Microelectromechanical systems and nephrology: the next frontier in renal replacement technology

Microneedles-mediated drug delivery system for the diagnosis and treatment of melanoma

As an emerging novel drug delivery system, microneedles (MNs) have a wide range of applications in the medical field. They can overcome the physiological barriers of the skin, penetrate the outermost skin of the human body, and form hundreds of reversible microchannels to enhance the penetration of drugs and deliver drugs to the diseased sites. So they have great applications in the diagnosis and treatment of melanoma. Melanoma is a kind of malignant tumor, the survival rate of patients with metastases is extremely low. The traditional methods of surgery and drug treatment for melanoma are often accompanied by large adverse reactions in the whole body, and the drug concentration is low. The use of MNs for transdermal administration can increase the drug concentration, reduce adverse reactions in the treatment process, and have good therapeutic effect on melanoma. This paper introduced various types of MNs and their preparation methods, summarized the diagnosis and various treatment options for melanoma with MNs, focused on the treatment of melanoma with dissolved MNs, and made prospect of MNs-mediated transdermal drug delivery in the treatment of melanoma.

Artificial Kidney Engineering: The Development of Dialysis Membranes for Blood Purification

The artificial kidney, one of the greatest medical inventions in the 20th century, has saved innumerable lives with end stage renal disease. Designs of artificial kidney evolved dramatically in decades of development. A hollow-fibered membrane with well controlled blood and dialysate flow became the major design of the modern artificial kidney. Although they have been well established to prolong patients’ lives, the modern blood purification system is still imperfect. Patient’s quality of life, complications, and lack of metabolic functions are shortcomings of current blood purification treatment. The direction of future artificial kidneys is toward miniaturization, better biocompatibility, and providing metabolic functions. Studies and trials of silicon nanopore membranes, tissue engineering for renal cell bioreactors, and dialysate regeneration are all under development to overcome the shortcomings of current artificial kidneys. With all these advancements, wearable or implantable artificial kidneys will be achievable.

A pumpless multi-organ-on-a-chip (MOC) combined with a pharmacokinetic-pharmacodynamic (PK-PD) model

A multi-organ-on-a-chip (MOC), also known as a human-on-a-chip, aims to simulate whole body response to drugs by connecting microscale cell cultures of multiple tissue types via fluidic channels and reproducing the interaction between them. While several studies have demonstrated the usefulness of MOC at a proof-of-concept level, improvements are needed to enable wider acceptance of such systems; ease of use for general biological researchers, and a mathematical framework to design and interpret the MOC systems. Here, we introduce a pumpless, user-friendly MOC which can be easily assembled and operated, and demonstrate the use of a PK-PD model for interpreting drug's action inside the MOC. The metabolism-dependent anticancer activity of a flavonoid, luteolin, was evaluated in a two-compartment MOC containing the liver (HepG2) and the tumor (HeLa) cells, and the observed anticancer activity was significantly weaker than that anticipated from a well plate study. Simulation of a PK-PD model revealed that simultaneous metabolism and tumor-killing actions likely resulted in a decreased anti-cancer effect. Our work demonstrates that the combined platform of mathematical PK-PD model and an experimental MOC can be a useful tool for gaining an insight into the mechanism of action of drugs with interactions between multiple organs. Biotechnol. Bioeng. 2017;114: 432-443. © 2016 Wiley Periodicals, Inc.

The use of micro-electro mechanical systems in vascular monitoring: implications for clinical use

INTRODUCTION

BioMEMS relates to the implementation of Micro-Electro-Mechanical Systems (MEMS), in the biological and medical sphere. BioMEMS sensors are being utilized for many clinical applications, including a wireless urinary pressure system, right heart pressure sensor, and measurements on shearing force on the vascular system An important application of BioMEMS is on Heart failure (HF), a common disease, with a prevalence of 10% or more in persons 70 years of age or older, associated with high morbidity and mortality. HF affects over 5 million people and contributes to over 200,000 deaths a year in the United States alone.

AREAS COVERED

The purpose of this paper is to provide a short overview on the successful implementation of BioMEMS sensors in heart failure and vascular medicine. Expert commentary: BioMEMS devices have overcome current limitations in pharmacotherapies for resistant hypertension by electrical modulation of the baroreceeptors. This represents a step towards the development of biomedical micro-devices for those conditions in which pharmacotherapies result poorly effective or elicit unacceptable toxicity.

Diffusive Silicon Nanopore Membranes for Hemodialysis Applications

Hemodialysis using hollow-fiber membranes provides life-sustaining treatment for nearly 2 million patients worldwide with end stage renal disease (ESRD). However, patients on hemodialysis have worse long-term outcomes compared to kidney transplant or other chronic illnesses. Additionally, the underlying membrane technology of polymer hollow-fiber membranes has not fundamentally changed in over four decades. Therefore, we have proposed a fundamentally different approach using microelectromechanical systems (MEMS) fabrication techniques to create thin-flat sheets of silicon-based membranes for implantable or portable hemodialysis applications. The silicon nanopore membranes (SNM) have biomimetic slit-pore geometry and uniform pores size distribution that allow for exceptional permeability and selectivity. A quantitative diffusion model identified structural limits to diffusive solute transport and motivated a new microfabrication technique to create SNM with enhanced diffusive transport. We performed in vitro testing and extracorporeal testing in pigs on prototype membranes with an effective surface area of 2.52 cm² and 2.02 cm², respectively. The diffusive clearance was a two-fold improvement in with the new microfabrication technique and was consistent with our mathematical model. These results establish the feasibility of using SNM for hemodialysis applications with additional scale-up.