Amnion membrane which was derived from internal fetal membrane during normal delivery contained 5 layers[10-11]: epithelial cells consisting of cuboidal epithelium without cilium, basal lamina consisting of network structure below epithelial cells, tectum, fibroblast layer, and sponge layer. Vessel, nerve, and lymphatic system were not observed in those layers. Collagen fibers and fibroblasts were the major components, and the thickness ranged 0.02 to 0.50 mm. The layers characterizing by thin and clear could inhibit invasion of bacterium and actively transport substances, such as urea, glucose, and NaCl. They were similar to survival tissues by breaking away from human body for a short term. Therefore, the basic structure determined that that was the amnion membrane which had well permeability and histocompatibility. Following transplanting into peripheral tissue of tendon, local inflammatory reaction and foreign-body giant cell reaction were slight or even they generally disappeared. Smooth amnion membrane which was transplanted into peripheral tissue of tendon could inhibit adhesion between tendon and peripheral tissue. Histopathological observation, gross observation, or even optic microscope in this study demonstrated that amnion membrane was observed around tendon.
Amnion membrane characterizing by great bio-structure and permeability could not influence nutrition permeation but promote tendon healing[12]. Additionally, due to light rejection reaction, amnion membrane characterizing by thin surface could not influence repairing and healing of tendon tissue[13-16]. Pathological observation in this study demonstrated that fissures were observed around tendon tissue in the amnion membrane preserved in Honghua injection group and amnion membrane along group at 4 weeks after transplantation, while tendon did not adhere to peripheral tissues. Collagen fiber of tendon was arranged in order and smooth. The light rejection reaction possibly correlated to the gradual absorption of amnion membrane with the time prolonging, which was similar to symptoms within three or four weeks after healing on clinic. The experimental amnion membrane was gradually absorbed, and the newborn fissures were beneficial for tendon movement.
Honghua injection which was used to preserve amnion membrane still needs to be further studied[17-19]. Compendium of Materia Medica indicates that Honghua characterizes by promoting blood circulation, moisturizing dryness, relieving pain, reducing swelling, and restoring menstruation. Therefore, it plays an important role in promoting blood circulation by removing blood stasis. Modern studies demonstrate that Honghua injection acts as anti-inflammatory and anti-coagulation[8]. Amnion membrane belongs to placenta, i.e., a component of placenta hominis and can supply qi and invigorate blood circulation. Amnion membrane preserved in Honghua injection could inhibit proliferative quantity of fiber tissue and relieve adhesion. The effect was superior to positive control and blank control groups. The tendon was healed via promoting blood circulation by removing blood stasis, and supplying qi and invigorating blood circulation.
Results in this study demonstrated that the effect of amnion membrane preserved in Honghua injection on preventing adhesion and promoting healing was superior to that in the blank control and positive control groups. Amnion membrane preserved in Honghua injection is an ideal implant for preventing tendon adhesion.
In this study, hydroxyproline which was the major chemical composition synthesized by collagen during tendon healing was considered as the measurement indicator. The results demonstrated that hydroxyproline content of amnion membrane preserved in Honghua injection was significantly lower than positive control and blank control groups. Hydroxyproline content was decreased in the tendon tissue. This might correlate to hydroxyproline which inhibited collagen synthesis being transcribed into collagen, influencing collagen-induced platelet aggregation, preventing thrombosis, promoting thromboclasis[20-22], and making sure normal blood supplying. Biomechanics demonstrated that the effect of amnion membrane preserved in Honghua injection on tendon adhesion and proliferation of fiber tissue was superior to positive control and blank control groups. Tendon was able to move freely. Therefore, pathological changes were successfully proved.
In a word, results in this study combined with previous studies[23-30] demonstrated that amnion membrane preserved in Honghua injection could keep the integrality of tendinous sheath and promote tendon healing. Amnion membrane alone could also prevent tendon adhesion to a certain degree. The mechanisms on inhibiting transcription from hydroxyproline to collagen, influencing collagen-induced platelet aggregation, preventing thrombosis, and promoting thromboclasis need to be further studied in the future.
