Polymers, Colloids & Interfaces, Short talk
PI-027

Alginate-based hydrogels as multifunctional materials for cell transplantation, and production of microspheres with a microfluidic technique

L. Szabo1, S. Gerber-Lemaire1*
1Institute of chemical sciences & engineering, EPFL Lausanne, 2Institute of chemical sciences & engineering, EPFL, 3Univ. Grenoble Alpes, CEA, LETI, DTBS, LSMB, Grenoble, France

Transplantation of encapsulated xenogeneic cells is a promising treatment alternative for several diseases, where shortage of human donors and the invasive nature of surgery puts the lives of patients at risk. The main field of application is Type I diabetes treatment, where encapsulation of islet producing cells provides protection to the cells while allowing an insulin release to control blood glucose levels.1 The main shortcomings of the encapsulation materials include instability and poor durability, and the fibrotic cellular overgrowth around the transplanted microspheres. In addition, the field would benefit from new technologies, such as microfluidics, that produce monodisperse microspheres of desired sizes with a high throughput.

We developed a hydrogel matrix that targets the two main issues related to encapsulation materials; enhances stability and elutes anti-inflammatory drugs to mitigate fibrosis. PEGylated alginate hydrogels were prepared by a robust, straightforward grafting process, that resulted in hydrogels with either a reactive functionality to provide a strong covalent cross-linking,2 or with an anti-inflammatory compound that is released via a hydrolytic reaction.3 Combination of these PEGylated alginate derivatives led to multifunctional microspheres presenting improved stability, resistance and shape recovery performance compared to unmodified Ca-alginate microspheres, and eluted ketoprofen anti-inflammatory drug for over two weeks in a sustained, controlled manner.

In addition, cross-linked PEGylated alginate and ketoprofen drug eluting hydrogel microspheres were produced with a microfluidic system. Encapsulation of neonatal pig islets within these materials resulted in good cell viability and homogeneous microcapsules of around 400 µm diameter.

[1] David W. Scharp, Piero Marchetti, Advanced Drug Delivery Reviews, 2014, 67-68, 35-73.
[2] Luca Szabo et al. ACS Appl. Polym. Mater., 2019, 1, 1326-1333.
[3] François Noverraz et al. Bioconjugate Chem., 2018, 29, 1932-1941.