Topographical effects on fiber-mediated microRNA delivery to control oligodendroglial precursor cells development

Abstract

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.

Extrinsic and Intrinsic Regulation of Axon Regeneration by MicroRNAs after Spinal Cord Injury

“…MicroRNAs are a big class of critical epigenetic regulation factors, and about 77% of the identified mature noncoding microRNAs have been discovered in the rodent spinal cord [15]. MicroRNAs play important roles in regulating the process of neuronal plasticity, neuronal degeneration, axonal regeneration, and remyelination via translational repression or leading to mRNA degradation [16–19]. Alterations in the expression of many genes during spinal cord process have been shown to play vital roles in the pathogenesis of secondary SCI or axon regeneration [20].…”

Scaffold‐Based microRNA Therapies in Regenerative Medicine and Cancer

“…[102,106] Whether one of the routes may be better suited for clinical translation remains to be elucidated, although in situ transfecting scaffolds hold greater potential to exist as "off-the-shelf" products. [107] Many distinct scaffold types have been tuned to serve the purpose of miRNA delivery, including several hydrogels, [58,92,106,[108][109][110][111][112][113][114] electrospun fibers, [63,[115][116][117][118] and more prolifically porous or spongy scaffolds. [46,47,50,54,55,96,112,[119][120][121][122][123][124][125][126][127][128][129][130] Before reviewing the details of their applications, summarized in Table 2 and described further in the next section, we will discuss the key characteristics making these materials amenable to miRNA delivery.…”

“…Electrospinning is a distinct fabrication method that produces nanofibrous scaffolds typically using material sources such as gelatin, [115] synthetic PLLA, [63] PCL, [92,117] or PEG-PCL copolymers. [116] Interestingly, most of the nonviral, nonlipid vectors tested for 3D-miRNA delivery have utilized biomaterials fabricated using this method: Qureshi's photocleavable silver NPs, [92] the commercial Transit-TKO transfection reagent, [115,117,139] an innovative peptic sequence REDV-trimethyl chitosan-PEG complex, [116] and hyperbranched (HP) PEI-PEG polyplexes.…”

“…[116] Interestingly, most of the nonviral, nonlipid vectors tested for 3D-miRNA delivery have utilized biomaterials fabricated using this method: Qureshi's photocleavable silver NPs, [92] the commercial Transit-TKO transfection reagent, [115,117,139] an innovative peptic sequence REDV-trimethyl chitosan-PEG complex, [116] and hyperbranched (HP) PEI-PEG polyplexes. [63] Moreover, with the exception of the Ag-NPs, all the remaining systems have been developed as in situ "cell-free" miRNA transfecting platforms, underscoring great clinical potential and versatility of this fabrication method.…”

“…[117] The miRNAs, complexed with TransIT-TKO, were integrated onto electrospun PCL fiber scaffolds with various fiber diameters and orientations. Efficient knockdown of differentiation inhibitory factors was achieved irrespective of fiber size or orientation.…”