Towards understanding structure-stability and surface properties of laminin peptide YIGSR and mutants

Rapid repair of rat sciatic nerve injury using a nanosilver-embedded collagen scaffold coated with laminin and fibronectin

AIM

Scaffold with micro-channels has shown great promise in facilitating axonal regeneration after peripheral nerve injury. Significant research has focused on mimicking, in terms of composition and function, the ability of the basement membrane of Schwann cells to both promote and guide axonal regeneration. We aim to investigate the ability of a tissue-engineered scaffold with nanosilver and collagen to adsorb laminin and fibronectin, and the usefulness of this scaffold for repairing and regenerating a 10-mm peripheral nerve gap in rats.

METHODS

In this study, nanosilver-embedded collagen scaffolds were prepared and coated with laminin (LN) or LN plus fibronectin (FN). Scanning electron microscopy of the transverse and longitudinal sections of the scaffold revealed axially oriented microtubules ranging from 20 to 80 µm in diameter, and the internal surface of microtubules was found to be evenly coated with LN and FN. Energy dispersive spectrometry also confirmed an even distribution of nanosilver particles within the scaffold. To test its effectiveness in restoring neuronal connection, the scaffold was used in order to bridge 10 mm gaps in the severed sciatic nerve of rats. The rats were divided into an experimental group (receiving scaffold coated with LN and FN), a control group (receiving scaffold coated with LN only) and an autologous graft group. The functional recovery 40 days after surgery was examined by electrophysiology and sciatic nerve functional index (SFI) evaluation. FluoroGold™ (FG) retrograde tracing, toluidine blue staining and transmission electron microscopy were also used to examine the regenerated nerve fibers and to establish their myelination status.

RESULTS

The experimental group displayed partially restored nerve function. The recovery was comparable to the effect of autologous nerve graft and was better than that observed in the control group. A better functional recovery correlated with more FG-labeled neurons, higher density of toluidine blue stained nerve fibers and thicker myelin sheath.

CONCLUSION

Our results demonstrated that nanosilver-embedded collagen scaffolds with LN and FN coating is effective in aiding axonal regeneration, and recovery is comparable to the effect of an autologous nerve graft.

Pentapeptide-modified poly(N,N-diethylacrylamide) hydrogel scaffolds for tissue engineering

Poly(N,N-diethylacrylamide) (PDEAAm) hydrogel scaffolds were prepared by radical copolymerization of N,N-diethylacrylamide (DEAAm), N,N'-methylenebisacrylamide and methacrylic acid in the presence of (NH₄)₂SO₄ or NaCl. The hydrogels were characterized by low-vacuum scanning electron microscopy in the water-swollen state, water and cyclohexane regain, and by mercury porosimetry. The pentapeptide, YIGSR-NH₂, was immobilized on the hydrogel. Human embryonic stem cells (hESCs) were cultured with the hydrogels to test their biocompatibility. The results suggest that the PDEAAm hydrogel scaffolds are nontoxic and support hESC attachment and proliferation, and that interconnected pores of the scaffolds are important for hESC cultivation. Immobilization of YIGSR-NH₂ pentapeptide on the PDEAAm surface improved both adhesion and growth of hESCs compared with the unmodified hydrogel. The YIGSR-NH₂-modified PDEAAm hydrogels may be a useful tool for tissue-engineering purposes.