Electrospinner: Preparation of hDPSC-GelMA dental pulp regeneration microspheres using electrostatic microdroplet method

Background

In recent years, microsphere systems have attracted widespread attention as stem cell carriers in the field of dental pulp regeneration due to their injectability, rapid material exchange ability, and ability to simulate natural three-dimensional environments. However, according to current literature reports on dental pulp regeneration, the microsphere materials used still have problems such as slow degradation and poor cell adhesion, which are not conducive to the regeneration of dental pulp tissue. Therefore, it is very necessary to develop or find suitable microsphere preparation materials for dental pulp regeneration.

Recently, Professor Tian Weidong's team at the West China Hospital of Stomatology, Sichuan University, used an electrostatic droplet device consisting of a microinjection pump and a high-voltage electrostatic field generator, combined with the light-cured GelMA hydrogel provided by the EFL team, to prepare GelMA microspheres carrying human dental pulp stem cells (hDPSC), and studied their application potential in dental pulp regeneration. The related paper "hDPSC-laden GelMA microspheres fabricated using electrostatic microdroplet method for endodontic regeneration" was published in "Materials Science & Engineering C", with Master Yang Ting as the first author, Associate Researcher Xie Li and Professor Tian Weidong as the corresponding authors.

The overall idea of this study (Figure 1) is to first use a cell suspension made by mixing human dental pulp stem cells (hDPSC) and GelMA solution as a precursor solution, then use an electrostatic droplet device to prepare cell-loaded microspheres, and culture them in ultra-low adhesion culture plates for subsequent experiments such as cell behavior, cryopreservation and recovery, and in vivo transplantation.

The main point of this paper

First, the researchers tested the particle size, surface morphology, cross-sectional structure and elastic modulus of GelMA microspheres and hDPSC-loaded GelMA microspheres in detail, and tested the swelling and degradability of GelMA materials (Figure 2). The diameter of GelMA microspheres is about 200 µm, and the diameter of GelMA microspheres encapsulating hDPSCs is slightly larger, which can ensure better oxygen supply to the cells in the microspheres. The surface of freeze-dried GelMA microspheres showed a wrinkled porous morphology, while the surface of freeze-dried GelMA microspheres loaded with hDPSCs shrank after 7 days of culture. It is worth mentioning that the elastic modulus of cell-loaded GelMA microspheres is similar to that of natural human pulp tissue. GelMA microspheres have a certain swelling rate. In vitro degradation experiments show that the microspheres have good degradation properties in the presence of collagenase.

Subsequently, by culturing the hDPSC-loaded GelMA microspheres in vitro for 2 weeks (Figure 3), it can be observed that the cells in the GelMA microspheres always maintain a high survival rate (>90%), and continue to adhere, stretch, proliferate, and secrete a large amount of extracellular matrix.

Afterwards, the researchers also experimented on the feasibility of cryopreservation of hDPSC-loaded GelMA microspheres. The hDPSC-loaded GelMA microspheres pre-cultured for 1 day and cultured for 7 days were frozen for 3 months. Figure 4 shows the morphology and cytological behavior of the two microspheres after recovery. The continued cultivation of the recovered microspheres showed that the newly recovered GelMA microspheres not only maintained the integrity of the microsphere structure and a high cell survival rate (>70%), but also increased with the extension of the culture time. Cell survival rate and spreading occurred.

Finally, in order to verify the potential of cell-loaded hydrogel microspheres to regenerate dental pulp-like tissue in vivo, the researchers conducted tissue regeneration experiments in nude mice (Figure 5). hDPSC-loaded GelMA hydrogel microspheres and GelMA hydrogel clumps loaded with the same number of hDPSCs were compounded into the dentin segment to provide an odontogenic differentiation induction environment, and then implanted subcutaneously in nude mice for 8 weeks. The ability of regenerating dental pulp tissue and the in vivo degradation of the hydrogel were compared. The results showed that hDPSC-loaded GelMA hydrogel microspheres could not only regenerate more vascularized dental pulp-like tissue, but also the material was almost completely degraded.

In summary, this study used the electrostatic droplet method to prepare hDPSC-loaded GelMA microspheres for dental pulp regeneration. They showed excellent bioactivity and cryopreservation performance in vitro, and were superior to hydrogel clumps in in vivo degradation performance and dental pulp tissue regeneration ability. Therefore, cell-loaded gel microspheres have great application potential in dental pulp regeneration.

Electrospinning Nanofibers Article Source:

https://www.sciencedirect.com/science/article/pii/S0928493120337693?via%3Dihub