Promotion of healing of Achilles tendon rupture (in vivo)
Tendons connect muscles and bones in the body. The most representative one is the "Achilles tendon" which connects the calf and the heel. The tendon consists of over 80 percent collagen fiber. When its collagen has been reduced by aging, the tendon has less elasticity and less flexibility and tends to be torn easily. Hence, we studied the effect of oral ingestion of CTP-containing collagen on a healing process of tendon rupture.
Test for promotion of healing of tendon rupture
1) Methods
Male SD rats at 7 weeks age were prepared and had their Achilles tendons torn. They were administered CTP-containing collagen with 0 and 80 mg/kg per day for 2weeks, 3 weeks and 4 weeks respectively since the next day of preparation. One day after the final administration, those Achilles tendons and their surroundings (bones and tendons) were removed and subjected to histological observation, tensile strength test, and measurement of hydroxyproline content (index of collagen quantity). In the tensile strength test and the measurement of hydroxyproline content, when the ratio (left/right) of measured values between a non-ruptured right Achilles tendon and a ruptured left Achilles tendon was closer to 1.0, we concluded that the ruptured left Achilles tendon had been recovered toward a normal healthy level.
2) Results
The tissue images around the Achilles tendon (typical examples) are shown in Figure 1. At the stage of 2 weeks, the "control" (0 mg/kg) group shows many inflammatory cells and a collapsed calcaneus which means it is in the early process of healing. In contrast, the image of the "CTP-containing collagen administration" (80 mg/kg) group shows few inflammatory cells and a nearly normal calcaneus which means it is in a higher and advanced healing level than the "control" group.
The result of the tensile strength test is shown in Figure 2. Regarding the breaking load of the ruptured left Achilles tendon at the stage of 2 weeks, the "control" group shows only about 30 percent of the normal value (measured against its non-ruptured right Achilles tendon), but the "CTP-containing collagen administration" group shows recovery up to about 70 percent of the normal value. The result of hydroxyproline content values as an index of collagen amount in the Achilles tendon is shown in Figure 3. It confirms that the "CTP-containing collagen administration" group has become significantly closer to the normal collagen amount in comparison with the "control" group.
Figure 1: Tissue images (typical examples)
Figure 2: Tensile strength
Figure 3: Hydroxyproline content
3) Discussion
In this study with the Achilles tendon ruptured model rats, we found that CTP-containing collagen promoted the effect on healing of tendon rupture. Therefore, we can expect that ingestion of CTP-containing collagen will greatly contribute to early recovery of tendon rupture of athletes.
