Mesenchymal stem cells and collagen patches for anteriorcruciate ligament repair

AIM To investigate collagen patches seeded withmesenchymal stem cells （MSCs） and/or tenocytes （TCs）with regards to their suitability for anterior cruciateligament （ACL） repair.METHODS： Dynamic intraligamentary stabilizationutilizes a dynamic screw system to keep ACL remnantsin place and promote biological healing, supplementedby collagen patches. How these scaffolds interact withcells and what type of benefit they provide has not yetbeen investigated in detail. Primary ACL-derived TCsand human bone marrow derived MSCs were seededonto two different types of 3D collagen scaffolds,Chondro-Gide？ （CG） and Novocart？ （NC）. Cells wereseeded onto the scaffolds and cultured for 7 d eitheras a pure populations or as ＂premix＂ containing a 1：1ratio of TCs to MSCs. Additionally, as controls, cells wereseeded in monolayers and in co-cultures on both sidesof porous high-density membrane inserts （0.4 μm）. Weanalyzed the patches by real time polymerase chainreaction, glycosaminoglycan （GAG）, DNA and hydroxyproline（HYP） content. To determine cell spreadingand adherence in the scaffolds microscopic imagingtechniques, i.e. , confocal laser scanning microscopy（cLSM） and scanning electron microscopy （SEM）, wereapplied.RESULTS： CLSM and SEM imaging analysis confirmedcell adherence onto scaffolds. The metabolic cellactivity revealed that patches promote adherenceand proliferation of cells. The most dramatic increasein absolute metabolic cell activity was measuredfor CG samples seeded with tenocytes or a 1：1 cellpremix. Analysis of DNA content and cLSM imagingalso indicated MSCs were not proliferating as nicely astenocytes on CG. The HYP to GAG ratio significantlychanged for the premix group, resulting from a slightlylower GAG content, demonstrating that the cells aremodifying the underlying matrix. Real-time quantitative Gantenbein B et al . Mesenchymal stem cells for ACL repair polymerase chain reaction data indicated that MSCs showed a trend of differentiation towards a more teno