title: Mass spectrometric monitoring of Sr-enriched bone cements--from in vitro to in vivo.
abstract: Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a well-established technique in materials science, but is now increasingly applied also in the life sciences. Here, we demonstrate the potential of this analytical technique for use in the development of new bone implant materials. We tracked strontium-enriched calcium phosphate cements, which were developed for the treatment of osteoporotic bone, from in vitro to in vivo. Essentially, the spatial distribution of strontium in two different types of strontium-modified calcium phosphate cements is analysed by SIMS depth profiling. To gain information about the strontium release kinetics, the cements were immersed for 3, 7, 14 and 21 days in α-MEM and tris(hydroxymethyl)-aminomethane solution and analysed afterwards by ToF-SIMS depth profiling. For cements stored in α-MEM solution an inhibited strontium release was observed. By using principal component analysis to evaluate TOF-SIMS surface spectra, we are able to prove the adsorption of proteins on the cement surface, which inhibit the release kinetics. Cell experiments with human osteoblast-like cells cultured on the strontium-modified cements and subsequent mass spectrometric analysis of the mineralised extracellular matrix (mECM) prove clearly that strontium is incorporated into the mECM of the osteoblast-like cells. Finally, in an animal experiment, the strontium-doped cements are implanted into the femur of osteoporotic rats. After 6 weeks, only a slight release of strontium was found in the vicinity of the implant material. By using ToF-SIMS, it is proven that strontium is localised in regions of newly formed bone but also within the pre-existing tissue.
authors.affiliation: Institute for Physical Chemistry, Justus-Liebig-University of Giessen, Heinrich-Buff-Ring 58, 35392, Giessen, Germany, Marcus.Rohnke@phys.chemie.uni-giessen.de.
authors.forename: Marcus
authors.initials: M
authors.lastname: Rohnke
authors.forename: Anja
authors.initials: A
authors.lastname: Henss
authors.forename: Julia
authors.initials: J
authors.lastname: Kokesch-Himmelreich
authors.forename: Matthias
authors.initials: M
authors.lastname: Schumacher
authors.forename: Seemun
authors.initials: S
authors.lastname: Ray
authors.forename: Volker
authors.initials: V
authors.lastname: Alt
authors.forename: Michael
authors.initials: M
authors.lastname: Gelinsky
authors.forename: Juergen
authors.initials: J
authors.lastname: Janek
mesh_terms: D000818:Animals; D001843:Bone Cements / Q000737:chemistry / Q000494:pharmacology*; D002130:Calcium Phosphates / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D002478:Cells, Cultured; D004058:Diffusion; D005260:Female; D005269:Femur / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D007700:Kinetics; D009930:Organic Chemicals / Q000737:chemistry; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D010024:Osteoporosis / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D010052:Ovariectomy; D010710:Phosphates / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D025341:Principal Component Analysis; D019736:Prostheses and Implants; D017207:Rats, Sprague-Dawley; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013324:Strontium / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; D009930:Organic Chemicals; D010710:Phosphates; C420642:alpha minimal essential medium; C020243:calcium phosphate; C052774:strontium phosphate; D013324:Strontium