title: Chondrogenesis of human bone marrow-derived mesenchymal stem cells is modulated by complex mechanical stimulation and adenoviral-mediated overexpression of bone morphogenetic protein 2.
abstract: Currently available methods to treat articular cartilage defects still fail to demonstrate satisfactory outcomes for many patients. Functional tissue engineering using human bone marrow-derived mesenchymal stem cells (hMSCs) is a promising alternative approach for the treatment of these defects. This study strived to investigate the combined effect of complex mechanical stimulation and adenoviral-mediated overexpression of bone morphogenetic protein 2 (BMP-2) on hMSC chondrogenesis. hMSCs were encapsulated in a fibrin hydrogel and seeded into biodegradable polyurethane (PU) scaffolds. A novel three-dimensional transduction protocol was used to transduce cells with an adenovirus encoding for BMP-2 (Ad.BMP-2). Control cells were left untransduced. Cells were cultured for 7 or 28 days in a chondropermessive medium, which lacks any exogenous growth factors. Thereby, the in vivo situation is mimicked more precisely. hMSCs in fibrin-PU composite scaffolds were either left as free-swelling controls or mechanically stimulated using a custom-built bioreactor system that is able to generate joint-like forces. Outcome parameters measured were BMP-2 concentration within the culture medium, and biochemical and gene expression analysis. Mechanical stimulation resulted in an upregulation of chondrogenic genes. Further, glycosaminoglycan (GAG)/DNA ratios were elevated in mechanically stimulated groups. Transduction with Ad.BMP-2 led to a pronounced upregulation of the gene aggrecan and an upregulation of Sox9 message after 7 days. Furthermore, a synergistic effect in combination with mechanical stimulation on collagen 2 message was detected after 7 days. This synergistic increase was more than 8-fold if compared to the additive effect of the application of each stimulus on its own. However, BMP-2 overexpression consistently resulted in a trend toward decreased GAG/DNA ratios in both mechanical stimulated and unloaded groups.
authors.affiliation: Musculoskeletal Regeneration Program, AO Research Institute Davos, AO Foundation, Davos Platz, Switzerland.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Neumann
authors.forename: Mauro
authors.initials: M
authors.lastname: Alini
authors.forename: Charles W
authors.initials: CW
authors.lastname: Archer
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Stoddart
mesh_terms: D000256:Adenoviridae / Q000378:metabolism*; D053674:Aggrecans / Q000235:genetics / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism*; D020219:Chondrogenesis / Q000187:drug effects / Q000235:genetics; D003470:Culture Media / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D005337:Fibrin / Q000494:pharmacology; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D011140:Polyurethanes / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000378:metabolism; D013314:Stress, Mechanical; D014161:Transduction, Genetic; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D053674:Aggrecans; D055396:Bone Morphogenetic Protein 2; D003470:Culture Media; D006025:Glycosaminoglycans; D011140:Polyurethanes; D012333:RNA, Messenger; D055758:SOX9 Transcription Factor; D005337:Fibrin; D004247:DNA