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3D-bioprinted HERS-DPCs for Alveolar Bone Regeneration
culturing for 1, 4, and 7 days. According to the statistical arrow) and proliferated since day 3. To evaluate the
results (Figure 2C), the cells encapsulated in GelMA cells proliferation, cell number and cell confluence
showed high viability (all over 80% on days 1, 4, and 7) were calculated (Figure 4D and E). The number and
and GelMA was proved biocompatible in 3D bioprinting. confluence of cells increased significantly, indicating
rapid cell proliferation at this stage.
3.3. HERS-DPCs interaction
To observe the interaction of HERS cells and DPCs in 3.5. Alveolar socket transplantation in SD rats
the 3D-printed GelMA scaffold in vitro, HERS cells were In the process of alveolar socket transplantation in SD rats,
marked red and DPCs were marked green (Figure 3A). we first exposed the right posterior area of maxillary bone
Next, we recorded the confocal images on day 0, day 3, clearly (Figure 4F, a) and took a digital X-ray film before
and day 8. The results indicate that HERS cells and tooth extraction (Figure 4G, a). Then the first and second
DPCs migrated to each other along the scaffold on day 8 molars were extracted completely (Figure 4F, b and c)
(Figure 3B and Figure S3). The corresponding 3D videos before mechanical preparation of the alveolar bone defect
of printed constructs were shown in Figures S4-S6 and (Figure 4F, d). After transplanting the constructs, the
the graph schema showed the migration of the two kinds oral mucosa and skin were tightened with layered sutures
of cells (Figure 3C). (Figure 4F, e and f). At last, a digital X-ray film was
taken after operation (Figure 4G, b).
3.4. Microscopic observation of printed
construct 3.6. Histological and immunohistochemical
The staggered grid structure of GelMA hydrogel analysis of transplantation in vivo
scaffold was observed under optical and scanning The HE and Masson staining marked plenty of newly
electron microscopy (Figure 4A-C). Besides, cells formed collagen fiber in the operation area of all groups
crawled out from the scaffold (Figure 4C, red (Figure 5). The blank group, compared to other groups,
A C

B

Figure 2. Isolation, culture, identification, and viability of HERS cells. (A) The isolation, culture, and identification of primary HERS cells.
HERS cells expressed both epithelial marker CK14 and mesenchymal marker vimentin. (B) Live/dead images of HERS cells encapsulated
in GelMA hydrogel on days 1, 4, and 7. BF: Bright field; Merge 1, merge of Live and Dead images; Merge 2, merge of live, dead, and BF
images. (C) Quantitative analysis of cell viability, P < 0.001. HERS: Hertwig’s epithelial root sheath, GelMA: Gelatin methacrylate.
∗∗∗
144 International Journal of Bioprinting (2022)–Volume 8, Issue 3