Pleiotrophin is involved in the amniotic epithelial cell-induced differentiation of human umbilical cord blood-derived mesenchymal stem cells into dopaminergic neuron-like cells

► PTN was synthesized and released by AECs. ► hUCB-MSCs were cultured in ACM, rPTN or control medium. ► ACM or rPTN induced more hUCB-MSCs to differentiate into DA neuron-like cells. ► ACM might be a potential inducer to obtain DA neuron-like cells from hUCB-MSCs. We have reported that human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) are capable of differentiating into dopaminergic (DA) neuron-like cells upon being induced by amniotic epithelial cells (AECs). However, what factor(s) is involved in the differentiation process has not been explored out thoroughly. Because pleiotrophin (PTN) is known to exert important trophic effects on DA neurons, in the present study, we investigated whether PTN is released by AECs and whether it is involved in the differentiation of hUCB-MSCs into DA neuron-like cells. The expression and secretion of PTN by AECs were detected by immunofluorescence, RT-PCR and ELISA. The hUCB-MSCs were isolated and treated with AEC-conditioned medium (ACM) or recombinant human PTN. Compared to the controls, a higher proportion of treated cells differentiated into DA neuron-like cells, indicated by the increased expression of TH and DAT and the increased dopamine content. These results indicate that PTN released by AECs acts as a synergetic factor with other neurotrophic factors and is involved in the differentiation of hUCB-MSCs into DA neuron-like cells. We suggest that ACM, which contains PTN and other neurotrophic factors, could potentially be used as an agent to promote the differentiation of DA neuron-like cells from hUCB-MSCs for cell therapy of Parkinson's disease without creating legal or ethical issues.