Rat bone marrow stromal cells express retinal phenotypic markers following different induction protocols

To investigate and compare the effects of two different protocols on inducing bone marrow stromal cells (BMSCs) to differentiate into retinal neurons.

BMSCs from adult rat femurs were cultured and passaged 3 times. The cells were then induced by either the basic fibroblast growth factor (bFGF) protocol or by co-culturing with neonatal rat retina. Morphological changes were monitored and immunocytochemistry was used to detect the expression of neuronal and retinal neuron-specific markers.

The bFGF protocol induced a maximum of 74% of the BMSCs to assume a neuronal-like morphology, but this was also associated with significant cell detachment during the 7-day culture period. By comparison, with the co-culture method only a maximum of 10% of cells became neuronal-like, but without marked cell detachment. The cells expressed microtubule-associated protein-2 (MAP-2, a neuronal marker) and Thy1.1 (a retinal ganglion cell marker) at all time points under both protocols. The percentage of MAP-2- and Thy1.1-positive cells was much higher following bFGF induction compared to co-culture induction. Following bFGF induction a small number of opsin-positive cells (a photoreceptor marker) were observed only on day 1. These cells were first observed at day 5 with co-culturing. The expression of protein kinase Calpha (a bipolar cell marker) and glial fibrillary acidic protein was not detected after either protocol.

BMSCs can express retinal neuron-specific phenotypic markers in response to bFGF induction or retinal co-cultures in vitro. When a short induction time is used the bFGF induction is superior, albeit with certain limitations, to retinal co-cultures for inducing BMSCs to express retinal neuron-specific markers.