Introduction: Disc degeneration is consistent with advancing age and in many cases is associated with back pain and restricted mobility. The traditional surgical treatment for chronic back pain has been spinal fusion to immobilize the painful level. Long-term studies, however, suggest that fusion actually promotes degeneration at adjacent levels. One of the hallmarks of disc degeneration is aggregation of chondrocytes in the nucleus of chondrones, and more recently apoptosis has been implicated as a factor controlling the longevity of the cells. Recent research suggests that it may be possible to restore normal function to degenerate discs by introducing a fresh population of cells. This study investigated the potential for autologous costal chondrocyte implantation to prevent lumbar disc degeneration after annular injury in the sheep.

Methods: the lumbar spines of eight adult sheep were exposed. In four animals, full thickness annular incisions were made in three alternate discs. No annular incisions were made in the other four sheep. A minimum of 500 mg of cartilaginous tissue was harvested from the twelfth rib of all animals. Tissue was cultured in vitro and the chondrocytes were labelled with a fluorescent marker for retrospective identification. After six weeks the chondrocytes were injected into the lower two alternate discs of all animals, leaving the uppermost discs and those untouched as internal controls. The animals were killed at intervals from three to twenty-four weeks and MRI, plain x-ray, histology and immunocytochemistry were evaluated.

Results: MRI at twelve and twenty-four weeks showed apparent preservation of all incised discs that had been transplanted with autologous chondrocytes. Histology revealed clusters of viable chondrocytes of normal appearance within the nucleus. These cells stained positive for the fluorescent label. The same cells and the surrounding matrix were also positive for collagen type II. Serial X-ray measurements suggested that progressive disc degeneration was arrested in the discs that received autologous costal chondrocytes.

Discussion: This pilot study showed evidence that cultured autologous costal chondrocytes remained viable and produced extracellular matrix following transplantation into normal and degenerate discs. In contrast to other studies that have used mesenchymal stem cells or chondrocytes harvested directly from discs, this study demonstrated success with cells from a source other than the disc. Costal cartilage is a convenient source of cells for transplantation and this technique warrants further investigation as a potential treatment for degenerative disc disease.

Introduction: The development of laboratory techniques in the last ten years has enabled the successful harvest, in vitro selection, culture and transplant of chondrocytes. The study proposes that transplantation of autologous chondrocytes prevents degeneration of the intervertebral disc following outer annular injury in an ovine model.

Methods: Eight sheep were anaesthetised and five contiguous lumbar discs were exposed via a left-sided posterolateral approach. Four of the animals were given full thickness annular incisions in three alternate discs. No annular incisions were made in the other 4 sheep. Costal cartilage was harvested from the left twelfth rib of all animals. Tissue was cultured and the chondrocytes were labelled in vitro with CFSE for verification following transplantation. Six weeks later autologous cultured chondrocytes were injected into the lower two alternate discs of all animals, leaving the uppermost discs and those untouched in between as internal controls. Animals were sacrificed after three, six, twelve and twenty-four weeks. Results were based on X rays, histological, and immunocytochemical assessments.

Results: Preliminary histological results up to three months showed viability of cultured chondrocytes and matrix production post transplantation. Serial X rays suggested that progressive disc degeneration was arrested in the treated discs.

Discussion: In this pilot study we have shown that cultured autologous chondrocytes can remain viable long term in vivo. These preliminary results suggest that these transplanted chondrocytes have the ability to retard and possibly prevent disc degeneration following annular incision. Previous similar studies have reported the use of chondrocytes cultured from disc, whilst this study showed that chondrocytes from a source foreign to the disc can exert positive effects. The encouraging result from this pilot study needs to be further validated to realise its potential as a treatment for degenerative disc disease.

INTRODUCTION: The development of laboratory techniques in the last ten years has enabled the successful harvest, in vitro selection, culture and transplant of chondrocytes. The study proposes that transplantation of autologous chondrocytes prevents degeneration of the intervertebral disc following outer annular injury in an ovine model.

METHODS: Eight sheep were anaesthetised and five contiguous lumbar discs were exposed via a left-sided posterolateral approach. Four of the animals were given full thickness annular incisions in three alternate discs. No annular incisions were made in the other four sheep. Costal cartilage was harvested from the left twelfth rib of all animals. Tissue was cultured and the chondrocytes were labelled in vitro with CFSE for verification following transplantation. Six weeks later autologous cultured chondrocytes were injected into the lower two alternate discs of all animals, leaving the uppermost discs and those untouched in between as internal controls. Animals were sacrificed after three, six, twelve and twenty-four weeks. Results were based on X-rays, histological, and immunocytochemical assessments.

RESULTS: Preliminary histological results up to three months showed viability of cultured chondrocytes and matrix production post transplantation. Serial X-rays suggested that progressive disc degeneration was arrested in the treated discs.

DISCUSSION: In this pilot study we have shown that cultured autologous chondrocytes can remain viable long term in vivo. These preliminary results suggest that these transplanted chondrocytes have the ability to retard and possibly prevent disc degeneration following annular incision. Previous similar studies have reported the use of chondrocytes cultured from disc, whilst this study showed that chondrocytes from a source foreign to the disc can exert positive effects. The encouraging result from this pilot study needs to be further validated to realise its potential as a treatment for degenerative disc disease.