Mechanisms of cartilage growth: modulation of balance between proteoglycan and collagen in vitro using chondroitinase ABC.
OBJECTIVE
To examine the cartilage growth-associated effects of a disruption in the balance between the swelling pressure of glycosaminoglycans (GAGs) and the restraining function of the collagen network, by diminishing GAG content prior to culture using enzymatic treatment with chondroitinase ABC.


METHODS
Immature bovine articular cartilage explants from the superficial and middle layers were analyzed immediately or after incubation in serum-supplemented medium for 13 days. Other explants were treated with chondroitinase ABC to deplete tissue GAG and also either analyzed immediately or after incubation in serum-supplemented medium for 13 days. Treatment- and incubation-associated variations in tissue volume, contents of proteoglycan and collagen network components, and tensile mechanical properties were assessed.


RESULTS
Incubation in serum-supplemented medium resulted in expansive growth with a marked increase in tissue volume that was associated with a diminution of tensile integrity. In contrast, chondroitinase ABC treatment on day 0 led to a marked reduction of GAG content and enhancement of tensile integrity, and subsequent incubation led to maturational growth with minimal changes in tissue volume and maintenance of tensile integrity at the enhanced levels.


CONCLUSIONS
The data demonstrate that a manipulation of GAG content in articular cartilage explants can distinctly alter the growth phenotype of cartilage. This may have practical utility for tissue engineering and cartilage repair. For example, the expansive growth phenotype may be useful to fill cartilage defects, while the maturational growth phenotype may be useful to induce matrix stabilization after filling defect spaces.
Asanbaeva
Anna
A
University of California, San Diego, La Jolla, CA 92093, USA.
Masuda
Koichi
K
Thonar
Eugene J-M A
EJ
Klisch
Stephen M
SM
Sah
Robert L
RL
D000818:Animals; D000831:Animals, Newborn; D002358:Cartilage, Articular / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D002417:Cattle; D019765:Chondroitin ABC Lyase / Q000494:pharmacology*; D003094:Collagen / Q000378:metabolism*; D011509:Proteoglycans / Q000378:metabolism*; D013718:Tensile Strength / Q000187:drug effects / Q000502:physiology; D046509:Tissue Culture Techniques; D023822:Tissue Engineering / Q000379:methods
D011509:Proteoglycans; D003094:Collagen; D019765:Chondroitin ABC Lyase