Surface Microstructure on Hydroxyapatite Spherules and Its Regulation on Stem Cells

doi:10.15541/jim20160260

Abstract

Abstract:

HA spheres with different surface microstructures were prepared by a Sol-Gel route with various hydroxyapatite (HA)/chitin ratios. The surface morphologies, phase compositions, and biomimetic mineralization ability of samples were respectively analyzed with scanning electron microscopy (SEM), X-ray diffraction (XRD), and biomimetic mineralization test. Furthermore, the influences of the surface microstructure on biological behavior of bone marrow-derived mesenchymal stem cells were examined by Alamar blue, SEM, alkaline phosphatase assay and flow cytometry. When the mass ratio of HA/Chitin was increased from 4/1 to 35/1, the surface microstructure of HA spheres changed substantially, as showed by a reduction of micro-porosity from (35%±0.8%) to (10.4%±0.7%), decrease of surface roughness, and gradual disappearance of micro-creases. The result of biomimetic mineralization test showed that the surface microstructure had important influence to the ability of biomimetic mineralization for HA spheres. In vitro culture of bone marrow-derived mesenchymal stem cells demonstrated that the rougher sphere surface, with abundant micro-creases and micro-pores, supported cell spreading and proliferation. In comparison, the smoother sphere surface with fewer micro-pores effectively induced cell elongation and up-regulated ALP expression, which suggested stem cells osteogenic differentiation. Meanwhile, the surface microstructure of spherules also modulated the expression of characteristic antigen makers on the surface of stem cells.

Key words: hydroxyapatite, surface microstructure, stem cell, biological behavior

CLC Number:

R318
TQ174

ZHI Wei, SHI Feng, LI Jing-Yu, ZHOU Teng, QU Shu-Xin, WANG Jian-Xin, ZHANG Cong, WENG Jie. Surface Microstructure on Hydroxyapatite Spherules and Its Regulation on Stem Cells[J]. Journal of Inorganic Materials, 2017, 32(3): 319-325.

Figures/Tables 8

Fig. 1 XRD patterns of HA4 spherules and HA35 spherules

Fig. 2 SEM images of surface HA spheres with different initial ratios of Chitin/HAa1, b1: HA4; a2, b2: HA10; a3, b3: HA20; a4, b4: HA30; a5, b5: HA35

Table 1 Microporosity and specific surface area of HA spheres with different ratios of HA/Chitin

HA/Chitin	Micro-porosity/%	BET/(m²·g^-1)
4/1	35±0.8	152.49
10/1	30.1±0.9	/
20/1	25.7±0.4	86.39
30/1	19.6±0.5	/
35/1	10.4±0.7	17.25

Fig. 3 SEM images of the surface of HA spheres (a, b) mineralized for 3 da1, b1: HA4; a2, b2: HA20; a3, b3: HA35

Fig. 4 SEM images of BM-MSCs cultured on HA spehres with different surface microstructures after 3 da, d: HA4; b, e: HA20; c, f: HA35

Fig. 5 Proliferation of BM-MSCs cultured on tissue culture plates and HA spheres with different surface microstructures at 1, 3, 5 and 7 d(* represents statistical difference, P<0.05)

Table 2 Surface characteristic markers expression of BM- MSCs cultured on HA spheres with different surface microstructures after 7 d

	CD29	CD44	CD90
Control	99.2%	93%	98.9%
HA₄	89.4%	67%	90.9%
HA₂₀	74.6%	56%	76.0%
HA₃₅	66.9%	40%	59.7%

Fig. 6 Expression of ALP of BM-MSCs cultured on HA spheres with different surface microstructures at 7 d(* represents statistical difference, P<0.05)

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