A comparison of rabbit mesenchymal stem cells and anterior cruciate ligament fibroblasts responses on combined silk scaffolds

The aim of this study was to compare the cellular responses of bone marrow-derived mesenchymal stem cells (BMSCs) and anterior cruciate ligament fibroblasts (ACLFs) on combined silk scaffolds for ligament tissue engineering application. Rabbit BMSCs and ACLFs were isolated and cultured in vitro for two weeks after seeding on the silk scaffolds. Samples were evaluated and compared for their cellular morphology, proliferation, gene and protein expression of tenascin-C, type I and type III collagen. In addition, the two cell types were transfected with green fluorescent protein (GFP) to trace their fate in the knee joints. Preliminary results comparing cell proliferation indicated that BMSCs proliferated faster than ACLFs. Gene expression of the phenotypic markers measured using real-time reverse transcription polymerase chain reaction (RT-PCR) indicated the transcript levels of BMSCs were significantly increased after two weeks of culture, whereas those of ACLFs had no significant difference. The protein levels and localization were determined by western blotting and immunohistochemical staining, the results showed more production of ligament-related extracellular matrix (ECM) by BMSCs as compared to ACLFs. Moreover, 4 weeks postoperatively, more fluorescent cells were presented in BMSC-loaded constructs than in ACLF-loaded constructs. Therefore, based on the cellular response in vitro and in vivo, BMSCs were found to be a better cell source than ACLFs for the further study of ACL tissue engineering.