[Experimental study on neural stem cell transplantation delaying denervated muscle atrophy]

To observe the delaying effect of neural stem cell (NSC) transplantation on denervated muscle atrophy after peripheral nerve injury, and to investigate its mechanism.

NSCs were separated from the spinal cords of green fluorescent protein (GFP) transgenic rats aged 12-14 days mechanically and were cultured and induced to differentiate in vitro. Thirty-two F344 rats, aged 2 months and weighed (180 +/- 20) g, were randomized into two groups (n=16 per group). The animal models of denervated musculus triceps surae were established by transecting right tibial nerve and common peroneal nerve 1.5 cm above the knee joints. In the experimental and the control group, 5 microL of GFP-NSC suspension and 5 microL of culture supernatant were injected into the distal stump of the tibial nerve, respectively. The general condition of rats after operation was observed. At 4 and 12 weeks postoperatively, the wet weight of right musculus triceps surae was measured, the HE staining, the Mallory trichrome staining and the postsynaptic membrane staining were adopted for the histological observation. Meanwhile, the section area of gastrocnemius fiber and the area of postsynaptic membrane were detected by image analysis software and statistical analysis.

The wounds in both groups of animals healed by first intension, no ulcer occurred in the right hind limbs. At 4 and 12 weeks postoperatively, the wet weight of right musculus triceps surae was (0.849 +/- 0.064) g and (0.596 +/- 0.047) g in the experimental group, respectively, and was (0.651 +/- 0.040) g and (0.298 +/- 0.016) g in the control group, respectively, showing a significant difference (P < 0.05). The fiber section area of the gastrocnemius was 72.55% +/- 8.12% and 58.96% +/- 6.07% in the experimental group, respectively, and was 50.23% +/- 4.76% and 33.63% +/- 4.41% in the control group, respectively. There were significant differences between them (P < 0.05). Mallory trichrome staining of muscle notified that there was more collagen fiber hyperplasia of denervated gastrocnemius in the control group than that in the experimental group at 4 and 12 weeks postoperatively. After 12 weeks of operation, the area of postsynaptic membrane in the experimental group was (137.29 +/- 29.14) microm2, which doubled that in the control group as (61.03 +/- 11.38) microm2 and was closer to that in normal postsynaptic membrane as (198.63 +/- 23.11) microm2, showing significant differences (P < 0.05).

The transplantation in vivo of allogenic embryonic spinal cord NSCs is capable of delaying denervated muscle atrophy and maintaining the normal appearance of postsynaptic membrane, providing a new approach to prevent and treat the denervated muscle atrophy clinically.