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only with pMNs decreased apoptosis and neuronal differentiation while simultane-

ously promoting axonal elongation and transplant integration into the host tissue

[ 412 ]. While these studies do show promise for the effectiveness of combinatorial

methods using only biomaterials, trophic factors, and a single cell type, more work

is necessary to fi ne-tune the sensitive interactions between carrier, signaling factors,

and cells.

Other groups have provided evidence that multiple neural cell types and

neurotrophic factors transplanted in biomaterial scaffolds may support cellular

transplantation. For example, co-transplantation of NPSCs and Schwann cells in

electrospun PLGA scaffolds has been shown to enhance axonal regeneration in sev-

eral studies [ 413 – 415 ]. Xia et al. demonstrated that NPSCs and Schwann cells in

PLGA scaffolds promote axonal elongation in vivo; however, there was no differen-

tiation of NPSCs into neuronal phenotypes in groups transplanted with Schwann

cells, and axons were not able to form synaptic connections. Xiong et al. expanded

on this approach by co-seeding NPSCs and Schwann cells in NT-3 loaded PLGA

scaffolds in vitro [ 413 ]. The authors reported increased differentiation of NPSCSs

into neurons and enhanced formation of active synaptic connections and myelina-

tion of neurites by the accompanied Schwann cells in vitro [ 413 ]. Taken together,

this information suggests that while combinatorial techniques may indeed be capa-

ble of addressing current therapeutic limitations, there is still work to be done in

determining the most effective therapeutic combinations.

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