Articular cartilage vesicles generate calcium pyrophosphate dihydrate-like crystals in vitro.
OBJECTIVE
To identify the morphology of a mineral-forming of adult porcine hyaline articular cartilage digest and characterize the mineral it forms.


METHODS
Electron microscopy, Fourier transform infrared (FTIR) spectroscopy, x-ray microanalysis, compensated polarized light microscopy, and biochemical studies including 14C-labeled UDPG pyrophosphohydrolase radiometric assay.


RESULTS
This fraction of articular cartilage digest contained membrane-limited vesicles resembling growth plate cartilage matrix vesicles and formed mineral after only 24 hours in physiologic salt solution containing 1 mM ATP: The mineral contained inorganic pyrophosphate, 95% of which derived from ATP, and phosphate, 93% of which derived from inorganic phosphate in the medium. The FTIR spectrum of this mineral closely resembled the spectrum of standard calcium pyrophosphate dihydrate (CPPD) crystals. Compensated polarized light microscopy showed positively birefringent, rod-shaped crystals morphologically identical to CPPD. Ca:P ratios, defined by energy-dispersive microanalysis, were also consistent with CPPD.


CONCLUSIONS
The articular cartilage vesicle fraction of porcine hyaline cartilage is capable of generating mineral that strongly resembles CPPD.
Derfus
B A
BA
Division of Rheumatology, Medical College of Wisconsin, Milwaukee.
Rachow
J W
JW
Mandel
N S
NS
Boskey
A L
AL
Buday
M
M
Kushnaryov
V M
VM
Ryan
L M
LM
D000255:Adenosine Triphosphate / Q000737:chemistry; D000327:Adsorption; D000818:Animals; D002131:Calcium Pyrophosphate / Q000737:chemistry* / Q000378:metabolism; D002358:Cartilage, Articular / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D003460:Crystallization; D004577:Electron Probe Microanalysis; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D013055:Spectrophotometry, Infrared; D013552:Swine
D000255:Adenosine Triphosphate; D002131:Calcium Pyrophosphate