Structured bilaminar coculture outperforms stem cells and disc cells in a simulated degenerate disc environment.
METHODS
This study explores the use of bilaminar coculture pellets of mesenchymal stem cells (MSCs) and nucleus pulposus cells (NPCs) as a cell-based therapy for intervertebral disc regeneration. The pellets were tested under conditions that mimic the degenerative disc.


OBJECTIVE
Our goal was to optimize our cell-based therapy in vitro under conditions representative of the eventual diseased tissue.


BACKGROUND
Harnessing the potential of stem cells is an important strategy for regenerative medicine. Our approach directed the behavior of stem cells by mimicking embryonic processes underlying cartilage and intervertebral disc development. Prior experiments have shown that bilaminar coculture can help differentiate MSC and substantially improve new matrix deposition.


METHODS
We have designed a novel spherical bilaminar cell pellet (BCP) where MSCs are enclosed in a shell of NPC. There were 3 groups: MSC, NPC, and BCP. The pellets were tested under 3 different culture conditions: 1) in a bioreactor that provides pressure and hypoxia (mimicking normal disc conditions): 2) with inflammatory cytokines (IL-1b and TNF-a); and 3) a bioreactor with inflammation (mimicking painful disc conditions).


RESULTS
When cultured in the bioreactor, the NPC pellets produced significantly more glycosaminoglycans (GAGs) per cell than the other groups: 70% to 80% more than the BCP and the MSC alone. When cultured in an inflammatory environment, the MSC and BCP groups produced 30% to 34% more GAGs per cell than NPC (P < 0.05). When the pellets were cultured in a bioreactor with inflammation, the BCP made 25% more GAGs per cell than the MSC and 57% more than the NPC (P < 0.05).


CONCLUSIONS
This study shows that BCPs outperform controls in a simulated degenerated disc environment. Adapting inductive mechanisms from development to trigger differentiation and restore diseased tissue has many advantages. As opposed to strategies that require growth factor supplements or genetic manipulations, our method is self-sustaining, targeted, and minimally invasive injection.
Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, USA.
Aliza A
AA
Allon
Kristin
K
Butcher
Richard A
RA
Schneider
Jeffrey C
JC
Lotz
D000818:Animals; D019149:Bioreactors; D002417:Cattle; D002454:Cell Differentiation / Q000502:physiology; D018920:Coculture Techniques / Q000379:methods; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology*; D055959:Intervertebral Disc Degeneration / Q000473:pathology*; D059630:Mesenchymal Stem Cells / Q000473:pathology*; D023822:Tissue Engineering / Q000295:instrumentation / Q000379:methods*