Effects of the surface characteristics of polyhydroxyalkanoate (PHA) films on the behaviors of human mesenchymal stem cells (hMSCs)
Date Issued
2008
Date
2008
Author(s)
Yu, Bo-Yi
Abstract
Polyhydroxyalkanoates (PHAs) are a newer family of biomaterials for tissue engineering applications. Especially, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), the third generation commercializated product, attained lots of attention. Its mechanical and processible properties have been shown to better than that of PHB and PHBV. Human mesenchymal stem cells (hMSCs) have great proliferation and differentiation abilities without an ethic problem in obtaining. The aim of this study was to present a deeper picture of the relationship between hMSCs and the surface characteristics of PHAs films. In other words, it is to investigate the behaviors of human mesenchymal stem cells (hMSCs) grown on the surface of various PHA membranes and to evaluate if PHAs have potential application in regenerative medicine. The surface characteristics of PHA copolymer membranes were varied by the content of 3-hydroxyvalerate (HV) or 3-hydroxyhexanoate (HHx) and by the membrane preparation methods such as compression-molding, solvent-casting and electrospinning methods. Hyaluronic acid (HA) and poly acrylic acid (PAAc) were further applied to modify the surface properties of the PHA membranes. The acrylic acid molecules were grafted on PHBHHx membrane surface by UV irradiation. hen the HV content increased, the crystallinity and the hydrophobicity of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) membranes reduced and the metabolic activity of hMSCs improved after being cultured for three days. Hyaluronic acid (HA) coating on PHA membranes could improve the metabolic activity and reduce the death rate of hMSCs. HMSCs could adhere to the surface, and then spread, migrated, aggregated and formed cellular clusters with time only on the solvent-cast PHBHHx films (the evaporation temperature was at 18 ℃). The hydrophilicity and surface roughness of various PHBHHx films were controlled by adjusting the acrylic acid concentration and the UV irradiation time. The hydrophilicity could effectively improve the spread of hMSCs, and the orientation of surface scars could guide the growth direction of cytoskeleton (actin) inside hMSCs. he behaviors of hMSCs were modulated by the surface characteristics of these films although the base material was all the same. HMSCs could also adhere to the surface, and then spread, migrate, aggregate and form cellular clusters with time on the solvent-cast PHBHHx films (the evaporation temperature was at 32 ℃). HMSCs needed more time to form cellular aggregation on the solvent-cast film with an arising degree of the surface roughness. HMSCs at the aggregative status on the solvent-cast film kept their original surface markers and presented obviously higher viability and lower differentiation ability than that at the spreading status on the compression-molded films or TCPS. HMSCs spread well on the surface and performed a regular orientation on the random electrospun fibrous films. Although hMSCs was not able to migrate into the interior of electrospun film, the interconnected porous structure of this film have an obvious influence on the behaviors of hMSCs. The chemical signals and mitogens produced by hMSCs itself or the growth factor in the medium could easily transport through the connected pores within the films. HMSCs on the electrospun films revealed the highest viability but the second lowest differentiation activity among that on all the tested films. The electrospun fibrous PHBHHx films are able to serve as suitable substrates for large quantity culturing of hMSCs when undifferentiated hMSCs are desired. The morphology, proliferation and differentiation of hMSCs were remarkably influenced by various surface characteristics of the PHA membranes.
Subjects
cell-substrate interaction
cell aggregation
electrospun films
stem cells
SDGs
Type
thesis
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