Efeitos do hialuronato de sódio e dos nanotubos de carbono funcionalizados com hialuronato de sódio no reparo de tíbias de ratos

Abstract

Sodium hyaluronate (HY) is an extracellular matrix component and it facilitates the cell migration, adhesion, proliferation and differentiation. Additionally, carbon nanotubes (CNT) serve as nucleation sites for deposition of bone matrix and cell proliferation. The aim of this study was to evaluate the effects of HY, single-wall (SWCNT) and multi-wall (MWCNT) CNT functionalized (CNT-HY) or not with HY on bone repair of tibia of rats. The animals were divided into sixgroups: (i) control, (ii) HY (1%), (iii) SWCNT (100µg/mL), (iv) SWCNT-HY (100µg/mL), (v) MWCNT (100µg/mL) and (vi) MWCNT-HY (100µg/mL). The bone defect was created by an 1.6mm diameter drill and after seven or fourteen days of the induction of the defects, the rats were sacrificed and the tibias were processed for histological, morphometric and immunohistochemistry analysis. The control group showed poor bone formation with immature bone trabeculae located in the periphery of the bone defect. On the other hand, tibias treated with HY, SWCNT, SWCNT-HY, MWCNT or MWCNT-HY presented an increased number of neoformed bone trabeculae which were more organized and thicker than the control. Morphometric analysis showed that HY, SWCNT, SWCNT-HY, MWCNT or MWCNT-HY treatment significantly increased the percentage of bone trabeculae when compared with tibias of control animals (38.58 ± 2.57 % - HY; 38.96 ± 4.24 % - SWCNT; 33.72 ± 2.56 % - SWCNT-HY; 35.78 ± 2.11 % - MWCNT; 39.42 ± 2.40 % - MWCNT-HY and 23.50 ± 2.08 % -control, p<0.05). Furthermore, tibias treated with HY showed a lower expression of VEGF than tibias control. In contrast, the expression of this factor was greater in tibias treated with MWCNT and MWCNT-HY. No significant differences in VEGF expression were observed between control and tibias treated with SWCNT or SWCNT-HY. Thus, the results of this study indicate that the treatment with HY, SWCNT, SWCNT-HY, MWCNT or MWCNT-HY accelerates the bone repair of tibias of rats by a mechanism involving, at least in part, the stimulation of growth factors such as VEGF.