Inhibitors of in vitro mineralization from rabbit aorta and their role in biomineralization

Abstract

Mineralization of aorta is known to occur late in life and appears to be a pathological phenomenon. In vitro studies revealed that the matrix prepared from the thoracic aorta pieces after their extraction with 3% Na2HPO4 and 0.1 mM CaCl2 were mineralized under physiological conditions of temperature, pH, and ionic strength of the media to form matrix-bound mineral phase resembling hydroxyapatite in nature. However, the matrix identically prepared from the unextracted rabbits aortae failed to mineralize under identical assay conditions. The addition of the aorta extract in the assay system inhibited the above mineralization process. Standard biochemical techniques, e.g., dialysis, ion exchange, and molecular sieve chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and amino acid analysis by high-performance liquid chromatography were employed to isolate, purify, and characterize the potent inhibitory biomolecules from the aorta extract. The inhibitory activity of the aorta extract was found to be primarily due to the presence of three biomolecules having molecular weights of 66, 45, and 27-29 kDa. The above inhibitory biomolecules loosely associated with aorta may be involved in the control of calcification associated with arteriosclerosis.

Concentration of a potent calcium oxalate monohydrate crystal growth inhibitor in the urine of normal persons and kidney stone patients by ELISA‐based assay system employing monoclonal antibodies

“…and high molecular weight substances (e.g., polypeptides, proteins, glycoproteins, etc. ), which by acting as inhibitors of mineral phase formation may play an important role in the etiology of urolithiasis [Howard and Thomas, 1958; Grover et al, 1994; Tandon et al, 1997, 1998; Aggarwal et al, 2000].…”

Tendon gradient mineralization for tendon to bone interface integration

“…This theory is supported by data showing that tendon extraction with 3% Na 2 HPO 4 leads to a quick mineralization and re‐adding the extract significantly inhibits the rates of calcium and phosphate uptake from the soluble phase . However, a recent study showed that when the Na 2 HPO 4 ‐extracted tendon was incubated in a solution containing both calcium and phosphate, the mineralization process only lasted for several hours . A decline in free calcium occurred quickly because of the spontaneous formation of apatite crystals in solution containing increased levels of calcium and phosphate .…”

“…However, it usually does not occur in humans, unless subjected to a pathological change resulting from injury, degenerative disorders, or tendinitis, which alter the normal tendon function. To prevent or treat this problem, many studies were conducted to explore the mechanism of mineralization, some of which indicated that a still unidentified macromolecular inhibitor plays an important role to preclude tendon or other soft tissue calcification . This theory is supported by data showing that tendon extraction with 3% Na 2 HPO 4 leads to a quick mineralization and re‐adding the extract significantly inhibits the rates of calcium and phosphate uptake from the soluble phase .…”

“…To prevent or treat this problem, many studies were conducted to explore the mechanism of mineralization, some of which indicated that a still unidentified macromolecular inhibitor plays an important role to preclude tendon or other soft tissue calcification . This theory is supported by data showing that tendon extraction with 3% Na 2 HPO 4 leads to a quick mineralization and re‐adding the extract significantly inhibits the rates of calcium and phosphate uptake from the soluble phase . However, a recent study showed that when the Na 2 HPO 4 ‐extracted tendon was incubated in a solution containing both calcium and phosphate, the mineralization process only lasted for several hours .…”

“…While the phenomenon of tendon mineralization has been investigated in the context of tendinopathy or engineering material mineralization for bone formation, benefits of this abnormal mineralization to tendon‐to‐bone healing could be realized by converting a tendon partially into a bone‐like tissue, thereby, adapting a tendon‐to‐bone interface into a “bone‐to‐bone” interface for better healing. We studied the conditions that would optimize tendon mineralization as a prelude to studying the ability of mineralized tendon to heal to bone.…”