Abstract
Objective: This study aimed to observe the cell growth status and multidirectional differentiation ability in a 3D-bioprinted tissue model of self-assembled nanopeptides and human adipose-derived mesenchymal stem cells (Ad-MSCs).Methods: Primary Ad-MSCs were isolated, cultured, and identified by flow cytometry. Tissue models were printed via 3D bioprinting technology using a “biological ink” consisting of a mixed solution of self-assembled nanopeptides and Ad-MSCs. Ad-MSCs were induced into osteogenic, adipogenic, and endothelial differentiation and compared with the control groups by staining.Results: The nanopeptide fiber was 10–30 nm in diameter and 200–500 nm in length under the atomic-force microscope. It had the characteristics of nano-scale materials. Flow cytometry showed that the isolated and cultured cells were positive for CD29 (98.51%), CD90 (97.87%), and CD166 (98.32%) but did not express CD31 (1.58%), CD34 (2.42%), CD45 (2.95%), or human leukocyte antigen (HLA)-DR (0.53%), consistent with the immunophenotype of Ad-MSCs. Then, a tissue model was printed using the biological ink, followed by induction of differentiation of Ad-MSCs within the tissue model. Alizarin red S staining showed the formation of calcium nodules in the osteogenesis induction experimental group, and oil red O stained lipid droplets in Ad-MSCs in the adipogenesis induction experimental group, whereas the two control groups were not stained.Conclusion: Ad-MSCs from primary cultures have the characteristics of stem cells. Self-assembled nanopeptide hydrogel is a good tissue engineering material that can serve as an extracellular matrix. Ad-MSCs in the 3D-printed tissue model using a biological ink consisting of a mixed solution of self-assembled nanopeptides and Ad-MSCs grew well and still had strong differentiation ability.
Highlights
Stem cell differentiation is related to the pre-existing programming inside the cell and regulated by the microenvironment in which the cell is located
Regulation of stem cell differentiation mainly occurs between cells and between the cell and the extracellular matrix, with cytokines fulfilling the functions of signal transduction and nutrition between cells and between the cell and the extracellular matrix
Zuk et al isolated, cultured, and identified adipose tissue–derived mesenchymal stem cells (Ad-MSCs) and showed that under specific induction conditions, Ad-MSCs could differentiate into osteoblasts, chondrocytes, adipocytes, cardiac muscle cells, and endothelial cells, making them new seed cells of great interest (Shojaei et al, 2013; Minonzio et al, 2014)
Summary
Stem cell differentiation is related to the pre-existing programming inside the cell and regulated by the microenvironment in which the cell is located. The common materials for the preparation of extracellular matrix scaffold include alginate, polysaccharide and collagen, and artificial degradable materials such as PLA, polyhydroxyacetic acid and PLGA (Romagnoli et al, 1990; Saito et al, 2005). Both kinds of biomaterials have no biological activity, can not simulate the micro environment of normal tissue, and have certain limitations, which make seed cells unable to fully play their cell activities and functions. It is difficult to use these biomaterials to study completely controllable in clinical (Diduch et al, 2000; Jiang et al, 2014)
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