Human Periodontal Ligament Stem Cell and Umbilical Vein Endothelial Cell Co-Culture to Prevascularize Scaffolds for Angiogenic and Osteogenic Tissue Engineering.

Zeqing Zhao,Qingchen Qiao,Yuxing Bai,Ke Zhang,Ning Zhang,Hockin H K Xu,Xianju Xie,Yaxi Sun,Li Zhang,Michael D Weir,Abraham Schneider

doi:10.3390/ijms222212363

Abstract

(1) Background: Vascularization remains a critical challenge in bone tissue engineering. The objective of this study was to prevascularize calcium phosphate cement (CPC) scaffold by co-culturing human periodontal ligament stem cells (hPDLSCs) and human umbilical vein endothelial cells (hUVECs) for the first time; (2) Methods: hPDLSCs and/or hUVECs were seeded on CPC scaffolds. Three groups were tested: (i) hUVEC group (hUVECs on CPC); (ii) hPDLSC group (hPDLSCs on CPC); (iii) co-culture group (hPDLSCs + hUVECs on CPC). Osteogenic differentiation, bone mineral synthesis, and microcapillary-like structures were evaluated; (3) Results: Angiogenic gene expressions of co-culture group were 6–9 fold those of monoculture. vWF expression of co-culture group was 3 times lower than hUVEC-monoculture group. Osteogenic expressions of co-culture group were 2–3 folds those of the hPDLSC-monoculture group. ALP activity and bone mineral synthesis of co-culture were much higher than hPDLSC-monoculture group. Co-culture group formed capillary-like structures at 14–21 days. Vessel length and junction numbers increased with time; (4) Conclusions: The hUVECs + hPDLSCs co-culture on CPC scaffold achieved excellent osteogenic and angiogenic capability in vitro for the first time, generating prevascularized networks. The hPDLSCs + hUVECs co-culture had much better osteogenesis and angiogenesis than monoculture. CPC scaffolds prevacularized via hPDLSCs + hUVECs are promising for dental, craniofacial, and orthopedic applications.

Highlights

Regeneration of large skeletal defects remains a major challenge in bone tissue engineering
The objectives of this study were to: (1) co-culture human periodontal ligament stem cells (hPDLSCs) with human umbilical vein endothelial cells (hUVECs) for prevascularization of calcium phosphate cement (CPC) scaffolds for the first time; (2) compare the osteogenic effects of monocultured hPDLSCs and hPDLSCs co-cultured with hUVECs; and (3) compare the angiogenic effects of monocultured and co-cultured hPDLSCs and hUVECs
The results of this study demonstrate that CPC scaffold prevascularized via co-seeding of hPDLSCs and hUVECs is a promising strategy for periodontal tissue regeneration and bone tissue engineering applications

Summary

Introduction

Regeneration of large skeletal defects remains a major challenge in bone tissue engineering. Prevascularized bone grafts were developed to address this problem [2]. Several animal studies indicated that the pre-built microcapilliary-like structures of prevascularized bone grafts eventually interconnected into the microvascular network of hosts [4]. Seeding blood vessel-forming cells onto scaffolds is the most widely used in vitro prevascularization method [3]. Vascular endothelial cells (VECs) play a critical role in angiogenesis. Co-culturing VECs and osteogenic cells (such as osteoblasts and mesenchymal stem cells (MSCs)) is a valid strategy to generate stable vascular structures [5]. The capillary-like structures formed by VECs were stable in the presence of MSCs due to their pericyte-like role in co-culture system [7]. MSCs can form a pericyte-like coverage around endothelial tubes, which enables the immature vessels to remain stable [7]

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Conclusion