Regeneration of large bone defects remains a challenge in orthopedics since it is beyond the natural self-healing ability of bone. Bone tissue engineering involving a combination of biocompatible scaffolds and autologous stem cells is an attractive potential solution. Since electrical stimulation has been found to significantly enhance bone cell functions, we investigated the use of an electrically conductive scaffold for application of direct current (DC) stimulation to adipose-derived mesenchymal stem cells (AD-MSCs) in monoculture and in co-culture with endothelial cells (HUVECs). Polypyrrole/chitosan (PPY/CS) scaffolds with an average pore size of ~240 μm, porosity of 89% and electrical conductivity of 0.27 S/cm were prepared. The in vitro biocompatibility of the PPY/CS scaffold is similar to that of the CS scaffold. DC stimulation of AD-MSCs cultured in the PPY/CS scaffold for 4 h per day resulted in maximum metabolic activity when 200 μA was used. Applying this electrical stimulation condition for 7 days increased calcium deposition in AD-MSC monoculture by 56% as compared to that without electrical stimulation. Similarly, the maturation of HUVECs was accelerated. When the same level of electrical stimulation was applied to AD-MSC/HUVEC co-culture, the increase in the amount of calcium deposition was 86% compared to that without electrical stimulation, and 346% compared to AD-MSC monoculture without electrical stimulation. Moreover, CD31 expression by HUVECs co-cultured with AD-MSCs increased by 542% compared to HUVEC monoculture without electrical stimulation. Gene expression analysis indicates that electrical stimulation induced promotion of autocrine bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) signaling while crosstalk between AD-MSCs and HUVECs via paracrine signaling in co-culture further enhanced the cellular functions compared to the respective monoculture.

Chitosan-based conductive scaffolds for enhancement of stem cell functions by electrical stimulation

254th National Meeting (2017)

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