Baeckkyoung Sung

Acupuncture Meridian and Intravascular Bonghan Duct

Current anatomical theory does not recognize the existence of an extended floating threadlike structure inside the blood vessels. Nonetheless, this study developed a new method for observing such an intravascular threadlike structure. The key technique involves injecting acridineorange into the femoral vein to circulate along the blood vessels and stain the nuclei of the intravascular threads inside the blood vessels. In-situ observations were then made under a fluorescence stereomicroscope after saline-perfusion. Confocal microscope images revealed a distinctive characteristic pattern of nucleus distribution that was clearly distinguishable from fibrin, capillaries, small venules, arterioles, or lymph vessels. Accordingly, it is suggested that the identified intravascular threads are part of the Bonghans circulatory network that is distributed throughout the body, including inside the blood vessels.

Network of Endocardial Vessels

Background: Although there have been reports on threadlike structures inside the heart, they have received little attention. We aimed to develop a method for observing such structures and to reveal their ultrastructures. Methods:An in situ staining method, which uses a series of procedures of 0.2–0.4% trypan blue spraying and washing, was applied to observe threadlike structures on the surfaces of endocardia. The threadlike structures were isolated and observed by using confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). Results: Networks of endocardial vessels (20 µm in thickness) with expansions (40–100 µm in diameter) were visualized; they were movable on the endocardium of the bovine atrium and ventricle. CLSM showed that (1) rod-shaped nuclei were aligned along the longitudinal direction of the endocardial vessel and (2) there were many cells inside the expansion. TEM on the endocardial vessel revealed that (1) there existed multiple lumens (1–7 µm in diameter) and (2) the extracellular matrices mostly consisted of collagen fibers, which were aligned along the longitudinal direction of the endocardial vessel or were locally organized in reticular structures. Conclusion: We investigated the endocardial circulatory system in bovine cardiac chambers and its ultrastructures, such as nucleic distributions, microlumens, and collagenous extracellular matrices.

Biodegradable colloidal microgels with tunable thermosensitive volume phase transitions for controllable drug delivery.

In this study, we present gelatin-based thermoresponsive colloidal microgels that enable the controlled release of drugs by volume phase transition. The microgel was fabricated by physically entrapping poly(N-isopropylacrylamide-co-acrylamide) chains as a minor component within three-dimensional gelatin networks crosslinked by genipin. We demonstrate that our gelatin-based thermoresponsive microgel exhibits a tunable deswelling to temperature increase, which positively correlated to the release of bovine serum albumin (BSA) as a function of poly(N-isopropylacrylamide-co-acrylamide) concentration. The microgel was enzymatically degradable by collagenase treatment. The extent of BSA release and biodegradability were tuned by controlling the crosslinking degree of the gelatin matrix. Meeting a great need for design and synthesis of auto-degenerating smart microgels that enable the controlled release of therapeutic proteins in responsive to external stimuli, our gelatin-based microgels that satisfy both thermoresponsivity and biodegradability have a great potential in tissue engineering applications as a soft microdevice element for drug delivery.

The Flow Path of Alcian Blue From the Acupoint BL23 to the Surface of Abdominal Organs

Two hours after Alcian Blue (AB) dye was injected at the rat acupoint BL23, the abdominal cavity was examined and AB-stained threadlike structures were observed on the right abdominal cavity. Those threadlike structures were mainly distributed on the surfaces of the duodenum, colon and cecum. These threadlike structures were thin (about 50 microm) and moved freely, and were connected to corpuscles that were about 500 x 200 microm wide and also stained with AB. On analyzing the histology of the threadlike structures, rod-shaped nuclei, bundles of collagen fibers, reticulofibers, and squamous-like epithelial cells were observed. Immune cells and some sinuses were inside the threadlike structures. These characteristics describe those of Bonghan ducts. The flow paths from the acupoint to internal organs can possibly be used as paths for drug delivery.

A cytological observation of the fluid in the primo-nodes and vessels on the surfaces of mammalian internal organs

We report on the preliminary cytological observation of fluid in the primo-nodes and vessels on the surfaces of the internal organs of mammals. With some microsurgical procedures, we observed many cells and microcells that spread out of the nodes on the organ surfaces of rats and rabbits. These cells generally showed the following morphologies: (1) round or oval cells, 10 μm in size, with predominantly little cytoplasm; (2) cells with nuclei that exhibited a collapsed shape; (3) binucleated cells, 20 μm in size; (4) spherical granules, ranging 0.5–2.0 μm in size (primo-microcells); and (5) aggregations of such granules. These findings on the existence of cells with diverse morphologies in the fluid of primo-nodes and vessels could be evidence supporting the hypothesis that the anatomical basis of acupuncture meridians (i.e., primo-vascular system) may be a migration channel for various kind of cells.

Structure of the Sinus in the Primo Vessel Inside the Bovine Cardiac Chambers

We report the structure of sinuses in the primo vessels on the surfaces of endocardia of atriums and ventricles in the bovine heart. About 1–5 sinuses (0.5–7 μm in diameter) were observed in the cross sections of the primo vessels (20–50 μm in diameter). The boundary of the sinus was clear and was regularly surrounded mainly by collagenous fibers (∼30 nm in diameter) and partly by 1–2 cells.

Nanofluid transport in a living soft microtube

The mechanism of hydrodynamic transport of nanoparticles in living tissues by intrinsic lymphatic pumping remains one of the fundamental questions in the field of nanomedicine. However, despite its importance, direct visualization of the nanofluid transport mechanism has not been achieved. In this article, we report a novel in situ fluorescence bioimaging method for observing real-time microflow patterns of nanofluids confined in a contracting and expanding soft microtube. This method allows for physiological monitoring of spatiotemporally resolved microfluidic behaviour and channel undulation during the peristaltic transport of fluorescent nanoparticle suspensions by lymph vessels embedded in bulky tissues at the location of the hindlimb. The fluorescent nanofluid conferred a high optical contrast for the visualization of the lymphatic microtube, with which the concentration and viscosity of the nanofluid could be determined. The nanofluid and microtube mechanics of the hindlimb lymph vessels exhibited similar behaviours as the previously described base fluid flow of peristaltic mesenteric lymph vessels. Specifically, the microtube contraction and expansion induced increased forward flows, and a reverse flow developed at the maximum contraction, all of which corresponded to Poiseuille flow and implied that higher tube wall shear stress was related to increased axial flow velocity. On the other hand, our study identified a highly heterogeneous flow pattern that could appear during the microtube expansion phase, whose axial velocity profile remarkably deviated from the Hagen–Poiseuille equation. In addition, the peristaltic pumping power was estimated to be on the nanowatt order of magnitude. Finally, we discuss the possible applications of this nanofluidic model system in the context of nanobiotechnology.

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.

Electromechanical method coupling non-invasive skin impedance probing and in vivo subcutaneous liquid microinjection: controlling the diffusion pattern of nanoparticles within living soft tissues

Transdermal drug delivery is the way to transport drug carriers, such as nanoparticles, across the skin barrier to the dermal and/or subcutaneous layer. In order to control the transdermal drug delivery process, based on the heterogeneous and nonlinear structures of the skin tissues, we developed a novel electromechanical method combining in vivo local skin impedance probing, subcutaneous micro-injection of colloidal nanoparticles, and transcutaneous electrical stimulation. Experiments on the nude mice using in vivo fluorescence imaging exhibited significantly different apparent diffusion patterns of the nanoparticles depending on the skin impedance: Anisotropic and isotropic patterns were observed upon injection into low and high impedance points, respectively. This result implies that the physical complexity in living tissues may cause anisotropic diffusion of drug carriers, and can be used as a parameter for controlling drug delivery process. This method also can be combined with microneedle-based drug release systems, micro-fabricated needle-electrodes, and/or advanced in vivo targeting/imaging technologies using nanoparticles.

Network of the Primo Vascular System in the Rat Hypodermis

Anatomical and histological studies on acupuncture points (acupoints) and meridians have been one of the most important approaches to revealing the mechanism of acupuncture analgesia and therapeutics. However, researchers have not yet reached a conclusion on the exact anatomical structure of the acupuncture meridians. In this chapter, the network of primo-vessels and nodes in rat hypodermis is reported. Fluorescence imaging showed the network of the primo-vascular system on the layer of superficial fascia (stratum fibrosum) that existed around the location of the stomach meridian from the knee to the middle of the tibia about 24 h after the subcutaneous injection of fluorescent nanoparticles at the acupoint ST36. Its fine morphologies were analyzed by using confocal laser scanning microscopy and transmission electron microscopy. The primo-vessel had a sinus (3–4 μm in diameter) surrounded by a layer of cells, and had a bundle-like collagen architecture (covered by a cellular layer) in which collagen fibers were regularly aligned along the longitudinal direction of the primo-vessel. Nanoparticles were also found in the cellular or extracellular layer. Since it seems evident that the primo-vascular system mainly exists in the fascia, a new perspective is needed to investigate the whole mechanism of the propagation of acupoint stimulation through the primo-vascular system in relation to fascia physiology.