In medicine biomaterials, in particular biodegradable materials are being increasingly used. On their own they serve as structural support and replacement, and as platforms for drug release, embedding of cells and tissue engineering. However, several materials and devices are unsuccessful in clinical tests as they do not function as anticipated from in vitro experiments. There has not been concise method of predicting in vivo performance from in vitro experiments, restricting the development of novel materials and evaluation of safety, effectiveness and applicability of existing materials.

Dr. Natalie Artzi, a Research Scientist working with Prof. Elazer Edelman in the Biomedical Engineering Center, said:

“In many experimental studies, mice are euthanized to evaluate material fate and erosion. This process uses large number of animals and yet cannot provide sequential time-lapse measures of the same specimen, results in high variability and only a qualitative measure of erosion.”

In the design of erodible materials the crucial component is the ability to program their in vivo retention time, instructing the need for monitoring the effect of these devices in real time. This inspired Dr. Artiz who designed and directed the investigation to create ways to track erosion of devices in a noninvasive way and to predict their therapeutic capacity.

Elazer R. Edelman, principal investigator and MIT’s Thomas D. and Virginia W. Cabot Professor of Health Sciences and Technology, explained:

“This paper is exciting on multiple levels as it addresses at once multiple outstanding issues in materials science. The work explains how material function is context dependent and defines how, when and why observations in vitro can predict performance in vivo. These findings can now set the stage for characterizing material-tissue interactions on a broad scale, optimizing materials design, and developing novel materials for specific tissue, conditions and applications.”

In a recent article in Nature Materials, for the first time, the team which was led by Dr. Artzi, uniquely controlled fluorescence imaging to track material loss in vivo in a sequential manner. They also used mathematical modeling in order to figure out in vivo erosion of materials from in vitro erosion kinetics. These techniques can act as a rapid in vitro tool for screening material candidates and accelerate the development of medical devices.

They analyzed the effect of material shape, composition and environmental conditions dictated by the choice of implantation site, on the erosion profile of natural and synthetic materials. This profile dictates how effective the material is and when drugs and cells are embedded in to it, material erosion will dictate drug release and the cells effectiveness and secretion profile determining the therapeutic outcome.

Dr. Artzi explained:

“We envision that an integrative approach that considers dynamic changes in erodible materials and matches their properties with those of specific tissue type and state, will allow the development of medical devices with tunable and predictable clinical outcomes. The ability to detect and forecast the time course of in vivo erosion is crucial to the design, informed regulatory scrutiny and use of the increasing number of biomedical devices with erosive properties.”

Dr. Artzi and her team use these discoveries and methods to characterize and design composite materials that degrade in a programmed manner to enable programmed drug release and controlled cellular function for cardiovascular and cancer applications.

In addition to Artzi and Edelman, co-authors of the paper are Nuria Oliva, Cristina Puron, Sagi Shitreet, Shay Artzi, Adriana bon Ramos, Adam Groothuis, and Gary Sahagian.

The work was supported by NIH (GM/HL 49039, UL1 RR 025758) and the MIT Deshpande Centre.

Written by Grace Rattue