This protocol describes a simple device that mimics Ding’s roll method, establishes a rat model of skeletal muscle injury, and uses hematoxylin-eosin staining to observe the pathology of damaged tissue and enzyme-linked immunosorbent assay to detect changes in serum damage markers.
Ding’s roll method is one of the most commonly used manipulations in traditional Chinese massage (Tuina) clinics and one of the most influential contemporary Tuina manipulations in China. It is based on the traditional rolling method commonly used in the one finger Zen genre and named Ding’s roll method. Due to its anti-inflammatory and blood circulation-promoting effects, Ding’s rolling method has sound therapeutic effects on myopathy. Because of the large area of force applied to human skin, Ding’s roll method is challenging to perform on experimental animals with small skin areas, such as rats and rabbits. Additionally, the strength of Tuina applied to the human body differs from that applied to experimental animals, so it may happen that the strength is too high or too low to achieve the therapeutic effect of Tuina during the experiment. This experiment aims to create a simple massager suitable for rats based on Ding’s rolling manipulation parameters (strength, frequency, Tuina duration). The device can standardize manipulation in animal experiments and reduce the variation in Tuina force applied to different animals due to subjective factors. A rat model of notexin-induced skeletal muscle injury was established, and plasma injury markers creatine kinase (CK) and fatty acid binding protein 3 (FABP3) were used to assess the therapeutic effect of Tuina on skeletal muscle injury. The results showed that this Tuina massager could reduce the levels of CK and FABP3 expression and slow down the degree of skeletal muscle injury. Therefore, the Tuina massager described here, mimicking Ding’s roll method, contributes to standardizing Tuina manipulation in experimental research and is of great help for subsequent research on the molecular mechanism of Tuina for myopathy.
Muscle injuries are common traumatic injuries in clinical and daily life, caused by external blows (contusions) or chronic overstrain of muscle fibers (strains), etc., resulting in muscle dysfunction and pain, even seriously affecting the patient's quality of life1. Starting rehabilitation as early as possible after an acute strain injury is the key to reducing the time to return to sports2 and in reducing pain3,4. In modern Western medicine, clinical first aid for muscle injuries follows the principles of rest, ice, compression, and elevation (RICE) to stop injurious bleeding into the muscle tissue5 and non-steroidal anti-inflammatory drugs to relieve pain6. The discovery of novel therapies such as exosomes7 and tissue engineering8 became potential treatment strategies for skeletal muscle diseases, compensating for previous pharmacological treatments' shortcomings. However, it can also increase the cost of treatment for patients, putting them under tremendous financial pressure9. Therefore, alternative and complementary therapies are recommended for treating musculoskeletal problems10. Tuina is widely used clinically in China as a traditional medical method and is popular among patients for its efficacy and fewer side effects. Tuina therapy for musculoskeletal disorders can alleviate pain and improve function11,12,13. Mr. Ding Jifeng, a famous Shanghai Tuina practitioner, founded Ding's roll method14. It is a unique rolling and crushing technique with a large force area, uniform and gentle force, and intense penetration.
Different animal models are based on different etiologies. They have advantages and disadvantages, and the selection of correct and appropriate animal models is of great significance to basic experiments, which helps understand the cellular and molecular signaling pathways of regeneration and repair after skeletal muscle injury to develop new therapies for treating the treatment of skeletal muscle diseases. Chemically induced models of muscle injury are widely used, with injections of skeletal muscle causing myofiber necrosis and producing regenerated areas that can effectively regenerate within 2 weeks15. Both notexin and bupivacaine can cause muscle damage. However, notexin can cause more severe myotoxic damage to skeletal muscle than bupivacaine, and natural functional recovery is relatively slower16. Drug intramuscular injection molding not only takes less time but also has controlled effects and extent of skeletal muscle damage. This quantifiable control makes successful molding less difficult15,17.
Inflammatory response is an essential biological response that has been extensively studied in the context of myopathy18,19. In the early stages of skeletal muscle injury, myofiber necrosis disrupts local muscle homeostasis, and many inflammatory cells infiltrate the injury site, secreting many pro-inflammatory cytokines19. Creatine kinase (CK) is a traditional serum biomarker for assessing skeletal muscle injury. However, it lacks tissue specificity20 and sensitivity21, which limits its ability to assess the extent of drug-induced muscle damage and indirectly report the extent of muscle recovery after injury. Novel biomarkers, including fatty acid binding protein 3 (FABP3), have recently shown relatively high tissue specificity and sensitivity in rodent models of skeletal muscle injury. FABP3 is a family of binding proteins expressed primarily in cardiac and skeletal muscle cells and implicated in fatty acid metabolism, transport, and signaling22. Therefore, we chose a combination of two biomarkers, CK and FABP3, to assess the extent of notexin-induced skeletal muscle damage and recovery after treatment.
In rodents, the muscles are shallow, and the skin area is small, which also determines that the various parameters of massage in rodents will not be the same as in humans, such as in animal therapy, the massage therapist should treat them with less force using Ding's roll method, and may not be conducive to the operation of this technique due to the small size of the injured area, which can ultimately lead to a reduction in the effectiveness of the massage. Therefore, the experiment utilized the rolling massager made in-house, which conforms to the characteristics of Ding's roll method, to intervene and evaluate the therapeutic effect of the notexin-induced skeletal muscle injury model in rats, which helps to standardize the parameters of Tuina in experimental animal studies in order to profoundly investigate the molecular mechanism of action of Tuina, a traditional Chinese medicine treatment method, on musculoskeletal diseases.
Procedures involving animals have been approved by the Institutional Care and Use Committee at Hunan University of Chinese Medicine.
1. Assembly of the rolling massager
2. Establishment of a rat model of skeletal muscle injury
3. Tuina therapy
4. Collecting blood and tissues from rats after the experiment
5. Detection of plasma CK and FABP 3 levels by ELISA
6. Histological analysis of notexin-induced gastrocnemius muscle injury in rats
7. Image processing and data analysis
In order to observe the morphological properties of rat skeletal muscle after injury, the gastrocnemius muscle was stained with hematoxylin and eosin, and the stained images were read with an analysis software as described in the protocol for 8 rats per group. In rats with gastrocnemius muscle injury induced by notexin (NTX group), many muscle cells were ruptured, atrophic, necrotic, and irregularly arranged. There was also a high infiltration of neutrophils and lymphocytes around the affected area (Figure 4B). However, after Tuina treatment with the rolling massager, the pathological condition of muscle cells in the NTX+Tuina group improved, with fewer ruptured, atrophic, and necrotic cells, and only a small number of inflammatory cells infiltrating as compared to the NTX group (Figure 4C). In the control group, the muscle cells of rats were evenly sized, closely arranged, and without inflammatory cell infiltration (Figure 4A).
To further confirm the therapeutic effect of Tuina on gastrocnemius injury in rats utilizing Ding's rolling massager, we used ELISA to detect the levels of skeletal muscle injury markers CK and FABP3 for 8 rats per group. Compared with the control group, CK and FABP3 levels were significantly increased in the NTX group, and both CK and FABP3 levels were markedly decreased in the NTX+Tuina group compared with the NTX group (Figure 5). These results suggest that injection of notexin caused severe damage to the gastrocnemius muscle in rats, while Tuina can reduce this damage.
Figure 1: Rolling massager physical map. It mainly comprises a rubber roller, fork holder, spring, limit baffle, adjustment splint, screw, and acrylic handle. Scale bar = 1 cm. Please click here to view a larger version of this figure.
Figure 2: Rolling massager force measurement. The maximum pressure of forward rolling is 0.3 N, and the minimum pressure is about 0.08 N when rolling back. Please click here to view a larger version of this figure.
Figure 3: Tuina therapy using rolling massager. Place the roller on the gastrocnemius muscle of the rat and roll forward until the spring contacts the limit baffle, then retract the force and return to its original position, thereby reciprocating the movement. Please click here to view a larger version of this figure.
Figure 4: Representative images of HE-stained cross-section of rat gastrocnemius muscle. (A) The gastrocnemius muscle of the control (C) group rats was not injured significantly after saline injection. (B) Notexin injection into the gastrocnemius muscle of rats in the notexin (NTX) group caused severe muscle injury, resulting in myocyte atrophy, necrosis, and varying sizes, accompanied by a massive infiltration of neutrophils and lymphocytes. (C) The gastrocnemius muscle injury was attenuated in the notexin and Tuina (NTX+Tuina) group of rats, and the number of atrophic and necrotic myocytes, neutrophils, and lymphocytes were reduced. Scale bar = 100 µm. Please click here to view a larger version of this figure.
Figure 5: CK and FABP3 expression. Plasma was harvested after the completion of Tuina, and the concentrations of CK and FABP3 in the plasma of rats in control (C), notexin (NTX), and notexin and Tuina (NTX+Tuina) were detected by ELISA. *P < 0.05, **P < 0.01 using one-way ANOVA with post-hoc LSD test. Values are mean ± SEM, n=8 in all groups. Please click here to view a larger version of this figure.
Here, we described a protocol for Tuina treatment of skeletal muscle injury in rats and then analyzed the degree of skeletal muscle injury after treatment to verify the effectiveness of the method. Notably, rat skeletal muscle injury models, including but not limited to drug induction (notexin, bupivacaine)16, blunt contusion26, crush27, and ischemia-reperfusion28, can be intervened with Tuina. Through HE staining to observe the histopathological changes and ELISA detection to determine the markers of skeletal muscle damage, it is intuitively shown that the notexin causes severe damage to the gastrocnemius muscle of rats, while the massager simulating the Ding’s roll method can reduce the muscle damage. These provide convincing evidence for the effectiveness of Tuina in treating skeletal muscle injuries.
There are several necessary procedures that should be considered when performing Tuina on rats mimicking Ding’s roll method. Before the treatment, the Tuina operator should be trained in advance to use the rolling massager at least 3x, to adjust the angle of the baffle with the assistance of the pressure sensor for proper force control, and to control the frequency of Tuina at 140 rolls/min. Meanwhile, keep the rats quiet by covering their heads with a black bandana without being unduly tight to ensure they can breathe freely. If the rat suddenly struggles to be active in the Tuina process, wait until it is quiet before continuing the Tuina.
The limitation of this experiment is that this massager is suitable for rats rather than smaller animals, such as mice. For animals other than rats, some instrument configurations can be changed. Such as the size of the rollers, the angle of the baffle, the strength of the spring, and naturally, the pressure sensor needs to be used to test the rolling force. We have only made a Tuina massager simulating Ding’s roll method here. However, as a non-pharmacological therapy of traditional Chinese medicine, there are various Tuina manipulations, such as pushing, moistening, pressing, and kneading. All these manipulations can be made according to the operating parameters of relevant famous Tuina masters to produce an instrument more suitable for animal research to standardize the experimental operation and allow the experimental results to be more accurate and credible.
In conclusion, we provide a detailed description of the manufacturing method of the rolling massager that effectively simulates Ding’s roll method during animal experiments. The massager has significant therapeutic efficacy on skeletal muscle injury in rats and lays the foundation for further research on the standardization of Tuina.
The authors have nothing to disclose.
This research was supported by grants from the National Natural Science Foundation of China (Grant Nos.82174521), Innovation Project for Graduate Students of Hunan University of Chinese Medicine(2022CX109)
1 mL syringe | JIANGXI FENGLIN | 20220521 | |
1.5 microtubes | Servicebio | EP-150X-J | |
15 mL centrifuge tube | Servicebio | EP-1501-J | |
30G needle | CONPUVON | 220318 | |
5 mL blood collection tube | Servicebio | QX0023 | |
Acrylic handle | Guangdong Guangxingwang Plastic Materials Co., Ltd | 65643645 | |
Adjustment splint | CREROMEM | 20220729 | |
Cotton Swab | INOHV | 22080215 | |
Enzyme-labeled Instrument | Rayto | RT-6100 | |
Ethanol | INOHV | 211106 | |
Fork holder | Yongkang Kangzhe Health Technology Co., Ltd | JL001 | |
Hair removal cream | Veet, France | LOTC190922002 | |
Hematoxylin dyeing solution set | Wuhan Google Biotech | G1005 | |
Imaging system | Nikon, Japan | Nikon DS-U3 | |
IODOPHOR disfecting solution | Hale&Hearty | 20221205 | |
Light microscope | Nikon, Japan | Nikon Eclipse E100 | |
Limit baffle | CREROMEM | 20220724 | |
Notexin | Latoxan S.A.S. | L8104-100UG | |
Pentobarbital sodium | Merck KGaA | P3761 | |
Rat creatine kinase (CK) ELISA kit | LunChangShuoBiotech | YD-35237 | |
Rat fatty acid-binding protein 3 (FABP3) ELISA kit | LunChangShuoBiotech | YD-35730 | |
Rubber roller | Hebei Mgkui Chemical Technology Co.,Ltd | 202207 | |
Screw | Weiyan Hardware | B05Z122 | |
Sprague Dawley rats | Hunan Slake Kingda Laboratory Animal Co. | SYXK2019-0009 | |
Spring | Bingzhang Hardware | TH001 | |
Surgical blade | Covetrus | #23 | |
Weigh controller | Iyoys | HY-XSQ |