Self-Expanding Anchors for Stabilizing Percutaneously Implanted Microdevices in Biological Tissues.

Sharath Bhagavatula,Oliver Jonas,Irfanullah Haider,Devon Thompson,Christine Dominas

doi:10.3390/mi12040404

Sharath Bhagavatula, Oliver Jonas + Show 3 more

Open Access

https://doi.org/10.3390/mi12040404

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Abstract

Percutaneously implanted miniaturized devices such as fiducial markers, miniaturized sensors, and drug delivery devices have an important and expanding role in diagnosing and treating a variety of diseases. However, there is a need to develop and evaluate anchoring methods to ensure that these microdevices remain secure without dislodgement, as even minimal migration within tissues could result in loss of microdevice functionality or clinical complications. Here we describe two anchoring methods made from biocompatible materials: (1) a self-expanding nitinol mesh anchor and (2) self-expanding hydrogel particles contained within pliable netting. We integrate these anchors into existing drug-screening microdevices and experimentally measure forces required to dislodge them from varying tissues. We report similar dislodgement forces of 738 ± 37, 707 ± 40, 688 ± 29, and 520 ± 28 mN for nitinol-anchored microdevices, and 735 ± 98, 702 ± 46, 457 ± 47, and 459 ± 39 mN for hydrogel-anchored microdevices in liver, kidney, fat, and muscle tissues, respectively—significantly higher compared with 13 ± 2, 15 ± 3, 15 ± 2, and 15 ± 3 mN for non-anchored microdevices (p < 0.001 in all tissues). The anchoring methods increased resistance to dislodgement by a factor of 30–50× in all tissues, did not increase the required needle gauge for insertion, and were compatible with percutaneous implantation and removal. These results indicate that anchoring significantly improves microdevice stability and should reduce migration risk in a variety of biological tissues.

Highlights

IntroductionThere has been increasing emergence of implantable device technologies that can be directly inserted into patients’ tissues (in vivo) to carry out specific functions
This allows numerous drugs to be tested immediately without exposing patients to prolonged trials of toxic and potentially ineffective systemic chemotherapy trials. This has been shown in several pre-clinical models to be capable of optimizing systemic treatment strategies, and early clinical trials have been promising [7,8,9,10]
We have previously developed a method for minimally invasive removal of implanted implantable microdevice (IMD) [14]

Summary

Introduction

There has been increasing emergence of implantable device technologies that can be directly inserted into patients’ tissues (in vivo) to carry out specific functions Such technologies include fiducial markers and brachytherapy seeds for radiation treatment [1,2], biopsy markers for tumor localization, and emerging preclinical and early clinical devices for precision drug delivery, disease monitoring, and early detection [3,4,5,6]. After ~1–3 days to allow each drug to interact with the tissue, the microdevice and adjacent tissue are removed and evaluated histologically to determine the efficacy of each drug and identify the optimal systemic treatment This allows numerous drugs to be tested immediately without exposing patients to prolonged trials of toxic and potentially ineffective systemic chemotherapy trials. This has been shown in several pre-clinical models to be capable of optimizing systemic treatment strategies, and early clinical trials have been promising [7,8,9,10]

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