Advances in Degradable Embolic Microspheres: A State of the Art Review

Abstract

Considerable efforts have been placed on the development of degradable microspheres for use in transarterial embolization indications. Using the guidance of the U.S. Food and Drug Administration (FDA) special controls document for the preclinical evaluation of vascular embolization devices, this review consolidates all relevant data pertaining to novel degradable microsphere technologies for bland embolization into a single reference. This review emphasizes intended use, chemical composition, degradative mechanisms, and pre-clinical safety, efficacy, and performance, while summarizing the key advantages and disadvantages for each degradable technology that is currently under development for transarterial embolization. This review is intended to provide an inclusive reference for clinicians that may facilitate an understanding of clinical and technical concepts related to this field of interventional radiology. For materials scientists, this review highlights innovative devices and current evaluation methodologies (i.e., preclinical models), and is designed to be instructive in the development of innovative/new technologies and evaluation methodologies.

Interventional radiology for liver diseases

“…Interestingly, degradable starch microspheres combined with a chemotherapeutic are finding their way into clinical practice, even in advanced HCC [ 21 ]. Biodegradable microspheres are captivating with a range of “biogel” materials now under investigation [ 22 ]. First in queue for clinical testing are combined degradable and drug-eluting beads (BioPearl, Terumo), which might provide more insight into the anti-tumoral mode of action.…”

The feasibility of degradable glass microspheres as transient embolic medical devices

“…There is increasing emphasis on the development and use of degradable microspheres for transarterial embolization (TAE) indications. 1 Motivated by the improved patient experience which can arise as a result of transient ischemia of a target tissue(s), 2 it is contended that with suitable engineering, degradable microspheres may one day deliver the idealized performance requirements, 3 while minimizing the potential for long-term sequelae caused by permanent alterations in vascular capacity, histological architecture, and/or injury to both ‘on target’ and ‘off target’ locations. 4 Secondarily, the advantages of degradable embolic microspheres are thought to also include, but are not limited to, a reduction in duration of exposure to foreign materials for patients, and the ability to a repeat treatment(s) where necessary.…”

“…4 Secondarily, the advantages of degradable embolic microspheres are thought to also include, but are not limited to, a reduction in duration of exposure to foreign materials for patients, and the ability to a repeat treatment(s) where necessary. 2, 3 However, in order to attain safe and effective transient embolotherapy, appropriate user needs and design inputs must be balanced. 5 This is especially important when considering a degradable embolic; as the degradation timeline, and level of occlusion achievable, are critical parameters which much be considered during the clinical process.…”

“…Currently, there are a small number of transient embolization materials options available to the physician, each exhibiting functional limitations with respect to desired clinical attributes. 3 For example, the embolization effectiveness of gelatin sponge relies heavily on preparation technique (i.e. cutting and pumping slurries between syringes), which creates a broad range of particle sizes and unpredictable degradation timeframes 1 ; gelatin sponge particles (non-spherical) reported in the clinical literature exhibit particle size distributions from <500 µm to >2000 µm and degrade between 7 days and 3 months.…”

“…However, to date, no commercially available product allows for controlled degradation within a microsphere engineered for multimodal imageability. 3…”