No abstract

Remyelination in the central nervous system (CNS) is critical in the treatment of many neural pathological conditions. Unfortunately, the ability to direct and enhance oligodendrocyte (OL) differentiation and maturation remains limited. It is known that microenvironmental signals, such as substrate topography and biochemical signaling, regulate cell fate commitment. Therefore, in this study, we developed a nanofiber-mediated microRNA (miR) delivery method to control oligodendroglial precursor cell (OPC) differentiation through a combination of fiber topography and gene silencing. Using poly(ɛ-caprolactone) nanofibers, efficient knockdown of OL differentiation inhibitory regulators were achieved by either nanofiber alone (20–40%, p < 0.05) or the synergistic integration with miR-219 and miR-338 (up to 60%, p < 0.05). As compared to two-dimensional culture, nanofiber topography enhanced OPC differentiation by inducing 2-fold increase in RIP+ cells (p < 0.01) while the presence of miRs further enhanced the result to 3-fold (p < 0.001). In addition, nanofiber-mediated delivery of miR-219 and miR-338 promoted OL maturation by increasing the number of MBP+ cells significantly (p < 0.01). Taken together, the results demonstrate the efficacy of nanofibers in providing topographical cues and microRNA reverse transfection to direct OPC differentiation. Such scaffolds may find useful applications in directing oligodendrocyte differentiation and myelination for treatment of CNS pathological conditions that require remyelination.

Effective remyelination in the central nervous system (CNS) facilitates the reversal of disability in patients with demyelinating diseases such as multiple sclerosis. Unfortunately until now, effective strategies of controlling oligodendrocyte (OL) differentiation and maturation remain limited. It is well known that topographical and biochemical signals play crucial roles in modulating cell fate commitment. Therefore, in this study, we explored the combined effects of scaffold topography and sustained gene silencing on oligodendroglial precursor cell (OPC) development. Specifically, microRNAs (miRs) were incorporated onto electrospun polycaprolactone (PCL) fiber scaffolds with different fiber diameters and orientations. Regardless of fiber diameter and orientation, efficient knockdown of differentiation inhibitory factors were achieved by either topography alone (up to 70%) or fibers integrated with miR-219 and miR-338 (up to 80%, p < 0.05). Small fiber promoted OPC differentiation by inducing more RIP+ cells (p < 0.05) while large fiber promoted OL maturation by inducing more MBP+ cells (p < 0.05). Random fiber enhanced more RIP+ cells than aligned fibers (p < 0.05), regardless of fiber diameter. Upon miR-219/miR-338 incorporation, 2 μm aligned fibers supported the most MBP+ cells (~17%). These findings indicated that the coupling of substrate topographic cues with efficient gene silencing by sustained microRNA delivery is a promising way for directing OPC maturation in neural tissue engineering and controlling remyelination in the CNS.

In this study, we promote neuronal differentiation of human mesenchymal stem cells (MSCs) through scaffold-mediated sustained release of siRNA targeting RE-1 silencing transcription factor (REST). Poly (ϵ-caprolactone) nanofibers were surface modified with mussel inspired DOPA-melanin (DM) coating for adsorption of REST siRNA. DM modification increased siRNA-loading efficiency and reduced the initial burst release. Fiber alignment and DM modification enhanced REST knockdown efficiencies. Under non-specific differentiation condition, REST silencing and fiber topography enhanced MSC neuronal markers expressions and reduced glial cell commitment. Such scaffolds may find useful applications in enhancing MSCs neuronal differentiation under non-specific conditions such as an in vivo environment.

Although stem cell therapy holds tremendous promise in tissue regeneration and disease treatment, its full potential may only be realized through the thorough understanding and capability in specifically directing stem cell fate commitment. A scaffold-based approach of imparting physical and biochemical cues appears to be a logical method in reconstructing the complex three-dimensional configuration of stem cell niches. In fact, interest in this area has gained significant momentum over the recent years. This review summarizes and evaluates the recent outcomes of studies associated with a scaffold-based approach to directing and understanding stem cell neural and cardiovascular differentiation.