Biomedical subjects

Zhengrong Chen

Publications and source records attributed to Zhengrong Chen.

9 recordsLinked to original sources

PubMed2004

Ciliary neurotrophic factor for acceleration of peripheral nerve regeneration: an experimental study.

The objective of this study was to investigate the effect of topically administrated ciliary neurotrophic factor (CNTF) on peripheral nerve regeneration. Sixty-eight Sprague Dawley rats underwent a unilateral sciatic nerve transection and silicon tubulization, with a 10-mm gap between the proximal and distal nerve stumps. Recombinant human CNTF (1 mg/kg) was injected into the rats of the experimental group, while normal saline was injected into the control group animals. Electrophysiologic and histologic studies, including nerve morphometry and electron microscopic observation, were performed at 1, 3, and 4 months postoperatively. HRP tracing was carried out at 3 months postoperatively to label spinal-cord, ventral-horn, and dorsal-root ganglia. The results revealed that CNTF-treated animals showed a higher motor nerve conduction velocity of the sciatic nerve and a higher muscle action potential amplitude of the anterior tibial muscle, compared to the controls ( p < 0.01). Nerves repaired with CNTF had larger axon diameter, greater number of axons, and more advanced myelination ( p < 0.05). More HRP-labeled motor neurons were also found in the ventral horns of CNTF-treated animals. These results indicate that topical application of CNTF to the injury site potentiates motor nerve axonal regrowth and axon maturation during peripheral nerve regeneration.

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PubMed2003

Enhancement of rat sciatic nerve regeneration by fibronectin and laminin through a silicone chamber.

In this study, the authors examined the effects of fibronectin and laminin on sciatic nerve regeneration in rats. Sixty-eight Sprague-Dawley rats underwent bilateral sciatic nerve transections and silicone tubulizations, with a 10-mm gap between the proximal and distal nerve stumps. Thirty rats (n=30) received 10 microg of fibronectin injection into the right sciatic nerve chamber, while saline was injected into the left nerve chamber, serving as the control. Another 30 rats (n=30) were given 6 microg of laminin injection into the right nerve chambers and saline into the left chambers. At 1, 3, and 4 months postoperatively, electrophysiologic and histologic examinations, including nerve morphometry, were performed. Eight additional rats, receiving fibronectin (n=4) and laminin (n=4) injections, were used for horseradish peroxidase (HRP) tracing at 3 months postoperatively. Results from the study showed that fibronectin- and laminin-treated groups had significantly higher motor nerve conduction velocity and evoked muscle action potential amplitude of the anterior tibial muscle than the control group (p<0.01). Nerve diameter and the number of myelinated axons from the groups receiving fibronectin and laminin applications were greater than the controls (p<0.01). Also, a greater number of HRP-labeled motor neurons were found in the ventral horns and dorsal root ganglia of the fibronectin- and laminin-treatment groups compared to the controls. The authors conclude that local applications of fibronectin and laminin into the nerve chambers can significantly improve axonal regeneration and maturation of injured rat sciatic nerves.

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PubMed2002

Fabricating autologous tissue to engineer artificial nerve.

This study reports on the successful fabrication of artificial nerves with tissue engineering methods. Schwann cells were cultured for 2 weeks, seeded on polyglactin 910 scaffolds, and biomembrane-coated with rat-tail glue and laminin. Observation of the scaffolds' adsorptivity to Schwann cells, and of the growth and migration of Schwann cells, was made using a light microscope, and by scanning and transmission electron microscopy. The Schwann cells were able to migrate and proliferate on the polyglactin 910 fiber. Schwann cells were well-distributed, and formed a Büngner band on which the Schwann cells produced more matrices. Schwann cells on the biomembrane also grew well. We investigated the role of the tissue engineering conduit guide in vivo, using an established rabbit peripheral nerve regeneration model. At 8 weeks, axonal regeneration was observed in the distal nerve stump. Adult Schwann cells can be produced on the coated fiber and the biomembrane. Three-dimensional scaffolds with Schwann cells had the basic characteristics of the artificial nerve. These findings will provide a practical method for fabricating tissue-engineered artificial nerve to repair long nerve defects.

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PubMed2002

Autogenous venous graft with one-stage prepared Schwann cells as a conduit for repair of long segmental nerve defects.

The use of autogenous venous graft with intraluminal injection of Schwann cells to enhance nerve regeneration of long segmental nerve defects was evaluated in a rabbit tibial nerve-repair model. Schwann cells were isolated from the excised rabbit tibial nerve by using the polylysine differential adhesion method. The cultured cells were identified by immunocytochemical labeling for S-100 protein. Tibial nerve defects in 4-cm segments were created in 24 animals, which were then divided into three groups. In Group 1, the tibial nerve defect was repaired with interposition vein graft alone; in Group 2, the nerve defect was repaired with a vein graft with intraluminal injection of Schwann-cell suspension; in Group 3, the nerve defect was repaired by autogenous nerve graft alone. At 2 months postoperatively, electrophysiologic evaluation showed that an evoked muscle action potential was recorded for the animals in Group 2, with vein grafting plus Schwann cells, and for those in Group 3, with autogenous nerve grafting, but not for those in Group 1, where vein grafting alone was used. The average motor nerve conduction velocity in the group with vein grafting and Schwann cells was 3.4 +/- 1.5 m/sec, which was slower than the nerve grafting group (7.8 +/- 1.8 m/sec). Histologic analysis confirmed there was formation of new nerve fascicles with myelination in the vein graft filled with Schwann cells. No nerve regrowth was found in the vein grafts without Schwann cells. These results suggested that isolated Schwann cells are able to survive in a vein graft, and that the vein graft with intraluminal seeded Schwann cells could be an alternative for repairing injured nerves with long gaps.

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PubMed2002

To fabricate artificial nerves with tissue engineering methods.

OBJECTIVE: To fabricate artificial nerves with tissue engineering methods in vitro. METHODS: Schwann cells (SCs) were cultured and seeded on polyglactin 910 fibers wrapped by biomembrane coated with rat tail glue and laminin for 2 weeks. The absorbability on the scaffolds, growth and migration of SCs were assessed with a light microscope, a scanning electron microscope and a transmission electron microscope. RESULTS: SCs could migrate and proliferate on polyglactin 910 fibers. They were well distributed between scaffolds and absorbed on surface of scaffolds and formed a bungner band, on which SCs produced more matrices. SCs seeded on the biomembrane could also grow well. Axon regeneration in the distal nerve stump was observed at 8 weeks. CONCLUSIONS: Adult SCs can be expanded on coated fibers and biomembrane. Three-dimensional scaffold of SCs has the basic characteristics of artificial nerves. These findings offer a novel method to fabricate artificial nerves with tissue engineering methods for repairing defected long nerves.

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PubMed2002

Recombinant human heparin-binding neurite-promoting factor expressed with yeast stimulates neurites outgrowth.

OBJECTIVES: Heparin-binding neurite-promoting factor (HBNF) is a heparin-binding protein primarily found in the brain, which can stimulate neurite outgrowth in vitro. We expressed recombinant human heparin-binding neurite-promoting factor (hrHBNF) using a yeast system, and observed its activity in stimulating neurite outgrowth in vitro. METHODS: cDNA encoding mature human HBNF was amplified from total RNA isolated from an 18-week aborted human fetal brain by RT-PCR method. After amplification, the HBNF cDNA gene was cloned into pPIC9K, a shuttle expression vector for yeast system. The positive clone of expression vector bearing HBNF cDNA gene was obtained by screening. Verified recombinant vector was then used to transform Pichia strain GS115 by electroporation. His(+) transformants were selected on minimal dextrose medium (MD) plates which were histidine free. His(+) yeast recombinants with multi-copy inserts were screened in vivo by their resistance to G418. PCR analysis was used to confirm the integration of the HBNF cDNA gene into the Pichia genome. Secreted expression of hrHBNF protein in culture medium was obtained when the positive clone containing the HBNF cDNA gene was induced by methanol. The hrHBNF product purified by gel chromatography was added to cultured rat pheochromocytoma (PC12) cells to observe its ability to stimulate neurite outgrowth. RESULTS: In the recombinant expression vector, the insert was sequenced to show exactly the sequence encoding human HBNF according to Genbank data. The HBNF cDNA gene was cloned downstream to the alpha-factor, and its open reading frame was in frame with the alpha-factor signal sequence in pPIC9K. SDS-PAGE showed that the molecular weight of the induced expression product was about 18 kDa, consistent with that of human HBNF reported in the literature. The protein product did promote neurite outgrowth in cultured rat pheochromocytoma (PC12) cells. CONCLUSION: Recombinant human heparin-binding neurite-promoting factor can be expressed with a yeast system, and its product possesses the biological activity to promote neurite outgrowth.

Animals↗

PubMed2002

Progress of peripheral nerve repair.

Study on repair of peripheral nerve injury has been proceeding over a long period of time. With the use of microsurgery technique since 1960s the quality of nerve repair has been greatly improved. In the past 40 years, with the continuous increase of surgical repair methods, more progress has been made on the basic research of peripheral nerve repair.

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PubMed2000

Modulation of nitric oxide synthase isoenzymes in reperfused skeletal muscle.

OBJECTIVE: To investigate the modulation of nitric oxide synthase (NOS) isoenzymes in skeletal muscle during 3 h ischemia/reperfusion (I/R, 3 h ischemia followed by 3 h reperfusion). METHODS: The extensor digitorum longuses (EDLs) from 20 adult rats were divided into 4 groups: the normal, the sham operation, the ischemia (3 h), and the ischemia/reperfusion group. One normal EDL from each rat was used as the non-operated control, and the opposite ones are distributed into the 3 remaining groups. All the samples were studied with Western blotting technique and immunohistochemistry staining. RESULTS: Three sizes of protein bands verified with the proteins of relative molecule to be of 155000, 140000 and 135000, were detected in the EDL homogenate by Western blotting, which were comparable with the positive controls for nNOS, eNOS and iNOS, respectively. Immunostaining demonstrated that nNOS was present in the muscle fiber, with a similar location of the muscle stria, eNOS was found apparently in microvascular endothelia, but not found in muscle fibers, and iNOS was found in the leukocytes around the muscle fiber and some endothelia cells. Immunostaining paralleled the Western blotting results. CONCLUSIONS: It suggests that the constitutive nNOS and eNOS protein can be regulated by I/R, and I/R results in a down regulation of nNOS and up-regulation of eNOS and iNOS in reperfused skeletal muscle. The fact that nNOS is present around stria suggests that nNOS may have a close relationship with muscle function. The localization of eNOS in endothelial cell indicates its role in regulating blood supply of the muscle. Based on these findings, it is possible that NO produced by distinct NOS may play a different role in I/R injury.

Journal Article↗

PubMed2000

Electronic artificial hand controlled by reconstructed digit.

OBJECTIVE: To treat the loss of part of the forearm with a multi-dimension-freedom electronic artificial hand, which is controlled by a reconstructed finger transplanted from the second toe to the forearm stump. METHODS: The female patient was 19 years old, whose right hand and wrist were crushed into pieces by machine at work and her forearm was amputated at the level of 8 cm proximal to the wrist. The second toe of her left foot was transplanted to reconstruct the digit onto the stump of her forearm. Two months after the transplantation, the patient was transferred to the rehabilitation center for further rehabilitation training, which consisted of: training for adaptation to weight bearing, testing and training of sensibility to weight. testing and training for stability of the hand, and testing and training for the controlling function of the reconstructed digit. RESULTS: The transplanted toe survived well. After rehabilitation the reconstructed digit functioned well. In testing the performance under control mandate, the accuracy rate of the electronic artificial hand was 100%. CONCLUSIONS: A 100% accuracy rate of the electronic artificial hand can be achieved by transplantation of the toe onto the stump of the forearm. It provides a useful pathway and an example for improvement of control accuracy of a multiple-freedom electronic artificial hand and reduction of false action.

Journal Article↗