Exogenous collagen-enhanced recruitment of mesenchymal stem cells during rabbit articular cartilage repair.
BACKGROUND
Despite the well-known effect of type-I collagen in promoting cartilage repair, the mechanism still remains unknown. In this study we investigated this mechanism using a rabbit model of cartilage defects.


METHODS
5-mm-diameter full-thickness defects were created on both patellar grooves of 53 Japanese white rabbits (approximately 13 weeks old). The left defect was filled with collagen gel and the right defect was left empty. The rabbits were killed and examined morphometrically until the twenty-fourth postoperative week, by (1) evaluation of matrix production, (2) enumeration of the total number of cells engaged in cartilage repair, (3) enumeration of the proliferating cells, (4) localization of mesenchymal stem cells, and (v) localization of apoptotic cells.


RESULTS
We found that type-I collagen enhances cell recruitment, and thereby increases the number of proliferating cells. A considerable proportion of the proliferating cells were identified as bone marrow-derived mesenchymal stem cells. However, type-I collagen does not prevent the chondrocyte precursors from undergoing apoptotic disengagement from the chondrogenic lineage.


CONCLUSIONS
Type-I collagen promotes cartilage repair by enhancing recruitment of bone marrow-derived mesenchymal stem cells. Additional use of agent(s) that sustain mesenchymal stem cells along the chondrogenic path of differentiation may constitute an appropriate environment for cartilage repair.
Kubo
Mitsuhiko
M
Department of Orthopedic Surgery, Shiga University of Medical Science, Japan. mkubo@belle.shiga-med.ac.jp
Imai
Shinji
S
Fujimiya
Mineko
M
Isoya
Eiji
E
Ando
Kosei
K
Mimura
Tomohiro
T
Matsusue
Yoshitaka
Y
D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D020219:Chondrogenesis / Q000187:drug effects; D024042:Collagen Type I / Q000008:administration & dosage* / Q000502:physiology; D048091:Guided Tissue Regeneration; D059630:Mesenchymal Stem Cells / Q000187:drug effects* / Q000502:physiology; D011817:Rabbits; D014945:Wound Healing / Q000187:drug effects
D024042:Collagen Type I