Tissue engineering technologies offer new treatment strategies for the repair of peripheral nerve injury, but cell loss between seeding and adhesion to the scaffold remains inevitable. A thermo-sensitive collagen hydrogel was used as an extracellular matrix in this study and combined with bone marrow mesenchymal stem cells to construct tissue-engineered peripheral nerve compos-ites in vitro. Dynamic culture was performed at an oscillating frequency of 0.5 Hz and 35° swing angle above and below the horizontal plane. The results demonstrated that bone marrow mesen-chymal stem cells formed membrane-like structures around the poly-L-lactic acid scaffolds and exhibited regular alignment on the composite surface. Collagen was used to ifll in the pores, and seeded cells adhered onto the poly-L-lactic acid ifbers. The DNA content of the bone marrow mesenchymal stem cells was higher in the composites constructed with a thermosensitive colla-gen hydrogel compared with that in collagen I scaffold controls. The cellular DNA content was also higher in the thermosensitive collagen hydrogel composites constructed with the thermo-sensitive collagen hydrogel in dynamic culture than that in static culture. These results indicate that tissue-engineered composites formed with thermosensitive collagen hydrogel in dynamic culture can maintain larger numbers of seeded cells by avoiding cell loss during the initial adhe-sion stage. Moreover, seeded cells were distributed throughout the material.

In this study, we constructed tissue-engineered nerves with acel ular nerve al ografts in Sprague-Dawley rats, which were prepared using chemical detergents-enzymatic digestion and mechanical methods, in combination with bone marrow mesenchymal stem cel s of Wistar rats cultured in vitro, to repair 15 mm sciatic bone defects in Wistar rats. At postoperative 12 weeks, electrophysiological detection results showed that the conduction velocity of regenerated nerve after repair with tis-sue-engineered nerves was similar to that after autologous nerve grafting, and was higher than that after repair with acel ular nerve al ografts. Immunohistochemical staining revealed that motor endplates with acetylcholinesterase-positive nerve fibers were orderly arranged in the middle and superior parts of the gastrocnemius muscle;regenerated nerve tracts and sprouted branches were connected with motor endplates, as shown by acetylcholinesterase histochemistry combined with silver staining. The wet weight ratio of the tibialis anterior muscle at the affected contralateral hind limb was similar to the sciatic nerve after repair with autologous nerve grafts, and higher than that after repair with acel ular nerve al ografts. The hind limb motor function at the affected side was significantly improved, indicating that acel ular nerve al ografts combined with bone marrow me-senchymal stem cel bridging could promote functional recovery of rats with sciatic nerve defects.