Repair of full-thickness cartilage defects with cells of different origin in a rabbit model.
OBJECTIVE
The purpose of this study was to evaluate the repaired tissues formed in full-thickness cartilage defects in a rabbit model implanted with 4 types of chondrogenic cells, including chondrocytes, mesenchymal stem cells (MSCs) and fibroblasts from rabbit, and human umbilical cord blood (hUCB) stem cells.


METHODS
Chondrocytes, MSCs, and fibroblasts were isolated from 6-week-old New Zealand rabbits; hUCB stem cells were isolated from the umbilical cord blood of newborn children. These 4 types of cells were cultured in vitro and embedded in polylactic acid (PLA) matrices. Full-thickness defects were produced in the femoral trochlear grooves of both knees in 36 adult New Zealand White rabbits. Cell/PLA composites were transplanted into cartilage defects. A total of 5 groups were formed according to implanted cell type: Group A, chondrocytes; Group B, MSCs; Group C, fibroblasts; Group D, hUCB stem cells; and Group E, no cells (control group). Repaired tissues were evaluated grossly, histologically, and immunohistochemically at 6 weeks and 12 weeks after implantation.


RESULTS
In Groups A and B, defects were repaired with hyaline-like cartilage. In Group C, defects were repaired with fibrous tissue. In Group D, defects were repaired primarily with fibrous tissue and scattered chondrocytes; in some specimens, defects were repaired with a thin layer of hyaline-like cartilage at 12 weeks. In Group E, defects were repaired with fibrous tissue. Histologic scores in Groups A and B were significantly higher than those in Groups C, D, and E at 6 and 12 weeks after transplantation.


CONCLUSIONS
Full-thickness cartilage defects treated with chondrocyte or MSC transplantation were repaired with hyaline-like cartilage tissue, and repair was significantly better than in tissues treated with fibroblasts and hUCB stem cells, as well as in the control group. Repaired tissues treated with MSCs appeared to have better cell arrangement, subchondral bone remodeling, and integration with surrounding cartilage than did repaired tissues generated by chondrocyte implantation. MSCs might be the most suitable cell source for cartilage repair. Further investigation into hUCB stem cell transplantation is needed.


CONCLUSIONS
In our study of rabbits, MSCs supplied the most promising cell source for cartilage repair.
Yan
Hui
H
Institute of Sports Medicine, Third Hospital, Peking University, Beijing, China.
Yu
Changlong
C
D000818:Animals; D002358:Cartilage, Articular / Q000293:injuries* / Q000473:pathology; D017690:Cell Transplantation; D002478:Cells, Cultured; D019902:Chondrocytes / Q000637:transplantation; D036101:Cord Blood Stem Cell Transplantation; D004195:Disease Models, Animal; D005347:Fibroblasts / Q000637:transplantation; D048091:Guided Tissue Regeneration; D006801:Humans; D007231:Infant, Newborn; D019344:Lactic Acid; D008567:Membranes, Artificial; D045164:Mesenchymal Stem Cell Transplantation; D011091:Polyesters; D011108:Polymers; D011817:Rabbits; D023822:Tissue Engineering; D014945:Wound Healing
D008567:Membranes, Artificial; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide)