Protocol for the observation of the primo vascular system in the lymph vessels of rabbits

The involvement of the primo vascular system in local enteritis and its modification by electroacupuncture

Introduction

The primo vascular system (PVS), an intensive network structure, has been claimed to be representative of the acupuncture meridian. Here, we explored the role of the PVS in local enteritis and its modification by acupuncture.

Methods

Chronic cecitis in rabbits was induced by 2,4,6-trinitro-benzene-sulfonic acid (TNBS). The PVS on the cecum was visualized with trypan blue staining, and collected with the help of microsurgical forceps under an optical stereomicroscope.

Results

The increased primo vessels (PVs) and primo nodes (PNs) of the PVS on the surface of the cecum were induced by local inflammation, which was positively correlated with the inflammatory cells in the cecal mucosa. Tandem mass tag (TMT) based proteomic analysis revealed that 110 differentiated proteins of the PVS existed between TNBS-treated and control rabbits; 65 proteins were upregulated, while 45 proteins were downregulated. These proteins were mainly enriched in inflammation- and immunity-related processes, such as inflammatory cell proliferation, antigen presentation, and cell adhesion in the proliferated PVS (data are available via ProteomeXchange with the identifiers PXD034280). Importantly, TNBS-induced cecitis, the proliferated PVS and inflammation response-related proteins (CD40, CD45, HLA-DRA1, LAMP1, JAGN1 and FGL1) in the PVS were alleviated or reversed by repetitive electroacupuncture (EA) stimulations.

Conclusion

These results suggest that the proliferated PVS and its active inclusions were related to the inflammatory process, which was modified by EA. Our study provides a new avenue for further exploration of the mechanism by which EA exerts anti-inflammatory effects.

Primo Vascular System: A Unique Biological System Shifting a Medical Paradigm

The primo vascular system has a specific anatomical and immunohistochemical signature that sets it apart from the arteriovenous and lymphatic systems. With immune and endocrine functions, the primo vascular system has been found to play a large role in biological processes, including tissue regeneration, inflammation, and cancer metastases. Although scientifically confirmed in 2002, the original discovery was made in the early 1960s by Bong-Han Kim, a North Korean scientist. It would take nearly 40 years after that discovery for scientists to revisit Kim's research to confirm the early findings. The presence of primo vessels in and around blood and lymph vessels, nerves, viscera, and fascia, as well as in the brain and spinal cord, reveals a common link that could potentially open novel possibilities of integration with cranial, lymphatic, visceral, and fascial approaches in manual medicine.

Protocol for Detecting the Primo Vascular System in the Lymph Ducts of Mice

The primo vascular system (PVS), which is the proposed conduit for the acupuncture Qi, is a complex network distributed throughout an animal's body. However, even with a microscope, it is not easily detectable because of its transparency. Thus, its existence is largely unknown in current anatomy. A convincing demonstration of its existence is needed. The lymph-primo vessel (PV), which is a subsystem of the PVS, is a very effective visual demonstration of the PVS. The lymph-PVS is a mobile threadlike structure floating in lymph ducts that has been observed in rabbits, rats, and mice by several independent teams. The involved techniques are novel and rather complicated; therefore, we have already provided detailed protocols for the surgery; for the injection of the staining dye; and for the detection, extraction, and identification of the PVS in rabbits and rats. However, the mouse is one of the most important laboratory animals used for various biomedical research purposes. For the convenience of researchers who wish to initiate the PVS experiments in mice, we provide a shortened version of the protocol, despite many similarities with previously published protocols. Thus, researcher can easily obtain the samples of the lymph-PVS of mice.

A Novel Technique for Visualizing the Intralymphatic Primo Vascular System by Using Hollow Gold Nanospheres

Until recently, the primo vascular system (PVS) has been unnoticed by most anatomists due to the small diameter and translucent features of the threadlike network. These properties make primo vessels (PVs) difficult to visualize for harvest and for further characterization. One particular PVS subtype that is located within the lymphatic vessels (LVs) is of strong interest because with a proper contrast, these long PVs can be visualized through the transparent LV wall and can be harvested to provide sufficient sample material for analysis. The most common method to visualize this PVS subtype utilizes Alcian blue as the contrast agent. This technique is effective, but tedious, and has relatively low repeatability. The purpose of this study was to develop a new technique that allows reliable visualization of the intralymphatic PVS (IL-PVS) in a user-friendly manner. The method was designed to provide optical contrast to the PVS by taking advantage of the porous nature of the PV's external wall and interstitial matrix. Turquoise-green-colored hollow gold nanospheres (HGNs) in the size range of 50-125 nm were found to provide excellent optical contrast for the IL-PVS in rats. The PVS was visualized within 10 minutes after HGN administration at a 95% success rate.

Comparison of Alcian Blue, Trypan Blue, and Toluidine Blue for Visualization of the Primo Vascular System Floating in Lymph Ducts

The primo vascular system (PVS), floating in lymph ducts, was too transparent to be observed by using a stereomicroscope. It was only detectable with the aid of staining dyes, for instance, Alcian blue, which was injected into the lymph nodes. Some dyes were absorbed preferentially by the PVS than the lymph wall. It remains a standing problem to know what dyes are absorbed better by the PVS than the lymph walls. Such information would be useful to unravel the biochemical properties of the PVS that are badly in need for obtaining large amount of PVS specimens. In the current work we tried two other familiar dyes which were used in PVS research before. We found that Trypan blue and toluidine blue did not visualize the PVS. Trypan blue was cleared by the natural washing. Toluidine blue did not stain the PVS, but it did leave stained spots in the lymph wall and its surrounding tissues, and it leaked out of the lymph wall to stain surrounding connective tissues. These completely different behaviors of the three dyes were found for the first time in the current work and provide valuable information to elucidate the mechanism through which some special dyes stained the PVS preferentially compared to the lymphatic wall.

Visualization of the primo vascular system afloat in a lymph duct

Because of the potential roles of the primo vascular system (PVS) in cancer metastasis, immune function, and regeneration, understanding the molecular biology of the PVS is desirable. The current state of PVS research is comparable to that of lymph research prior to the advent of Lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1). There is very little knowledge of the molecular biology of the PVS due to difficulties in identifying and isolating primo endothelial cells. Present investigations rely on the morphology and the use of differential staining procedures to identify the PVS within tissues, making detailed molecular studies all but impossible. To overcome such difficulties, one may emulate the explosive development of lymph molecular biology. For this purpose, there is a need for a reliable method to obtain PVS specimens to initiate the molecular investigation. One of the most reliable methods is to detect the primo vessels and primo nodes afloat in the lymph flow. The protocols for observation of the PVS in the large lymph ducts in the abdominal cavity and the thoracic cavity were reported earlier. These methods require a laparectomy and skillful techniques. In this work, we present a protocol to identify and harvest PVS specimens from the lymph ducts connecting the inguinal and the axillary nodes, which are located entirely in the skin. Thus, the PVS specimen is more easily obtainable. This method is a stepping-stone toward development of a system to monitor migration of cancer cells in metastasis from a breast tumor to the axillary nodes, where cancer cells use the PVS as a survival rope in hostile lymph flow.

Primo vascular system floating in lymph ducts of rats

An epoch-making development in the gross anatomy of the lymph system has emerged: the observation of the primo vascular system (PVS), which is a threadlike structure floating in lymph ducts. The PVS, which was proposed as the conduit for the acupuncture Qi, is a complex network distributed throughout an animal's body. The lymph-PVS, which is a subsystem of the PVS, is one of the most convincing visual demonstrations of the PVS. Because its existence is not easily demonstrated, even with a microscope, due to its transparency, in current anatomy its existence is largely unknown despite its potential significance in physiology and medicine. The lymph-PVS has been observed in rabbits, rats, and mice by several independent teams. Because the involved techniques are rather complicated, we provide detailed protocols for surgery, for injection of the staining dye, and for detection, extraction, and identification of the PVS in a rat.

50 years of bong-han theory and 10 years of primo vascular system

The primo vascular system (PVS) was first introduced by Bong-Han Kim via his five research reports. Among these the third report was most extensive and conclusive in terms of the PVS anatomy and physiology relating to the acupuncture meridians. His study results, unfortunately, were not reproduced by other scientists because he did not describe the materials and methods in detail. In 2002, a research team in Seoul National University reinitiated the PVS research, confirmed the existence of PVS in various organs, and discovered new characteristics of PVS. Two important examples are as follows: PVS was found in the adipose tissue and around cancer tissues. In parallel to these new findings, new methods for observing and identifying PVS were developed. Studies on the cell and material content inside the PVS, including the immune function cells and stem cells, are being progressed. In this review, Bong-Han Kim's study results in his third report are summarized, and the new results after him are briefly reviewed. In the last section, the obstacles in finding the PVS in the skin as an anatomical structure of acupuncture meridian are discussed.

A method for the observation of the primo vascular system in the thoracic duct of a rat

Even though the primo vascular system (PVS) has been observed in large caliber lymph vessels by several independent teams, the presence of the PVS in the thoracic duct has been reported by only one team, probably because reproducing the experiment is technically difficult. This brief report presents a new, relatively straightforward method, which is a simple modification of the previous method of dye injection into the lumbar node, to observe the PVS in a thoracic duct of a rat by injecting Alcian blue into the renal node. When this new method was applied to a rat, the branching of the primo vessel in the thoracic duct was clearly displayed. Thus, this new method is expected to extend the network of the PVS from abdominal lymph ducts to thoracic ones.

Review and Comment on the Relationship between Primo Vascular System and Meridians

This paper aims to summarize the recent progress of researches on the primo vascular system (PVS) and to analyze characteristics between PVS and traditional Chinese meridians. With the distribution, position features, identification and origin of PVS, and its function related to meridians elaborated on, we propose that there is still a lack of enough evidence to support the correlation between PVS and traditional Chinese meridians.

Historical Review about Research on "Bonghan System" in China

The meridian-collateral theory is the theoretical basis of acupuncture-moxibustion therapy. Professor Bonghan Kim, a professor of the Pyongyang Medical University of the Democratic People's Republic of Korea, claimed that he found the anatomical structure of meridian-collaterals, named Bonghan corpuscles (BHCs) and Bonghan ducts (BHDs) system or primo vascular system (PVS), in 1962. From 1963 to 1965, researchers from our institute conducted a series of comparative anatomical experiments, trying to reproduce the so-called BHC- and BHD-like structures in different strains of animals. In the present paper, the authors introduced their research findings about BHC- and BHD-like structures in the young rabbit's umbilicus including its external appearance, ectoplasm and endoplasm, and about strip-like and node-like objects in the blood vessels and lymph vessels near the larger abdominal and cervical blood vessels and chromaffin tissue in the back wall of the rabbit's abdominal cavity and between the bilateral kidneys. In spite of existence of the BHC- and BHD-like structures in the rabbit, there has been no proved evidence for their association with the meridian-collateral system described in acupuncture medicine. In the present historical review, the authors also make a discussion about the significance of those findings.