Development of multifunctional films for peripheral nerve regeneration.
In this study, a poly(lactic acid) (PLLA) porous film with longitudinal surface micropatterns was fabricated by a dry phase inversion technique to be used as potential conduit material for peripheral nerve regeneration applications. The presence of a nerve growth factor (NGF) gradient on the patterned film surface and protein loaded, surface-eroding, biodegradable, and amphiphilic polyanhydride (PA) microparticles within the film matrix, enabled co-delivery of neurotrophic factors with controlled release properties and enhanced neurite outgrowth from PC12 cells. The protein loading capacity of PA particles was increased up to 80% using the spray drying technique, while the surface loading of NGF reached 300ng/cm2through ester-amine interactions. The NGF surface gradient provided initial fast release from the film surface and facilitated directional neurite outgrowth along with the longitudinal micropatterns. Furthermore, the variable backbone chemistry and surface eroding nature of protein-loaded PA microparticles within the film matrix ensured protein stability and enabled controlled protein release. This novel co-delivery strategy yielded tunable diffusion coefficients varying between 6×10-14and 1.67×10-10cm2/min and dissolution constants ranging from 1×10-4to 1×10-3min-1with released amounts of ∼100-300ng/mL. This strategy promoted guided neurite extension from PC12 cells of up to 10μm total neurite length per cell in 2days. Overall, this unique strategy can potentially be extended for individually programmed delivery of multiple growth factors through the use of PA microparticle cocktails and can further be investigated for in vivo performance as potential conduit material for peripheral nerve regeneration applications.



This manuscript focuses on the development of multifunctional degradable polymer films that provide topographic cues for guided growth, surface gradients of growth factors as well as nanoparticles in the films for tunable release of growth factors to enable peripheral nerve regeneration. The combination of cues was designed to overcome limitations of current strategies to facilitate peripheral nerve regeneration. These multifunctional films successfully provided high protein loading capacities while persevering activity, protein gradients on the surface, and tunable release of bioactive nerve growth factor that promoted directional and guided neurite extension of PC12 cells of up to 10μm in 2days. These multifunctional films can be made into conduits for peripheral nerve regeneration.
Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, United States.
Metin
M
Uz
Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, United States; Neuroscience Program, Iowa State University, Ames, IA 50011, United States.
Anup D
AD
Sharma
Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, United States; Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, United States.
Pratish
P
Adhikari
Neuroscience Program, Iowa State University, Ames, IA 50011, United States; Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, United States.
Donald S
DS
Sakaguchi
Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, United States; Neuroscience Program, Iowa State University, Ames, IA 50011, United States. Electronic address: suryakm@iastate.edu.
Surya K
SK
Mallapragada
D000818:Animals; D063566:Biodegradable Plastics / Q000737:chemistry; D008567:Membranes, Artificial; D020932:Nerve Growth Factor / Q000494:pharmacology; D009416:Nerve Regeneration / Q000187:drug effects*; D016501:Neurites / Q000378:metabolism*; D016716:PC12 Cells; D010525:Peripheral Nerves / Q000502:physiology*; D011091:Polyesters / Q000737:chemistry; D016062:Porosity; D051381:Rats
D063566:Biodegradable Plastics; D008567:Membranes, Artificial; D011091:Polyesters; C033616:poly(lactide); D020932:Nerve Growth Factor
Controlled release; Micropatterning; Nerve growth factor (NGF); Nerve regeneration; Poly(lactic acid) (PLLA) films; Polyanhydride microparticles; Surface gradient