A Novel Strategy to Engineer Pre-Vascularized Full-Length Dental Pulp-like Tissue Constructs

Abstract

The requirement for immediate vascularization of engineered dental pulp poses a major hurdle towards successful implementation of pulp regeneration as an effective therapeutic strategy for root canal therapy, especially in adult teeth. Here, we demonstrate a novel strategy to engineer pre-vascularized, cell-laden hydrogel pulp-like tissue constructs in full-length root canals for dental pulp regeneration. We utilized gelatin methacryloyl (GelMA) hydrogels with tunable physical and mechanical properties to determine the microenvironmental conditions (microstructure, degradation, swelling and elastic modulus) that enhanced viability, spreading and proliferation of encapsulated odontoblast-like cells (OD21), and the formation of endothelial monolayers by endothelial colony forming cells (ECFCs). GelMA hydrogels with higher polymer concentration (15% w/v) and stiffness enhanced OD21 cell viability, spreading and proliferation, as well as endothelial cell spreading and monolayer formation. We then fabricated pre-vascularized, full-length, dental pulp-like tissue constructs by dispensing OD21 cell-laden GelMA hydrogel prepolymer in root canals of extracted teeth and fabricating 500 µm channels throughout the root canals. ECFCs seeded into the microchannels successfully formed monolayers and underwent angiogenic sprouting within 7 days in culture. In summary, the proposed approach is a simple and effective strategy for engineering of pre-vascularized dental pulp constructs offering potentially beneficial translational outcomes.

Recent Advances in Photo-Crosslinkable Hydrogels for Biomedical Applications

“…UV light-crosslinked GelMA hydrogel has been used to create tissue engineered cartilage- and prevascularized dental pulp-like constructs for cartilage and tooth regeneration (Figure 3A), respectively [62,78]. Bioprinted articular cartilage-resident chondroprogenitor cell-laden GelMA hydrogel construct was shown to be more effective in non-hypertrophic neo-cartilage formation than chondrocyte- or mesenchymal stem cell-laden GelMA hydrogel construct [78].…”

“…For instance, when the pre-polymer concentration was increased from 5 to 15, enzymatic degradation of GelMA hydrogel was decreased from 83 to 22 after 1 day of incubation in collagenase solution [62]. On the other hand, when UV light exposure duration was increased from 2to 10min, degradation of GelMA hydrogel was decreased from 90 to 60 after 28days of immersion in collagenase solution [74].…”

“…Besides mechanical properties, the degradation rate of GelMA hydrogel can be tuned by varying the pre-polymer concentration and light exposure duration [62,67,74]. For instance, when the pre-polymer concentration was increased from 5 to 15, enzymatic degradation of GelMA hydrogel was decreased from 83 to 22 after 1 day of incubation in collagenase solution [62].…”

“… (A) Tooth regeneration; adapted with permission from [62]. (B) Air leak sealant; adapted with permission from [67] Elsevier (2017).…”

“…Photoinitiator concentration and light exposure duration are other parameters that can be used to tune the mechanical properties of GelMA hydrogel [59]. For example, by increasing concentration of Irgacure 2959 from 0.1 to 0.5 (w/v), elastic modulus of GelMA hydrogel was increased from 7 to 10kPa [62,72]. On the other hand, compressive modulus of GelMA hydrogel was increased from 0.68 to 2.03kPa when UV light exposure duration was increased from 15 to 40s (Table 3) [73].…”