Effect of microcapsules’ mechanical stability on the encapsulated cells’ behavior

Abstract

Stem cell microencapsulation offers immunoprotection, utilizing natural polymers such as sodium alginate (SA), chitosan, and derivatives such as trimethyl chitosan (TMC). Additive minerals improve microcapsule properties and cell differentiation. Layering increases mechanical strength and shields cells from the host’s immune system. This study explores the impact of incorporating nano-hydroxyapatite (nHA) and graphene oxide (GO) into the three-layer alginate–TMC–alginate microcapsules housing human adipose mesenchymal stem cells (haMSCs). The experimental design focused on optimizing the mechanical stability, with the ideal GO and nHA contents identified as 0.81% and 34% w/w, respectively. Rheological analysis revealed enhanced mechanical consistency, evidenced by higher storage modulus and lower loss factor in the optimized sample. Viability of the microencapsulated haMSCs, assessed through acridine orange/propidium iodide staining and MTT assays, affirmed the nontoxic nature of the microcapsules. Osteogenic potential was evaluated via alkaline phosphatase (ALP) activity measurement and immunocytochemistry staining. Microcapsules containing nHA and GO exhibited significantly elevated ALP activity, underscoring the pivotal role of these additives in enhancing mesenchymal stem cell differentiation. The highest osteocalcin deposition occurred in the optimized and SA/nHA 40% w/w groups in the differentiation medium. This comprehensive investigation highlights the potential of three-layer microcapsules with nHA and GO for bone tissue engineering applications.

GRAPHICAL ABSTRACT

Keywords:

• Alginate
• encapsulation
• graphene oxide (GO)
• human adipose mesenchymal stem cells (haMSCs)
• mechanical stability
• nano-hydroxyapatite (nHA)

Acknowledgments

The authors would like to acknowledge the support received from Tarbiat Modares University during the study. Additionally, we appreciate Ms. Samira Jafarzadeh, Ms. Zahra Ghasemi, Mr. Hojjat Basati, and Mr. Alireza Zarei for their valuable contributions in revising the article.

Disclosure statement

No potential conflict of interest was reported by the author(s).