Calcium Chloride/Chitosan-Crosslinked Alginate Microcapsules for Enhanced Parathyroid Cell Transplantation

Abstract

Allogeneic parathyroid transplantation is the only treatment for hypoparathyroidism characterized by low serum parathyroid hormone (PTH). This study aimed to enhance the encapsulation properties of alginate by incorporating chitosan into the gelling solution to produce durable therapeutic microcapsules suitable for transplantation. Alginate microcapsules were prepared individually using a standard and chitosan-containing gelling solution with pH values of 3.25, 4.75, and 5.65. The microcapsules were evaluated regarding capsule durability and microstructure by compression test, FTIR, and SEM. Parathyroid cell-encapsulated microcapsules were examined for two weeks to assess cell viability and PTH secretion. Viability test revealed that pH conditions did not exhibit cytotoxic effects. Moreover, microcapsules maintained their structural integrity and secreted PTH (>1000 pg/mL). Compression test showed a 50% deformation of microcapsules generated by increasing pH conditions and standard methodology upon exposure to forces of 0.266 +/- 0.035 N, 0.272 +/- 0.029 N, 0.316 +/- 0.028 N, and 0.241 +/- 0.035 N, respectively. SEM revealed that chitosan-crosslinked microcapsules exhibited reduced pore sizes and an increase in pore wall thickness. These improvements may potentially extend the lifespan and offer a promising approach to developing more resilient and effective therapeutic microcapsules for clinical applications. These positive findings pave the way for further preclinical studies.