title: In vitro interaction between muscle-derived stem cells and nucleus pulposus cells.
abstract: BACKGROUND
  Current therapies for intervertebral disc degeneration (IDD) are aimed at treating the clinical symptoms arising from IDD rather than directly treating the underlying problem. Pathophysiology of IDD is characterized by a progressive decrease in proteoglycan content and cell density in the nucleus pulposus (NP). A cell-based therapy is a promising concept that uses various cell types to repopulate the disc in an attempt to slow, stop, or reverse the progressive loss of proteoglycans. Stem cells appear to be an excellent candidate for this purpose, based on their ability to differentiate into various connective tissue lineages. The muscle tissue could serve as a good source of adult stem cells because of its vast abundance through out the human body.
  
  
  OBJECTIVE
  To examine the interaction between the nucleus pulposus cells (NPCs) and the muscle-derived stem cells (MDSCs) in vitro.
  
  
  METHODS
  NPCs and MDSCs were cocultured and proteoglycan production and cell proliferation were evaluated.
  
  
  METHODS
  Various ratios of human NPCs were cocultured for 2 weeks with murine MDSCs (transduced with retro/LacZ) in a monolayer culture. Each well contained an admixture of cells with NPC-to-MDSC ratios of 0:100, 25:75, 50:50, 75:25, 100:0. Glycosaminoglycan (GAG) content (1,9 dimethylmethylene blue [DMMB]), newly synthesized proteoglycan ((35)S incorporation), and DNA content were measured, and cultures were stained with 5-bromo-4-chloro-3-indolyl-beta-D-galactosidase (X-Gal) for cell counting.
  
  
  RESULTS
  The NPC-to-MDSC ratio of 75:25 resulted in a significant increase in GAG content compared with NPCs alone. All coculture ratios showed increase in GAG content in comparison with MDSC culture alone. In addition, cocultures showed a significant increase in (35)S incorporation normalized to DNA content in comparison with MDSC alone.
  
  
  CONCLUSIONS
  The data from this study shows a synergistic effect between MDSCs and NPCs resulting in an upregulated proteoglycan synthesis and NPCs proliferation in vitro.
authors.affiliation: Ferguson Laboratory for Orthopaedic Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA 15261, USA. g.vadala@gmail.com
authors.forename: Gianluca
authors.initials: G
authors.lastname: Vadalà
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sobajima
authors.forename: Joon Y
authors.initials: JY
authors.lastname: Lee
authors.forename: Johnny
authors.initials: J
authors.lastname: Huard
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Denaro
authors.forename: James D
authors.initials: JD
authors.lastname: Kang
authors.forename: Lars G
authors.initials: LG
authors.lastname: Gilbertson
mesh_terms: D053687:Adult Stem Cells / Q000166:cytology* / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D049109:Cell Proliferation; D018920:Coculture Techniques; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005260:Female; D006025:Glycosaminoglycans / Q000096:biosynthesis; D006801:Humans; D007403:Intervertebral Disc / Q000166:cytology* / Q000378:metabolism; D007405:Intervertebral Disc Displacement / Q000628:therapy; D051379:Mice; D018482:Muscle, Skeletal / Q000166:cytology*; D011509:Proteoglycans / Q000096:biosynthesis; D023822:Tissue Engineering / Q000379:methods; D014161:Transduction, Genetic
chemical_list: D016326:Extracellular Matrix Proteins; D006025:Glycosaminoglycans; D011509:Proteoglycans; C020341:glucosaminoglycans