Calcein Binding to Assess Mineralization in Hydrogel Microspheres

Kristopher White; Rabab Chalaby; Gina Lowe; Jacob Berlin; Carlotta Glackin; Ronke Olabisi

doi:10.3390/polym13142274

Calcein Binding to Assess Mineralization in Hydrogel Microspheres

Polymers (Basel). 2021 Jul 11;13(14):2274. doi: 10.3390/polym13142274.

Authors

Kristopher White¹, Rabab Chalaby², Gina Lowe³, Jacob Berlin⁴, Carlotta Glackin³, Ronke Olabisi¹

Affiliations

¹ Department of Biomedical Engineering, The Henry Samueli School of Engineering, University of California-Irvine, Irvine, CA 92697, USA.
² Department of Materials Engineering, University of Technology, Baghdad 10066, Iraq.
³ Department of Neuroscience, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA.
⁴ Department of Molecular Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA.

Abstract

We describe a method to assess mineralization by osteoblasts within microspheres using calcein. Fluorescence imaging of calcein bound to the calcium in hydroxyapatite permits assessment of the mineralized portion of the extracellular matrix. Colorimetric imaging of Alizarin Red S complexed with calcium also gives measures of mineralization, and in tissue cultures calcein and Alizarin Red S have been shown to bind to the same regions of mineral deposits. We show that when the mineralization takes place within hydrogel microspheres, Alizarin Red S does not stain mineral deposits as consistently as calcein. As tissue engineers increasingly encapsulate osteoprogenitors within hydrogel scaffolds, calcein staining may prove a more reliable method to assess this mineralization.

Keywords: calcein; hydrogel; microsphere; mineralization; osteogenesis; polymer.