Apoptosis, Nutrition, and Metabolism of Transplanted Intervertebral Disc Cells: Consequences for Regenerative Cell Viability Apoptose, Nutrição e Metabolismo de Células de Discos Intervertebrais Transplantadas: Consequências da Viabilidade de Células Re

Morgan Giers, Liudmila Bardonova, Kyle Ester, Vadim Byvaltsev, Mark C Preul

Resumo


Abstract

Introduction: Apoptosis is a contributing factor to degenerating intervertebral discs (IVD). Disc regeneration has been attempted by transplanting cells into the disc, with some gains in disc height achieved in animal models. Here we study if the apoptotic microenvironment affects the transplanted disc cells.

Methods: Human annulus fibrosus (AF) and nucleus pulposus (NP) cells were grown in media then starved for 5 days in vitro by not changing the media. Three aspects of apoptotic cell influence on transplanted cells were tested in a total of 32 samples: 1) the effect of apoptotic cytokines in the media, 2) reduced glucose in the media, and 3) apoptotic cell bodies in the flask. Trypan Blue, AlamarBlue®, and 1,9-Dimethyl-Methylene Blue assays for sulfated glycosaminoglycan (sGAG) content were performed (n=4).

Results: There were significant decreases in cell viability between the control, 25% conditioned media (CM) and starved control group. There were no significant differences in cell number, metabolic activity or sGAG production in cells grown in different conditioned media compared to complete media. Cells decreased viability and cell number from the control during 5 days without feeding, then improve dramatically when feeding was resumed. Flasks that received transplanted cells in addition to renewed feeding did not recover as much as cells in the re-fed group.

Conclusions: Cytokines from starved cells negatively impacted healthy cells' viability. Starving cells that receive new sources of nutrition have even higher viability than transplanted cells. This indicates that altering and improving the nutrient supply problem in the IVD could be a valuable option.

Palavras-chave


apoptosis, intervertebral disc, disc regeneration, intervertebral disc cell nutrition, intervertebral disc transplantation, metabolism