Evaluation of RGD Modification on Collagen Matrix

Indirect co-culture of osteoblasts and endothelial cells in vitro based on a biomimetic 3D composite hydrogel scaffold to promote the proliferation and differentiation of osteoblasts

The field of orthopedics has long struggled with the challenge of repairing and regenerating bone defects, which involves a complex process of osteogenesis requiring coordinated interactions among different types of cells. The crucial role of endothelial cells and osteoblasts in bone vascularization and osteogenesis underscores the importance of their intimate interaction. However, efforts to bioengineer bone tissue have been impeded by the difficulty in establishing proper angiogenesis and osteogenesis in tissue structures. This study presents a novel approach to bone tissue engineering, involving a three-dimensional composite hydrogel scaffold composed of sodium alginate microspheres encapsulated in type I collagen. Using this scaffold, a three-dimensional indirect co-culture system was established for osteoblasts and endothelial cells to evaluate the osteogenic differentiation potential of osteoblasts. Results demonstrate that the non-contact co-culture system of endothelial cells and osteoblasts constructed by the composite hydrogel scaffold loaded with microspheres holds promise for bone tissue engineering. The innovative concept of an indirect co-culture system presents exciting prospects for conducting intercellular communication studies and offers a valuable in vitro tissue platform to investigate tissue regeneration.

A novel mixed-type stem cell pellet for cementum/periodontal ligament-like complex

BACKGROUND

Functional tissue regeneration underscores the construction of favorable extracellular matrix environment and neovascularization. In this study, we propose a mixed-type stem cell-pellet cultivation system for human periodontal ligament stem cells (hPDLSCs) to recreate a favorable regeneration microenvironment.

METHODS

The hPDLSCs were cocultured with human bone marrow mesenchymal stem cells (hBMMSCs) and mixed by osteoinduced ceramic bovine bone (CBB) powder as a mixed-type stem cell sheet. The influence of osteoinduced CBB on hPDLSCs was analyzed by alkaline phosphatase (ALP) and osteogenic differentiation assays. The effects of hBMMSCs on hPDLSCs were estimated by proliferating cell nuclear antigen, ALP, real-time reverse transcription polymerase chain reaction, and Western blot assays. The mixed-cell sheet was the preliminary observations in vitro that laid the foundation for additional implantation. After the cells were detached, the mixed-type sheet spontaneously contracted to produce a mixed-type stem cell pellet, which was transplanted into immunocompromised mice.

RESULTS

In vitro, the results showed that osteoinduced CBB could upregulate ALP activity and accelerate mineralization of hPDLSCs. When the hPDLSCs were cocultured with hBMMSCs, the ALP activity and proliferation kinetics were upregulated and also indicated in the expression of collagen I, osteocalcin, and vascular endothelial growth factor. It was found that, in vivo, the mixed-type hPDLSC pellets support cementum/periodontal ligament (PDL)-like tissue regeneration with neovascularization.

CONCLUSIONS

These results suggest that the mixed-type hPDLSC pellet could mimic the microenvironment of PDL and enhance the reconstruction of physiologic architecture of a dental cementum/PDL-like complex. This tissue mimicking may also be a promising alternative to promote periodontal defect repair for additional clinical applications.