Coseeded Schwann cells myelinate neurites from differentiated neural stem cells in neurotrophin-3-loaded PLGA carriers

Abstract

Biomaterials and neurotrophic factors represent promising guidance for neural repair. In this study, we combined poly-(lactic acid-co-glycolic acid) (PLGA) conduits and neurotrophin-3 (NT-3) to generate NT-3-loaded PLGA carriers in vitro. Bioactive NT-3 was released stably and constantly from PLGA conduits for up to 4 weeks. Neural stem cells (NSCs) and Schwann cells (SCs) were coseeded into an NT-releasing scaffold system and cultured for 14 days. Immunoreactivity against Map2 showed that most of the grafted cells (.80%) were differentiated toward neurons. Double-immunostaining for synaptogenesis and myelination revealed the formation of synaptic structures and myelin sheaths in the coculture, which was also observed under electron microscope. Furthermore, under depolarizing conditions, these synapses were excitable and capable of releasing synaptic vesicles labeled with FM1-43 or FM4-64. Taken together, coseeding NSCs and SCs into NT-3-loaded PLGA carriers increased the differentiation of NSCs into neurons, developed synaptic connections, exhibited synaptic activities, and myelination of neurites by the accompanying SCs. These results provide an experimental basis that supports transplantation of functional neural construction in spinal cord injury.

Graft of a Tissue-Engineered Neural Scaffold Serves as a Promising Strategy to Restore Myelination after Rat Spinal Cord Transection

“…This was confirmed by the intense expression of APC, an oligodendrocyte marker, notably in the N-SCs + NSCs and NSCs + T-NSCs groups. The results are consistent with the known evidence that NT-3 promotes oligodendrocyte precursor cell (OPC) maturation and myelination [14,24]. We speculate that NT-3 may facilitate oligodendrocyte development through p75…”

“…Therefore, it is necessary to search for strategies to harness the therapeutic potential of NSCs in bridging lesion gap of SCI. One ideal counterstrategy would be to genetically strengthen the capacities of viability and lineage differentiation of NSCs into neurons and oligodendrocytes [13,14].…”

“…Schwann cells (SCs) secrete a plethora of trophic factors, such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), and basic fibroblast growth factor (bFGF), as well as promote extracellular matrix (ECM) and adhesion molecules [15], which have beneficial effects in supporting the function and the well-being of neurons and oligodendroglia [14]. Transplantation of SCs facilitates remyelination and axonal regeneration in the animal model of SCI [15].…”

Engineering Biomaterials to Influence Oligodendroglial Growth, Maturation, and Myelin Production

“…Similarly, Xiong et al [2012] showed that myelination occurred from Schwann cells in their PLGA matrix, which released NT-3 from silk fibroin. They utilized a high molecular weight PLGA with a 3: 1 ( D , L -lactide:glycolide) block copolymer, but more importantly utilized sodium chloride as a porogen to achieve a porous structure.…”

“…However, in these studies myelination still occurred by Schwann cells rather than oligodendrocytes [Pittier et al, 2005]. Since then, numerous groups have observed myelination from Schwann cells in biomaterials [Gingras et al, 2008;Xiong et al, 2012;Thomas et al, 2014].…”