[Extraction techniques and biocompatibility evaluations of naturally derived nerve extracellular matrix]

Native extracellular matrix (ECM) is comprised of a complex network of structural and regulatory proteins that are arrayed into a tissue-specific, biomechanically optimal, fibrous matrix. The multifunctional nature of the native ECM will need to be considered in the design and fabrication of tissue engineering scaffolds. To investigate the extraction techniques of naturally derived nerve ECM and the feasibility of nerve tissue engineering scaffold.

Ten fresh canine sciatic nerves were harvested; nerve ECM material was prepared by hypotonic freeze-thawing, mechanical grinding, and differential centrifugation. The ECM was observed by scanning electron microscope. Immunofluorescence staining was performed to detect specific ECM proteins including collagen type I, laminin, and fibronectin. Total collagen and glycosaminoglycan (GAG) contents were assessed using biochemical assays. The degree of decellularization was evaluated with staining for nuclei using Hoechst33258. The dorsal root ganglion and Schwann cells of rats were respectively seeded onto nerve tissue-specific ECM films. The biocompatibility was observed by specific antibodies for cell markers.

Scanning electron microscope analysis revealed that nerve-derived ECM consisted of a nanofibrous structure, which diameter was 30-130 nm. Immunofluorescence staining confirmed that the nerve-derived ECM was made up of collagen type I, laminin, and fibronectin. The histological staining showed that the staining results of sirius red, Safranin O, and toluidine blue were positive. Hoechst33258 staining showed no DNA within the decellularized ECM. Those ECM films had good biocompatibility for dorsal root ganglion and Schwann cells. The contents of total collagen and GAG in the nerve-derived ECM were (114.88 +/- 13.33) microg/mg and (17.52 +/- 2.34) microg/mg, showing significant difference in the content of total collagen (P < 0.01) and no significant difference in the content of GAG (P > 0.05) when compared with the contents of normal nerve tissue [(54.07 +/- 5.06) microg/mg and (25.25 +/- 1.56) microg/mg)]. The results of immunofluorescence staining were positive for neurofilament 200 after 7 days and for S100 after 2 days.

Nerve-derived ECM is rich in collagen type I, laminin, and fibronectin and has good biocompatibility, so it can be used as a nerve tissue engineering scaffold.