An implantable human stem cell-derived tissue-engineered rostral migratory stream for directed neuronal replacement

Abstract

The rostral migratory stream (RMS) facilitates neuroblast migration from the subventricular zone to the olfactory bulb throughout adulthood. Brain lesions attract neuroblast migration out of the RMS, but resultant regeneration is insufficient. Increasing neuroblast migration into lesions has improved recovery in rodent studies. We previously developed techniques for fabricating an astrocyte-based Tissue-Engineered RMS (TE-RMS) intended to redirect endogenous neuroblasts into distal brain lesions for sustained neuronal replacement. Here, we demonstrate that astrocyte-like-cells can be derived from adult human gingiva mesenchymal stem cells and used for TE-RMS fabrication. We report that key proteins enriched in the RMS are enriched in TE-RMSs. Furthermore, the human TE-RMS facilitates directed migration of immature neurons in vitro. Finally, human TE-RMSs implanted in athymic rat brains redirect migration of neuroblasts out of the endogenous RMS. By emulating the brain’s most efficient means for directing neuroblast migration, the TE-RMS offers a promising new approach to neuroregenerative medicine.

Unique Astrocyte Cytoskeletal and Nuclear Morphology in a Three-Dimensional Tissue-Engineered Rostral Migratory Stream

“…In in vivo images, protoplasmic and RMS astrocytes were quantified only if they possessed visible, non-overlapping nuclei and clear GFAP process extensions. Endogenous RMS astrocytes were identified within the dense, distinct meshwork of GFAP processes extending from the lateral ventricle to the olfactory bulb, as reliably identified previously by our laboratory and others [29,34]. Protoplasmic astrocytes were identified as astrocytes outside of this distinct structure.…”

“…Fabrication of TE-RMSs has been recently described [ 29 ]. Micro-columns were cut to a 4 mm length and the inner lumen was seeded with 1 mg/mL rat tail type 1 collagen (Corning Catalog # 354236) diluted in in serum free co-culture media consisting of Neurobasal medium supplemented with 2% B27, 1% G-5, 0.25% L-glutamine, and 1% penicillin-streptomycin.…”

“…These strategies have increased the quantity of neuroblasts entering injured brain regions by augmenting chemoattractant cues and/or by providing a physical substrate for migration [23]. Drawing inspiration from the SVZ-RMS-OB pathway, our laboratory has developed a biologically relevant, implantable "living scaffold" that emulates the glial tube of the endogenous RMS [26][27][28][29]. This tissue-engineered rostral migratory stream (TE-RMS) is designed to promote the sustained delivery of endogenous NPCs into injured brain regions by replicating and expanding upon the endogenous RMS, which is one of the brain's intrinsic mechanisms for neuronal replacement.…”

“…This tissue-engineered rostral migratory stream (TE-RMS) is designed to promote the sustained delivery of endogenous NPCs into injured brain regions by replicating and expanding upon the endogenous RMS, which is one of the brain’s intrinsic mechanisms for neuronal replacement. Previous experiments not presented herein have demonstrated that the TE-RMS can be reliably fabricated from sources of rat and human astrocytes, mimics increased expression of key functional proteins of the endogenous rat RMS, can redirect immature rat neurons in vitro, and when implanted into the rat brain can facilitate migration of endogenous neuroblasts out of the RMS and throughout the TE-RMS [ 29 ].…”

Harnessing 3D collagen hydrogel-directed conversion of human GMSCs into SCP-like cells to generate functionalized nerve conduits

“…In traditional scaffold-based TE, supportive cells can be delivered by incorporation/encapsulation into the scaffolds or seeding on the surface of engineered scaffolds post-fabrication 29 – 32 . Cell incorporation/encapsulation before fabrication allows the formation of a high cell density within the scaffolds, but it is difficult to achieve homogeneous cell distribution, good patterning or layering of cells within the scaffolds; cell seeding methods post-fabrication can minimize cell damage caused by the harsh fabrication conditions, but the efficiency of cell seeding and penetration is also a significant issue even with the use of a bioreactor 29 , 30 .…”