. CLINICAL IMPLICATIONS OF VALVE CALCIFICATION • Major cause of failure in native valves • Major cause of failure in bioprosthetic valves • Highly prevalent in patients with end stage renal failure

20. Mechanisms of Vascular Calcification

21. Normal Vessels Don’t Mineralize Active Inducers Active Inhibitors

22. Both Inhibitors and Promotors of Calcification in Atherosclerotic Plaques Inhibitors Promotors Dhore et al. ATVB 2001

23. Major Theories of Vascular Calcification DISTURBED Ca/Pi BALANCE Hyperphosphatemia Hypercalcemia INDUCING FACTORS Pi Lipids Inflammatory cytokines Others LOSS OF INHIBITION Pyrophosphate MGP OPN Fetuin/alpha2-HS glycoprotein Others Ca x Pi INDUCTION OF BONE FORMATION Vascular bone and cartilage-like cells VASCULAR CALCIFICATION CIRCULATING NUCLEATIONAL COMPLEXES Matrix Vesicles Apoptotic bodies Bisphosphonates OPG Bone Remodeling CELL DEATH Adapted from Speer & Giachelli, Cardiovasc Path 2004

24. Major Theories of Vascular Calcification DISTURBED Ca/Pi BALANCE Hyperphosphatemia Hypercalcemia INDUCING FACTORS Pi Lipids Inflammatory cytokines Others LOSS OF INHIBITION Pyrophosphate MGP OPN Fetuin/alpha2-HS glycoprotein Others Ca x Pi INDUCTION OF BONE FORMATION Vascular bone and cartilage-like cells VASCULAR CALCIFICATION CIRCULATING NUCLEATIONAL COMPLEXES Matrix Vesicles Apoptotic bodies Bisphosphonates OPG Bone Remodeling CELL DEATH Adapted from Speer & Giachelli, Cardiovasc Path 2004

25. GENERALIZED INFANTILE ARTERIAL CALCIFICATION • Rare human genetic disorder; early lethal • Vascular medial calcification leading to a stenosing, fibroproliferative arterial process • Characterized by deficiency in extracellular pyrophosphate (PPi), due to a deficiency in PPi-generating nucleoside triphosphate pyrophosphohydrolase plasma membrane 1 enzyme (PC-1, ENPP1). Long-axis image of aorta and aortic arch Levine et al. Circulation 2001

26. Matrix Gla Protein (MGP) Inhibitor of Bone Morphogenetic Proteins (BMP) (Zebboudj 2002, Yao 2006) Dependent on Vitamin K for correct gamma-carboxylation of glutamates (Gla-modifications) and anti-calcific activity (Murshed 2004) Dependent on specific proline and Gla-residues for BMP binding (Yao 2008) MGP loss of function mutations in humans cause Keutel syndrome (Keutel 1971, Munroe 1999)

27. Vascular Calcification in MGP Null Mice Aortic media MGP null Wild type Aortic media Luo et al. Science 1997

28. BONE MORPHOGENETIC PROTEINS (BMP) • Potent inducers of bone formation • Inflammatory mediators induced in vascular endothelium by abnormal oscillatory flow (Sorescu et al. 2004) • Promotes hypertension and atherogenesis in mice (Miriyala et al. 2006, Jo et al. - in prep.) • MGP reduces formation of atherosclerotic plaques and lesions • calcification (Yao et al. - in revision)

29. Warfarin / Coumadin Use: • Inhibits MGP gamma-carboxylation, induces vascular calcification in growing rats (Price 1998, Essalihi 2003, Schurgers 2007) • Correlated with increased coronary and valve calcification (Schurgers 2004, Koos 2005) • Associated with calcific uremic arteriolopathy in dialysis patients (Coates 1998, Piccoli 2002)

30. Fetuin, 2 Hermann-Schmid Glycoprotein (AHSG) • Made in the liver • Inhibitor of spontaneous hydroxyapatite (HA) formation from supersaturated calcium- and phosphate containing solutions • Fetuin null mice have decreased serum HA inhibitory activity and increased soft tissue calcification (Jahnen-Dechent 1997, Schafer 2003) Normal mouse after phosphate challenge Fetuin-deficient mouse after phosphate challenge Westenfeld et al. Trends Cardiovasc Med 2007

31. OSTEOPONTIN • Acidic phosphoprotein found in bone and teeth • Inhibitor of apatite crystal growth • Promotes osteoclast function

32. Osteopontin Deficiency Worsens Calcification in MGP Null Mice Speer MY et al. 2002

33. Major Theories of Vascular Calcification DISTURBED Ca/Pi BALANCE Hyperphosphatemia Hypercalcemia INDUCING FACTORS Pi Lipids Inflammatory cytokines Others LOSS OF INHIBITION MGP OPN Fetuin/alpha2-HS glycoprotein Pyrophosphate Others Ca x Pi INDUCTION OF BONE FORMATION Vascular bone and cartilage-like cells VASCULAR CALCIFICATION CIRCULATING NUCLEATIONAL COMPLEXES Matrix Vesicles Apoptotic bodies Bisphosphonates OPG Bone Remodeling CELL DEATH Adapted from Speer & Giachelli, Cardiovasc Path 2004

34. Ectopic Calcification in Atherosclerotic Plaqes

35. Chondrocytes in Mouse Atherosclerotic Lesions Rattazzi et al. ATVB 2005

36. Mineral Precipitation Cell Differentiation osteoblast-like cell Ca2+ PO42- matrix vesicles CaPO4 mineral precipitation “Active” inhibitor osteoid (matrix) Ca2+ PO42- hydroxyapatite CaPO4 mineral precipitation

37. Potential Origins of Osteoblast-like Cells in the Artery Wall • Pericytes • Mesenchymal stem cells • Multipotent cells from the adventitia • Resident cells in the media or intima • Trans-differentiated SMC (Synthetic vs contractile phenotype)

38. Calcifying Vascular Cells (CVC) CONDENSATION UNDIFFERENTIATED CALCIFIED NODULES

39. Bone Related Factors in Calcified Artery Wall BMP-2 and -4 Cbfa1 Osterix Collagen I Alkaline Phosphatase Osteocalcin Hydroxyapatite Osteopontin Matrix GLA protein (MGP) Osteoprotegerin … and others …..

40. Both Inhibitors and Promotors of Calcification in Plaques Dhore et al. ATVB 2001

41. Major Theories of Vascular Calcification DISTURBED Ca/Pi BALANCE Hyperphosphatemia Hypercalcemia INDUCING FACTORS Pi Lipids Inflammatory cytokines Others LOSS OF INHIBITION MGP OPN Fetuin/alpha2-HS glycoprotein Pyrophosphate Others Ca x Pi INDUCTION OF BONE FORMATION Vascular bone and cartilage-like cells VASCULAR CALCIFICATION CIRCULATING NUCLEATIONAL COMPLEXES Matrix Vesicles Apoptotic bodies Bisphosphonates OPG Bone Remodeling CELL DEATH Adapted from Speer & Giachelli, Cardiovasc Path 2004

42. Normal Vessels Don’t Mineralize (Despite serum Ca x P at or near solubility product) Active Inducers Active Inhibitors

43. Intima Atherosclerosis Renal Failure Diabetes Mönckeberg’s (Media sclerosis) Renal Failure Diabetes Media Adventitia Diabetes Heart valves Atherosclerosis

44. Calcium x Phosphate Product Already above precipitation point at certain places Renal failure may increase Ca x P product further Hyperphosphatemia: Major independent risk factor for vascular calcification and cardiovascular mortality in dialysis patients (Block 1998, 2004, Goodman 2000, Shigematsu 2003, Young 2005)

45. Phosphate-Induced Changes in SMC Differentiation Pi/Ca Contractile SMC SM-MHC SM22alpha SM-alpha actin Desmin Osteochondrogenic cell Cbfa1 OPN Osteocalcin Alk Phos Type III sodium-dependent phosphate co-transporters (Pit-1, Pit-2) Blockage of these transporters leads to phosphate induced SMC mineralization Pit-1 can be induced by BMP-2

46. Calcified Vascular Smooth Muscle Cells Wada et al. Circ Res 1999

47. Major Theories of Vascular Calcification DISTURBED Ca/Pi BALANCE Hyperphosphatemia Hypercalcemia INDUCING FACTORS Pi Lipids Inflammatory cytokines Others LOSS OF INHIBITION MGP OPN Fetuin/alpha2-HS glycoprotein Pyrophosphate Others Ca x Pi INDUCTION OF BONE FORMATION Vascular bone and cartilage-like cells VASCULAR CALCIFICATION CIRCULATING NUCLEATIONAL COMPLEXES Matrix Vesicles Apoptotic bodies Bisphosphonates OPG Bone Remodeling CELL DEATH

48. Degenerative Joint Diseases are “Crystal diseases” where synovial fibroblasts have an inflammatory response to the crystals. Connection between Vascular Calcification and Bone

49. Aortic Calcification and Osteoporosis Frequently Coexist

50. Similarities to Bone: Bone Proteins Osteoblast-like Cells Osteoclast-like Cells “The paradox of arterial calcification in osteoporotic patients” Parhami et al. ATVB 1997 Oxidized lipids or other agents may be mediating the effect.