In vitro comparative study of drug loading and delivery properties of bioresorbable microspheres and LC bead

Preparation and application of hemostatic microspheres containing biological macromolecules and others

Bleeding from uncontrollable wounds can be fatal, and the body's clotting mechanisms are unable to control bleeding in a timely and effective manner in emergencies such as battlefields and traffic accidents. For irregular and inaccessible wounds, hemostatic materials are needed to intervene to stop bleeding. Hemostatic microspheres are promising for hemostasis, as their unique structural features can promote coagulation. There is a wide choice of materials for the preparation of microspheres, and the modification of natural macromolecular materials such as chitosan to enhance the hemostatic properties and make up for the deficiencies of synthetic macromolecular materials makes the hemostatic microspheres multifunctional and expands the application fields of hemostatic microspheres. Here, we focus on the hemostatic mechanism of different materials and the preparation methods of microspheres, and introduce the modification methods, related properties and applications (in cancer therapy) for the structural characteristics of hemostatic microspheres. Finally, we discuss the future trends of hemostatic microspheres and research opportunities for developing the next generation of hemostatic microsphere materials.

Embolization therapy with microspheres for the treatment of liver cancer: State-of-the-art of clinical translation

Embolization with microspheres is a therapeutic strategy based on the selective occlusion of the blood vessels feeding a tumor. This procedure is intraarterially performed in the clinical setting for the treatment of liver cancer. The practice has evolved over the last decade through the incorporation of drug loading ability, biodegradability and imageability with the subsequent added functionality for the physicians and improved clinical outcomes for the patients. This review highlights the evolution of the embolization systems developed through the analysis of the marketed embolic microspheres for the treatment of malignant hepatocellular carcinoma, namely the most predominant form of liver cancer. Embolic microspheres for the distinct modalities of embolization (i.e., bland embolization, chemoembolization and radioembolization) are here comprehensively compiled with emphasis on material characteristics and their impact on microsphere performance. Moreover, the future application of the embolics under clinical investigation is discussed along with the scientific and regulatory challenges ahead in the field. STATEMENT OF SIGNIFICANCE: Embolization therapy with microspheres is currently used in the clinical setting for the treatment of most liver cancer conditions. The progressive development of added functionalities on embolic microspheres (such as biodegradability, imageability or drug and radiopharmaceutical loading capability) provides further benefit to patients and widens the therapeutic armamentarium for physicians towards truly personalized therapies. Therefore, it is important to analyze the possibilities that advanced biomaterials offer in the field from a clinical translational perspective to outline the future trends in therapeutic embolization.

Drug-eluting embolic microspheres: State-of-the-art and emerging clinical applications

INTRODUCTION

Drug-eluting embolic (DEE) microspheres, or drug-eluting beads (DEB), delivered by transarterial chemoembolization (TACE) serve as a therapeutic embolic to stop blood flow to tumors and a drug delivery vehicle. New combinations of drugs and DEE microspheres may exploit the potential synergy between mechanisms of drug activity and local tissue responses generated by TACE to enhance the efficacy of this mainstay therapy.

AREAS COVERED

This review provides an overview of key drug delivery concepts related to DEE microspheres with a focus on recent technological developments and promising emerging clinical applications as well as speculation into the future.

EXPERT OPINION

TACE has been performed for nearly four decades by injecting chemotherapy drugs into the arterial supply of tumors while simultaneously cutting off their blood supply, trying to starve and kill cancer cells, with varying degrees of success. The practice has evolved over the decades but has yet to fulfill the promise of truly personalized therapies envisioned through rational selection of drugs and real-time multi-parametric image guidance to target tumor clonality or heterogeneity. Recent technologic and pharmacologic developments have opened the door for potentially groundbreaking advances in how TACE with DEE microspheres is performed with the goal of achieving advancements that benefit patients.

Long-Term Implantability of Resorbable Carboxymethyl Cellulose/Chitosan Microspheres in a Rabbit Renal Arterial Embolization Model

PURPOSE

To determine the physiologic response to resorbable carboxymethyl cellulose/chitosan (CMC/CN) microspheres in a long-term rabbit model, including the clinical response, gross pathology, and histopathology.

MATERIALS AND METHODS

Six rabbits were embolized with CMC/CN microspheres (300-500 µm) in one kidney via an inferior renal artery branch. Angiography was performed immediately before and after embolization and prior to killing at 6 months (180 ± 7 days, n = 3) and 12 months (365 ± 10 days, n = 3). A complete necropsy was performed on each animal with dissection of the kidneys and harvesting of additional tissues as per ISO-10993-part 6 and ISO-10993-part 11 guidelines. All tissues were processed and stained for pathological analysis.

RESULTS

The caudal third of target kidneys was successfully embolized with CMC/CN microspheres. Over the course of the study, there were neither notable clinical signs in either embolization group nor significant changes in the tissue/body weight ratio between 6- and 12-month time points. Gross examination revealed that all embolized kidneys had morphologic features consistent with infarction resulted from microsphere delivery. The percentage of infarction decreased from 9.1% ± 5.7% at 6 months to 1.9% ± 0.4% at 12 months. Microscopically, infarcted areas demonstrated evidence of chronic injury and repair, including loss of renal parenchyma with replacement fibrosis, tubular regeneration, and minimal to mild lymphoplasmacytic inflammation without any active changes such as necrosis or neutrophilic inflammation.

CONCLUSION

No systemic toxicity was observed in the animals 6 and 12 months after CMC/CN microspheres delivery. The local tissue response was mild.