Influence of Autologous Mononuclear Stem-Cells over Symptomatic Disk Disease in Experimental Animal Model

Abstract

IntroductionVarious therapeutic strategies have been used for controlling or at least slowing the degenerative cascade that leads to symptomatic disk degeneration. In this context, given its regenerative capability, stem cells (SC) therapy has shown promising results acting early on the degenerative cascade. This study aims to evaluate the influence of autologous adult mononuclear SC on the histological changes of experimentally induced disk degeneration. Materials and MethodsAfter local Ethical Committee approval, 16 rabbits-New Zealand, male, 3.5 to 4.5 kg-underwent needle puncture of the three caudal lumbar intervertebral discs using a previously validated technique, and the remaining discs were used as controls. The animals received either autologous mesenchymal SC or saline solution after 2 weeks (group 1) or 2 months (group 2). Animals underwent euthanasia 8 weeks after the cell administration, and the discs were harvested for analysis.The slides were analyzed on hematoxylin-eosin stains for the presence of degeneration by a previously validated score, and by automated color morphometry, also previously validated by the authors, defining cellular size and cellular population within the nucleus pulposus (NP). ResultsTotal 91 intervertebral discs (IVDs) were obtained for histological analysis, extracted from 16 animals-4 animals were excluded due to inadequate tissue preparation. The study group was divided as follows: 55 control-not punctured-IVDs and 36 experimental IVDs; were 21 have received SC and 15, isotonic saline solution.The microscopically characteristic alterations of the experimental disk degeneration have been observed in all punctured IVDs; however, some slides suggested a less intensive degeneration process and normal areas inside de nucleus pulposus, meaning recovery areas in the IVDs which have received mononuclear stem cells.Through color morphometry, significant differences favoring the SC group regarding number of cells and especially nuclear size (p = 0.03) give indirect evidence that the injected cells survived within the NP. There was also a trend favoring the group receiving SC earlier (2 weeks). ConclusionInjection of SC was not able to interrupt the degenerative process triggered by disk puncture. However, the histological changes were less severe in the groups receiving cell therapy. Color morphometry showed clusters of cells within the NP, not seen in the control groups.I confirm having declared any potential conflict of interest for all authors listed on this abstractYesDisclosure of InterestNone declared