Fluid in the tissue channels of vascular adventitia investigated by AFM and TEM

A robust MRI contrast agent for specific display of the interstitial stream

Experimental and clinical studies have reported phenomena of long-range fluid flow in interstitial space. However, its behaviours and functions are yet to be addressed. The imaging of the interstitial stream in vivo can clarify its transportation route and allow further understanding of physiological mechanisms and clinical relevance. Here to illustrate the route of the interstitial stream leading to the kidney, we design and synthesize a magnetic resonance imaging (MRI) contrast agent PAA-g-(DTPA-gadolinium). This MRI agent has a high longitudinal relaxivity for higher MRI contrast and large size to avoid leakage across the interstitial space. Using dynamic contrast enhanced MRI, histochemical staining, and trace element analysis of gadolinium, we track the nano-scale PAA-g-(DTPA-gadolinium) transported in the interstitial stream. The agent can be applied for a wide range of imaging and analysis of tissues and organs, thereby enabling advances in the fields of physiology, pathology, and pharmacology.

Interstitial Fluid Behavior and Diseases

Living things comprise a typical hierarchical and porous medium, and their most fundamental logical architectures are interstitial structures encapsulating parenchymal structures. The recent discovery of the efficient transport mechanisms of interstitial streams has provided a new understanding of these complex activities. The substance transport of interstitial streams follows mesoscopic fluid behavior dynamics, which is intimately associated with material transfer in nanoconfined spaces and a unique signal transmission. Accordingly, the evaluation of interstitial stream transport behavior at the mesoscopic scale is essential. In this review, recent advances in physical and chemical properties, the substance transport model, and the characterization methods of interstitial streams at the mesoscopic scale, as well as the relationships between interstitial streams and disease are summarized. Interstitial stream transport can be used as a basis to fully mine hierarchal behavior in images to expand imaging behavior into an omics field. By starting from the perspective of soft matter, a new understanding can be gained of health and disease and quantitative physical markers for research, clinical diagnosis, and treatment can be provided, as well as prognosis evaluation in complex diseases such as cancer and Alzheimer's disease. This will provide a foundation for the development of medicine of soft matter.

In Situ Self-Organizing Materials for Local Stress-Responsive Reconstruction of Skin Interstitium

Remodeling of the fibrous network in the skin interstitium is a crucial step in the process of skin wound healing. In the present study, a hierarchically structured xanthan gum-chitosan (XG-CS) composite hydrogel is developed as a skin wound healing material that responds to stress at wound sites by in situ self-organizing and self-repairing the interstitial fibrous network. The composite gel adheres tightly to the injured fibers forming an intact interstitial pathway, and thereby promotes the physiological function of fibroblasts. A software-based quantitative assessment is performed to evaluate the stress state at wound sites, which confirms that the composite gel adapted in vivo to wound stress and ultimately promotes fast wound healing. The results highlight the importance of interstitial reconstruction in tissue recovery, and will inspire novel strategies in regenerative medicine.