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Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 206 - 207
1 May 2011
Gorensek M Gorensek B Vengust R Kosak R Travnik L Tovsak Z Kregar-Velikonja N Cör A Pavlovcic V
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Objective: To find clinically the most suitable tissue-engineered replacement for nucleus pulposus which should be able to prevent, or at least delay, the process of intervertebral disc degeneration, as well as narrowing of the intervertebral disc space after surgery of disc herniation.

Methods: We chose to transplant chondrocytes derived from elastic cartilage in site of previously evacuated nucleus pulposus from the lumbar intervertebral discs of New Zeeland White Rabbits. Elastic cartilage cells of the rabbit ear have been used as an easily accessible and quality source of chondrocytes. A small piece of ear cartilage has been sampled and disintegrated. Free chondrocytes have been isolated and labeled with a fluorescent marker before transplantation procedure in order to trace them after implantation. Both cultured chondrocytes and chondrocytes harvested after isolation have been used as a transplant. Prior to implantation these cells have been divided into two groups – the first group as a cell suspension and the second group as a cellular construct on plasma-thrombin gel as a carrier. Animals were sacrificed in groups: after two weeks, one month and three months, with their lumbar intervertebral discs removed. In control group only nucleus was removed and then replaced either with suspension or carrier without cells. Survival of transplanted cells in the intervertebral disc space and their extracellular matrix synthesis has both been evaluated by fluorescent microscopy, histological and gene expression analysis. Radiological analysis has been used to test the efficiency in preventing the narrowing of intervertebral space after evacuation of nucleus pulposus.

Results: By using labeled transplanted cells we were able to trace their viability with fluorescent microscope up to one month. Thereby we have proven the transplanted cells are able to survive in the environment of the rabbit’s intervertebral disc. In addition, they are able to produce basic structural molecules of extra cellular matrix, histological similar to native nucleus pulposus, in contrast with control group where only remnants of carrier and scar tissue were found. However, the gene expression studies have shown that the cells of the new-formed tissue express less tissue-specific extra cellular matrix genes, e.g. aggrecan, collagen II, then cells in the native tissue. Radiological analysis has not shown any significant differences between the two groups in prevention of intervertebral space narrowing following the discectomy.

Conclusion: Cell therapy has much to offer in the development of tissue-engineered replacements used in clinical orthopedics. results and techniques of this research may turn out to be useful in clinical practice, but further examinations are needed especially on the field of annular closure, before any clinical investigation.


The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 3 | Pages 421 - 426
1 Mar 2011
Maličev E Barlič A Kregar-Velikonja N Stražar K Drobnič M

The aim of this study was to evaluate the cultivation potential of cartilage taken from the debrided edge of a chronic lesion of the articular surface. A total of 14 patients underwent arthroscopy of the knee for a chronic lesion on the femoral condyles or trochlea. In addition to the routine cartilage biopsy, a second biopsy of cartilage was taken from the edge of the lesion. The cells isolated from both sources underwent parallel cultivation as monolayer and three-dimensional (3D) alginate culture. The cell yield, viability, capacity for proliferation, morphology and the expressions of typical cartilage genes (collagen I, COL1; collagen II, COL2; aggrecan, AGR; and versican, VER) were assessed. The cartilage differentiation indices (COL2/COL1, AGR/VER) were calculated. The control biopsies revealed a higher mean cell yield (1346 cells/mg vs 341 cells/mg), but similar cell proliferation, viability and morphology compared with the cells from the edge of the lesion. The cartilage differentiation indices were superior in control cells: COL2/COL1 (threefold in biopsies (non-significant)); sixfold in monolayer cultures (p = 0.012), and 7.5-fold in hydrogels (non-significant), AGR/VER (sevenfold in biopsies (p = 0.04), threefold (p = 0.003) in primary cultures and 3.5-fold in hydrogels (non-significant)).

Our results suggest that the cultivation of chondrocytes solely from the edges of the lesion cannot be recommended for use in autologous chondrocyte implantation.