[Optical coherence tomography (OCT) to evaluate cartilage tissue engineering].
OBJECTIVE
The aim of this study was to investigate hyaline cartilage defects treated with cell-seeded artificial matrix systems (two different collagen type I gels) with the method of optical coherence tomography (OCT) and to correlate the results with conventional histological and immunocytochemical staining.


METHODS
Osteochondral blocks were harvested from 20 patients undergoing total knee replacement and trimmed to 2 x 2 cm. Under sterile conditions, chondral defects of 8 mm diameter were either filled with a collagen type I gel plug seeded with autologous chondrocytes (2 x 10 (5)/mL gel), or with a corresponding gel plug which was stabilised by a 20-fold compression. Of each group, 5 specimens were cultivated for 6 weeks under standardised in vitro conditions (37 degrees C, 5 % CO (2), humidified atmosphere), while the remaining 5 specimens were implanted subcutaneously in nude mice (BALBc -/-). Immediately after recovery, the repair tissue and bonding zones were investigated by OCT. Subsequently, specimens were decalcified and investigated by H&E staining and collagen type II immunostaining. The results of OCT and conventional staining were correlated.


RESULTS
By OCT, repair tissue could be investigated up to 1.6 mm in depth, physically limited by the utilised OCT system. In the denser hyaline cartilage regions, OCT resolution was reduced. Regardless of cultivation (in vitro or nude mouse), ultrastructural features of the repair tissue could be demonstrated. In particular, ultrastructural differences between the two investigated collagen gels could be detected. Moreover, the bonding region between repair tissue and hyaline cartilage could be evaluated by OCT investigation. The results of the OCT measurements were confirmed by H&E and collagen type II immunostaining.


CONCLUSIONS
By OCT, repair tissue generated by the treatment of cartilage defects with tissue-engineered matrix systems could be evaluated in vitro. Future studies may show if repair tissue quality may be monitored in situ by OCT.
Gavenis
K
K
Klinik für Orthopädie und Unfallchirurgie, Schwerpunkt Orthopädie, RWTH Aachen. kgavenis@ukaachen.de
Schmitt
R
R
Eder
K
K
Mumme
T
T
Andereya
S
S
Schneider
U
U
Müller-Rath
R
R
D000818:Animals; D019645:Arthroplasty, Replacement, Knee; D019902:Chondrocytes / Q000473:pathology / Q000637:transplantation*; D024042:Collagen Type I / Q000008:administration & dosage*; D015718:Fibrin Tissue Adhesive / Q000627:therapeutic use; D005782:Gels; D006801:Humans; D051457:Hyaline Cartilage / Q000473:pathology / Q000601:surgery*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D023822:Tissue Engineering / Q000379:methods*; D041623:Tomography, Optical Coherence; D014945:Wound Healing / Q000502:physiology
D024042:Collagen Type I; D015718:Fibrin Tissue Adhesive; D005782:Gels