Researchers at the Adolphe Merkle Institute have developed a new method that mimics more closely injury and wound healing response in epithelial tissues that line the outer surfaces of organs throughout the body, as well as cavities in many internal organs. Besides providing additional knowledge about regeneration after injury, this should lead to a better understanding of how some nanomaterials affect cell mechanics during tissue repair.

The number of in vitro and in vivo toxicity studies of nanomaterials has increased dramatically over recent past decades. Unfortunately, the availability of information regarding the alteration of cell mechanics due to interaction with nanomaterials is still limited. Wound healing assays are one method extensively used to study tissue repair mechanisms; they are typically performed by physically detaching cells to create an open space in which live cells can lodge, which is not necessarily a true reflection of what happens in real life. This method is for example unsuitable for studying the repair response of tissue at a small injury site where dead cells are still present. The researchers from the AMI BioNanomaterials group chose another approach by inflicting damage on a specific zone of an assay of lung epithelial tissue using photobleaching, and leaving any dead cells in place. 

They found that healthy individual epithelial cells are able to clear the dead cells by pushing them to one side, unlike macrophages, the body’s cellular cleaning crew, which actively swallow cellular debris, creating an empty space. However, the push repair mechanism is hampered when carbon nanotubes (CNTs) are introduced, suggesting CNTs can interfere with lung repair, either by delaying or hindering wound recovery. Exposure to high aspect ratio nanomaterials such as these nanotubes has been shown to induce cell death and micro-injuries in epithelial lung tissue, potentially leading to pulmonary scarring (fibrosis). The AMI research could therefore also help understand the early development of fibrosis induced by CNTs in a wound healing context.

This study, whose results are published in the latest issue of the leading scientific journal Advanced Materials, are part of a wider effort undertaken by the AMI BioNanomaterials group under the leadership of co-chair Professor Barbara Rothen-Rutishauser to develop alternative methods to in vivo testing.

This project was featured on the cover of Advanced Materials:

Reference: Septiadi, D. , Abdussalam, W. , Rodriguez‐Lorenzo, L. , Spuch‐Calvar, M. , Bourquin, J. , Petri‐Fink, A. and Rothen‐Rutishauser, B. (2018), Bio‐nanomechanics: Revealing the Role of Epithelial Mechanics and Macrophage Clearance during Pulmonary Epithelial Injury Recovery in the Presence of Carbon Nanotubes. Adv. Mater., 30: 1870396. doi: 10.1002/adma.201870396