| 摘要: | 背景
周邊神經損傷在臨床上仍然是一個相當重要的問題，雖然在過去幾年之中，外科技術已有明顯進步，但是神經嚴重損傷之後功能的恢復，仍然不完全且令人不滿意，所以當斷裂的神經間隙太大時，就必須使用神經移植術或神經管接合術治療。神經移植術除了神經移植段不易取得和易有疤痕及神經瘤的形成外，同時在取得神經移植段時可能導致其他部位功能的損壞，此時神經管接合術不失為好的替代方式。神經管接合術是將神經兩個斷端以手術方法縫合於一圓管的兩端，並利用此圓管來導引及支持再生神經纖維成長，其優點是可以減少神經疤痕組織的形成及導引再生神經生長正確的方向。
方法
在本實驗中，四十隻老鼠被隨機分成四組，每組有十隻老鼠。以手術方式將其右側坐骨神經截斷並接上10 mm間距的神經管，然後每一個神經管内分別裝填不同濃度的黃耆(0,1.25,12.5,125 mg/ml)。術後八星期，再次將老鼠手術使其右側坐骨神經曝露，並進行電生理檢測，之後再取出含有再生神經組織之神經管，將再生神經組織經過處理切片後，於顯微鏡下觀看神經再生情形。
結果
經過八周的包埋，神經管在老鼠體內維持原來的形狀及位置。在電生理檢測方面，當黃耆在濃度12.5 mg/ml時，其動作電位中的振幅明顯優於其他各組，尤其黃耆濃度12.5 mg/ml和1.25 mg/ml兩組做比較時，達統計上顯著差異(P<0.05)。在顯微鏡下，當黃耆在濃度12.5 mg/ml時，擁有較多數目的再生神經軸突，且黃耆濃度12.5 mg/ml和對照組做比較時，也有統計上顯著差異(P<0.05)。
結論
傳統上，神經斷傷若間距過大時，自體神經移植是一個很好的選擇，但是我們希望藉由黃耆與神經管的作用，提供神經更好的再生與生長方向。在本實驗中，當黃耆在濃度12.5 mg/ml時，明顯可促進神經再生，此結果可提供未來組織工程上生醫材料選材之參考。至於黃耆對神經再生的機轉，目前似乎沒有直接證據，但許多研究已經證實黃耆有促進免疫的功能，是否藉由巨噬細胞來改變神經生長環境而間接促進神經再生，是未來研究的方向。
BACKGROUND
Peripheral nerve injuries still represent a problem of considerable clinical importance. The most significant peripheral nerve injuries are those that result in a gap in nerve continuity. Although enormous progress has been made in surgical techniques over the past three decades, functional recovery after a severe lesion is often incomplete and sometimes unsatisfactory. When the nerve tissue defect is extensive, nerve graft or nerve bridge may be considered. Complications associated with nerve graft include difficult to obtain the nerve transplant section, scar and neuroma formation, and donor site morbidity. A nerve bridge which connect both ends of injured nerve stumps can offer the advantages of minimizing invasion and scarring of the nerve, aiding guidance of growing fibers along appropriate paths.
METHODS
In this study, the right sciatic nerves of 40 rats which were randomly assigned to one of the four groups were used to evaluate peripheral nerve regeneration across a 10 mm gap, using a silicone rubber nerve guide filled with different concentrations of Radix Astragali (0, 1.25, 12.5, 125 mg/ml). At the end of eighth weeks, the sciatic nerves were reexposed and electrophysiological analyses were performed. After electrophysiological recordings, the sciatic nerves, including the repaired segments were removed from all groups for counting of the myelinated axons with a stereological method.
RESULTS
At eighth weeks after implantation, the conduit persisted maintaining its shape and location in the animal. The peak amplitude under the muscle action potential showed an increase on the group of Radix Astragali at 12.5 mg/ml. Specifically, the difference of the peak amplitude between the two groups which concentrations of Radix Astragali at 12.5 mg/ml and 1.25 mg/ml reached a significant level of p < 0.05. Besides, the group of Radix Astragali at 12.5 mg/ml had a relatively mature structure composed of numerous myelinated axons. The differences of the axon number between the two groups which concentrations of Radix Astragali at 12.5 mg/ml and normal saline reached a significant level of p < 0.05.
DISCUSSION
Our aim is to improve the efficacy of a conventional autograft, with better axonal orientation and regeneration, by combining Radix Astragali and silicone conduit graft. In the present study, use of Radix Astragali in silicone rubber chamber shows that significantly promoted peripheral nerve regeneration across a gap at the concentration of 12.5 mg/ml. The mechanism of Radix Astragali to the peripheral nerve regeneration is unclear. The Radix Astragali can enhance the function of immune system, specifically the macrophages. Macrophages have been considered a vital role in the peripheral nerve regeneration. This will provide the futurology direction. |
