The incorporation of a zone of calcified cartilage improves the interfacial shear strength between in vitro-formed cartilage and the underlying substrate.
A major challenge for cartilage tissue engineering remains the proper integration of constructs with surrounding tissues in the joint. Biphasic osteochondral constructs that can be anchored in a joint through bone ingrowth partially address this requirement. In this study, a methodology was devised to generate a cell-mediated zone of calcified cartilage (ZCC) between the in vitro-formed cartilage and a porous calcium polyphosphate (CPP) bone substitute in an attempt to improve the mechanical integrity of that interface. To do so, a calcium phosphate (CaP) film was deposited on CPP by a sol-gel process to prevent the accumulation of polyphosphates and associated inhibition of mineralization as the substrate degrades. Cartilage formed in vitro on the top surface of CaP-coated CPP by deep-zone chondrocytes was histologically and biochemically comparable to that formed on uncoated CPP. Furthermore, the mineral in the ZCC was similar in crystal structure, morphology and length to that formed on uncoated CPP and native articular cartilage. The generation of a ZCC at the cartilage-CPP interface led to a 3.3-fold increase in the interfacial shear strength of biphasic constructs. Improved interfacial strength of these constructs may be critical to their clinical success for the repair of large cartilage defects.
CIHR BioEngineering of Skeletal Tissues Team, Mount Sinai Hospital, Canada M5G 1X5.
Jean-Philippe
JP
St-Pierre
Lu
L
Gan
Jian
J
Wang
Robert M
RM
Pilliar
Marc D
MD
Grynpas
Rita A
RA
Kandel
D000818:Animals; D018786:Bone Substitutes / Q000494:pharmacology; D002113:Calcification, Physiologic / Q000187:drug effects*; D002130:Calcium Phosphates / Q000494:pharmacology*; D002356:Cartilage / Q000166:cytology / Q000187:drug effects* / Q000502:physiology* / Q000648:ultrastructure; D002417:Cattle; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D020219:Chondrogenesis / Q000187:drug effects*; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D011122:Polyphosphates / Q000494:pharmacology*; D033081:Shear Strength / Q000187:drug effects*; D012996:Solutions
D018786:Bone Substitutes; D002130:Calcium Phosphates; D011122:Polyphosphates; D012996:Solutions; C020243:calcium phosphate