Evidence for an additional metastatic route: in vivo imaging of cancer cells in the primo-vascular system around tumors and organs

Bonghan (primo vascular) system, elucidated by Bong Han Kim: Kim’s findings, later verifications, new findings, and prospective: A review

The Bonghan system (BHS) was discovered in the 1950s by Dr. Bong Han Kim in North Korea. His first report, published in 1962, revealed the identity of ‘acupuncture meridian’ as a vascular system. Kim published five reports, containing completely new facts on BHS: its distribution throughout the entire body, even in blood and lymphatic vessels and self-renovating function via a new cell cycle, demonstrating its fundamental nature in life. In about 1966, Kim’s research abruptly ceased but in about 2000, it was revived by Dr. Kwang-Sup Soh in South Korea, who later gave it another name, primo vascular system (PVS). Soh and other PVS scientists also uncovered new BHS/PVS facts: e.g., its roles in stem cell productions and in cancer metastasis. The review provides a glimpse of BHS/PVS science, which is so worthy of furthering. It includes: BHS and acupuncture meridian; BHS subtypes; sanal (산알)-cell cycle for cell-renovation and blood cell productions; sanals and stem cells; and cancer associated-PVS. The bases of BHS/PVS sciences are now laid out in front of us and it is up to us to combine our efforts together to further this important science. The review invites scientists in all fields to active debates to move forward and implement BHS/PVS sciences in healthcare.

Spatial and Temporal Electrodynamics in Acuzones: Test-Induced Kinematics and Synchronous Structuring. Phenomenological Study

Background: So far there is no confidence in the basics of acupoint/meridian phenomena, specifically in spatial and temporal electrical manifestations in the skin.Methods: Using the skin electrodynamic introscopy, the skin areas of 32 × 64 mm² were monitored for spectral electrical impedance landscape with spatial resolution of 1 mm, at 2 kHz and 1 MHz frequencies. The detailed baseline and 2D test-induced 2 kHz-impedance phase dynamics and the 4-parameter time plots of dozens of individual points in the St32-34 regions were examined in a healthy participant and a patient with mild gastritis. Non-thermal stimuli were used: (1) (for the sick subject), microwaves and ultraviolet radiation applied alternately from opposite directions of the meridian; and (2) (for the healthy one) microwaves to St17, and cathodic/anodic stimulation of the outermost St45, alternately.Results: In both cases, the following phenomena have been observed: emergence of in-phase and/or antiphase coherent structures, exceeding the acupoint conditional size of 1 cm; collective movement along the meridian; reversible with a reversed stimulus; counter-directional dynamics of both whole structures and adjacent points; local abnormalities in sensitivity and dynamics of the 1 MHz and 2 kHz parameters indicating existence of different waveguide paths.Conclusion: It is assumed that these findings necessitate reconsideration of some basic methodological issues regarding neurogenic/acupuncture points as spatial and temporal phenomena; this requires development of an appropriate approach for identifying the acuzones patterns. These findings may be used for developing new approaches to personalized/controlled therapy/treatment.

Sanal-Cell Cycle and Primo Vascular System: Regeneration via Sanals

The Primo Vascular System (PVS) is new to most scientists despite that it was discovered in the 1960s by Bonghan Kim. Out of the many physiological functions reported, one of the most important PVS functions appears to be its role in the regeneration via a small (~1 μm) subcellular body called 'sanal.' According to Kim, a cell generates multiple sanals and the sanals arriving at the primo nodes (PNs) via primo vessels (PV) eventually produce new cells, by way of the 'Sanal-Cell Cycle.' Sanals express stem cell biomarkers. Appropriately differentiated sanals have been shown to perform non-marrow hematopoiesis and repair damaged tissues. However, many questions on sanals still remain: e.g., how sanals reside in the PN; whether sanals are a new type of stem cells; and how exactly sanals produce cells and/or tissue. Our preliminary studies show that sanals reside inside the sinus formed by sub-PVs in the PNs; and in the PNs, there are more than one form of sanal-originated bodies of various sizes.

Technical Challenges in Current Primo Vascular System Research and Potential Solutions

Since Bonghan Kim's discovery of the Bonghan system (BHS) in the 1960s, numerous reports have suggested that the system is fundamental for maintaining mammalian life. The BHS is a circulatory system independent of the blood or the lymphatic system, forms an extensive network throughout the entire mammalian body, has been reported to be the acupuncture meridian, stores distinct types of stem cells, and appears to have some roles in cancer metastasis. Despite Kim's first report having been published as early as 1962, research progress has been rather slow mainly because the system is very small and translucent, making it optically difficult to distinguish it from the hemoglobin-rich surrounding tissues. Unfortunately, Kim did not describe in detail the methods that he used for identifying and harvesting the system and the components of the system. In 2000, Kwang-Sup Soh reopened the BHS research, and since then, new and important scientific findings on the system have been reported, and many of Kim's results have been verified. In 2010, the BHS was renamed the primo vascular system. Nevertheless, good tools to properly deal with this system are still lacking. In this article, we address some of the technical difficulties involved in studying the primo vascular system and attempt to discuss potential ways to overcome those difficulties.

The role of lymphangiogenesis and angiogenesis in tumor metastasis

BACKGROUND

Metastasis is the main cause of mortality in cancer patients. Two major routes of cancer cell spread are currently being recognized: dissemination via blood vessels (hematogenous spread) and dissemination via the lymphatic system (lymphogenous spread). Here, our current knowledge on the role of both blood and lymphatic vessels in cancer cell metastasis is summarized. In addition, I will discuss why cancer cells select one or both of the two routes to disseminate and I will provide a short description of the passive and active models of intravasation. Finally, lymphatic vessel density (LVD), blood vessel density (BVD), interstitial fluid pressure (IFP) and tumor hypoxia, as well as regional lymph node metastasis and the recently discovered primo vascular system (PVS) will be highlighted as important factors influencing tumor cell motility and spread and, ultimately, clinical outcome.

CONCLUSIONS

Lymphangiogenesis and angiogenesis are important phenomena involved in the spread of cancer cells and they are associated with a poor prognosis. It is anticipated that new discoveries and advancing knowledge on these phenomena will allow an improvement in the treatment of cancer patients.

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.

A Hyaluronic Acid-Rich Node and Duct System in Which Pluripotent Adult Stem Cells Circulate

Regenerative medicine is in demand of adult pluripotent stem cells (PSCs). The "Bonghan System (BHS)" was discovered and suggested to contain cells with regenerative capacity in the early 1960s. It had been ignored for a long time due to the lack of sufficient details of experiments, but about 37 years after the initial report, the BHS was rediscovered and named as the "primo vascular system." Recently, we have discovered a similar structure, which contained a high level of hyaluronic acid, and hence, named the structure as hyaluronic acid-rich node and duct system (HAR-NDS). Here we discuss the HAR-NDS concept starting from the discovery of BHS, and findings pointing to its importance in regenerative medicine. This HAR-NDS contained adult PSCs, called node and duct stem cells (NDSCs), which appeared to circulate in it. We describe the evidence that NDSCs can differentiate into hemangioblasts that further produced differentiated blood cells. The NDSCs had a potential to differentiate into neuronal cells and hepatocytes; thus, NDSCs had a capability to become cells from all three germ layers. This system appears to be a promising alternative source of adult stem cells that can be easily delivered to their target tissues and participate in tissue regeneration.

Fascia and Primo Vascular System

The anatomical basis for the concept of acupuncture points/meridians in traditional Chinese medicine (TCM) has not been resolved. This paper reviews the fascia research progress and the relationship among acupuncture points/meridians, primo vascular system (PVS), and fascia. Fascia is as a covering, with common origins of layers of the fascial system despite diverse names for individual parts. Fascia assists gliding and fluid flow and holds memory and is highly innervated. Fascia is intimately involved with nourishment of all cells of the body, including those of disease and cancer. The human body's fascia network may be the physical substrate represented by the meridians of TCM. The PVS is a newly found circulatory system; recent increased interest has led to new research and new discoveries in the anatomical and functional aspects of the PVS. The fasciology theory provides new insights into the physiological effects of acupuncture needling on basic cellular mechanisms including connective tissue mechanotransduction and regeneration. This view represents a theoretical basis and means for applying modern biomedical research to examining TCM principles and therapies, and it favors a holistic approach to diagnosis and treatment.

Cellular fibronectin 1 promotes VEGF-C expression, lymphangiogenesis and lymph node metastasis associated with human oral squamous cell carcinoma

Lymph node metastasis (LNM) is associated with poor survival in patients with oral squamous cell carcinoma (OSCC). Vascular endothelial growth factor-C (VEGF-C) is thought to be responsible for increased lymphangiogenesis and LNM. Understanding of the mechanism by which VEGF-C expression is regulated in OSCC is thus important to design logic therapeutic interventions. We showed that inoculation of the SAS human OSCC cells expressing the venus GFP (V-SAS cells) into the tongue in nude mice developed LNM. V-SAS cells in LNM were isolated by FACS and re-inoculated into the tongue. This procedure was repeated eight times, establishing V-SAS-LM8 cells. Differential metastasis PCR array between the parental V-SAS and V-SAS-LM8 was performed to identify a molecule responsible for lymphangiogenesis and LNM. Fibronectin 1 (FN1) expression was elevated in V-SAS-LM8 cells compared to V-SAS-cells. V-SAS-LM8 tongue tumor showed increased expression of FN1 and VEGF-C, and promoted lymphangiogenesis and LNM compared with V-SAS tumor. Further, phosphorylation of focal adhesion kinase (FAK), a main downstream signaling molecule of FN1, was up-regulated, and epithelial-mesenchymal transition (EMT) was promoted in V-SAS-LM8 cells. Silencing of FN1 by shRNA in V-SAS-LM8 cells decreased FAK phosphorylation, VEGF-C expression and inhibited lymphangiogenesis and LNM. EMT was also reversed. The FAK phosphorylation inhibitor PF573228 also decreased VEGF-C expression and reversed EMT in V-SAS-LM8 cells. Finally, we detected intense FN1 expression in some clinical specimens obtained from OSCC patients with LNM. These results demonstrate that elevated expression of cellular FN1 and following activation of FAK lead to increased VEGF-C expression, lymphangiogenesis and LNM and promoted EMT in SAS human OSCC cells and suggest that FN1-phosphorylated FAK signaling cascade is a potential therapeutic target in the treatment of LNM in OSCC.

Hypothesis on the Treatment of Gliomas with Acupuncture at the Primo Node Corresponding to Zusanli (ST 36)

Background: The primo vascular system (PVS) is an anatomical structure that is a network of ducts with fluid flowing in them, which are called primo vessels and correspond to acupuncture meridians, and primo nodes that correspond to acupoints. The PVS' main function is considered to be the maintenance of regenerative homeostasis in human and animal bodies. This system is distributed throughout the bodies of normal animals and develops around and in cancer tissues. This cancer-associated PVS may be a critical metastatic path besides the blood and the lymph vessels. The author of this article proposes a hypothesis on cancer treatment: Injecting anticancer drugs into acupoints according to the pharmacopuncture method can be effective as a result of the flow channels of the PVS. The author considers the acupoint Zusanli (ST 36) and the route of the primo vessels starting from it. This specific PVS route runs along the perineurium of the sciatic nerve, the pia mater, and the arachnoid mater of the spinal cord to the brain. Thus, by injecting a suitable anticancer drug into ST 36, one can deliver the drug into the brain to treat gliomas and other brain tumors. This new drug-delivery method is just one of the new clinical applications that are possible by combining acupuncture and using the PVS. Conclusions: Anticancer drugs for glioma can be injected into the primo node at the acupoint ST 36 to reach the cancer tissue through the PVS in the sciatic nerve, spine, and brain that can avoid the blood-brain barrier.

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.

Observation of the Primo Vessel Approaching the Axillary Lymph Node with the Fluorescent Dye, DiI

The primo vascular system (PVS) floating in lymph fluid has mostly been observed in large caliber ducts around the caudal vena cava and the thoracic duct of rabbits, rats, and mice. But the PVS has not been traced up to the lymph nodes. It has not been established whether the PVS leaves the lymph vessel through the lymph vessel wall or it enters the lymph nodes. Therefore, observing the PVS entering a lymph node, for example, the axillary node, is desirable. In the current work, we traced the PVS approaching up to the surface of axillary node of a rat. The method used for this study was based upon a method that was recently developed to detect the PVS in the lymph duct from the inguinal to the axillary nodes in the skin of a rat by injecting Alcian blue into the inguinal node. However, the Alcian blue blurred near the lymph nodes and tracing the PVS up to the lymph nodes has not been possible. The current method clearly showed the PVS approaching the axillary node.

Delivering colloidal nanoparticles to mammalian cells: a nano-bio interface perspective

Understanding the behavior of multifunctional colloidal nanoparticles capable of biomolecular targeting remains a fascinating challenge in materials science with dramatic implications in view of a possible clinical translation. In several circumstances, assumptions on structure-activity relationships have failed in determining the expected responses of these complex systems in a biological environment. The present Review depicts the most recent advances about colloidal nanoparticles designed for use as tools for cellular nanobiotechnology, in particular, for the preferential transport through different target compartments, including cell membrane, cytoplasm, mitochondria, and nucleus. Besides the conventional entry mechanisms based on crossing the cellular membrane, an insight into modern physical approaches to quantitatively deliver nanomaterials inside cells, such as microinjection and electro-poration, is provided. Recent hypotheses on how the nanoparticle structure and functionalization may affect the interactions at the nano-bio interface, which in turn mediate the nanoparticle internalization routes, are highlighted. In addition, some hurdles when this small interface faces the physiological environment and how this phenomenon can turn into different unexpected responses, are discussed. Finally, possible future developments oriented to synergistically tailor biological and chemical properties of nanoconjugates to improve the control over nanoparticle transport, which could open new scenarios in the field of nanomedicine, are addressed.

Motion properties of the sanals of the primo vascular system under a magnetic field

The motion properties of the sanals of the primo vascular system were investigated under a low static magnetic field of 100 Oe. Sanals of about 1 μm were selected and separated from the primo vessels and nodes on a rabbit's organ surface. The average velocity of five sanals in a physiologic saline solution parallel and perpendicular to the direction of the applied magnetic field was approximately 1.0 pixel/second in random directions, which implies that the rotating motion of sanals with nuclei composed of DNA containing many inorganic magnetic elements such as manganese and cobalt is monotonically weakened by increasing an applied magnetic field.

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.

Formative research on the primo vascular system and acceptance by the korean scientific community: the gap between creative basic science and practical convergence technology

The purpose of this study was to trace the formative process of primo vascular system (PVS) research over the past decade and to describe the characteristics of the Korean scientific community. By publishing approximately 30 papers in journals ranking in the Science Citation Index (Expanded), the PVS research team actively convinced domestic and international scientists of the anatomical existence of the PVS and its possible application to Korean and Western medicine. In addition, by sharing the PVS observation technique, the team promoted the dissemination and further pursuit of the research. In 2012, however, PVS researchers performed smaller scale research without advancing to a higher level as compared to the early days. The main reasons were found to be the Korean Research and Development policy of supporting creative, small-scale basic research and applied research of Western scientific fields that promised potentially greater success on an extensive scale; the indifference concerning, and the disbelief in, the existence of a new circulatory system were shown by the Western medical community. In addition, the Oriental medical community was apathetic about working with the PVS team. Professors Kwang-Sup Soh and Byung-Cheon Lee were the prime movers of PVS research under difficult conditions. Spurred by their belief in the existence and significance of the PVS, they continued with their research despite insufficient experimental data. The Korean scientific community is not ready to promote the Korea-oriented creative field of the PVS team.

Primo vessel as a novel cancer cell migration path from testis with nanoparticle-labeled and GFP expressing cancer cells

BACKGROUND/AIM

Recently, a novel circulatory system, the primo vascular system (PVS), was found to be a potent metastatic route of cancer cells. The aim of the current work is to demonstrate that cancer cells injected into the testis migrate through the primo vessel (PV).

MATERIALS AND METHODS

NCI-H460 cells labeled with fluorescent nanoparticles (FNP) or green fluorescent protein (GFP) gene transfection were injected into testicular parenchyma in 24 rats. After 24 hours of injection, the abdominal cavity was investigated via a stereomicroscope, to detect the PVS, and the samples were analyzed histologically with 4',6-diamidino-2-phenylindole (DAPI) and hematoxylin and eosin.

RESULTS

Injected cancer cells were detected inside the PVS distributed on the abdominal organs. Some were detected inside intestinal parenchyma into which the attached primo vessels (PVs) entered.

CONCLUSION

The results supported the fact that the PVS may be a novel migration path of cancer cells, in addition to the lymphatic and hematogenous routes.

Preliminary Research of Relationship between Acute Peritonitis and Celiac Primo Vessels

Previous studies demonstrated that primo vessels (PVs) were distributed in different parts of the body in mammals, and PVs were also involved in some processes of pathology such as cancer. Whether PVs are intrinsic structures in mammals or not is still ignored. In this study, a peritonitis model rat was induced by i.p. administration of E. coli in rats. PVs were observed in all infected rats, but it appeared less in untreated rats, taking 10.53% (4/38). In addition, we examined cell types in celiac PVs by fluorescent staining with 4',6-diamidino-2-phenylindole (DAPI) and Alexa Fluor 488 phalloidin, as well as immunofluorescent staining with CD11b and intercellular adhesion molecule-1(ICAM-1), and found the following. (1) The rod-shaped nuclei aligned longitudinally along PVs. (2) DAPI-, phalloidin-, CD11b-, and ICAM-1-positive labeling coexisted in PVs, suggesting that fibroblasts and leucocytes might be two kinds of cell types in PVs for both infected and control rats. (3) The difference was that numerous cells in PVs of the infected rats contained DAPI-labeled multilobal nucleus and were expressed with CD11b- and ICAM-1-positive labeling on the cytoplasm and membrane, showing the typical characteristics of neutrophil. (4) The cells in PVs from the untreated rats are those of loose connective tissue. Therefore, it is reasonably considered that PVs from infected rats might be the pathological products which might be involved in inflammation.

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.

Observation of a long primo vessel in a lymph vessel from the inguinal node of a rabbit

Though primo vessels are frequently found in the lymph near the abdominal aorta of rabbit by Alcian blue dye, the reproductions are still difficult to require considerable skills and technical know-how at dissected tissue of animal species. However, in the inguinal lymph node of a rabbit we found a long-type primo vascular system (LTP) dyed with Alcian blue, from an abdominal lymph vessel to an inguinal lymph node. The length of LTP was over an average length of 9.1 cm. The average diameters of the primo and the lymph vessels were about 23.9 μm and 242 μm, respectively. The primo vessels were not floating but adhered to lymph vessels with fascial connective tissue. These primo vessels might be a functional integration in the lymph system.

Primo vascular system accompanying a blood vessel from tumor tissue and a method to distinguish it from the blood or the lymph system

A primo vessel was observed in the abdominal cavity in the lung cancer mouse model, and its function as an extra metastatic path was observed. In this work, we found a primo vessel accompanying a blood vessel emanating from a tumor in the skin. We also presented simple and efficient criteria to distinguish a primo vessel from a blood or a lymph vessel and from a nerve. The criteria for using DAPI and Phalloidin will be useful in clinical situations to find and identify the primo vessels among the blood vessels, lymph vessels, or nerves in the tissue surrounding a tumor such as a melanoma or breast cancer.

Surface engineering of inorganic nanoparticles for imaging and therapy

Many kinds of inorganic nanoparticles (NPs) including semiconductor, metal, metal oxide, and lanthanide-doped NPs have been developed for imaging and therapy applications. Their unique optical, magnetic, and electronic properties can be tailored by controlling the composition, size, shape, and structure. Interaction of such NPs with cells and/or in vivo compartments is critically determined by the surface properties, and sophisticated control over the NP surface is essential to control their fate in biological environments. We review NP surface coating strategies using the categories of small surface ligand, polymer, and lipid. Use of small ligand molecules has the advantage of maintaining the minimal hydrodynamic (HD) size. Polymers can be advantageous in NP anchoring by combining multiple affinity groups. Encapsulation of NPs in polymers, lipids or surfactants can preserve the as-synthesized NPs. NP surface properties and reaction conditions should be carefully considered to obtain a bioconjugate that maintains the physicochemical properties of NP and functionalities of the conjugated biomolecules. We highlight how the surface properties of NPs impact their interactions with cells and in vivo compartments, especially focused on the important surface design parameters such as HD size, surface charge, and targeting. Typically, maximal cellular uptake can take place in the intermediate NP size range of 40-60nm. Clearance of NPs from blood circulation is largely dependent on the degree of uptake by reticuloendothelial system when they are larger than 10nm. When the HD size is below 10nm, NPs show broad distribution over many organs. Reduction of HD size below the limit of renal barrier can achieve fast clearance of NPs. For maximal tumor accumulation, NPs should have long blood circulation time and should be large enough to prevent rapid penetration. NPs are also desired to rapidly clear out from the body after the mission before they cause toxic side effects. However, efficient clearance from the body to avoid side effects may result in the reduction in residence time required for accumulation in target tissues. Smart design of NP surface coating that can meet the conflicting demands can open a new avenue of NP applications. Surface charge and hydrophobicity need to be carefully considered for NP surface design. Positively charged NPs more adsorb on cell membranes and consequently show higher level of internalizations when compared with negatively charged or neutral NPs. NPs encounter a large variety of biomolecules in vivo, where non-specific adsorptions can potentially alter the physicochemical properties of the NPs. For optimal performance, NPs are suggested to have neutral surface charge at physiological conditions, small HD size, and minimal non-specific adsorption levels. Zwitterionic NP surface coating by small surface ligands can be a promising approach. Toxicity is one of most critical issues, where proper control of the NP surface can significantly reduce the toxicities.

Discovery of endothelium and mesenchymal properties of primo vessels in the mesentery

Recent evidences demonstrated that endothelial-to-mesenchymal transition (EndMT) has a crucial role in cancer and is recognized as a unique source of cancer-associated fibroblasts (CAFs). Primo vascular system (PVS) is a new circulatory system which may play an important role in cancer metastasis and regeneration. In the current study, we applied previously established time-saving method to identify primo vessels and further investigated the immunocytochemical properties of primo vessels. Both primo vessels and primary primo vessel cells in the mesentery expressed endothelial markers and fibroblast markers. Double-labeling experiments demonstrated that endothelial and fibroblast markers are coexpressed in primo vessels. In addition, under the stimulation of TGF-β1 in vitro, primary primo vessel cells differentiated into fibroblasts. Therefore, we found that primo vessels in the mesentery had a transitional structure between endothelium and mesenchymal. This is a new finding of EndMT in normal postnatal animals.

Novel threadlike structures on the surfaces of mammalian abdominal organs are loose bundles of fibrous stroma with microchannels embedded with fibroblasts and inflammatory cells

Novel threadlike structures (NTSs) on the surfaces of mammalian abdominal organs have recently attracted interests regarding their ability to transport fluid, enable cell migration, and possibly facilitate cancer metastasis. Nevertheless, histological studies of NTSs have been sporadic and often have inconsistent interpretations of the NTS internal structure. In this article, we provide a synthetic and consistent view of the NTS internal structure: the NTS is a loose bundle of fibrous stroma that forms interstitial channels and microsinusoids infiltrated with inflammatory cells. The fibroblasts are embedded in the stroma and mostly aligned along the major axis of the NTS. The sinusoids, which are in inconsecutive cross sections, have boundaries more or less delineated by extracellular fibers, partly surrounded by endothelial-like cells, or both. We compare these morphological features to other well-known connective tissues (i.e., trabecular meshwork and lymphatic capillary) and discuss the biomechanical and biological functions of NTSs based on their structural characteristics.

Differentiating Blood, Lymph, and Primo Vessels by Residual Time Characteristic of Fluorescent Nanoparticles in a Tumor Model

Fluorescent nanoparticles (FNPs) which were injected into a tumor tissue flowed out through the blood and lymph vessels. The FNPs in blood vessels remained only in the order for few minutes while those in lymph vessels remained for a long time disappearing completely in 25 hours. We found a primo vessel inside a lymph vessel near a blood vessel, and FNPs remained in the primo vessel for longer than 25 hours. In addition, we examined in detail the residual time characteristics of lymph vessels because it could be useful in a future study of fluid dynamical comparison of the three conduits. These residual time characteristics of FNPs in the three kinds of vessels may have implications for the dynamics of nanoparticle drugs for cancer chemotherapy.

Nonendocytic delivery of functional engineered nanoparticles into the cytoplasm of live cells using a novel, high-throughput microfluidic device

The ability to straightforwardly deliver engineered nanoparticles into the cell cytosol with high viability will vastly expand the range of biological applications. Nanoparticles could potentially be used as delivery vehicles or as fluorescent sensors to probe the cell. In particular, quantum dots (QDs) may be used to illuminate cytosolic proteins for long-term microscopy studies. Whereas recent advances have been successful in specifically labeling proteins with QDs on the cell membrane, cytosolic delivery of QDs into live cells has remained challenging. In this report, we demonstrate high throughput delivery of QDs into live cell cytoplasm using an uncomplicated microfluidic device while maintaining cell viabilities of 80-90%. We verify that the nanoparticle surface interacts with the cytosolic environment and that the QDs remain nonaggregated so that single QDs can be observed.

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

Molecular-level understanding of the structure and the functions of the lymphatic system has greatly enhanced the importance of this second circulation system, especially in connection with cancer metastasis and inflammation. Recently, a third circulatory system, the primo vascular system (PVS) was found in various parts of an animal's body, especially as threadlike structures floating in the lymphatic flow in lymph vessels. Although the medical significance of this emerging system will require much work in the future, at present, several important suggestions in connection with immune cells, stem cells, and cancer metastasis have already appeared. Experiments to observe the PVS in the lymph vessels near the caudal vena cava of rabbits and rats have been performed by several independent teams, but reproduction requires considerable skill and technical know-how. In this article, we provide a detailed protocol to detect the PVS inside the lymph vessels of a rabbit. Detection and isolation are the first steps in unraveling the physiological functions of the PVS, which awaits intensive research.

Tumor-associated primo vascular system is derived from xenograft, not host

The primo vascular system (PVS), which is composed of very small primo-vessels (PV) and primo-nodes (PN), has recently emerged as a third component of circulatory system. Here, we report the presence of a tumor derived PVS in murine xenografts of human histiocytic lymphoma (U937) in close proximity to the tumor. Within this system, PNs are small (~500-600 μM diameter) membranous sac-like structures which contain numerous small cells which can be demonstrated by DAPI staining. Hematoxylin and Eosin (H&E) staining of the peri-tumoral PVS shows the presence of loose structures lined by fibroblasts but filled with dense fibers, cells, lacunae and nerve-like structures. The origin and type of cells within the PVS was characterized by immunostaining with antibodies for CD68, CD45 and lysozyme. The results of these studies reveal that the PVS of the xenograft originates from the human U937 tumor cells. qRT-PCR analysis of mRNA isolated from PVS cells reveals a striking predominance of human, rather than mouse, sequences. Of particular interest, human stem cell specific transcription factors were overexpressed, most notably KLF4, an upstream regulator of NANOG which maintains the pluripotent and undifferentiated state of stem cells. These results suggest that the cells present within the PVS are derived from the human xenograft and suggests that the primo-vessels associated with the xenografted tumor may provide a safe haven for a select population of cancer stem cells. Further understanding of the biological properties of these cells may allow the development of new anti-cancer interventions.

Primo vessel inside a lymph vessel emerging from a cancer tissue

Primo vessels were observed inside the lymph vessels near the caudal vena cava of a rabbit and a rat and in the thoracic lymph duct of a mouse. In the current work we found a primo vessel inside the lymph vessel that came out from the tumor tissue of a mouse. A cancer model of a nude mouse was made with human lung cancer cell line NCI-H460. We injected fluorescent nanoparticles into the xenografted tumor tissue and studied their flow in blood, lymph, and primo vessels. Fluorescent nanoparticles flowed through the blood vessels quickly in few minutes, and but slowly in the lymph vessels. The bright fluorescent signals of nanoparticles disappeared within one hour in the blood vessels but remained much longer up to several hours in the case of lymph vessels. We found an exceptional case of lymph vessels that remained bright with fluorescence up to 24 hours. After detailed examination we found that the bright fluorescence was due to a putative primo vessel inside the lymph vessel. This rare observation is consistent with Bong-Han Kim's claim on the presence of a primo vascular system in lymph vessels. It provides a significant suggestion on the cancer metastasis through primo vessels and lymph vessels.

Mathematical Distinction in Action Potential between Primo-Vessels and Smooth Muscle

We studied the action potential of Primo-vessels in rats to determine the electrophysiological characteristics of these structures. We introduced a mathematical analysis method, a normalized Fourier transform that displays the sine and cosine components separately, to compare the action potentials of Primo-vessels with those for the smooth muscle. We found that Primo-vessels generated two types of action potential pulses that differed from those of smooth muscle: (1) Type I pulse had rapid depolarizing and repolarizing phases, and (2) Type II pulse had a rapid depolarizing phase and a gradually slowing repolarizing phase.

Estimating the density of fluorescent nanoparticles in the primo vessels in the fourth ventricle and the spinal cord of a rat

The primo vascular system is a novel circulatory system forming a network throughout an animal's body. Primo vessels were recently observed in the fourth ventricle of the brain and in the spinal cord of a rat by using fluorescent nanoparticles. In order to quantify the nanoparticles in the primo vessels, we measured the florescence of the nanoparticles and calibrated the measurements by using a reference suspension. We removed the noise due to autofluorescence with the technique of multispectral imaging. The line densities of nanoparticles and the contrast values of their images were, respectively, 0.5 ± 0.5 ng/mm and 0.7 ± 0.5 for primo vessels in the fourth ventricle, and 1.3 ± 0.6 ng/mm and 1.4 ± 0.2 for primo vessels in the spinal cord. The data obtained from and the procedures used in this work could be useful in evaluating the feasibility of using nanoparticles as a contrast agent during MRI or CT imaging of primo vessels in the brain or the spinal cord.

Intravital imaging of anti-tumor immune response and the tumor microenvironment

Tumor growth, invasiveness, and metastasis are dynamic processes involving cancer interactions with the extracellular matrix, the vasculature, and various types of non-cancerous host cells that form the tumor stroma. An often-present stromal component is the immune cells, such as tumor-associated myeloid and lymphocytic infiltrates, yet endogenous anti-tumor immune responses are typically ineffective in tumor rejection and may even contribute to the progression of some cancers. How exactly cancer cells interact with the stroma and invade healthy tissues while avoiding anti-tumor immune responses, and which interactions should be targeted for anti-tumor therapy, can now be studied by minimally invasive observation using multiphoton and other low impact confocal microscopy techniques and fluorescent animal tumor models. Intravital video microscopy has already been instrumental in defining the roles and modes of cellular motility in the angiogenic process and during tissue invasion at the tumor margin. In the hands of cancer immunologists, intravital video microscopy is beginning to unravel the complexity of effector and suppressory lymphocytic interactions in tumors and in the draining lymphoid organs. As the intravital microscopy approach is beginning to move beyond fundamental description and into analyzing the molecular underpinnings of cell's dynamics, future technical advances will undoubtedly provide yet deeper insight while stitching together a systems dynamics view of cancer-host interactions that will keep on inspiring cancer researchers and therapists.