Vascular remodeling occurs in atherosclerosis, hypertension, and restenosis after percutaneous coronary intervention. Adventitial remodeling may be a potential therapeutic target. Yiqihuoxuejiedu formula uses therapeutic principles from Chinese medicine to supplement Qi, activate blood circulation, and resolve toxin and it has been shown to inhibit vascular stenosis. To investigate effects and mechanisms of the formula on inhibiting vascular remodeling, especially adventitial remodeling, rats with a balloon injury to their common carotid artery were used and were treated for 7 or 28 days after injury. The adventitial area and
Vascular remodeling occurs in a variety of diseases such as atherosclerosis, hypertension, and restenosis after PCI. Although these diseases have different causes, they ultimately lead to common pathological changes such as vascular remodeling, which results from and causes pathology in these diseases. Vascular remodeling results from activation, proliferation and migration of cells in the vessel wall, and extracellular matrix synthesis and degradation. Vascular smooth muscle cells (VSMC) in the media have been considered the core of vascular remodeling [
MF was first discovered in wound healing through electron microscopy. The evidence indicates that MF plays a pivotal role in tissue repair and remodeling and is also a key player in pathological conditions such as hypertrophic scars and organ fibrosis. Professor Jiazhen Liao, a famous cardiovascular disease expert on integrated Chinese and western medicine from China’s first generation, gets his inspiration from the surgical wound repair and thinks that the process of vascular remodeling after balloon injury, including thrombosis, inflammatory cell infiltration, and local tissue excessive repair that eventually leads to restenosis, is similar to the pathology of surgical wound repair. He used the wound repair idea and Chinese medicine therapeutic principles of supplementing Qi, activating blood circulation, and detoxifying to develop Yiqihuoxuejiedu formula. The formula is composed of Radix Astragali, Radix Salviae Miltiorrhizae, Flos Lonicerae, Cortex Moutan, and others. Clinical and basic researches, conducted for over 10 years, indicate that the Yiqihuoxuejiedu formula significantly inhibits vascular hyperplasia, lowers blood lipids [
According to 2011’s PCI guideline [
Normal male Sprague-Dawley (SD) rats were purchased from the Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences, Beijing, China. SD rats were raised in a specific pathogen free environment at a room temperature of 22°C to 24°C, 40%–50% relative humidity, and a 12-hour light/dark cycle. Procedures were performed in accordance with the National Institute of Health’s Guide for the Use and Care of Laboratory Animals and were approved by the Committee on Animal Care and Use of the Dongzhimen Hospital. SD rats weighing 380–450 g (
A rat model of the common carotid artery after balloon injury was established to evaluate the vascular remodeling. Sodium pentobarbital 1% (40 mg/kg) was intraperitoneally injected to anaesthetize the rats. The left common carotid artery was isolated through a midline cervical incision to expose a 3 cm segment of the artery from the bifurcation and a 2F Fogarty balloon catheter (diameter of balloon 2 mm and length 20 mm, Baxter Company) was introduced through the left external carotid artery and advanced 4 cm towards the thoracic aorta with the left internal carotid artery blocked. The balloon was inflated with isotonic Na chloride (NS) at 0.5 atm to 0.6 atm to distend the artery and was then pulled back to the bifurcation with constant rotation. This procedure was repeated three times to ensure endothelial denudation and consistent vascular injury. After removing the catheter, the external carotid artery was ligated, the blood flow in the internal carotid artery was restored, the wound closed, and animals were allowed to recover. The external carotid artery of sham operated animal was ligated and common carotid artery was not exposed to balloon injury. Rats were sacrificed and both carotid arteries were collected at 7 or 28 days after balloon injury.
Yiqihuoxuejiedu formula was composed of ingredients such as
After balloon injury, rats were randomly divided into 3 groups of 10 rats each: the model group, Captopril group, and Yiqihuoxuejiedu formula group. The sham operated group served as a control. The dosages of Captopril and Yiqihuoxuejiedu formula, which are based on the clinical daily dosages for adult humans with a dose conversion coefficient, were the following: Yiqihuoxuejiedu formula group: 13.368 g/kg/d (corresponding with 12 times the clinical dosages), Captopril group: 12.857 mg/kg/d (12 times clinical dosages). In addition, Acenterine (17.143 mg/kg/d, 6 times) and Pravastatin sodium (1.714 mg/kg/d, 12 times) were used for basic medicine for the Captopril and Yiqihuoxuejiedu groups. Sham operated and model groups received distilled water, 10 mL/kg/d. Medicine was dissolved in distilled water and rats were administered the medicine using a gastric lavage once daily for 7 or 28 days.
At 7 or 28 days after balloon injury, animals were euthanized under terminal anaesthesia by exsanguination and retrograde aortic perfusion with 200 mL saline followed by 250 mL saline containing formalin (2% v/v) and glutaraldehyde (0.2% v/v) to fix the tissues before careful excision of the left common carotid artery to avoid any damage to the adventitial layer. The left common carotid arteries were fixed for 24 hours. The slices were stained with Sirius Red and Masson stains as well as haematoxylin and eosin following routine paraffin sections. The expression of smooth muscle
The complete cross sections of the left common carotid artery were photographed with a low power lens following haematoxylin and eosin stains to measure and calculate remodeling index including the area of intima, tunica media, and adventitia, as well as stenosis percentage: [(left lumen area around the internal elastic lamina−left narrow lumen area)/left lumen area around the internal elastic lamina] * 100%.
Three typical and discrete fields were photographed with high powered lens after immunohistochemical staining.
Statistical analyses were performed using SPSS 11.0 statistics software. The measurement data were presented as the mean ± standard deviation. One-way analysis of variance (ANOVA) followed by Dunnett’s test was used to determine the differences among groups.
At 7 days after injury, the areas of neointima and adventitia in the model group and two treatment groups were larger than those of the sham group (
(a) Vessel wall area at 7 days after injury; (b) vessel wall area at 28 days after injury (*
Left common carotid artery slices stained with HE at 7 days after injury. (a) Sham group, (b) model group, (c) Captopril group, and (d) Yiqihuoxuejiedu group.
The areas of neointima and of the whole vessel wall were increased in the model group compared with the sham group (
At 28 days after injury, the percent stenosis in the model group and two treatment groups increased compared with the sham group (
Percentage of arterial stenosis at 28 days after injury (*
Positive
(a)
Twenty-eight days after balloon injury,
A large amount of collagen, observed using Masson staining, accumulated in the vessel wall of the model group compared with the sham group (
Percent collagen content percent in the vessel wall at 28 days after injury (**
Rats of the model group obviously increased in the ratio of type I/type III collagen in the adventitia compared with rats in the sham group (
Ratio of type I/type III collagen in the adventitia at 28 days after injury. (*
Representative images of adventitia at 28 days after injury (Sirius Red staining ×400). Type I collagen closely spaced and showed strong double refraction, yellow or red fibers. Type III collagen showed weak double refraction, greenish fine fibers. (a) Sham group, (b) model group, (c) Captopril group, and (d) Yiqihuoxuejiedu group.
There are three types of pathological changes in vascular remodeling: vascular structure, cell biology, and function. Structural remodeling refers to transformation of vessel lumen and thickness or area of the vessel wall. Cell biology changes mean that cells in the vascular wall activate, proliferate, migrate, and secrete extracellular matrix (ECM), and the function variation refers to reduced vascular compliance and the reaction to vasoactive substances.
Vascular remodeling is also divided into positive remodeling and negative remodeling. The positive remodeling, also known as compensatory or expansion remodeling, has a compensatory vessel enlargement and relatively sustained changes to the lumen to maintain a constant flow despite an increased plaque burden [
Various pathological stimuli (e.g., stretch injury from a balloon angioplasty or endothelial lesion) can induce adventitial fibroblasts differentiation into myofibroblasts (MF, a key player in wound healing and a slow, irreversible retraction [
The vascular remodeling mechanism of the formula still requires more research. The present study focuses on the proliferation, activation, and secretion of adventitial fibroblasts following balloon injury and aims to provide experimental evidence on the adventitia. A rat model was established by injuring the common carotid artery, and rats were treated with Yiqihuoxuejiedu formula for 7 or 28 days. At 7 days after injury, the area and
In this study, Captopril did not reduce neointimal proliferation or diminish stenosis, although it reduced
Thus, Yiqihuoxuejiedu formula inhibits positive and negative remodeling by reducing hyperplasia in the adventitia in the early stages and suppresses intimal proliferation, reduces the vessel wall content, and elevates adventitial compliance in the later stages. Inhibiting proliferation and secretion of adventitial fibroblasts is characteristic of the formula. This study suggests new information and a new, complementary method for alternative treatment in the prevention of vascular remodeling, which contributes to further improving atherosclerosis, hypertension, and restenosis after PCI.
The authors declare that they have no conflict of interests.
Ming-Jing Zhao, Ai-Ming Wu, Jie Wang, and Hong Chang contributed equally to this work.
This paper was supported by the National Natural Science Foundation Project of China (no. 30672689).