Issue 2, Volume 2
Intervertebral Disc Regeneration
Research Review

Clustered Cells in Intervertebral Discs Are Not More Viable Sources for Regenerative Therapies Than Single Cells

Eur Spine J. 2014;Aug 6:Epub ahead of print

Introduction: Previous research suggests that autologous intravertebral disc cells may be used as a form of biologic therapy for repair of degenerative disc disease. Because clusters of cells are often found in samples of intervertebral discs, and are believed to result from a repair response, the researchers investigated whether these cell clusters are more viable (ie, have an enhanced population of stem cells) than single cells for biological repair of degenerative discs.

Methods: The researchers examined surgical samples from 95 patients (aged 41±10 years) who underwent routine surgery for intravertebral disc disorders. Both single and clustered cells from the samples were examined for cell viability, growth kinetics, and stem or progenitor cell markers.

Results: Overall, 69% of the cells in the samples were considered viable. The incidence of progenitor cells did not differ among the cell clusters versus the single cells. However, the clustered cells consistently proliferated more slowly than single cells.

Conclusion: Both clustered cells and single cells extracted from human intravertebral disc samples show good viability and a similar proportion of stem cells or progenitor cell properties; however, cultured clustered cells proliferate more slowly than single cells, suggesting that they offer no benefit over single cells isolated for repair of degenerative disc disease. The authors noted that it may be beneficial to avoid use of clustered cells in this context.


This paper answers the question of whether there are more progenitor cells in clusters of intervertebral disc cells compared to single loci of cells. The answer is that there is no difference of these cells in either population.

The findings suggest that the progenitor cells proliferate more slowly in vitro when they are grown in clusters versus single cell population. In addition, senescent cells also were found in equal amounts in both cell populations. This finding is contrary to earlier findings suggesting that cluster cells had more senescent cells.

The authors conclude that cluster cells proliferate more slowly while having the same amount of progenitor cells as single cell population. Thus, there is no advantage in using them for intervertebral disc regeneration therapy.


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