Fabrication of gelatin methacrylate/nanohydroxyapatite microgel arrays for periodontal tissue regeneration

Abstract

Introduction

Periodontitis is a chronic infectious disease and is the major cause of tooth loss and other oral health issues around the world. Periodontal tissue regeneration has therefore always been the ultimate goal of dentists and researchers. Existing fabrication methods mainly focused on a top–down tissue engineering strategy in which several drawbacks remain, including low throughput and limited diffusion properties resulting from a large sample size. Gelatin methacrylate (GelMA) is a kind of photocrosslinkable and biocompatible hydrogel, with the capacities of enabling cell encapsulation and regeneration of functional tissues. Here, we developed a novel method to fabricate GelMA/nanohydroxylapatite (nHA) microgel arrays using a photocrosslinkable strategy. The viability, proliferation, and osteogenic differentiation and in vivo osteogenesis of human periodontal ligament stem cells (hPDLSCs) encapsulated in microgels were evaluated. The results suggested that such microgels provide great potential for periodontal tissue repair and regeneration.

Methods

Microgel arrays were fabricated by blending different weight ratios of GelMA and nHA. hPDLSCs were encapsulated in GelMA/nHA microgels of various ratios for a systematic evaluation of cell viability, proliferation, and osteogenic differentiation. In vivo osteogenesis in nude mice was also studied.

Results

The GelMA/nHA microgels exhibited appropriate microarchitecture, mechanical strength, and surface roughness, thus enabling cell adhesion and proliferation. Additionally, the GelMA/nHA microgels (10%/2% w/v) enhanced the osteogenic differentiation of hPDLSCs by elevating the expression levels of osteogenic biomarker genes, such as ALP, BSP, OCN, and RUNX2. In vivo ectopic transplantation results showed that GelMA/nHA microgels (10%/2% w/v) increased mineralized tissue formation with abundant vascularization, compared with the 1%, 3%, and the pure GelMA group.

Conclusion

The GelMA/nHA microgels (10%/2% w/v) facilitated hPDLSCs viability, proliferation, and osteogenic differentiation in vitro and further promoted new bone formation in vivo, suggesting that the GelMA/nHA microgels (10%/2% w/v) provide great potential for periodontal tissue regeneration.

Keywords:

• periodontal ligament stem cells
• gelatin methacrylate
• nanohydroxyapatite
• microgel array
• differentiation
• periodontal tissue regeneration

Supplementary material

Figure S1 Evaluation of degradation profile of cell-laden GelMA hydrogels.

Abbreviation: GelMA, gelatin methacrylate.

Acknowledgments

This work was financially supported by the National Natural Science Foundation of China grants (no 81271188 and no 81200823). The authors appreciate Prof Feng Xu and Doctor Yuhui Li from Bioinspired Engineering and Biomechanics Center (BEBC) of Xi’an Jiaotong University for their kind help.

Author contributions

YZ, SB, and XC designed the experiments. XC, BL, and HL performed the in vitro experiments. XC and SL performed the in vivo experiments. YZ and GW interpreted the results and revised the paper. XC wrote the main text of the manuscript. All authors contributed toward data analysis, drafting and revising the paper, and agreed to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.