Biological Consequences of using Ferrofluids for Surgical Retraction

Background: Minimal access surgery (MAS) allows access to the internal anatomy using slender instruments via sealed ports, thus reducing traumatic insult, post-operative pain and hospitalisation times with accelerated recovery to resuming full activity. The instruments for MAS include devices for direct tissue manipulation, e.g. forceps, graspers and retractors and in order to provide sufficient traction often incorporate ridges or toothed patterns, which inflict significant trauma on the tissues. Magnetic retraction using ferromagnetic nano- or microparticles offers an advantage over retraction using graspers because of the reduced tissue trauma with the added potential for noncontact retraction for tumour resection. Several recent studies have indicated that injected ferrofluids provide sufficient magnetic forces for localised tissue retraction. However, the biological consequences and tissue reaction to these particles have not been investigated.

Aims, Objectives and rationale: The aims of this project are to investigate the response of specific peritoneal cells (1777N Rpmet, a human peritoneal epithelial cell line, and human colon fibroblast cell line) to challenge with different concentrations of ferromagnetic micro and nanoparticles (stainless steel AISI 410 powder and superparamagnetic iron oxide nanoparticles (SPION)) in 2D tissue culture, in order to gain an understanding of the cellular responses to these particles in terms of cytotoxicity, inflammatory responses, and intracellular location. Simple organ culture will be also attempted to investigate particle uptake and location of the particles within the tissue over time. The combination of 2D tissue culture and 3D organ culture models will provide insight into the cellular responses and potential adverse tissue responses to ferrofluids for use in surgery.

Cell proliferation, viability and inflammatory responses will be investigated using ATP-Lite (cytotoxicity) and quantified using confocal microscopy, fluorescence microscopy, RT-PCR, ELISA and immunocytochemistry. Tissue responses and particle location will be investigated using a combination of histology, immunohistochemistry, XTT cell viability assay, live/dead staining and both scanning (FEGESEM) and transmission electron microscopy.