title: Optimization of protein crosslinking formulations for the treatment of degenerative disc disease.
abstract: METHODS
  Biochemical studies aimed at optimization of protein crosslinking formulations for the treatment of degenerative disc disease and subsequent biomechanical testing of tissues treated with these formulations.
  
  
  OBJECTIVE
  To optimize protein crosslinking formulations for treatment of degenerating spinal discs.
  
  
  BACKGROUND
  Nonsurgical exogenous crosslinking therapy is a potential new, noninvasive technology for the treatment of degenerative disc disease. The technology is based on the injection of protein crosslinking reagents into the pathologic disc to restore its mechanical properties and also to potentially increase the permeability of the tissue and so facilitate the exchange of waste products and nutrients.
  
  
  METHODS
  Diffusion of genipin (GP) was monitored following injection into spinal discs and the effects of surfactants on diffusion studied. Formulations for GP and methylglyoxal (MG) were biochemically optimized and used to treat bovine spinal discs. Their effects on bovine anulus tissue were evaluated using a circumferential tensile test, while the GP formulation was also tested with respect to its ability to reduce disc bulge under load.
  
  
  RESULTS
  GP exhibited a distinct time-dependent diffusion and sodium-dodecyl-sulfate, but not Tween-20, enhanced diffusion by 30%. Two crosslinkers, GP and MG, were inhibited by amines but enhanced by phosphate ions. Both formulations could enhance a number of physical parameters of bovine anulus tissue, while the GP formulation could reduce disc bulge following injections into spinal discs.
  
  
  CONCLUSIONS
  Formulations lacking amines and containing phosphate ions appear to be promising candidates for clinical use of the crosslinkers GP and MG.
authors.affiliation: Orthopeutics LP, Georgetown, TX, USA. pslusarewicz@orthopeutics.com
authors.forename: Paul
authors.initials: P
authors.lastname: Slusarewicz
authors.forename: Keng
authors.initials: K
authors.lastname: Zhu
authors.forename: Bryan
authors.initials: B
authors.lastname: Kirking
authors.forename: Justin
authors.initials: J
authors.lastname: Toungate
authors.forename: Tom
authors.initials: T
authors.lastname: Hedman
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D003432:Cross-Linking Reagents / Q000008:administration & dosage*; D004058:Diffusion; D066298:In Vitro Techniques; D007278:Injections, Spinal; D007403:Intervertebral Disc / Q000187:drug effects* / Q000378:metabolism; D055959:Intervertebral Disc Degeneration / Q000188:drug therapy* / Q000378:metabolism; D057889:Iridoid Glycosides / Q000008:administration & dosage*; D039823:Iridoids; D008159:Lumbar Vertebrae / Q000187:drug effects* / Q000378:metabolism; D011136:Polysorbates / Q000008:administration & dosage; D011765:Pyruvaldehyde / Q000008:administration & dosage*; D012967:Sodium Dodecyl Sulfate / Q000008:administration & dosage; D013501:Surface-Active Agents / Q000008:administration & dosage; D013718:Tensile Strength; D013997:Time Factors
chemical_list: D003432:Cross-Linking Reagents; D057889:Iridoid Glycosides; D039823:Iridoids; D011136:Polysorbates; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D011765:Pyruvaldehyde; C007834:genipin