Production of Human Dental Pulp Cells with a Medicinal Manufacturing Approach

Introduction: Human dental pulp cells (HDPCs) are generally isolated and cultured with xenogeneic products and in stress conditions that may alter their biological features. However, guidelines from the American Food and Drug Administration and the European Medicines Agency currently recommend the use of protocols compliant with medicinal manufacturing. Our aim was to design an ex vivo procedure to produce large amounts of HDPCs for dentin/pulp and bone engineering according to these international recommendations.

Methods: HDPC isolation was performed from pulp explant cultures. After appropriate serum-free medium selection, cultured HDPCs were immunophenotyped with flow cytometry. Samples were then cryopreserved for 510 days. The post-thaw cell doubling time was determined up to passage 4 (P4). Karyotyping was performed by G-band analysis. Osteo/odontoblastic differentiation capability was determined after culture in a differentiation medium by gene expression analysis of osteo/odontoblast markers and mineralization quantification.

Results: Immunophenotyping of cultured HDPCs revealed a mesenchymal profile of the cells, some of which also expressed the stem/progenitor cell markers CD271, Stro-1, CD146, or MSCA-1. The post-thaw cell doubling times were stable and similar to fresh HDPCs. Cells displayed no karyotype abnormality. Alkaline phosphatase, osteocalcin, and dentin sialophosphoprotein gene expression and culture mineralization were increased in post-thaw HDPC cultures performed in differentiation medium compared with cultures in control medium.

Conclusions: We successfully isolated, cryopreserved, and amplified human dental pulp cells with a medicinal manufacturing approach. These findings may constitute a basis on which to investigate how HDPC production can be optimized for human pulp/dentin and bone tissue engineering.