Abstract: Objective To investigate the biocompatibility of dog bone marrow stromal cells (BMSCs) in vitro with silk fibroin material and to explore the possibility of using silk fibroin as a novel material in the fabrication of tissue-engineered nerve scaffolds combined with the introduction of BMSCs. Methods Dog bone marrow stromal cells were isolated from other cells by adherence to plastic. The dog BMSCs were then cultured on the substrate silk fibroin fibers and the cell attachment and growth observed using immunofluorescence light microscopy and scanning electron microscopy. The dog BMSCs were also cultured in the silk fibroin extract fluid. The cell ultrastructure was observed by transmission electron microscopy. MTT test was used to detect cell viability in different medium after 12, 24, 48 and 72 hours or 7 days in culture (EM>n/EM>=12 for each group). Flow cytometry was employed to detect BMSCs cell cycle and phenotypes (EM>n/EM>=3). Results BMSCs were tightly attached to the silk fibroin fibers and grew along the silk fibroin as demonstrated by immunofluorescence light microscopy and scanning electron microscopy, some of which exhibited a spherical, oval or spindle shape. The results of transmission electron microscopy, MTT test and flow cytometry analysis showed that there were no significant morphological, cell viability, proliferation and phenotypes differences between BMSCs cultured in the silk fibroin extract fluid and those in plain IMDM medium. Conclusion These data indicate that silk fibroin has good biocompatibility with BMSCs and does not exert any significant cytotoxic effects on their phenotype, thus it is a potential scaffold material combined with the introduction of BMSCs in the fabrication of tissue-engineered nerve.

Key words: Bone marrow stromal cell, Silk fibroin, Biocompatibility, Ultrastructure, Immunofluorescence, Flow cytometry, Dog