Lab-on-a-brane: nanofibrous polymer membranes to recreate organ–capillary interfaces

Significance Statement

It has been estimated that cancer will surpass cardiovascular disease as a leading cause of death which has led to vigorous investigation of improved treatment options and drug development in order to challenge this menace. However, drug research and development remains expensive and slow in large part due to inadequate methods for disease modeling and therapeutics evaluation.

In a recent article published in Journal of Micromechanics and Microengineering by Budhwani et al., the researchers from University of Alabama at Birmingham developed a platform in recapitulating blood vessel organ interface which simulates in vivo pressure, flow and stretch conditions essential to maintaining endothelial cell phenotype and functions for studying transendothelial molecular transport suitable for effective pharmacokinetic evaluation.

There has been a growing interest in exploring Microphysiological Systems (MPS) to complement or substitute in vivo animal models during research due to the fact that 90% of drugs that succeed in animal models subsequently fail in human trials. Investigations are underway to adapt microfluidics-based MPS platforms, known as organ-on-a-chip which are typically a single culture system, with multi-well or multi-chamber configurations to approximate multi-organ or full-body-lab-on-chips. Microporous membranes in these circuits-based microfluidic devices have been shown as an effective interface between pulmonary epithelial and endothelial cell layers. Moreover, repeating –O-Si(CH3)2– units in thin Polydimethylsiloxane layers, activated on both sides, have been used to create layered sandwich or 3D scaffold models.

Based on these, Budhwani et al. (2016), hypothesized that a nanofibrous microporous substrate, cultured with Smooth Muscle Cell layers on one side and an Endothelial Cell layer on the other,  sandwiched and securely bonded between Polydimethylsiloxane cell chamber housings in a nanofluidics pulsating flow configurations would form a convenient abstraction of in vivo arterial structure and physiological function effective for studying transendothelial molecular transport.

The platform designed by Budhwani et al. (2016) replaces the higher cost and complexity of photolithography with cost-effective and simple electro-spinning for membrane fabrication, and in so doing, deprecates the narrower “chip” in lab-on-a-chip in favor of a broader lab-on-a-brane class of platforms.

The nanofibrous membranes were manufactured by electrospinning 10 wt% solution, obtained by dissolving Nylon 6 pellets in 1,1,1,3,3,3-hexafluoro-2-propanol (HFP), directly onto Polydimethylsiloxane chambers. Scanning Electron Microscopy imaging confirmed that electrospun membranes were 70±20μm in thickness with non-beaded 425±157μm diameter fibers and up to 82% porosity. Fourier Transform Infrared spectroscopic analysis showed characteristics peak of amide-I (C=O) and oxide –II (C-N and N-H) to be 1648cm-1 and 1549cm-1 respectively. Infrared peaks corresponding to –CH2 associated with aliphatic chain of Nylon 6 were at 2911cm-1 and 2862cm-1 and IR peak due to N-H (Amide A) was seen to be 3291cm-1. Collagen+PLLA and collagen membranes had characteristics peaks associated with stretching vibration of C=O bond at 1644-1628cm-1 (amide I) and 1545cm-1 associated with bonding vibration of C-N and N-H bond.

Further results showed that stiffness for Nylon-6 and Collagen+PLLA nanofibrous membrane were consistent with previous values of collagen fibers, with Nylon-6 membrane having higher strength and durability. Chemical composition and Young’s Modulus were compared to and found to be compatible with in vivo vascular collagen matrix. Secure binding of nanofibrous membrane between cell chambers in a watertight seal was achieved using a self-rivet technique leveraging activation of repeating –O-Si(CH3)2– structural units in cell chamber PDMS surfaces.

Immunofluorescence microscopy confirmed actin filaments predominantly oriented towards the cell periphery and images show multiple layers of highly confluent smooth muscle micro-tissues across the entire area of the channels. Hemodynamic loading, hydraulic loading and hydraulic conductivity showed that membranes maintained integrity under in vivo hemodynamic loading. Structural and mechanical compliance was confirmed using confocal microscopy, Scanning Electron Microscopy imaging, stress/strain analysis and infrared spectroscopy.

Assessment of hydraulic conductivity was shown in two ways. At first, an independent flow sensor was connected to outlets leading to collector chambers and monitored to ensure no flow was recorded under hemodynamic loading. Secondly, FITC-labelled samples were collected periodically from across the interface and analyzed for transport and failure.

Budhwani et al. (2016), successfully fabricated and bonded biomimetic micro-porous membranes to cell culture chambers recapitulating anatomical and physiological organ-capillary interface and barrier functions in vitro.

lab-on-a-brane offers a highly effective and efficient, yet considerable inexpensive physiological relevant alternative for pharmacokinetic evaluation allowing more precise modelling and testing of specific biological environment when compared to animal studies.

 

Lab-on-a-brane: nanofibrous polymer membranes to recreate organ–capillary interfaces. Advances in Engineering

With recent interest in creating Microphysiological Systems constructed using human cells where complex interactions between different organ systems can be replicated, it is extremely critical to recreate the organ-capillary interfaces which represents the path for communication between circulating blood and perfused organs. The  ‘Lab-on-a-brane’ platform demonstrates that these interfaces can be created and studies can be performed with high physiological relevance” said Dr. Sethu who is an expert in microfluidics and bioengineering at UAB.

About the author

Karim I. Budhwani : In addition to his professional responsibilities as CEO of elixir international, Karim I. Budhwani serves as a lecturer at the University of Alabama’s School of Business and Information Systems covering Health Informatics, Globalization, and Operational Planning and Optimization.

He has served as Ambassador of Trade for his home State of Alabama on key trade missions to India, Australia, New Zealand, and Russia. He is recently retired as the Chairman for both the Ismail Professionals Network (IPN) USA and the broader Global IPN Forum (GIF) which spans over 15 countries on 5 continents. Karim received his Bachelor of Arts magna cum laude in Computer Science, Economics, and Business Administration from Coe College, IA in May 1993. He received his Master of Science in Biomedical Engineering from the University of Alabama at Birmingham (UAB), AL in May 2015.

He is currently also pursuing a PhD in Materials Science and Engineering and Biomedical Engineering with a focus in Nanomedicine at the UAB. Educated in true liberal arts tradition, he knows everything about nothing and nothing about everything; a 21st century polymath.  

About the author

Dr. Palaniappan Sethu is an Associate Professor of Medicine and Biomedical Engineering at the University of Alabama at Birmingham. He received his PhD at the University of Michigan in Biomedical Engineering and completed his postdoctoral training at the Center for Engineering in Medicine at Massachusetts General Hospital and Harvard Medical School.

Dr. Sethu’s research program focuses on development of physiologically relevant cell culture models for tissue engineering, drug discovery and testing and biotoxicity studies. His laboratory invented the Cardiac and Endothelial Cell Culture Models which represent the current state-of-the-art in cardiac and vascular cell culture.

About the author

Dr. Vinoy Thomas is an Assistant Professor at the Department of Materials Science & Engineering, University of Alabama at Birmingham (UAB) USA. He is also a Senior Research Scientist at the Center for Nanoscale Materials and Biointegration (CNMB). After his PhD in Biomaterials & Biomedical Technology from Sree Chitra Tirunal Institute for Medical Sciences & Technology (SCTIMST), India, he completed postdoctoral training at the Institute of Materials Sciences & Technology (IMST), Friedrich-Schiller University (FSU), Jena, Germany, and at the National Institute of Standards & Technology (NIST), Gaithersburg, MD [as NRC Fellow from National Research Council of National Academies (Science, Engineering & Medicine) USA].

Dr. Thomas is a life-member of Society for Biomaterials & Artificial Organs India (SBAOI) and Society for Tissue Engineering & Regenerative Medicine- India (STERMI), He serves in the Editorial Board of many journals in his discipline of Polymers/ Biomaterials, Tissue engineering & Drug delivery, and Nanoscience & Nanotechnology.

His research programs focus on the development of biomaterials and processing-structure-property characterizations of polymeric-nanocomposites and nano-scaffolds for tissue engineering (vascular, dental and spine & neural tissues), nanodiamonds for orthopedic and dental joints, materials chemistry of interfaces and interface tissue engineering. He has published more than 80 research papers.

Journal Reference

Karim I Budhwani1,2,3, Vinoy Thomas2,4 and Palaniappan Sethu1,5 . Lab-on-a-brane: Nanofibrous Polymer Membranes to Recreate Organ-Capillary Interface.  Journal of Micromechanics and Microengineering, 2016, Volume 26, Number 3.

[expand title=”Show Affiliations”]
  1. Department of Biomedical Engineering, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA
  2. Department of Materials Science and Engineering, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA
  3. Department of Radiation Oncology, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA
  4. Center for Nanoscale Materials and Biointegration (CNMB), University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA
  5. Department of Medicine, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA
[/expand]

 

 

Go To Journal of Micromechanics and Microengineering

 

 

Check Also

Applying electric field to assemble nanostructured filaments for sustainable electronics - Advances in Engineering

Applying electric field to assemble nanostructured filaments for sustainable electronics