title: Mesenchymal stem cells and collagen patches for anterior cruciate ligament repair.
abstract: OBJECTIVE
  To investigate collagen patches seeded with mesenchymal stem cells (MSCs) and/or tenocytes (TCs) with regards to their suitability for anterior cruciate ligament (ACL) repair.
  
  
  METHODS
  Dynamic intraligamentary stabilization utilizes a dynamic screw system to keep ACL remnants in place and promote biological healing, supplemented by collagen patches. How these scaffolds interact with cells and what type of benefit they provide has not yet been investigated in detail. Primary ACL-derived TCs and human bone marrow derived MSCs were seeded onto two different types of 3D collagen scaffolds, Chondro-Gide(®) (CG) and Novocart(®) (NC). Cells were seeded onto the scaffolds and cultured for 7 d either as a pure populations or as "premix" containing a 1:1 ratio of TCs to MSCs. Additionally, as controls, cells were seeded in monolayers and in co-cultures on both sides of porous high-density membrane inserts (0.4 μm). We analyzed the patches by real time polymerase chain reaction, glycosaminoglycan (GAG), DNA and hydroxy-proline (HYP) content. To determine cell spreading and adherence in the scaffolds microscopic imaging techniques, i.e., confocal laser scanning microscopy (cLSM) and scanning electron microscopy (SEM), were applied.
  
  
  RESULTS
  CLSM and SEM imaging analysis confirmed cell adherence onto scaffolds. The metabolic cell activity revealed that patches promote adherence and proliferation of cells. The most dramatic increase in absolute metabolic cell activity was measured for CG samples seeded with tenocytes or a 1:1 cell premix. Analysis of DNA content and cLSM imaging also indicated MSCs were not proliferating as nicely as tenocytes on CG. The HYP to GAG ratio significantly changed for the premix group, resulting from a slightly lower GAG content, demonstrating that the cells are modifying the underlying matrix. Real-time quantitative polymerase chain reaction data indicated that MSCs showed a trend of differentiation towards a more tenogenic-like phenotype after 7 d.
  
  
  CONCLUSIONS
  CG and NC are both cyto-compatible with primary MSCs and TCs; TCs seemed to perform better on these collagen patches than MSCs.
authors: Benjamin Gantenbein, Neha Gadhari, Samantha CW Chan, Sufian S Ahmad, Tissue and Organ Mechanobiology, Institute for Surgical Technology and Biomechanics, University of Bern, CH-3014 Bern, Switzerland.
authors: Benjamin
authors: B
authors: Gantenbein
authors: Benjamin Gantenbein, Neha Gadhari, Samantha CW Chan, Sufian S Ahmad, Tissue and Organ Mechanobiology, Institute for Surgical Technology and Biomechanics, University of Bern, CH-3014 Bern, Switzerland.
authors: Neha
authors: N
authors: Gadhari
authors: Benjamin Gantenbein, Neha Gadhari, Samantha CW Chan, Sufian S Ahmad, Tissue and Organ Mechanobiology, Institute for Surgical Technology and Biomechanics, University of Bern, CH-3014 Bern, Switzerland.
authors: Samantha Cw
authors: SC
authors: Chan
authors: Benjamin Gantenbein, Neha Gadhari, Samantha CW Chan, Sufian S Ahmad, Tissue and Organ Mechanobiology, Institute for Surgical Technology and Biomechanics, University of Bern, CH-3014 Bern, Switzerland.
authors: Sandro
authors: S
authors: Kohl
authors: Benjamin Gantenbein, Neha Gadhari, Samantha CW Chan, Sufian S Ahmad, Tissue and Organ Mechanobiology, Institute for Surgical Technology and Biomechanics, University of Bern, CH-3014 Bern, Switzerland.
authors: Sufian S
authors: SS
authors: Ahmad
keywords: Anterior cruciate ligament rupture; Anterior cruciate ligament tenocyte; Dynamic intraligamentary stabilization system; Histology; Mesenchymal stem cells; Real-time polymerase chain reaction; Resazurin red assay; Scanning electron microscopy; Scanning electron microscopy microscopy