Table 3.
Natural polymers and drug delivery systems for BDNF
| Polymer | Formulation or modification | Preparation | Results | References |
|---|---|---|---|---|
| Collagen | Collagen scaffold-BDNF complex | (1) Prepared LOCS from bovine aponeurosis; (2) Fused CBD to BDNF; (3) Linked CBD-BDNF to LOCS | CBD-BDNF can bind to collagen and concentrate at the injury site; promotes neuronal regeneration and locomotion recovery | [457] |
| Reduces cell loss and decreases apoptosis | [438] | |||
| Promotes axonal regeneration; Increases functional nerve growth; Enhances neuronal re-myelination | [458] | |||
| Chitosan | Chitosan scaffolds | Cross-linked BDNF to chitosan scaffolds by genipin | Maintains a 30-day-period release; Induces tissue regeneration after traumatic brain injury | [459] |
| Alginate | Calcium alginate hydrogel | (1) Mixed BDNF into sodium alginate; (2) Dropped CaCl2 to form hydrogel microbeads or microspheres | Sustained release of BDNF over 48 days; Promotes axonal regeneration in vivo; Alleviates neuropathic pain | [460] |
| Controlled release of BDNF for more than 7 days; Improves depressive-like behavior | [461] | |||
| Cell-seeded alginate hydrogel scaffold | (1) Placed sodium alginate solution in a cylindrical aluminum mold; (2) Cross-linked with Sr2+ or Zn2+; (3) Socked BMSCs-BDNF suspensions into the hydrogel scaffolds | Releases BDNF from the scaffolds; BMSCs survive in the alginate hydrogel channels; Guides axons to orient parallel to the hydrogel channel and promoted axons growth | [462] | |
| Agarose | Agarose scaffolds | (1) Loaded BDNF into lipid microtubules and mixed with agarose solution; (2) Prepared agarose in situ gel via cooled nitrogen gas | Encourages neurite growth into the scaffolds; Reduces inflammatory response induced by agarose; Enhances regeneration after spinal cord injury in vivo | [463, 464] |
| Fabricated scaffolds by freeze-dry processing | Maintains high stability and biocompatibility for at least 1 month in vivo; Supports the growth of injured axons | [465] | ||
| Cell-seeded agarose scaffolds | (1) Fabricated agarose scaffolds and PS fibers to form multi-channels; (2) Filled BMSCs into scaffolds | Secretes BDNF from the scaffolds; Supports host axon regeneration across the lesion gap | [366] |
BDNF brain-derived neurotrophic factor, CBD collagen-binding domain, HP-β-CD hydroxypropyl-β-cyclodextrin, LOCS linear-ordered collagen scaffold, BMSCs bone marrow stromal cells, PS polystyrene