gms | German Medical Science

Objective: Adipose-derived stem and regenerative cells (ADRCs) differentiate into a nucleus pulposus-like phenotype when exposed to in vivo environmental factors. A study was initiated to evaluate whether autologous cells derived from adipose tissue would be effective in an established dog model for acute disc injury.

Methods: Four, adult, male dogs weighing 25-30 kg were anesthetised, and radiographs made to assess baseline morphology and disc height. In each dog adipose tissue was harvested from the thigh and ADRCs were collected from the tissue using enzymatic digestion and cell concentration. Lumbar discs were exposed and nucleotomy performed on three levels. One million cells were suspended in either (a) hyaluronic acid (HA) or (b) saline, and, using C-arm fluoroscopy, placed centrally into two of the three levels. The third, un-injected level, served as a degeneration control. MRI was performed on all four dogs at six weeks and on two dogs twelve weeks after cell placement. Two dogs were euthanized at six weeks, and two dogs were euthanized at twelve weeks following the placement of the cells. Radiographic anatomy, MRI, histology and gross pathology were used to assess the outcomes of the intervention.

Results: Disc levels that received cells in an HA carrier at both six weeks and twelve weeks had thicker discs, a higher cell content with better organized colonies of cells, more matrix production, and relative protection from endplate inflammation compared to the levels receiving cells with a saline carrier. Levels that had only the nucleotomy (degeneration controls) showed anular prolapse into the central space. These levels lacked significant regeneration of either matrix or the ability to structure cells during the repair process.

Conclusions: This feasibility study provides additional evidence that ADRCs can be transplanted at the time of surgery and injected safely by percutaneous means. Coupled with encouraging results described here, plus other clinical studies using autologous disc chondrocyte transplantation, this project has now been extended to include six-month and one-year assessments of ADRCs injected with an HA carrier.