Polylysine modified hydrogels: brain mimetic materials for neural tissue engineering

Poster: 3rd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)Disorders arising from central nervous system (CNS) damage affect over a million individuals in the United States each year. Unfortunately, the CNS neurons do not possess regeneration potential under normal conditions. To address these issues, researchers have developed biomaterials that function as regenerative scaffolds or are incorporated into neural prosthetic devices (e.g., deep brain stimulators). Neural biomaterials primarily consist of natural or artificial polymeric materials. Natural materials can replicate the native tissue environment very well; however manipulating their properties may be difficult. On the other hand, synthetic materials chosen for their tunable properties do not favor neural cell adhesion, a process which initiates neural regeneration. To improve the compatibility of synthetic materials, it is vital to enhance their cell adhesive capability, which would also improve biomaterial-tissue integration. To achieve these goals, we have developed synthetic hydrogels, cross linked, hydrophilic polymeric materials, that closely mimic the native brain tissue. Further, we have incorporated the non-native cell adhesion molecule polylysine into the backbone of poly (ethylene glycol)-diacrylate (PEG-DA) hydrogels using standard bioconjugation techniques. Briefly, unmodified PEG-DA hydrogels were prepared through UV photocrosslinking. Polylysine was conjugated to Acryl-PEG-N- hydroxysuccinimide (Acryl-PEG-NHS) using standard NHS chemistry. The resulting Acryl-PEG-Polylysine was incorporated into PEG-DA hydrogels using UV photocrosslinking. Polylysine conjugation was monitored by observing the diffusion of fluorescent FITC-polylysine over a period of one week against a negative control (no polylysine) and a sham (unconjugated polylysine) using a fluorescent plate reader. PC12 (a model cell line for studying neural behavior) cell response (i.e., neural adhesion) to polylysine conjugated materials was then assessed against suitable controls. Live-dead staining was employed to quantify neural cell adhesion on modified hydrogel materials. It was observed that cell adhesion molecule-modified hydrogels promote PC12 cell adhesion and hence can be used extensively in neural tissue engineering applications to promote neural regeneration. Additionally, these materials could be employed as surface coatings for neural stimulation or recording electrodes to improve electrode-tissue biocompatibility and enhance device performance.No embarg